No full-text available
To read the full-text of this research,
you can request a copy directly from the author.
Not Just Uterine Adenocarcinoma—Neoplastic and Non-Neoplastic Masses in Domestic Pet Rabbits ( Oryctolagus cuniculus ): A Review
Abstract
With increasing numbers of pet rabbits living out their natural lifespan, rabbit oncology is stepping more and more into the limelight. On the other hand, rabbit tumors are less covered in recent editions of textbooks of veterinary pathology than before. We present 1238 cases with neoplastic and non-neoplastic masses in rabbit tissue, submitted from 2008 to 2019, supplemented by a review of the literature on neoplasms in rabbits. Cutaneous masses comprised 47% of submissions. Trichoblastoma was by far the most common skin neoplasm, and nodular suppurative panniculitis was the second most frequent skin nodule in this series. Epithelial as well as mesenchymal cutaneous neoplasms can be virally induced in rabbits (eg, Shope papilloma, myxomatosis) but were infrequent in the current cases. Mammary neoplasms comprised 21% of submitted masses and 94% of these had histologic features of malignancy. Tumors of the female reproductive tract were responsible for 9% of biopsies and were predominantly uterine adenocarcinoma. Polypoid proliferation of rectal mucosa was the most common lesion in the alimentary tract. A broad spectrum of other neoplasms was described, including sarcomas at vaccination sites and ocular posttraumatic sarcomas, comparable to lesions described in cats.
... In humans, the diverse environments and situations in the different regions (Asia vs. the West) generated different lifestyles and cultures, which in turn led to different cancer patterns based on gender and age [9,23]. Studies on the occurrence and prevalence of tumors in pet rabbits were conducted in various regions of the world [3,4,6,34], with Asia having the fewest reports [29]. ...
... In this study, reproductive tumors were the most common, followed by cutaneous tumors in pet rabbits. This was compatible with some studies [6], but it was contrary to some earlier claims suggesting cutaneous tumors were more common [3]. Animal sex and age were the potential risk factors for the occurrence of the tumor. ...
... When comparing the prevalence with the life stage of the rabbits, tumor prevalence gradually increased in aged rabbits, whereas that of tumor-like lesions did not (Fig. 1). The common life stage of rabbits with tumors was old age (median: 6.7 years of life; IQR: 1-11 years), while previous study in European country reported that the life stage of rabbits with neoplasms occurred earlier at late middle age (median: 6 years of life [6] and mean: 5.7 years of age [3]). This different result implied that Asian environmental factors, in addition to host factors, might influence the age-related tumor's occurrence in various parts of the world. ...
Rabbit oncology is gaining more attention as more pet rabbits are surviving beyond their normal lifespans. Due to the limited epidemiological information on pet rabbits’ tumors in Thailand, this study aimed to report the prevalence and the potential risk factors associated with tumors in pet rabbits in Thailand. From 2018 to 2022, 93 tissue biopsies from tumor-suspected lesions on pet rabbits were gathered from animal hospitals in Bangkok and Chonburi provinces, Thailand. According to histopathology confirmation, tumors and tumor-like lesions were diagnosed. In this study, the overall tumors were 67.74% (n=63) out of the submitted cases (n=93). The most commonly affected organ systems were reproduction (65.08%) and integumentary (22.22%). Rabbits older than 5 years were 3.85 times more likely to have reproductive tumors than younger rabbits (95% confidence interval (CI): 1.45–10.27, P-value ≤0.01), and the most frequently occurring tumor type was uterine adenocarcinoma. Furthermore, male rabbits had a 17.02 times higher probability of developing cutaneous tumors than female rabbits (95% CI: 4.19–69.11, P-value ≤0.001), and the most frequently occurring tumor type was soft tissue sarcoma. The results of this study thus suggested that the age and sex of the rabbits were potential risk factors for tumor development in Thailand. The knowledge gained from our study also provided the recommendation for owners to monitor their rabbits’ health annually, particularly after late middle age, and rendered guidance for tumor detection in practical clinics.
... Neoplastic disease in pet rabbits (Oryctolagus cuniculus) has emerged in recent years as they are allowed to age and medical care is required with increasing frequency [1][2][3]. Indeed, the risk of developing neoplastic disease is positively correlated with aging, and pet rabbits are commonly allowed to live their normal lifespan [1][2][3]. An increasing number of different spontaneous neoplasms have recently been documented in pet rabbits in largescale retrospective studies, with higher prevalence rates than routinely diagnosed tumours in laboratory rabbits, whose prevalence rates reach 2.7% in animals older than 2 years, as well as in rabbits kept for meat and fur production, otherwise scarified at younger ages [1][2][3][4]. ...
... Neoplastic disease in pet rabbits (Oryctolagus cuniculus) has emerged in recent years as they are allowed to age and medical care is required with increasing frequency [1][2][3]. Indeed, the risk of developing neoplastic disease is positively correlated with aging, and pet rabbits are commonly allowed to live their normal lifespan [1][2][3]. An increasing number of different spontaneous neoplasms have recently been documented in pet rabbits in largescale retrospective studies, with higher prevalence rates than routinely diagnosed tumours in laboratory rabbits, whose prevalence rates reach 2.7% in animals older than 2 years, as well as in rabbits kept for meat and fur production, otherwise scarified at younger ages [1][2][3][4]. ...
... Indeed, the risk of developing neoplastic disease is positively correlated with aging, and pet rabbits are commonly allowed to live their normal lifespan [1][2][3]. An increasing number of different spontaneous neoplasms have recently been documented in pet rabbits in largescale retrospective studies, with higher prevalence rates than routinely diagnosed tumours in laboratory rabbits, whose prevalence rates reach 2.7% in animals older than 2 years, as well as in rabbits kept for meat and fur production, otherwise scarified at younger ages [1][2][3][4]. ...
Melanocytic skin tumours have been rarely described in pet rabbits, and exposure to UV light in sparsely haired areas has been hypothesised to play a cancerogenic role. Here, we describe a case of cutaneous malignant melanoma arising from the skin of the scrotum in an 8-year-old male wild rabbit, with testicular metastases as an unusual metastatic site for melanoma reported in humans to date. The tumour was nearly 5 cm in size, firm, and highly pigmented, with multifocal superficial ulcerations and large areas of intratumoural necrosis. The adjacent testis was 1.5 cm, multinodular, and black, obscuring tissue morphology. Histologically, the dermis was expanded by an infiltrative, densely cellular neoplasm composed of nests and sheets of polygonal to spindle neoplastic melanocytes, supported by scant fibrovascular stroma. Neoplastic cells showed intermediate N/C ratio, moderate basophilic cytoplasm, often obscured by abundant brownish granular pigment, and eccentric nuclei with prominent nucleoli. Cellular pleomorphism and nuclear atypia were severe, and high mitotic activity was observed. Diffuse dermal lymphovascular invasion was also observed. The testis was delimited by a thin tunica albuginea, and the parenchyma was largely obscured in its morphology by densely packed neoplastic cells. Seminiferous tubules, lined with a thin basement membrane and containing neoplastic and scattered spermatogenic cells, were occasionally observed. Neoplastic cells within the skin and the testis were positive for HMB-45, Melan-A, and S-100. The growing popularity of rabbits as pets allows for a greater ability to accumulate data on the spontaneous occurrence of tumours in these animals. Furthermore, descriptions of the biological aspects of spontaneously occurring tumours may serve to improve current knowledge in animal species and humans in which the same neoplasm may occur.
... In contrast, carcinoma of the uterus is rare and apart from individual case reports in different species, such as the cat [4], dog [5], horse [6], sika deer (Cervus nippon) [7], and elk (Cervus elaphus nelsoni) [8], it has typically only been reported in rabbits and older cows at slaughter. For example, in a review of rabbit neoplastic and non-neoplastic masses submitted for histological examination, 9% of the biopsies were from tumours of the female reproductive tract and were predominantly uterine (endometrial) adenocarcinoma [9]. In addition, uterine adenocarcinoma was the most commonly reported neoplasm found in histological assessments of uterine lesions in pet rabbits in Japan following ovariohysterectomy (1035/1928 cases, 53.7%) [10]. ...
... Sci. 2022, 9,339 3 of 9 in the proximal part in the red marrow (Figure 1f). A peripheral blood sample from the ear was taken to generate a blood smear, and the results were within normal limits. ...
... Invasion into the veins and/or lymphatics is frequently present with metastasis to other parenchymal organs, such as the lung and liver, also observed [2]. In a study of bovine neoplasms encountered in Canadian slaughterhouses, metastatic lesions of uterine adenocarcinoma accounted for the majority of neoplasms found in the lung [9], and there have been case reports of uterine adenocarcinoma in cows presenting with metastasis to a range of sites including the lung, liver, mesentery, and ovaries [28][29][30][31]. There are also three case reports of pigs [12][13][14] and two case reports of deer [7,8] with uterine adenocarcinoma that have metastasized to the lymph nodes, liver, lungs, and/or ovaries. ...
A nine-year-old intact female sable antelope (Hippotragus niger) with a six-week history of gradual loss of body condition was found dead by the owner and presented for autopsy. Macroscopic examination revealed an enlarged spleen and liver with the hepatic and splenic parenchyma showing extensive infiltration with firm, white to cream-coloured nodules. The uterus showed a few small, firm, well-demarcated, white-to-cream-coloured nodules in the uterine body. Similar nodules were present in the mediastinum, parietal pleura, heart, and marrow cavity of the femur. Histological analysis of the uterus revealed densely cellular neoplastic proliferations, forming nests, tubules, and acini within an abundant fibrovascular stroma. The samples from the other tissues revealed neoplastic cells with a similar appearance to those seen in the uterus, also forming nests and acini in a fibrovascular stroma. Importantly, multiple neoplastic cells were also seen in the peribronchiolar lymphatic vessels. The neoplastic cells in the uterine sections showed positive immunohistochemical labelling for cytokeratin, as did the neoplastic cells in the sections of liver and parietal pleura, confirming they were of epithelial origin. In addition, transmission electron microscopy of the uterus and liver showed neoplastic cells arranged in groups surrounded by basement membranes and interspersed with collagen fibres. Junctions were present between the cells, and junctional complexes could be seen at some cell surfaces. This confirmed that the neoplastic cells seen in the liver sample were the same as those seen in the uterine sample and were of epithelial origin. Thus, a diagnosis was made of uterine adenocarcinoma with widespread metastasis. This is the first report of uterine adenocarcinoma in a sable antelope.
... In this study, cutaneous tumours were seen mainly in middle-aged to older pet rabbits, and the majority of these tumours were benign, with the most frequent being trichoblastoma (trabecular type), consistent with previous studies [3,11,23,24]. Furthermore, the majority of cutaneous tumours were diagnosed in males. ...
... Furthermore, the majority of cutaneous tumours were diagnosed in males. According to previous studies, male predilection was observed mostly or exclusively in mesenchymal tumours [23,24] and can result from the overall greater longevity of male rabbits [24]. Some mesenchymal neoplasms, such as fibromas (also known as collagenous hamartomas), occur exclusively in males, so hormonal pathogenesis is suspected [11,23,24]. ...
... Furthermore, the majority of cutaneous tumours were diagnosed in males. According to previous studies, male predilection was observed mostly or exclusively in mesenchymal tumours [23,24] and can result from the overall greater longevity of male rabbits [24]. Some mesenchymal neoplasms, such as fibromas (also known as collagenous hamartomas), occur exclusively in males, so hormonal pathogenesis is suspected [11,23,24]. ...
Since small mammals are gaining popularity as pets in Poland, the number of tumour samples submitted for histopathological examination is quite high. This study was a retrospective analysis of cutaneous and subcutaneous tumours in small pet mammals submitted for histopathology in 2014–2021. The analysis included 256 tumours sampled from 103 guinea pigs, 53 rats, 43 pet rabbits, 21 ferrets, 17 hamsters, 8 degus, 5 African pygmy hedgehogs, 3 Mongolian gerbils and 3 chinchillas. Tumours were diagnosed based on routine histopathology, with additional immunohistochemistry when necessary. The results of this study revealed that the vast majority of cutaneous tumours in guinea pigs were benign, with a predominance of lipoma. Adnexal tumours constituted a significant percentage of cutaneous tumours in guinea pigs (24.3%, with the most common being trichofolliculoma), pet rabbits (46.5%, with the most common being trichoblastoma), ferrets (33.3%, mostly derived from sebaceous glands), hamsters (52.9%, with the most common being trichoepithelioma) and gerbils (66.7%, scent gland epithelioma). Soft tissue sarcomas were a predominant group of tumours in rats (52.8%, with the most common being fibrosarcoma), African pygmy hedgehogs (100%), degus (87.5%) and chinchillas (66.7%). Melanocytic tumours were only sporadically seen in small mammal pets. Mast cell tumours were diagnosed only in ferrets, while epitheliotropic T-cell lymphoma was diagnosed only in a hamster and a degu. In summary, malignant tumours constitute a significant percentage of cutaneous tumours in many species of small mammal pets. Therefore, each cutaneous tumour should be sampled for further cytologic or histopathologic diagnosis.
... Haemangiomas, teratomas, malignant mixed Müllerian tumours and myxosarcomas are rare uterine tumours in rabbits (Bertram et al., 2018;Bertram et al., 2021;Baum, 2021;Kunzel et al., 2015;Walter et al., 2010). To the best of our knowledge, uterine haemangiosarcoma is extremely rare; the frequency of vascular tumours is relatively low in rabbits and little is known about their occurrence (Bertram et al., 2018;Bertram et al., 2021;Baum, 2021;Kunzel et al., 2015;Walter et al., 2010). ...
... Haemangiomas, teratomas, malignant mixed Müllerian tumours and myxosarcomas are rare uterine tumours in rabbits (Bertram et al., 2018;Bertram et al., 2021;Baum, 2021;Kunzel et al., 2015;Walter et al., 2010). To the best of our knowledge, uterine haemangiosarcoma is extremely rare; the frequency of vascular tumours is relatively low in rabbits and little is known about their occurrence (Bertram et al., 2018;Bertram et al., 2021;Baum, 2021;Kunzel et al., 2015;Walter et al., 2010). Although one case of haemangiosarcoma of the uterus in rabbits has been reported, no description of the histological or clinical details was provided (Bertram et al., 2018). ...
Graphical image of the uterine haemangiosarcoma in a Netherland Dwarf rabbit. (A) Gross appearance of a uterine haemangiosarcoma in a rabbit. The entirety of the right uterus and the area from the opening to the central part of the left uterus is enlarged. The vagina, which is the surgical margin of the resection, is dark red. (B‐E) Histological and immunohistochemical findings of a uterine haemangiosarcoma in a rabbit. (B) The mass is located in the myometrium (★) and poorly differentiated spindle‐shaped tumour cells proliferate (⁂), forming fascicular or vascular‐like structures with necrotic foci (*). (C) Tumour cells have oval nuclei and moderate‐to‐small amounts of spindle‐shaped eosinophilic cytoplasm. Nuclei vary in size, with distinct nucleoli and abundant mitotic figures (arrowheads) (D and E). Immunohistochemical staining reveals that the tumour cells are positive for the CD31 antigen. Scale bars: (A) 1 cm, (B)‐(E) 25 μm. image
... As an essential part of human life, more and more animals have been accepted to become our beloved companions and family members, especially rodents. Although they live longer with good care, they are still likely to suffer from diseases in life, as well as early spay/neuter of pets, cesarean section, etc. [1][2][3]. Many domestic pets have a common feature-namely, that their skin is covered with a dense hair layer, which makes hair removal necessary before surgery. ...
... For example, some studies confirmed that tumorpromoting inflammation closely resembles the inflammatory processes typically found during development, immunity, and tissue repair [21]. As reported, trichoblastoma was, by far, the most common skin neoplasm in pet rabbits [2]. Therefore, considering the reduction in impact on the wound and the perspectives of animal welfare, the potential side effect on skin condition and wound healing should be a principal factor in selecting the depilation method. ...
Hair removal is necessary before operating on animals with dense hair layers. To provide an appropriate hair removal method and maintain animal welfare, we introduced four commonly used depilation methods—namely, scissors shearing, electric shaving, depilatory cream, and sodium sulfide, and made systematic comparisons, instead of only examining one or two methods, as reported in the past. To further assess convenience and possible effects on skin wound healing, we performed a skin trauma model after depilation in C57BL/6J mice and recorded wound healing time. Meanwhile, the skin tissues around the wound were stained with H&E and Masson. The results showed that the wound contraction rate of the sodium sulfide group was significantly lower than other groups at different points in time. Furthermore, depilatory cream and sodium sulfide methods could induce a topical inflammatory response on the third day after the operation and delay the regeneration of collagen fibers. We concluded that sodium sulfide depilatory has a significant negative effect on wound healing. Depilatory cream is gentler, with mild skin irritation and symptoms of inflammation. The electric shaving method is more convenient and safer, and thus could be the best choice for preoperative depilation.
... 9,10 So as to not leave our lagomorph friends behind, the special issue also includes 2 studies detailing types of neoplasia and their prevalence in pet rabbits, with both articles offering additional insight into common and uncommon tumors of this species. 3,5 Immunohistochemistry remains a mainstay for the diagnostic pathology, and several articles of the special issue describe the expression of novel immunohistochemical markers in canine tumors such as periostin in canine osteosarcoma and nestin in canine mammary carcinoma. 1,20 Correlation of these markers with follow-up data offers insights on the prognostic significance and potential clinical relevance of these markers. ...
Orofacial masses or swellings are a common presenting complaint in lagomorphs. Similar gross appearances of the masses can complicate clinical interpretation, and histologic review often provides the final diagnosis. Underlying causes vary from infectious to neoplastic. Although inflammatory changes are most commonly reported, various neoplasms occur, although the prevalence of specific tumor types is relatively unknown. We reviewed retrospectively 120 cases (87.5% biopsy, 12.5% autopsy) of neoplastic and non-neoplastic orofacial masses received from January 2000–February 2023 at 2 institutions: University of Guelph, Canada (Animal Health Laboratory and Department of Pathobiology), and Finn Pathologists, United Kingdom. All final diagnoses were achieved through histologic assessment. We included masses or mass-like swellings from the oral cavity, including the mandible and maxilla, and surrounding skin and soft tissues of the oral cavity and jaw. Submissions included pet and commercial (meat and fur) rabbits. Neoplastic lesions were most common (60%), including trichoblastomas, papillomas, melanocytic neoplasms, sarcomas, round-cell tumors, carcinomas (including squamous cell carcinoma), lipomas, odontogenic neoplasms, polyps, osteoma, neuroma, peripheral keratinizing ameloblastoma, and apocrine adenoma. Inflammatory diagnoses (30%) included abscesses, osteomyelitis, dermatitis, and sialadenitis. Other diagnoses (7%) included cysts, as well as hyperplastic skin and proliferative bone lesions. Three cases had no definitive diagnosis. The importance of histologic assessment in diagnosing orofacial “masses” in rabbits is highlighted, given that the most common diagnostic category overall was neoplasia.
A cutaneous mass in a free-ranging brush rabbit (Sylvilagus bachmani) was composed of neoplastic spindle to polygonal cells with multinucleated giant cells, which were positive for CD204 and negative for smooth muscle actin and desmin. Histiocytic sarcoma with giant cells was diagnosed; this neoplasm has not been reported previously in free-ranging lagomorphs.
Spontaneous intraocular tumors are rarely reported in rabbits, despite their widespread use as laboratory animals. We describe two cases of intraocular neuroectodermal embryonal tumors, formerly primitive neuroectodermal tumors, in young rabbits. Histologically, both tumors exhibited prominent rosette or pseudorosettes, consistent with the histomorphology seen in human tumors. The neuroectodermal subtype is supported by immunoreactivity for the neuronal markers, SRY-box transcription factor 2, microtubule-associated protein 2, neuronal nuclear protein, and neuron-specific enolase. In one of the rabbits, there was metastasis to the contralateral conjunctiva. Intraocular neoplasms can occur in young rabbits and eyes with refractory disease should be enucleated for clinical management.
Odontogenic neoplasms demonstrate unique histopathological features and are thought to arise from the germinal tissues of the developing tooth germ, effectively restricting their anatomic origin to the tooth-bearing regions of the jaw and directly associated soft tissues of the oral cavity. Ectopic odontogenic-like neoplasms located in the skin of cats, rabbits, and human beings challenge these assumptions. Here we describe the clinical, pathological, and immunohistochemical features of 6 spontaneously occurring odontogenic-like neoplasms arising in the cutaneous tissue of the cheek in client-owned pet rabbits, including ameloblastoma-like (n = 3), ameloblastic fibroma-like (n = 2), and ameloblastic carcinoma-like neoplasms (n = 1). Microscopically, all the cheek tumors featured neoplastic epithelium exhibiting odontogenic architectural structures (plexiform ribbons, anastomosing trabeculae, follicles, cysts, and irregular structures with rounded botryoid protuberances) and 1 or more cardinal odontogenic epithelial features (basal palisading, antibasilar nuclei, and central stellate reticulum-like cells). The pancytokeratin, cytokeratin 5/6, cytokeratin 14, and vimentin immunohistochemical patterns of these odontogenic-like lesions were most similar to those of jaw-associated ameloblastoma and differed from those of cutaneous trichoblastoma. All neoplasms were narrowly excised, and for lesions with clinical follow-up information, none had evidence of recurrence 1-7 months after surgical removal. Although evidence suggests that these odontogenic-like tumors of the rabbit cheek may be derived from ectopic rests of transformed tooth germ, the histogenesis of these lesions remains unresolved.
Background
As the quality of care received by pet rabbits improves, the age at death of these animals is expected to increase; however, reliable data on the age at death of pet rabbits is lacking. The present retrospective study aims to clarify the age at death and cause of death of pet rabbits.
Materials and Methods
The age at death, cause of death, and clinical details of 898 rabbits that died between 2006 and 2020 were obtained by reviewing paper-based medical records, including necropsy and/or biopsy reports, at a referral exotic animal hospital in Japan.
Results
The median age at death in the 898 rabbits was 7 years (interquartile range: 5–9 years), and 18% of all rabbits lived beyond 9 years. The main causes of death included neoplasm (n = 223; 24.8%), gastrointestinal disease (n = 135; 15.0%), bacterial abscess (n = 90; 10.0%), urinary disease (n = 85; 9.5%), trauma (n = 44; 4.9%), and cardiac disease (n = 27; 3.0%). Gastrointestinal disease was the most common cause of death in younger-aged rabbits (4 years or less), while neoplasm was the most common cause of death in middle to older-aged rabbits (5 years or more).
Clinical significance
This is one of the largest retrospective studies on the age at death in pet rabbits conducted to date; thus, the findings will serve as a useful reference for veterinarians working with such rabbits. Nevertheless, additional studies are needed to elucidate differences in the age at death of rabbits according to sex and neutering status.
Neoplasms of the intestinal tract are uncommon in rabbits and primary lymphoma of the intestinal tract is rare. This case series is the first detailed description of primary intestinal lymphoma in rabbits. We reviewed four cases of primary intestinal lymphoma in rabbits aged 5–9.5 years old with an average age of 7.8 years. Neoplastic cells in three cases were large (8 μm diameter) while one case had intermediate cells (5 μm diameter). Neoplastic lymphocytes were of B-cell lineage and characterized by intense, multifocal, membranous immunoreactivity for CD79a and no immunoreactivity to CD3. Based on the Revised European-American Classification of Lymphoid Neoplasms/World Health Organization classification, three of the cases were consistent with diffuse large B-cell lymphoma and the case with intermediate-sized neoplastic cells was consistent with lymphoblastic lymphoma.
Earlier studies indicate that the risk for uterine tumours in rabbits may be as high as 60-80%. This high occurrence and the need for routine neutering of non-breeding pet rabbits have recently been in the spotlight. This study aimed to describe and compare macroscopic and histopathological alterations in uteri collected from domestic rabbits of various ages neutered, deceased or euthanized without a suspected uterine disorder (NoUD; n=94) and from rabbits with a suspected uterine disorder (UD; n=22).
In the NoUD group, uteri of 41 rabbits (44%) displayed histopathological findings and 12 rabbits (13%) had neoplasms. Samples from thirteen rabbits (14%) evinced histopathological findings with no macroscopic alterations. The most frequent diagnoses were cystic endometrial hyperplasia (26% of the 41 uteri), adenocarcinoma (9%) and polyps (5%). In the UD group, uteri from 21 (95%) out of 22 rabbits exhibited pathological alterations; in 2 (10%) of these, the changes (cystic endometrial hyperplasias) were seen only in histology. The most frequent diagnoses in the uteri of UD group were cystic endometrial hyperplasia (77%) and adenocarcinoma (54%). Uterine malignant neoplasia affected 40% of all rabbits aged over 3 years, and the odds of a malignant uterine tumour in these rabbits were approximately 19-fold higher than in rabbits aged under 3 years.
Uterine disorders are common in domestic rabbits, even without a suspected uterine disease, and the risk of uterine neoplasia markedly increases after 3 years of age. A macroscopically normal uterus may have pathological changes and ovariohysterectomy should be therefore preferred over ovariectomy at least in older rabbits.
A 4-year-old castrated male lop-eared rabbit (Oryctolagus cuniculus) presented for right thoracic limb weakness of one week's duration. Radiographs of the limb and adjacent spine were unremarkable. Despite treatment with meloxicam, limb weakness slowly progressed. Four months after initial presentation, neurologic examination revealed monoplegia without loss of pain perception in the right thoracic limb. Computed tomography scans showed multifocal regions of lobular, homogeneously contrast-enhancing tissue within the right ventral vertebral canal. This tissue extended into the right intervertebral foramina at C3-4 and C4-5 and at C5-6 and C6-7. A guarded-to-poor prognosis was given to the owners, who elected palliative care. Treatment with prednisolone and antibiotics resulted in short-term improvement. The rabbit became increasingly weak and passed away 4 weeks following the CT scan. Necropsy identified spinal cord compression due to a mass within the right vertebral canal that exited at C4-5 and continued into the right brachial plexus. The identified mass was morphologically and immunohistochemically consistent with a schwannoma. This case report documents the first clinical description of schwannoma of the spinal roots and brachial plexus in a rabbit.
Background: Malignant myoepithelioma is a rare neoplasm in humans and rats, poorly reported in dogs and not previously described in rabbits. This study aimed to report a case of malignant mammary myoepithelioma in a domestic rabbit (Oryctolagus cuniculus). Case: A domestic, hybrid, female, entire, nulliparous, 7-year-old rabbit was attended in the Veterinary Hospital Prof. Ri-cardo Alexandre Hippler at Universidade Vila Velha (UVV) with a history of apathy, lethargy and anorexia. In the clinical examination a 5 cm tumour was observed in the right abdominal mammary gland (M2), along with floating smaller lesions in M1 and M3. There were no palpable abnormalities in the axillary and inguinal lymph nodes. Complete blood count and serum biochemistry were within the normal range. Fine needle aspiration was performed for cytopathological evaluation of the tumour in M2 and it was suggestive of a malignant glandular neoplasm, with probable epithelial origin. Complete staging included chest and abdominal radiographs, but they were unremarkable. The patient was submitted to a right unilateral mastectomy, involving resection of the inguinal lymph node. The sample was sent to the Laboratory of Animal Pathology of UVV for routine histological evaluation. Histopathological evaluation in M2 was compatible with malignant myoepithelioma based on the literature, while nodules in M1 and M3 were classified as mammary cysts. The inguinal lymph node showed no significant abnormalities. An immunohistochemical panel was performed in the Comparative Pathology Laboratory of the Institute of Biological Sciences of the Universidade Federal de Minas Gerais (UFMG), using immuno-markers (pan-cytokeratin, p63 and vimentin) to characterize the tumour and confirm its diagnosis. Immunohistochemistry revealed expression of p63, and was negative for pan-cytokeratin and vimentin, which confirmed the myoepithelial origin, without involvement of the epithelial compartment. Clinical follow-up was recommended every 2-3 months, including abdominal ultrasonography, chest X-rays, complete blood count and serum biochemistry. Ultrasonography showed thinning of the uterine wall, dilation of 3.7 cm in diameter and presence of endometrial cysts of varied sizes, around 0.7 cm. Neutering was recommended but it was not elected by the pet's responsible. These findings remained stable throughout the follow-up, which was greater than 405 days. Discussion: This is the first report of a malignant myoepithelioma in rabbit, with a detailed description of the clinical, surgical, pathological and immunophenotypic aspects of this neoplasm in this species. This is a tumour characterized by proliferation of epithelioid to spindle-like myoepithelial cells, as observed in this case, forming an extensive and well delimited solid area with marked central necrosis, compatible with what has already been described in the literature on bitches and women. As observed in this case, the neoplastic cells usually exhibit moderate cellular and nuclear pleomorphism, moderate anisocytosis and anisokaryosis, and several mitotic figures; different from what is observed in women, in which mitotic figures vary from small to moderate amount. Neoplasia and mammary cysts were removed by mastectomy, and the owner choose not to castrate the animal. On ultrasonography, after 12 months, the endometrium presented structures similar to cysts and was hyperplastic, which is commonly reported in association to mammary neoplasia. Nervertheless, the pet's owner choose not to spay the rabbit and the lesions were stable on imaging follow-up.
In breast cancer of women, the estrogen receptor–α (ERα) and progesterone receptor (PR) status has prognostic and therapeutic significance. The aim of this study was (1) to characterize by immunohistochemistry the expression of ERα and PR in nonneoplastic and neoplastic mammary gland tissue of pet rabbits and (2) to correlate the ERα/PR status and histological features. All 124 rabbits included in this study had a mammary tumor; in addition, 2 rabbits had lobular hyperplasia and 25 had multiple cysts. Of the 124 neoplasms, 119 (96%) were carcinoma, 2 (2%) were carcinoma in situ, and 3 (2%) were adenoma. ERα or PR or both were detected in 2 of 2 carcinomas in situ, 3 of 3 adenomas, 19 of 25 cysts, and 2 of 2 lesions of lobular hyperplasia. Most carcinomas (75/119, 63%) were negative for both ERα and PR; 22 of 119 carcinomas (18%) were double-immunopositive. The ERα and PR expression was not influenced by histotype or histological tumor grade. In carcinomas, there was a statistically significant correlation between increased mitotic count and reduced expression of ERα and PR, and the mitotic count was higher in double-immunonegative carcinomas (75/119). The findings suggest that in rabbit mammary carcinomas, proliferative activity is mainly influenced by factors other than estrogen and progesterone and provides the basis for future investigations into the prognostic significance of the ERα and PR status of mammary tumors.
Despite being rarely reported, improved diagnostic and prognostic indicators are necessary for treating malignant melanoma in rabbits. In this study, two cases of primary skin lesions, on the scrotum and on eyelid, with systemic metastases, were examined. The tumors formed intra-dermally by sheet-like proliferation of polymorphic cells, with anisocytosis and varying amount of melanin granules. Tumors had displaced almost 50% of the lung and liver tissue, and tumor metastasis was the cause of early death in both rabbits. Ki-67-positive population was high in both, and it was found to be useful in assessing the outcome and malignancy. In addition, Melan-A, HMB-45, PNL2, and S100 established a useful immunohistochemical panel for the diagnosis of melanocytic tumor in rabbits.
The clinical and pathological records of 44 domestic, female rabbits with an age ranging from 6–124 months (median age: 63.5 month) were assessed retrospectively for ovarian lesions. Included were all rabbits that underwent an ovariohysterectomy with a subsequent pathological examination of the genital tract between March 1997 and June 2016. Pathological examination revealed ovarian lesions in 12 of the 44 rabbits including follicular cysts (n=7), cystic rete ovarii (n=3), widespread ovarian necrosis with dystrophic calcification (n=2), ovarian adenoma (n=1). Clinical examination including radiographs only suggested ovarian disorders in two cases of ovarian necrosis with dystrophic calcification and in two cases of cystic rete ovarii. Clinical significance was only conclusive in a case of cystic rete ovarii.
A 7-year-old female domestic rabbit suffered from labored respiration, poor appetite, mild anemia and thrombocytopenia. Radioscopic examination revealed masses in multiple locations including the intrapleural cavity and spleen. Forty-three days after the first visit to a private veterinary clinic, the rabbit died of severe respiratory distress. Microscopically, all of the masses were composed of round to polygonal neoplastic cells with distinct cell borders that were arranged in a sheet pattern. Multinucleated giant neoplastic cells were often observed. Some neoplastic cells had phagocytozed one or more erythrocytes. Immunohistochemical staining revealed that the neoplastic cells expressed vimentin, CD204, Iba-1 and lysozyme, but not CD163. Based on the morphological and immunohistochemical findings, this case was diagnosed as disseminated histiocytic sarcoma with hemophagocytosis.
An 11-year-old castrated male rabbit presented with a subcutaneous mass in the right hind limb. The mass comprised solid and myxoid areas. Solid areas were characterized by a storiform or interlacing pattern of spindle cells, strap cells, multinucleated giant cells and round cells with eccentrically located nuclei, whereas the myxoid areas were composed predominantly of elongated fusiform cells with hyperchromatic nuclei embedded in Alcian Blue-positive myxoid stroma. Immunohistochemically, tumor cells in both areas were positive for desmin and vimentin. Ultrastructurally, the tumor cells in the solid areas had abundant myofilaments with electron dense Z-band structures. Based on these pathological findings, this case was diagnosed as rhabdomyosarcoma in a rabbit.
This case was described briefly in a recent book chapter (Lennox AM, Fecteau KA: 2014, Endocrine disease. In: BSAVA Manual of Rabbit Medicine, eds. Meredith A, Lord B, pp 274–276. British Small Animal Veterinary Association, Gloucester, UK). In the previous description, the tumor was described as a pheochromocytoma; however, further evaluation suggested that it more closely resembled an adrenal cortical adenoma. A 10-year-old, spayed female rabbit was presented for a behavior change of 8 months’ duration. The rabbit was inappropriately urinating and defecating, as well as demonstrating aggressive behaviors such as chasing, biting, and mounting various objects. The rabbit had elevated progesterone, 17-hydroxyprogesterone, and testosterone concentrations, and ultrasound examination of the abdomen showed a round, homogenous nodule measuring 1.1 × 0.8 × 0.9 cm in the region of the left adrenal gland. Necropsy revealed a unilateral adrenal cortical adenoma. To the authors’ knowledge, this is the first complete description of a female rabbit with an adrenal cortical adenoma documented in the literature.
A 6-year-old female rabbit was presented to a veterinary clinic, and the result of ultrasound examination suggested a tumor in the uterine tube. Subsequently, both ovaries and uterus were surgically removed. In gross, a single large cyst in the right ovary and enlargement of the left uterine tube were observed. Histological examination revealed that the cyst had developed in the hilus of the ovary, and was lined by single-layered cuboidal cells. In the left uterine tube, a tumor composed of epithelial cells arranged in tubular structures and pleomorphic cells between the tubular structures was observed. Immunohistochemically, the epithelial cells of the cyst were positive for pan-cytokeratin, cytokeratin 18, CD10, E-cadherin, calretinin and estrogen receptor; the tumor cells of the left uterine tube were positive for pan-cytokeratin, cytokeratin 18, E-cadherin, vimentin, calretinin and estrogen receptor. From these results, the cyst was diagnosed as cystic rete ovarii and the tumor was diagnosed as adenoma of the uterine tube. This case is the first to demonstrate cystic rete ovarii and uterine tube adenoma in rabbits.
A spontaneously occurring subcutaneous mass in the left forelimb of a nine-year-old rabbit (Oryctolagus cuniculus) was examined histopathologically and immunohistochemically. Clinically, edema and hemorrhage were seen around the mass. No connection of the tumor mass to the appendicular skeleton was found. The tumor was arranged in a solid growth pattern and irregular bundles, and neoplastic cells were polygonal to spindle-shape. Osteoid (positive for osteocalcin) and multinucleated giant cells were diffusely or focally seen. Neoplastic cells were positive for vimentin, osterix and Ki-67, indicating the nature of osteoblasts with proliferating activity, but negative for α-smooth muscle actin, desmin or CD204. Based on these findings, a diagnosis of extraskeletal osteosarcoma was made, a very rare tumor both in laboratory and pet rabbits.
Multinucleated giant cells (MGCs) are a prominent histological feature of various mesenchymal neoplasms and are often considered a criterion of malignancy. Mesenchymal neoplasms with MGCs for which the cell lineage is unclear generally are referred to as giant cell sarcomas. Here we characterize the gross, histologic, and immunohistochemical features of 90 giant cell sarcomas in domestic pet rabbits. Based on the anatomic location and histologic and immunohistochemical findings, 18 cases were classified as histiocytic sarcomas (HS) and 72 cases as anaplastic sarcomas (AS). At postmortem examination, HS was either localized HS ( n = 7) always affecting the lungs, or disseminated HS ( n = 10) that affected the lungs ( n = 10), liver ( n = 6), kidneys ( n = 4), pleura ( n = 2), mediastinum ( n = 2), heart ( n = 4), skeletal muscle ( n = 1), adipose tissue ( n = 1), and lymph node ( n = 1). Additionally, one cecal biopsy was consistent with HS. Microscopically, HS were characterized by sheets of neoplastic polygonal to round cells that contained single to several, often greatly enlarged nuclei as well as abundant cytoplasm. HS were always positive for CD204 and always negative for SMA and desmin. In contrast, AS arose most commonly from the skin or subcutis ( n = 62) and rarely the skeletal muscle ( n = 8) or abdominal organs ( n = 2). In 29% of extra-abdominal AS, the tumor deeply invaded into surrounding connective tissue, skeletal muscle, tendons, and bone causing pathological fractures. Five of 9 postmortem cases metastasized to various organs often including the lungs. Microscopically, AS were characterized by sheets of spindle or pleomorphic cells admixed with variable numbers of MGCs. Immunohistochemically, AS were always negative for CD204 and often (71%) positive for SMA and/or desmin.
Background
Testicular torsion is a relatively common complication of cryptorchidism in domestic mammals but is currently unreported in rabbits.
Case Description
A 7- year-old Dutch rabbit was examined for sudden anorexia and lethargy. The rabbit was previously diagnosed with unilateral cryptorchidism 5 years earlier; however, the owner declined surgical treatment at that time. Transabdominal ultrasonography showed a structure consistent with an enlarged testis, with decreased echogenicity, and absent blood flow upon color Doppler ultrasonography. After induction of general anesthesia and during preparation for surgery, the patient had an episode of cardiac arrest. After successful resuscitation, bilateral cryptorchidectomy continued as planned. A ventral midline laparotomy was performed and confirmed presence of an enlarged, dark red left testicle torsed on its spermatic cord. The contralateral testicle was atrophic. Both testicles were removed after standard hemostasis. Recovery was uncomplicated. Histopathologic examination revealed a diagnosis of Sertoli cell tumor and extensive hemorrhage and necrosis in the torsed testicle.
Case relevance and conclusions
Based on literature search, this is the first reported case of intra-abdominal torsion of a neoplastic testicle in a cryptorchid rabbit. Early elective cryptorchidectomy before the potential development of life-threating complications may be beneficial in rabbits as in other species.
This retrospective study of a series of 18 cases aimed to describe the clinical and pathological findings of oral tumours in rabbits, as there have been few reports detailing spontaneous oral tumours in this species. A total of 13 different tumour types were diagnosed: squamous cell carcinoma (three), ameloblastoma (two), fibrosarcoma (two), osteosarcoma (two), cementoma (one), complex odontoma (one), giant cell epulis (one), sarcoma (one), chondrosarcoma (one), trichoepithelioma (one), papilloma (one), malignant melanoma (one) and basal cell carcinoma (one). Odontogenic tumours were relatively common in this study as compared to the oral tumours typically identified in dogs and cats. The most common clinical sign in this study was feeding abnormalities. Surgical excision and radiation therapy were found to be effective in rabbits.
Thirty interstitial cell tumors (ICTs) from domestic rabbits collected from Zoo/Exotic Pathology Service, Northwest ZooPath, and Cummings School of Veterinary Medicine at Tufts University were submitted for histologic review and immunohistochemistry for p53 and Ki-67 along with Periodic acid-Schiff (PAS) staining. The objectives of this cross-sectional study were: (1) to determine the prevalence of testicular granular cell tumors (GCTs) in domestic rabbits within ICTs using PAS staining, and (2) to evaluate morphologic criteria and immunohistochemical expression of Ki-67 and p53 to prognosticate testicular ICTs, in domestic rabbits. The prevalence of ICTs was 1.93% of all submissions and 87% of all testicular tumors. All cases histologically diagnosed as ICT were reclassified as GCT based on PAS staining. Neither labeling for p53 nor the Ki-67 index was prognostically significant. Median survival time of rabbits diagnosed with GCTs was 599 days. No metastatic disease was reported in rabbits diagnosed with ICTs following surgical removal. This study found that the majority of ICTs in rabbit testicles are GCTs and staining with PAS is required to confirm the diagnosis. Regardless, surgical removal (castration) of domestic rabbits with GCTs is an appropriate treatment for this disease and no further investigation is required.
A 5-year-old intact female rabbit was presented with bilateral ocular lesions. In both eyes, a fleshy mass was emerging from the iris. Focal corneal edema, neovascularization, generalized rubeosis iridis, +1 aqueous flare, and dyscoria could also be identified. In addition, hepatomegaly was detected by clinical examination. Hematology and serum biochemistry results included leukocytosis, slight anemia, hyperproteinemia, and mild increased liver enzyme activities. Abdominal ultrasound revealed a moderate enlarged liver with a heterogeneous structure as well as ascites. Thoracic radiography showed generalized pulmonary metastasis. By request of the owner, the rabbit was euthanized. Pathological examination revealed nodules composed of malignant epithelial cells in the lung, anterior and posterior uvea of both eyes, pericardium, diaphragm, liver, mammary gland, and the left ovary. A carcinoma of the mammary gland was suspected as the primary tumor. To our knowledge, this is the first report of a carcinoma with bilateral uveal metastasis in a rabbit.
Dyspnea is a very common clinical finding in rabbits and is often associated with infection of the respiratory tract or cranial mediastinal tumors. Airway obstruction as a cause of dyspnea has been very rarely reported to date. Here, 2 cases of airway tumors in a 4-year old and 4.5-year old rabbit, respectively, are described. Clinically, airway tumors of both patients were associated with progressive dyspnea that was initially considered to be caused by bacterial upper airway obstruction; however antimicrobial treatment was unrewarding. In case 1, a radiographic and computed tomographic examination revealed an intraluminal soft tissue-opaque mass in the thoracic trachea at the level of the first and second thoracic vertebrae. Surgical excision was considered to be difficult due to the intrathoracic location and the owner elected for humane euthanasia. A subsequent histopathological examination of the tracheal mass revealed that the mass was located in the tunica mucosa and exophytically protruded into the tracheal lumen. Immunohistochemically, tumors cells were positive for cytokeratin and negative for vimentin, which supports the histopathologic diagnosis of a tracheal adenocarcinoma. In case 2, clinical examination and thoracic radiography did not reveal an airway obstruction. Postmortem examination identified a laryngeal osteochondroma largely obstructing the laryngeal lumen. Both, laryngeal and tracheal neoplasia, should be considered as an uncommon cause of progressive dyspnea that is nonresponsive to antimicrobial treatment. Besides radiography and computed tomography, the authors recommend endoscopy as an ideal diagnostic tool to identify airway obstruction.
Genital tract disorders, especially uterine disorders, are the most common conditions of the female pet rabbit (Oryctolagus cuniculus); however, there have been few large studies of diseases of the female genital tract of this species. The present study examined diseases of the ovaries, Fallopian tubes, uterus and vagina, retrospectively over a period of 22 years, and included 854 full post-mortem examinations of female pet rabbits and 152 female genital tract biopsy samples. The age distribution of uterine neoplasia, endometrial hyperplasia and uterine inflammation was determined in the post-mortem cases. Uterine disorders were a common finding, occurring in 26.8% of all full necropsy examinations and in almost all genital tract biopsy samples. Uterine tumours (n = 205) were the most common uterine pathology, with adenocarcinoma being the most frequent tumour type. Metastasis was found in 46.2% of rabbits with uterine adenocarcinomas diagnosed at post-mortem examination, with metastatic spread to the lung occurring in 79.1% of these animals. The second most common uterine pathology was endometrial hyperplasia, which was glandular–cystic in most cases. The incidence of uterine tumours and endometrial hyperplasia increased with age, while endometrial hyperplasia was found more commonly in slightly younger animals. In contrast, uterine inflammation, the third most common finding, was found predominately in young to middle-aged rabbits. Ovarian disorders were found rarely at post-mortem examinations (3.3% of all animals), but comprised 16.9% of biopsy samples. Of these, ovarian cysts, especially follicular cysts, and secondary tumours were found most frequently. Disorders of the Fallopian tube and the vagina were found in <1% of cases and should be considered rare.
This report describes post-traumatic ocular lymphoma in 3 companion rabbits; 2 rabbits with unilateral disease and 1 with bilateral disease. Historical findings suggestive of a traumatic event included either external unilateral ocular trauma or bilateral phacoemulsification. Severe corneal changes, presence of an anterior chamber mass(es), low intraocular pressures, and ocular discomfort were noted on ophthalmic examinations. All eyes were treated for variable courses with standard ophthalmic topical medications (antibiotic, anti-inflammatories, and steroid) and systemic anti-inflammatories. Based upon progression of disease, all affected eyes were ultimately enucleated; lenticular capsular rupture and a round cell neoplasm effacing normal structures with variable mitotic indices were noted on histopathology. Neoplastic lymphocytes strongly expressed CD79a via immunohistochemistry and lacked expression for CD3, indicating B lymphocyte lineage and not of T cell lineage. A single animal had evidence of local metastasis to a regional lymph node. Post-traumatic sarcomas have been reported in this species previously, however, these cases are the first reports of this novel round cell variant, named post-traumatic ocular lymphoma due to the B cell lineage confirmed through immunohistochemistry. Clinicians should be aware of this clinical presentation and the possibility of metastasis when evaluating ocular pathology in this species.
Zusammenfassung
Ein 3,5 Jahre altes, männlich-kastriertes Zwergkaninchen wurde mit einer vorberichtlich schnell wachsenden Umfangsvermehrung in der Gingiva des Oberkiefers vorgestellt. Die Neubildung wurde vollständig chirurgisch exzidiert. Histopathologisch ließ sich ein expansiv wachsendes, multilobuläres, teils zystisches, peripheres keratinisierendes Ameloblastom nachweisen. Die immunhistologische Phänotypisierung der Tumorzellen ergab eine zytoplasmatische Markierung mit verschiedenen Panzytokeratin-Antikörpern. Graduell variabel wurden die Zytokeratine 5/6, 7, 10 und 14 exprimiert. Zytokeratin 20 war nicht nachweisbar. Vimentin wurde im Zytoplasma von mesenchymalen Zellen des Stromas exprimiert. Außerdem wurde im Kern von ca. 10% der Tumorzellen das Protein des Tumorsuppressorgens p53 und in ca. 5% der Proliferationsmarker Ki67 festgestellt. Odontogene Tumoren sollten bei Kaninchen mit Umfangsvermehrungen am Kiefer differenzialdiagnostisch berücksichtigt werden.
Trichoblastoma is the most common skin tumour in the rabbit. The aim of the present study was to characterize the histological and immunohistochemical features of trichoblastoma in 27 rabbits. Common sites of tumour occurrence were the neck (6/30, 20%), head (5/30, 16.7%), flank (4/30, 13.3%) and hindlimb (4/30, 13.3%). Histologically, rabbit trichoblastoma was categorized into ribbon (10/30, 33.3%), trabecular (8/30, 26.7%) and mixed types (12/30, 40%). The tumour tissue showed close interaction with the surrounding stroma where prominent fibroblastic aggregation, known as papillary mesenchymal bodies, was frequently observed (24/30; 80%). Peritumoural stroma of all cases was stained by Alcian blue (at pH 2.5 with weaker staining at pH 1.0). Immunohistochemically, the peripheral palisading basal-type cells of the tumour were positive for cytokeratin (CK) 14 while the inner cells were typically positive for CK17, differing from the immunohistochemical profile of the rabbit epidermis and hair follicle. The present study suggests that uncontrolled embryonic trichogenesis is involved in the development of trichoblastoma in the rabbit.
A 6-year-old, 1.9-kg female spayed lop-eared European rabbit (Oryctolagus cuniculus) was evaluated for acute hematuria and inappropriate urination and defecation of less than 12-hours duration. Abdominal ultrasonography revealed a suspected bladder mass. Ultrasound-guided cystocentesis was performed and the results of the urinalysis were unremarkable. An abdominal exploratory surgery revealed a nodular cystic mass at the cranial ventral apex of the bladder wall which measured 0.5 cm x 0.5 cm. Based on histopathologic evaluation, excision of the neoplasm was complete and the mass was diagnosed as transitional cell carcinoma (TCC) of the bladder. This case suggests that urinary bladder TCC should be considered in pet rabbits presenting with similar clinical signs.
A spontaneous osteosarcoma was observed in a 1 1/2 yr old female belted Dutch rabbit. The tumor originated in the midline of the frontal bones and extended into the frontal sinus and turbinates. Metastases were found in the lung, liver and muscle of the diaphragm. A review of the literature and discussion on localization of the tumor is presented.
Spontaneous age-related lesions of laboratory rabbits are not well documented in the contemporary scientific literature. A retrospective study of diagnostic necropsies of 36 rabbits >2 years of age found a number of common lung lesions. Fibromuscular intimal hyperplasia affected medium and to a lesser extent large pulmonary arteries and was present to a variable extent in all 36 rabbits >2 years of age. The lesions were characterized by fragmentation and/or reduplication of the internal elastic lamina (IEL), proliferation of smoothelin+/alpha-smooth muscle actin (α-SMA)+/vimentin− smooth muscle cells and fewer smoothelin−/α-SMA+/vimentin+ myofibroblasts, and intimal deposition of collagen without thrombosis, embolism, or evidence of pulmonary hypertension. Pulmonary emphysema, present in 30/36 rabbits, was characterized by the loss of alveolar septa; most affected rabbits did not have clinical signs of respiratory disease. In 8/13 rabbits of the inbred EIII/JC audiogenic strain, we identified a unique syndrome of granulomatous pneumonia containing hyaline brown to gray, globular to ring-like acellular material that was Alcian blue and periodic acid-Schiff positive. The material was immunoreactive for surfactant protein-A and had the ultrastructural appearance of multilamellar vesicles, suggesting a genetic defect in surfactant metabolism. Additionally, we found small benign primary lung tumors (fibropapillomas, 5 rabbits) not previously described. Other findings included heterotopic bone (5 rabbits), subacute to chronic suppurative bronchopneumonia, pyogranulomatous pneumonia with plant material, and pulmonary artifacts from barbiturate euthanasia solution.
A 9-year-old neutered male rabbit (Oryctolagus cuniculus) previously diagnosed with right nephromegaly was presented with increased sexual behavior associated with hypertestosteronemia. Left adrenomegaly and an obstructive mass in the right renal pelvis and proximal ureter leading to severe hydronephrosis of the right kidney were diagnosed by abdominal ultrasound. A left adrenalectomy and right nephrectomy were performed and samples were submitted for histopathology, confirming the diagnosis of adrenocortical carcinoma and a transitional cell carcinoma of the ureter and renal pelvis. Increased sexual behavior resolved within 2 months following surgical resection of the affected left adrenal gland, but recurred 8 months later. The right adrenal gland had increased in size when compared to earlier ultrasonographic evalution. A 4.7-mg deslorelin implant was placed subcutaneously, which resulted in a decrease of testosteronemia and sexual behaviors for up to 18 months.
Trichoblastoma is the most common skin neoplasm in pet rabbits, followed by collagenous hamartomas. Collagenous hamartomas are benign proliferations of connective tissue, which occur in rabbits in two forms: as a solitary nodule or in a disseminated form with multiple, sometimes more that ten, nodules.This second kind can easily be misinterpreted as a malignancy, particularly as malignant lymphoma. Here we present for the first time the clinical characteristics of this disease. Throughout a three year period, tissue samples from 30 rabbits with collagenous hamartomas were submitted for histopathology. With the exception of one, all rabbits were male or male castrated. Nine rabbits had a solitary nodule, in six cases rabbits had two to four noduies and seven rabbits had multiple (>10) disseminated nodules. The average age was 5.6 years. Nodules grew to maximum size of 1.5 cm in diameter, then remained steady in size. No recurrence was noted, however, three rabbits developed new nodules elsewhere on the body. Nodules were most commonly located on abdomen or thorax. Except for one rabbit, the general behaviour was not impaired. There rabbits also had testicular tumors. The etiology of collagenous hamartomas remains unclear. Almost exclusively middle aged male rabbits are affected. This is suggestive of a hormonal etiology or an x-linked recessive genetic disease. The disseminated form of this disease has to be differentiated from malignant lymphoma. Both diseases present similar however carry a completely different prognosis.
Es kann heute als gesichert angesehen werden, da? zumindest alle Wirbeltiere die F?higkeit zur Geschwulstbildung besitzen. Die Kasuistik der Tiergeschw?lste umfa?t eindeutige Geschwulstbefunde bei allen Wirbeltierklassen von den Fischen bis zu den S?ugern. Vereinzelt liegen auch bereits Mitteilungen ?ber das Vorkommen von Geschw?lsten oder doch wenigstens von geschwulst?hnlichen Neubildungen bei wirbellosen Tieren (Gersch 1955) vor. Soweit die bisherigen Unterlagen ein Urteil gestatten, d?rfte der, phylogenetische Determinationspunkt der Geschwulstbildung? (Teutschlaender, 1920) z. Z. noch an der Grenze zwischen Vertebraten und Avertebraten zu suchen sein. Es mu? aber zugegeben werden, da? Versuche gr??eren Umfangs zur experimentellen Geschwulsterzeugung mit Hilfe cancerogener Substanzen bei den Wirbellosen bis heute noch ausstehen. Da sich gerade diese Tierarten zu Lebzeiten weitgehend unserer Beobachtung entziehen, und spontane Geschw?lste bei ihnen nur ganz selten zur Feststellung kommen werden, so wird sich die Frage, inwieweit wirbellose Tiere zur Geschwulstbildung neigen, wohl nur durch experimentelle Untersuchungen kl?ren lassen.
The new Textbook of Rabbit Medicine draws on the latest information from around the world to make it a truly global resource on all aspects of rabbit medicine and health. It will continue to be indispensable to veterinary surgeons in general practice, veterinary students, referral veterinarians specializing in exotic pets, and veterinary surgeons studying for certificates in advanced veterinary practice. The book is carefully constructed to allow for the biology, husbandry and clinical techniques that pertain to rabbit medicine to be treated comprehensively and conveniently. Clinical chapters follow a logical progression from clinical pathology, through anaesthesia, therapeutics and diseases covered by body system, to surgery and post-mortem examination. The author offers a strong emphasis on clinical practice to ensure the content is as practically useful and accessible as possible. Key points boxes integrated throughout the book provide a stand-alone precis of important subjects. New clinical techniques boxes are packed with tips from a practising expert who regularly applies this same information in practice.
The authors present a case of primary uterine myxosarcoma in a 4-year-old, overweight, gray-coloured mixed breed female rabbit carcass, which was found during pathological examination. The malignant mesenchymal tumour developed from the left uterus and made paratumoural solitary metastasis in the broad ligament of the uterus, and distant multiple metastases in the visceral peritoneum, and lungs. The histopathological examination of both the primary and secondary tumours showed increased tumourinduced neoangiogenesis, extensive haemorrhage and necrosis. In the obese rabbit severe pathological necrobiotic fatty liver, atrophy and lipomatosis of the pancreas, furthermore liponecrosis in the omentum were observed. The primary and secondary tumours showed vimentin positivity, and pancytokeratin-, a-SMA-, daudin-5 negativity. The Ki-67 labelling index exhibited 18%. The authors assumed that the causes of the disseminated intravascular coagulopathy in the rabbit were the extensive haemorrhage, necrosis of the tumours, tumour-induced liponecrosis of the omentum and ketosis.
This chapter presents new data that have been accumulated on rabbit neoplasia from case reports, descriptions of biological aspects of a variety of naturally occurring tumors, and reports of experimentally induced tumor models. Although much of the early data originated from rabbit colonies associated with major research institutions, the growing popularity of domestic rabbits as pets allows an increased ability to accumulate data on the spontaneous incidence of tumors in rabbits that are allowed to live a natural life span. Naturally occurring neoplasms in the rabbit were previously thought to be sporadic but there is evidence for a regular pattern in the incidence of the various tumor types known to be naturally associated with Oryctolagus. It is difficult to determine the actual incidence of spontaneous neoplasms in the domestic rabbit. The normal lifespan of the domestic rabbit Oryctolagus is 7-8 years, but they are used at younger ages in most research studies and breeding colonies, and are seldom maintained through their natural lifespan. Rabbits are similar to most species in that neoplasia is infrequent in juveniles and young adults.
This chapter provides an overview of the neoplastic process in the various rabbit species. It discusses the naturally occurring tumors of Oryctolagus, Sylvilagus, and Lepus, namely, neoplasms without known antecedent triggering mechanisms, and at least one important case, chronic inflammation subsequent to syphilitic orchitis. Squamous cell carcinoma of the vaginal squamous–columnar junction is a rare tumor. It is an important tumor, however, because in the rabbit the columnar epithelium of the uterus is continued out over the cervix into the vagina. The transition to squamous epithelium occurs at the level of the urethral meatus. Bile duct adenoma and its malignant counterpart, the bile duct adenocarcinoma, are relatively common as spontaneous tumors of Oryctolagus. Bile duct adenomas are present as a massive solitary growth or as multiple tumors of variable size. The lesions are unencapsulated and sharply circumscribed from the normal liver. The tumor is frequently described as a cystadenoma because the gross appearance of multiple interloculating cysts filled with honey-like fluid is matched by the microscopic pattern of variably differentiated ductalforms within a myxoid to fibrotic stroma. The Brown–Pearce carcinoma, one of the most useful of the transplantable rabbit tumors, arose from the syphilitic scrotal chancre of a rabbit.
An 8-year-old male neutered miniature Rex rabbit (. Oryctolagus cuniculus) was evaluated for progressive left rear limb lameness. A smooth, hard mass was palpated over the proximolateral aspect of the left tibia. Initial radiographic evaluation of the area surrounding the mass revealed a proliferative bony lesion lateral to the tibia without evidence of pulmonary metastases. Cytology of the lesion was consistent with osseous proliferation. Follow up radiographs of the mass after the initial presentation, provided evidence of the mass increasing in size so a second cytologic evaluation was requested. The diagnostic interpretation of the second cytologic submission collected from the mass was osteosarcoma. A coxofemoral amputation was performed on the left rear limb of the rabbit, after which the patient recovered uneventfully from the procedure. Histopathologic evaluation of the mass confirmed osteoblastic osteosarcoma. There was no evidence of metastasis in radiographic images performed at 4 and slightly more than 6 months after the amputation procedure. The rabbit died 190 days after the amputation and several days after recovery from a gastrotomy for gastric bloat. A necropsy was not performed.
Mammary tumours are common in pet rabbits; however, published studies are predominantly derived from laboratory and meat rabbits. This study reports basic data on type and location of 119 separate tumours from 109 pet rabbits. The animals were aged 2-14 years (mean 5.5 years) and all 90 rabbits of known gender were female. Cranial and caudal mammary glands were affected equally. The majority of lesions (n = 105) were classified as carcinomas with 32 tubular, 16 papillary, 12 tubulopapillary, 11 solid, nine adenosquamous, nine comedo type, five complex, four ductal, three cribriform, three anaplastic and one spindle -cell carcinoma. Twelve percent of the lesions were benign, with eight intraductal papillary adenomas, three simple tubular adenomas and one complex adenoma. One non-neoplastic lesion was found in the form of cystic duct ectasia.
Copyright © 2015 Elsevier Ltd. All rights reserved.
A 2.4 kg, 7-year-old, female Rex rabbit was presented with a 4-month history of a left-sided head tilt, difficulty in mastication, lethargy, and chronic wasting. Diagnostic testing of the patient revealed a severe heterophilic leukocytosis and radiographic images of the skull radiographs indicated irregularity of the left tympanic bulla. A computed tomographic scan highlighted a heterogeneously contrast-enhancing mass, ventral and rostral to the left tympanic bulla, with contrast enhancement of the meninges on the left, consistent with an aggressive neoplasm. The patient was euthanized and the mass was identified as a salivary gland adenocarcinoma. The gland of origin is suspected to be the left parotid, owing to its location and close association with normal parotid tissue. To the authors' knowledge, this is the first report of a salivary gland adenocarcinoma in a domestic rabbit. A computed tomography (CT) scan and histopathology examination were useful modalities for identifying the neoplasm in this case.
The aim of this retrospective study (2004-2011) was to examine mammary tumors and tumor-like lesions in 24 pet rabbits by histopathology and immunohistochemistry. Rabbits were aged 2 to 8 years. Seventeen were female and 7 female-spayed. Diagnosed tumor-like lesions were lobular hyperplasia (2 rabbits) and multiple cysts (10 rabbits). Tumors included cystadenoma (7 tumors; 3 rabbits), intraductal papilloma (2 tumors; 1 rabbit), intraductal papillary carcinoma (1 tumor), adenocarcinoma (14 tumors; 13 rabbits), adenosquamous carcinoma (2 tumors; 2 rabbits), and matrix-producing carcinoma (1 tumor). The most frequently diagnosed lesion was invasive carcinoma (n = 17). Ten rabbits had several lesions. Immunohistochemistry for calponin and p63 showed that the diagnosed tumor-like lesions, benign tumors, and noninvasive carcinoma had a peripheral myoepithelial layer that was lacking in the invasive carcinomas. In 13 of 14 (93%) of the invasive carcinomas, however, variable numbers of calponin- and/or p63-immunopositive cells ranging from 0.1% to 40% with morphological features of either retained nonneoplastic myoepithelial cells or neoplastic epithelial cells with a myoepithelial differentiation were observed. Tumor recurrence was reported in the rabbit with the matrix-producing carcinoma and in 3 rabbits with mammary adenocarcinomas displaying ≥20 mitotic figures in 10 high-power fields and high numbers of neoplastic cells with a myoepithelial differentiation (19%-39%). The rabbit with the matrix-producing mammary carcinoma developed cutaneous metastases confirmed by histopathology. This study shows that different types of mammary tumor-like lesions and tumors can occur in pet rabbits.
Biliary tumors are rarely diagnosed in rabbits, and there are very few published case reports of this disease within this group of animals. This case involves an approximately 6-year-old spayed female pet rabbit that was referred for an abdominal mass noted on survey full-body radiographs obtained during an examination after presenting for acute onset anorexia. Otherwise, the patient had an unremarkable history, and physical examination abnormalities were limited to a slightly distended abdomen. Laboratory evaluation revealed an isolated elevation in gamma-glutamyl transpeptidase. Ultrasonography documented a 5.4-cm multicystic, intrahepatic mass with hyperechoic septations. The mass was surgically resected and described histopathologically as a proliferation of ectatic duct structures with a simple epithelial lining, supporting a diagnosis of biliary cystadenoma. The rabbit recovered without incident and was doing well 15 months postsurgery. The case is presented with a review of all reported cases and discussion of the potential origins of this unusual tumor in the rabbit. Surgery is recommended in rabbits that are diagnosed with a biliary tumor.
A 9-year-old male rabbit was presented for chronic intermittent anorexia and colic. A small abdominal mass was evident on palpation, and ultrasonography demonstrated a luminal mass and small intussusception in the distal cecum. Surgical resection of the distal third of the cecum was performed and histologic examination yielded a diagnosis of an inflammatory fibroid polyp. Although reported as causing intussusception in humans and other animals, the authors are unaware of any reports in pet or laboratory rabbits. The etiology and histogenesis of inflammatory fibroid polyps are still unclear.
This case report describes the clinical manifestations and ocular pathology of an intraocular sarcoma in a spayed female 7-year-old rabbit that developed clinical signs consistent with phacoclastic uveitis at 6 months of age, which was left untreated for most of the next 6 years. Ophthalmologic examination confirmed pupillary occlusion, aqueous flare, fibrin, and lens debris within the anterior chamber of the right eye. The right eye was blind and phthisical. The tentative clinical diagnosis was chronic phacoclastic uveitis, and a routine transconjunctival enucleation of the right eye was completed. The globe was formalin-fixed and submitted for histologic examination. Light microscopic examination revealed a ruptured cataractous lens, uveitis, retinal detachment, and an intraocular sarcoma centered around the lens. Immunohistochemical (IHC) staining was positive for smooth muscle actin and vimentin and negative for Desmin and cytokeratin intermediate filaments.
83 cases of an adenomatous tumor of the uterine mucosa have been observed in a colony of rabbits during the past 4 years The
results of a clinical and pathological study of the tumor, together with a description of transplantation experiments are
included in the present report.
The clinical histories of tumor bearing animals are similar in all cases. Discovery of the tumor is preceded by a long period
of reproductive disturbance, and its subsequent course is one of slow, continuous growth which has terminated in death with
metastasis in all animals held under observation for longer than 1 year.
Microscopically, the tumor shows an atypical alveolar structure, and its characteristics closely resemble those of an adenocarcinoma
of the uterine fundus in women. Pathological changes similar to those observed in mice after treatment with estrogenic substances
occur in the thyroid, suprarenal, pituitary and mammary glands.
Intraocular transplantation of the tumor has been successful, and at the present time the growth has been carried through
6 generations by serial transfer.
The clinical and pathological course of 25 mammary tumors in rabbits has been described. The antecedent breast history and
morphology of the growths allowed a natural classification into two distinct types, one of which was distinguished by a preexisting
cystic mastitis and a papillary structure, while the other originated in clinically normal mammary tissue and was characterized
by an adenomatous structure. The two types of neoplasia occurred almost exclusively in two family groups and heredity played
a fundamental rôle both in the occurrence of the tumors and in the determination of tumor type. Endocrine changes, comparable
with those found in animals after long continued administration of estrogenic substances, occurred in tumor-bearing rabbits
and it was inferred that the spontaneous growths represented a natural counterpart of the experimental induction of neoplasia
with estrone.
An investigation of uterine adenomata in the rabbit revealed an incidence of 16.7 per cent in the total female population
over 2 years of age. However, the incidence varied widely in relation to age, breed, and genetic constitution and closely
paralleled that of toxemia of pregnancy with reference to the same constitutional factors. In addition, all of the tumor bearing
animals suffered attacks of this disease during their earlier breeding history. The facts suggest that the association of
the two disorders occurred as a result of the liver damage incident to toxemia which impaired the function of this organ in
relation to estrin inactivation and the concentration of this substance in the blood stream subsequently rose to a carcinogenic
level.
A consideration of the disparity in the distribution of uterine growths in rabbits and women indicated that the absence of
squamous epithelium in the cervix of the rabbit and the greater physiological activity of the endometrium of the fundus in
this species were the determining factors.
This book results from requests from rabbit owners and veterinarians who were seeking reliable, up to date information about skin diseases and their treatment. Material related to rabbits is, indeed, not readily available, or limited to a chapter in rabbit medicine or veterinary books. Here, a comprehensive approach aims at describing a skin disorder and its rabbit-specific clinical signs, diagnosis, and rabbit-safe treatment options. The book chapters deal with rabbit skin anatomy, examination of rabbits, and viral, bacterial, fungal, parasitic, mechanical, genetic, hormonal, immune and neoplastic diseases. Pen drawings illustrate the different disorders.
The collaboration with a veterinarian and a rabbit owner has contributed to the clarity and the quality of the provided information. Hopefully “Skin Diseases of Rabbits” will appeal to the small animal and exotic practitioner, veterinary students, veterinary nurses, and owners, and become a helpful addition to their handling and treating rabbits.
It can beordered here:
http://www.lulu.com/shop/esther-van-praag-phd-with-amir-maurer-dvm-and-tal-saarony/skin-diseases-of-rabbits/paperback/product-12664126.html
Ein bei einem Kaninchen beobachteter Mißbildungstumor mit geweblichen Anteilen aller drei Keimblätter im Bereich des mediobasalen Stirnhirns ist Gegenstand der Darstellung. Neben der großen Seltenheit derartiger Teratome im Tierreich gewinnt der beschriebene Fall eine besondere Bedeutung durch die im Anschluß an eine Infektion mit dem Virus der westlichen Pferdeencephalitis aufgetretenen onkolytischen Alterationen.
A teratoma in the region of the optic chiasma in the rabbit
This is a report of a teratoma with tissues derived from all three germ layers and situated in the medio-basal region of the frontal lobe. Apart from the extreme rarity of such tumours in animals, the case assumes particular importance because the tumour showed areas of recent focal necrosis which may have been due to inoculation with the virus of Western equine encephalomyelitis. (The animal was being used to produce hyper-immune serum.)
Un dysembryome de la région du chiasma optique chez le lapin
Une tumeur embryonale comprenant des tissus dérivés des trois feuillets a été trouvée dans la région médio-basale du lobe frontal et est l'objet d'une description. Outre l'extrême rareté de tels dysembryomes dans le règne animal, le cas rapporté dans cet article prend une importance particulière du fait que cette tumeur présentait des alterations oncolytiques survenues après une infection par le virus ouest de l'encéphalite du cheval.
Un teratome en la región quiásmica del conejo
El objeto de la descripción es un tumor deformante con partes hísticas pertenecientes a las tres hojas blastodérmicas en la zona del lóbulo frontal mediobasal de un conejo. Al lado de la enorme rareza de tales teratomas en el reino animal, el caso descrito tiene una importancia significativa por las alteraciones oncolíticas aparecidas a continuación de la infección con el virus de la encefalomielitis equina tipo occidental.