Michael S Davis

Oklahoma State University - Stillwater | Oklahoma State · Department of Physiological Sciences

Introduction The purpose of this study was to evaluate medical record data from the 2018–2020 Yukon Quest International Sled Dog race to examine injury patterns and risk factors for dogs competing in multi-day ultra-endurance events. Specifically, we summarized injuries and illnesses that resulted in canine athletes being removed (“dropped”) from c...

Changes in serum biochemistry and skeletal muscle of horses in response to individual endurance rides of varying distance have been reported, as have the effects of submaximal treadmill training. This study evaluated the effects of a controlled field endurance training programme on energy metabolism. Five Arabian horses 6.8 ± 2.0 years (mean ± stan...

Exercise is associated with the development of oxidative stress, but the specific source and mechanism of production of pro-oxidant chemicals during exercise has not been confirmed. We used equine skeletal muscle mitochondria to test the hypothesis that hyperthermia and acidosis affect mitochondrial oxygen consumption and production of reactive oxy...

Objectives: Exercise-induced gastrointestinal syndrome occurs in dogs and people and might compromise athlete performance by increasing intestinal permeability and causing gastrointestinal erosions. Racing sled dogs often receive acid suppressant prophylaxis which decreases the incidence of gastric erosions induced by exercise. The objectives were...

Athletic conditioning can increase the capacity for insulin-stimulated skeletal muscle glucose uptake through increased sarcolemmal expression of GLUT4 and potentially additional novel glucose transporters. We used a canine model that has previously demonstrated conditioning-induced increases in basal, insulin- and contraction-stimulated glucose up...

Prolonged multiday exercise in dogs is often associated with a caloric deficit that can lead to changes in body composition but may also result in an increase in lean body mass due to a conditioning effect. To test the hypothesis that multiday exercise decreases fat mass but increases lean body mass, body composition was measured using deuterium ox...

Metabolic syndrome in humans is commonly associated with cardiovascular dysfunction, including atrial fibrillation and left ventricular diastolic dysfunction. Although many differences exist between human and equine metabolic syndrome, both of these conditions share some degree of insulin resistance. The aims of this pilot study were to investigate...

New findings: What is the topic of this review? This narrative review provides an up-to-date overview of the status and potential role of novel biological markers (biomarkers) that can help identify the patients at risk of organ injury or long-term complications following heatstroke. What advances does it highlight? This narrative review has ident...

Alaskan sled dogs develop a particular metabolic strategy during multiday submaximal exercise, allowing them to switch from intra-muscular to extra-muscular energy substrates thus postponing fatigue. Specifically, a progressively increasing stimulus for hepatic glycogenolysis and gluconeogenesis provides glucose for both fueling exercise and replen...

The rich history and global abundance of domestic dogs (Canis familiaris) present a unique opportunity and an ideal model for interdisciplinary research. Canine evolutionary history demonstrates unprecedented changes across all levels of biological organization. These include diversification from highly social, pack-dwelling wild carnivores (extant...

Objective To determine the location and periarticular shoulder‐muscle‐abnormalities detected via orthopedic examinations and ultrasonography in ultra‐endurance Alaskan sled‐dogs, returned from an ultra‐endurance sled‐dog‐race prior to finishing it. Study Design Prospective clinical study. Sample Population Sixty‐four dogs (128 shoulders). Method...

The total energy expenditure of a racing sled dog can exceed 500 kcal/kg bodyweight during typical events spanning a week or more. Based on early research, as well as practical considerations, modern commercial diets are formulated to meet these energy requirements using fat and protein. However, more recent research provides a clear picture of a c...

Exercise often causes skeletal muscle hyperthermia, likely resulting in decreased efficiency of mitochondrial respiration. We hypothesized that athletic conditioning would improve mitochondrial tolerance to hyperthermia. Skeletal muscle biopsies were obtained from 6 Alaskan sled dogs under light general anesthesia before and after a full season of...

The skeletal muscle of exercising horses develops pronounced hyperthermia and acidosis during strenuous or prolonged exercise, with very high tissue temperature and low pH associated with muscle fatigue or damage. The purpose of this study was to evaluate the individual effects of physiologically relevant hyperthermia and acidosis on equine skeleta...

Background Rehabilitation of tendon injuries in horses often involves cryotherapy to reduce inflammation and occasionally tissue heating to increase collagen extensibility. The application of alternating cold and hot (ie contrast therapy) is widely used in human physical therapy; however, its utility in equine rehabilitation is largely unknown. Ob...

Prolonged submaximal exercise relies on the steady delivery of oxidizable substrates to the working muscle, with the sources of those substrates either stored reserves or food absorbed from the gastrointestinal tract during exercise. Fat oxidation could be advantageous for this type of exercise because of potentially greater reserves, but recent st...

Background: Overheating is a common form of injury in working dogs. The purpose of this study was to evaluate the relative efficacy of three postexercise cooling methods in dogs with exercise-induced heat stress. Methods: Nine athletically conditioned dogs were exercised at 10kph for 15 minutes on a treadmill in a hot environmental chamber (30°C...

Introduction: Physical activity has been shown to improve insulin sensitivity in subjects with insulin resistance, but the effect of athletic conditioning on subjects with normal insulin sensitivity has received less scrutiny. Because strenuous exercise can be limited by the availability of substrates, it is reasonable to hypothesize that conditio...

Our objective was to evaluate the effect of conditioning and hypoxia on rectal and gastrointestinal temperature changes in dogs exercising at cold ambient temperature. Six Alaskan Husky sled dogs, each in a physically conditioned and unconditioned state, were used in the prospective study. Dogs in peak physical condition were run untethered on a tr...

Background Exercise increases water requirements, but there is little information regarding water loss in dogs performing multi‐day exercise Objectives Quantify the daily water turnover of working dogs during multi‐day exercise and establish the suitability of SC administration of tracer to determine water turnover. Animals Fifteen privately owne...

Increased nutritional demands for endurance exercise of dogs are typically met through increased amounts of their current food. As a result, protein intake is also increased, and excessive nitrogen may affect the dog's water balance. Sixteen unconditioned Alaskan sled dogs underwent a 6-week exercise training protocol, wherein 8 dogs were fed incre...

OBJECTIVE To evaluate the effect of brachycephaly and body condition score on respiratory thermoregulation of healthy dogs. DESIGN Prospective study. ANIMALS 52 brachycephalic and 53 nonbrachycephalic dogs. PROCEDURES All dogs were exposed to a cool treatment (temperature, 21.8 ± 1.7°C [71.2 ± 3.1°F]; relative humidity, 62.2 ± 9.7%; and ambient ent...

Oxygen consumption values for individual subjects and samples reported in this study. (XLSX)

Heart rate recovery (HRR) describes the rapid deceleration of heart rate after strenuous exercise and is an indicator of parasympathetic tone. A reduction in parasympathetic tone occurs in patients with congestive heart failure, resulting in prolonged HRR. Acetylcholinesterase inhibitors, such as pyridostigmine, can enhance parasympathetic tone by...

At the annual Iditarod Race, Alaskan Huskies repeatedly run for up to 8 hours at 16 km/h to complete 1600 km. We previously demonstrated high rates of mitochondrial protein synthesis in Alaskan Huskies, which we suspected allowed rapid remodeling of mitochondrial proteins in response to energetic stress. The purpose of this study was to examine mit...

The purpose of this study was to determine the incidence of post-anesthetic colic in non-fasted adult horses undergoing isoflurane inhalant anesthesia for an elective, non-abdominal procedure at a single referral center. Medical records were searched from May 1, 2012 to May 31, 2014. Inclusion criteria included non-fasted patients >= 2 years of age...

Gastritis and gastric ulcers are an important cause of morbidity and mortality in canine athletes. Although the majority of scientific work on this condition has been performed in ultraendurance racing sled dogs, this condition has been identified in other canine athletes, including sled dogs competing in shorter events and dogs performing off-leas...

Exercise-induced gastrointestinal disease (EIGD) has been reported in all domestic athletes. In dogs and humans, EIGD is most commonly associated with ultra-endurance racing sled dogs and marathon/triathlon competitors, respectively, suggesting that the syndrome is specifically a function of prolonged exercise. However, EIGD is also common in horse...

Rationale: Respiratory syncytial virus (RSV) infection in preterm and newborn infants can result in severe bronchiolitis and hospitalization. The lamb lung has several key features conducive to modeling RSV infection in human infants, including susceptibility to human strains of RSV such as the A2, Long, and Memphis Strain 37 (M37). In this study,...

Previous necropsy studies have shown that up to 60% of sled dogs competing in endurance sled dog races have areas of muscle damage. Human athletes and trainers have maintained a strong belief, based mostly on personal experiences, that massage can be effective for pre-race preparation and expedited recovery between consecutive events. We proposed t...

Improvised explosive device detection (IDD) dogs explore up to 40 km of land daily and therefore have energetic demands that may be above the National Research Council’s requirement for working dogs. This study was designed to quantify metabolic energy intake (MEI) and total energy expenditure (TEE) in a group of IDD dogs. Two groups of dogs that h...

Therapeutic exercises are the cornerstone of the rehabilitation programs of companion animals. Therapeutic exercises are used to improve active joint range of motion, to improve weight bearing and limb use, to build strength and muscle mass, and to increase conditioning (eg, endurance, speed). Each case is unique as chronicity, type of injury, pati...

Canis lupus familiaris, the domesticated dog, is capable of extreme endurance performance. The ability to perform sustained aerobic exercise is dependent on a well-developed mitochondrial reticulum. In this study we examined the cumulative muscle protein and DNA synthesis in groups of athletic dogs at the onset of an exercise-training program and f...

The Alaskan Husky has been specifically bred for endurance performance and is capable of extreme endurance performance. We examined sled dogs in the trained state at the beginning of the race season and after a 1600 km race (Iditarod). Our hypothesis was that lipids would be the predominant substrate during submaximal exercise in long-distance raci...

Endurance exercise relies on transsarcolemmal flux of substrates in order to avoid depletion of intramuscular reserves. Previous studies of endurance trained sled dogs have shown a remarkable capacity of these dogs to adapt rapidly to endurance exercise by decreasing the utilization of intramuscular reserves. The current study tested the hypothesis...

Exercise-induced gastric disease is well-recognised in dogs performing ultra-endurance racing, but has not been described in dogs performing non-competitive athletic activities. Explosive detection dogs often perform prolonged periods of exercise and are reported to have chronic inappetance and weight-loss consistent with gastric disease. Seven pri...

Two experiments were designed to investigate the role of exercise on insulin sensitivity (IS) in Alaskan racing sled dogs. In both experiments, IS was quantified with an isoglycemic-hyperinsulinemic clamp (IHC), whereby IS was defined as the glucose infusion rate (GIR) divided by the mean insulin concentration during the clamp. In Experiment 1, IS...

Alaskan racing sled dogs are a well-established model of exercise-induced gastric disease. The aim of this study was to define the temporal development of microscopical gastric lesions during long distance racing. Two groups of dogs were examined: group I comprised conditioned dogs that were exercising and group II were conditioned dogs not exercis...

A horse's hydration status is critical to its health. The accurate and quantitative determination of it has been problematic because of size, length and density of hair, and uneven topography. The objective of this study was to validate a bioelectrical impedance analysis (BIA) method for objectively quantifying hydration status. Monofrequency BIA v...

Successful completion of endurance exercise is facilitated by conditioning that enhances the capacity of the cardiovascular and musculoskeletal systems to maintain a high level of aerobic activity. Insufficiency or disease in these systems may be diagnosed using routine haematology and serum chemistry testing. Pre-race blood samples obtained from 8...

Omeprazole and famotidine both reduce severity of exercise-induced gastritis, but administering famotidine is easier than administering omeprazole during racing competition. Famotidine is more efficacious than no treatment in reducing severity of exercise-induced gastritis; and high-dose famotidine is more efficacious than omeprazole in reducing se...

Serum immunoglobulin dynamics have not been studied in racing sled dogs, despite hypoglobulinemia having been reported during racing events. Hypoglobulinemia in racing sled dogs is associated with decreases in serum IgA, IgE, IgG, and IgM concentrations during prolonged exercise. One hundred and fifty-seven Alaskan sled dogs that successfully compl...

The objective was to characterize the endoscopic appearance of the glossoepiglottic fold (GEF) in normal horses. Six clinically normal adult Quarter Horses between 5 and 7 years of age were used and ranged from 480 to 520 kg body weight. Prior to oropharyngeal endoscopic examination, all horses had demonstrated normal function of the upper respirat...

To assess changes in muscle glycogen (MG) and triglyceride (MT) concentrations in aerobically conditioned sled dogs during prolonged exercise. 54 Alaskan sled dogs fed a high-fat diet. 48 dogs ran 140-km distances on 4 consecutive days (cumulative distance, up to 560 km); 6 dogs remained as nonexercising control animals. Muscle biopsies were perfor...

To determine the effects of training and sustained submaximal exercise on hematologic values in racing sled dogs. Cohort study. 39 Alaskan sled dogs bred for endurance racing. Procedures-Blood samples were collected prior to initiation of a 7-month training regimen (n=39), after completion of the training regimen (19), and after completion of an 1,...

Omeprazole reduces the severity of exercise-induced gastritis but not the prevalence of gastric lesions in sled dogs. The frequent feeding of sled dogs during competition likely results in decreased absorption of omeprazole and, thereby, decreased efficacy. Famotidine, a histamine-2 blocker with good bioavailability in the presence of food, would r...

It is clear from a review of the current scientific literature that an evidence-based approach to medical treatment of equine respiratory disease can be applied, at least in the instance of common lower respiratory diseases. In particular, there is clear evidence for efficacious treatments for recurrent airway obstruction and exercise-induced pulmo...

To determine the impact of successive days of endurance exercise on select serum chemistry values in conditioned Alaskan sled dogs. Prospective cohort study. 10 conditioned Alaskan sled dogs. All dogs ran 160 km/d for 5 consecutive days. Serum was obtained prior to exercise and immediately after each exercise run; all samples were obtained before d...

To determine effects of exercise performed while breathing cold air on expression of cytokines and influx of neutrophils in airways of horses. 9 adult horses. In a crossover study, bronchoalveolar lavage fluid (BALF) was obtained 24 and 48 hours after each of 2 submaximal exercise sessions performed by horses while breathing warm (25 degrees C) or...

To determine whether prolonged exercise by conditioned sled dogs affects urine concentrations of homovanillic acid (a metabolite of dopamine), vanillylmandelic acid (a metabolite of norepinephrine and epinephrine), and cortisol. 24 conditioned Alaskan sled dogs (2 to 8.5 years old) that were in training for a multiday endurance race. Voided urine s...

Inspired air is warmed to body temperature and fully humidified by the upper airway mucosa under normal resting conditions. This conditioning process may not be completed by the upper airways during conditions of increased minute ventilation or when the inspired air is unusually cold, resulting in cooling and desiccation of lower respiratory surfac...

Alterations in the appearance and function of gastrointestinal mucosa are common after strenuous exercise. However, the duration of exercise required to alter the gastrointestinal mucosa has not been reported. We used 42 sled dogs to test the hypothesis that the magnitude of exercise-induced gastrointestinal mucosal dysfunction is related to exerci...

The purpose of the study reported here was to describe the bioavailability and pharmacokinetics of acyclovir after intravenous and oral administration to horses. Six healthy adult horses were used in a randomized cross-over study with a 3 x 3 Latin square design. Three treatments were administered to each horse: 10 mg of injectable acyclovir/kg of...

Humans undergoing intense exercise exhibit transient microalbuminuria. Previous studies have shown that swimming, but not running, induces microalbuminuria in dogs. In this study, urine samples were collected from nineteen well-conditioned Alaskan sled dogs and analysed by the Heska ERD-Screen Test for microalbuminuria. None of the dogs has microal...

To determine the depletion of muscle glycogen during five consecutive days of endurance exercise in Alaskan sled dogs consuming a high-fat, low-carbohydrate diet. Forty-two fit Alaskan sled dogs were used in the study, of which six dogs served as nonexercising control animals. The remaining 36 dogs ran 160 km x d(-1) for up to 5 d while consuming a...

Athletes who perform repeated exercise while breathing cold air have a high prevalence of asthmalike chronic airway disease, but the mechanism linking such activity to airway inflammation is unknown. We used a novel animal model (exercising horses) to test the hypothesis that exercise-induced chronic airway disease is caused by exposure of intrapul...

Repeated strenuous exercise while breathing cold air is believed to induce chronic airway inflammation and hyperreactivity, a condition referred to in humans as ‘ski asthma’. However, the time course of development and resolution of ski asthma is unknown. We have previously shown that multi-day aerobic exercise induces airway inflammation and hyper...

Racing Alaskan sled dogs develop exercise-induced airway inflammation, similar to that reported for elite human athletes participating in cold-weather sports. These human athletes also have airway hyperresponsiveness, but airway function in sled dogs has not been measured. To compare respiratory mechanical properties in trained, rested Alaskan sled...

Sustained strenuous exercise has been shown to produce gastrointestinal disease in athletic species, but the causative factors remain unknown. Since exercise results in oxidative stress and hypercortisolaemia, we tested the hypothesis that oxidative and physiological stress cause gastrointestinal disease in racing Alaskan sled dogs. Dogs from three...

We assessed gastric and intestinal permeability and performed gastroscopy to evaluate the effects of sustained strenuous exercise on the gastrointestinal tract in racing sled dogs. Three teams of racing Alaskan sled dogs were examined approximately 1 week before and 24 hours after the 2003 Iditarod sled dog race (1,100 miles in 10 days). Each exami...

To the Editor: We read with great interest the recent article by Kotaru et al. ([10][1]), “Desiccation and hypertonicity of the airway surface fluid and thermally induced asthma.” Unfortunately, we must disagree with the authors' interpretation of their data. Contrary to the authors' assertions

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs...

Elite winter athletes have an increased incidence of asthma, the cause of which is unknown. Strenuous exercise, particularly while breathing cold air, results in airway cooling and desiccation. We used a canine model of hyperpnea with cold, dry air to test the hypothesis that repeated cooling and desiccation of peripheral airways can cause asthma-l...

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs...

Exercise-induced gastritis and gastric ulcers are common in humans and horses, and recently have been described in racing sled dogs. The cause of exercise-induced gastric disease is not completely understood in any species, but pharmacologic suppression of acid secretion is an effective treatment in humans and horses. Thus, we tested the hypothesis...

Athletes who play sports in cold weather, particularly skaters and cross-country skiers, have an increased prevalence of lower airway disease that is hypothesized to result from repeated penetration of incompletely conditioned air into the lung periphery. In this study, we investigated the hypothesis that canine winter athletes also suffer from inc...

In human subjects that exercise strenuously in cold weather, there is evidence that hyperventilation with cold air leads to peripheral airway cooling, desiccation and mucosal injury. Our hypothesis was that hyperventilation with cold air can result in penetration of unconditioned air (air that is not completely warmed and humidified) into the perip...

An 18-month-old Quarter Horse filly was evaluated because of dorsal displacement of the soft palate associated with epiglottic dysfunction that caused exercise intolerance and an abnormal respiratory noise. The abnormality of the epiglottis was corrected by use of a sedative dose of xylazine hydrochloride. There was no familial predisposition to hy...

Acute bronchoconstriction after isocapnic hyperpnea can be produced in most asthmatic individuals. However, the existence of a late-phase response is less certain. We used a canine model of isocapnic hyperpnea to test the hypothesis that this discrepancy is due to differences in the challenge threshold for the responses. Acute-phase and late-phase...

A canine model of exercise-induced asthma was used to test the hypothesis that the development of a late phase response to hyperventilation depends on the acute production of pro-inflammatory mediators. Peripheral airway resistance, reactivity to hypocapnia and aerosol histamine, and bronchoalveolar lavage fluid (BALF) cell and eicosanoid content w...

To compare clinical outcome, healing, and effect of tracheostomy in conventional incisional and carbon dioxide (CO2) laser techniques for resection of soft palates in brachycephalic dogs. Prospective randomized trial. 20 adult brachycephalic dogs. Dogs were randomly allocated into 4 groups, and 1 of the following was performed: palate resection by...

Winter athletes have an increased incidence of asthma, suggesting that repetitive hyperventilation with cold air may predispose individuals to airways disease. We used a canine model of exercise-induced hyperpnea to examine the effects of repeated hyperventilation with cool, dry air (i.e., dry air challenge [DAC]) on peripheral airway resistance (R...

Elongated soft palate is the most common respiratory disease in brachycephalics. During inspiration, an elongated palate obstructs the glottal opening, causing respiratory distress. Left untreated, elongated soft palate may be life threatening. We conducted a randomized, prospective experimental trial in 20 brachycephalic dogs with redundant or elo...

Aerosol delivery of medications has recently gained acceptance in large animal veterinary medicine. However, delivery of therapeutic aerosols currently relies on equipment modified from human use and delivery of medical aerosols may be adversely affected by the equipment design. In this study, we demonstrate the effect of typical large animal inspi...

Hyperpnoea of canine peripheral airways with dry air results in airway obstruction, mucosal damage, and inflammation. The purpose of this study was to evaluate the effect of repeated dry air challenge (DAC) on airway obstruction, reactivity and the development of airway inflammation in dogs. Canine peripheral airways received DAC (delivered under g...

Hyperventilation-induced bronchoconstriction (HIB) is a component of exercise-induced asthma (EIA) believed to result from the penetration of unconditioned air into the lung periphery. We used a canine model of EIA to examine the effect of hyperventilation on airway surface fluid (ASF) volume and osmolality, and to determine if the observed kinetic...

This case report suggests that a standard treatment for a similar condition in people may also be effective in confirmed cases of clostridial colitis in horses.

There are limited methods of assessing pulmonary function in horses at rest. We developed clinical techniques to measure gas exchange efficiency in horses and evaluated 3 groups of horses that were 1) asymptomatic based on auscultation with rebreathing, transtracheal aspirate cytology, and thoracic radiographs (n = 6), 2) asymptomatic at rest but s...

Of 17 foals born on a Thoroughbred breeding farm between March and April 1995, infection with equine herpesvirus type 1 (EHV-1) was associated with neonatal morbidity in 5 foals, 3 of which died or were euthanized. Morbidity and mortality were associated with pulmonary inflammation, and EHV-1 was identified in the lungs of the 3 foals that died. Al...

Hyperventilation of canine peripheral airways with dry air results in airway obstruction, mucosal damage, and inflammation. The purpose of this study was to evaluate the effect of repeated dry air challenge (DAC) on airway inflammation and hyperreactivity in dogs. Six male mongrel dogs (15-20 kg) were anesthetized for ∼2 h every 48 hours for 2 week...