2004-2005 Projects

Determination of the effective dose of glucosamine hydrochloride in the equine.
Dr. M. Hurtig
The purpose of this project is to determine whether glucosamine hydrochloride can achieve therapeutic serum levels after oral administration in the horse. Despite considerable evidence that glucosamine has biologic activity in high concentration in tissue culture models, there is no direct evidence that this nutraceutical is even absorbed by the horse, or, distributed in sufficiently high concentrations to reach joint tissues. Further the study will determine the dose response of glucosamine hydrochloride after oral administration to adult horses.

Evaluation of glucosamine and chondroitin sulfate levels in commercial equine oral joint supplements.
Dr. S. Weese
Because of the limitations surrounding current treatment modalities for osteoarthritis, many horse owners and trainers are employing alternative therapies, most commonly in the form of nutritional supplements. The nutraceutical industry, however, remains unregulated in North America. As a result, it is suspected that many equine nutraceutical products, including oral joint supplements (OJS) may be of poor quality, or may not contain the type or amount of ingredient listed on the label. The purpose of this study is to measure the amount of glucosamine and/or chondroitin sulfate in commercially available equine OJSs.

Effects of Detomidine on Gastrointestinal Transit Time in Horses.
Dr. C. Kerr
A syndrome where horses develop a range of signs including a decrease in appetite, decreased fecal output, and colic three to five days following anesthesia for elective surgical procedures is commonly reported. The objective of this study is to provide baseline data for the development of sedative (pain killer) and management practices that will help minimize alterations in gastrointestinal transit time in the horse which leads to colic re-occurrence.

Osteoarthritis: estrogens and cartilage interactions in the horse.
Dr. J. Raeside
Osteoarthritis is a common joint disease causing lameness in horses. No satisfactory treatment exists for longer-term resolution, though some progress is being made with both surgical and pharmacological approaches. Estrogens are responsible for many changes beyond the reproductive system; and an emerging concept is that some responses are due to special actions of estrogen metabolites formed in the target tissues themselves such cartilage in the joint. The study will address local metabolism of estrogen by cartilage and then examine the actions of estrogens on cartilage with a view to treatment, including cartilage cells in culture in preparation for grafting.

An epidemiological investigation of horse racing wastage due to musculoskeletal injuries in Ontario.
Dr. A. Cruz
The frequency and nature of catastrophic horse racing injuries and their associated risk factors has not been studied thus far in Ontario racehorses. With the Ontario Racing Commission death registry database, a questionnaire to study potential correlations between affected and unaffected horses about training methods, incidence of injuries during training, nature of injuries, shoeing practices and treatment methods will be developed.

Pharmacokinetics and Analgesic effects of Epidural Morphine in Adult Horses and Foals.
Dr. C. Kerr
Severe soft tissue or orthopedic injuries in both adult horses and foals patients are associated with a high morbidity and mortality rate. This is likely due in part to the inability to manage the pain associated with these injuries. Currently, effective pain control of the equine patient is difficult because of the limited efficacy and side-effects of the available agents. Epidural (injection into spinal space) administration of opioid analgesics such as morphine is routinely used in humans and has the potential to improve our current level of pain management for the equine patient and eliminate the undesirable side-effects caused by intra-muscular or intra-venous injections.

Blood neutrophil and pulmonary leukocyte function in horses with heaves and the effect of inhaled fluticasone propionate therapy.
Dr. J. Hewson
Impaired lung function due persistent airway inflammation is seen clinically as exercise intolerance or prolonged recovery from exercise. The key inflammatory cells, neutrophils, found in the airways of affected young horses, are poorly understood. Neutrophil activity in the lung will be related to clinical signs, pulmonary function, airway hyper-reactivity, adrenal suppression, and airway inflammation over time in non-treated and treated horses with inhaled corticosteroids.

Peptide receptors in the equine large and small intestine.
Dr. I. Sonea
Currently, treatment of equine gastrointestinal disease is mostly symptomatic: fluid therapy and pain-killers may control the signs until the gastrointestinal disturbance resolves on its own. However, because so little is known about normal and abnormal equine intestinal function, there are very few treatments that restore normal gastrointestinal motility, secretion or absorption in the horse. As part of a long-term program to investigate the mechanism of action of intestinal motility, absorption and secretion in the horse, this study will determine the type and distribution of special hormone and nerve control receptors on the gut leading to the identification of potential therapeutic targets.

Identification and prediction of canon bone fractures in 2 and 3 year old racehorses.
Dr. M. Hurtig
This project is part of a more comprehensive program designed to reduce musculoskeletal injuries at Ontario racetracks by improving the monitoring of horses and racetrack surfaces. In previous work, the Comparative Orthopaedic Research Group has established the utility of using accelerometers for monitoring shoeing and track conditions. The current proposal expands the examination of horses presented from the Ontario Racing Commission Death Registry program to establish the incidence and location of microfractures in canon bones. Quantitative Ultrasound (QUS), a non-invasive technology that can be used on living horses for assessment of bone quality, will be correlated with three-dimensional imaging to link speed of sound measurements with bone pathology.

The role of Clara cells in the pathogenesis of equine allergic airway disease.
Dr. D. Bienzle
Clara cells are specialized epithelial cells present in the terminal small airways of the horse. The cells have the property to secrete a surfactant like substance to keep the non-cartilagenous small airways open during expiration and have the ability to secrete protective substances against bacterial/viral infections. A protein called CC10, produced by those specialized lining cells is important in the regulation of lung inflammation. The cells producing this protein are destroyed in horses with "heaves". A diagnostic test for CC10 in blood and lung fluid is presently being developed.

Immunoquantification of collagen fibre type in the pulmonary airways of horses with heaves.
Dr. L. Viel
Equine Respiratory disease manifested as inflammatory allergic airway disease has the potential to severely limit the athletic capacity of performance in racing horses. The study is designed to first recognise and identify airway injury such as scaring of the airways caused by the continuous exposures to environmental pollutants (track / stable environment) and second to assist the veterinarian in establishing long term effective therapy to minimize permanent airway damage of those athletic horses.

Surveillance of equine influenza virus prevalence and antigenic drift in young performance horses in Ontario.
Drs. J. Hewson and L. Viel
One of the most common causes of viral respiratory infection in the young horse is influenza. As a result of virus membrane changes, previously vaccinated animals may develop the infection. Accurate identification of viruses during outbreaks is essential in order to monitor variants and thus explain vaccination failures. This study aims to develop a surveillance program in Ontario that will provide assistance to veterinarians in evaluating influenza risk as well as contributing to international surveillance and providing pharmaceutical companies with information that helps them produce suitable vaccines.

Characterization of nutritional factors affecting the rate of post-exercise muscle glycogen synthesis in horses.
Dr. R. Geor
The optimization of the energy supply in horses during athletic events is crucial. Muscle glycogen is the most important source and the replenishment of these stores is essential. This study addresses the factors affecting the rate of muscle glycogen depletion as well as dietary and feeding strategies that will assist in recovery post exercise. New information about the ability of the horse to digest different carbohydrates will be acquired and can be used as guidelines in formulating products.

Quantifying the hoof's response to loading during exercise: changes in external shape, growth rate and internal anatomy.
Dr. J. Thomason
Hooves experience the shock of hitting the ground as well as the increasing force when bodyweight is transferred to the leg. The active response of the hoof to many factors such as gait, speed, substrate etc will be examined. With this knowledge, it should be possible to predict and prevent hoof lameness due to mechanical aetiology.

Factors regulating ovarian follicular development and formation of anovulatory follicles in horses.
Dr. J. Petrik
Ovarian cyst formation in horses is a common and important reproductive disorder. A selected group of mares known to have a high degree of spontaneous cyst formation and non-cystic follicles are used as a model for the induction of cyst formation. Ovarian follicular fluid is collected and fluid components studied for their role in the production of follicular cysts.