2006-2007 Projects

Effects of handling and housing on trainability and behaviour of young racehorses.
Dr. S. Millman
Aggression and stereotypic cribbing, weaving and boxwalking, are common behavioural problems in the equine industry. Factors causing behaviour problems are complex and multidimensional, and young racehorses are particularly at risk. This research program explores prevalence and risk factors for behaviour problems, specifically stereotypies and aggression, in racehorses. Effects of caregivers and stall design will be explored in detail, and opportunities for improvement will be identified and assessed.

Correlation of MRI and necropsy findings in horses with suspected wobblers.
Dr. S. Nykamp
Wobbler syndrome or Cervical Stenotic Myelopathy (CSM) causing spinal cord compression is a common and devastating disease affecting horses, especially young Thoroughbreds and Standardbreds. It causes progressive ataxia which often results in juvenile wastage either by euthanasia or retirement from training. This study would produce the first atlas of MRI anatomy of the equine cervical spine and also develop Magnetic Resonance Imaging (MRI) criteria for diagnosing wobbler syndrome in horses. The importance of this study is the increased accuracy in the live animal diagnosis of CSM and increased knowledge in the development and progression of the disease.

Equine therapeutic cloning to treat cartilage defects/injuries in the horse.
Dr. D. Betts
In horses, it is generally recognized that cartilage lesions over a certain size do not heal spontaneously and no universal treatment of osteoarthritis (OA) or cartilage defects exists today. Equine models of cartilage repair utilizing bone marrow stem cells for transplantation and various other cartilage grafting techniques have showed promising results. Our objectives are to: 1) Derive and maintain equine embryonic stem (ES) cell lines from in vivo-derived blastocysts; and 2) Characterize the ability of putative equine ES cells to maintain the undifferentiated state and to differentiate into various somatic cell types, including chondrocytic cells (joint cartilage cells).

Evaluation of a novel laparoscopic technique for collection of full-thickness small intestinal biopsies in standing sedated horses.
Dr. L. Boure
Diagnosing and identifying the cause of colic remains a challenge for equine veterinarians and researchers. Full wall thickness of small intestinal biopsies is a procedure, which could provide valuable information used to diagnose chronic intestinal disease and to research the underlying mechanisms of intestinal disease (colic) in horses. Laparoscopy (the passage of a small device(less than one-quarter inch) through the abdomen to visualize the intestine) is a well-established minimally invasive surgical procedure in horses with insignificant post-operative pain and complication in horses. This study aims at establishing standing laparoscopy, as the standard technique to collect full-thickness small intestinal biopsies in horses. The project is linked to Dr. Geor's project (above).

Small Intestinal Adaptive Responses to Grain Feeding: Implications for Colic.
Dr. R. Geor
Both the level of grain-concentrate feeding and a recent (within 2 weeks) change in grain feeding have been identified as important risk factors for colic in horses. We believe that slow and/or inadequate adaptation of the horse's intestinal tract to increased grain feeding contributes to the development of colic. However, at present there is very little information on the ability of the horse's intestinal tract to quickly respond to dietary changes, such as an increase in grain feeding. Our studies will provide important new information on the time course, extent and molecular mechanisms of adaptations in small intestinal carbohydrate digestive and absorptive function in response to increased dietary starch, and assess potential variations in the expression of these functions in horses with some forms of colic.

Effect of mechanical stress on laminar junction remodelling.
Dr. J. Thomason
Mechanical stresses occur in hooves with every footfall, usually leading to adaptive responses over time. That is, the living and inert components of the hoof are remodeled to continue to withstand the imposed stresses. Like bones and muscles, the hoof has a need for some mechanical stimulation, but not too much or too little. Stresses in a beneficial range promote vascular activity and apparently adaptive remodeling. What this study will describe is how the laminar junction remodels in response to stress in a beneficial range. In conjunction with previous work on stresses and strains during different activities and on different substrates, the results will indicate the levels of exercise that are appropriate for good hoof function and structure.

Comparison of continuous infusion with intermittent bolusing of cefotaxime in neonatal foals.
Dr. J. Hewson
Septicemia is the most significant cause of foal illness and death in the neonatal period (< 14 days of age). This study will continue to advance intensive care of the septicemic neonate, with the hope to improve short-term and long-term survivability of these foals by optimizing medical therapy and minimizing potential sequelae. To this end, the information provided by this study will allow veterinarians to determine the optimal method of administration of cefotaxime in critically ill neonates to treat various complications of septicemia, including peritonitis, septic arthritis, and pneumonia.

Evaluation of a rapid test for identification of methicillin-resistant Staphylococcus aureus (MRSA) colonization in horses.
Dr. S. Weese
MRSA infection and colonization appears to be widespread and increasing in prevalence in North America. With any emerging infectious disease, rapid identification of affected animals and early implementation of infection control measures can prevent or reduce the introduction of the pathogen into a population; be it a farm, veterinary clinic or geographic region. While culture is now used to detect MRSA colonization, the availability of a test with a rapid turnaround time would allow for earlier identification of carriers. This study will evaluate a potentially valuable diagnostic tool that could be used to assist with MRSA eradication and control in horses.

Vaccination against Rhodococcus equi pneumonia of foals
Dr. J. Prescott
Rhodococcus equi pneumonia is an important bacterial infection of foals. Current control procedures are expensive, inconvenient, and at best ineffective. What is needed is an active vaccine but developing such a vaccine is challenging. We have used targeted gene mutation to develop mutants that are attenuated for pneumonic disease in foals. This year's project will evaluate the value of these mutants for their ability to immunize foals against infection. This research project is a continuation of previously approved projects which specifically target the development of a vaccine against this disease.

Does prognosis for future performance in cases of longstanding equine atrial fibrillation justify treatment by transvenous electrical cardioversion?
Dr. P. Physick-Sheard
While drug therapy is often effective in the treatment of recent onset atrial fibrillation (AF) in the horse and carries an excellent prognosis, the prognosis for horses with longstanding AF (>4 months) is generally considered to be poor. A newly developed technique at the OVC called transvenous electrical cardioversion (TVEC) was shown to successfully treat AF. However in cases of up to seven years duration - such cases would most often be described as untreatable. The objective of this study is to determine whether horses with longstanding AF that are successfully treated with TVEC will subsequently remain in normal heart rhythm through training and return to regular athletic activity.

Arrythmias, poor performance and sudden death in racehorses.
Dr. P. Physick-Sheard
Cardiac arrhythmia is considered to be a common cause of poor performance in racehorses. Clinical manifestations range from mild reduction in performance to sudden death or collapse, dramatic and unfortunate events not only because of animal loss and welfare concerns, but also through adverse effects on the viewing public. Cardiac rhythm in normal horses immediately preceding and following a race has not been documented. Obtaining electrocardiographic recordings on race horses would establish the range of "normal" rhythm variation during this time period and the potential for sudden onset of cardiac arrhythmia.

Prospective evaluation of the presence of Salmonella spp. in horses housed at 4 different racetracks and horses admitted to a veterinary teaching hospital in Ontario, and the possible role of previous antibiotic treatment.
Dr. H. Staempfli
Outbreaks of salmonellosis in hospitalized horses pose a high risk for equine patients, and have been associated with economic loss for both the clients and the hospitals. Salmonella has been shown to cause nosocomial disease, but in many cases it is difficult to determine if silent carriers had an occult infection present before admission to a veterinary hospital facility, or if the infection is truly hospital-acquired. Horses that may shed the bacteria in their feces and remain asymptomatic become a source of infection for susceptible horses exposed to some of the associated risk factors, which are constantly present in horses that are hospitalized. The purpose of this study is 1) to monitor for shedding of Salmonella spp upon admission of horses with a presenting complaint of gastrointestinal disease (colic) at a veterinary teaching hospital in Ontario and 2) To test for shedding of Salmonella spp in a representative sample, at 4 different racetracks in Ontario with the purpose of determining its prevalence.

Comparing track surfaces using accelerometry and strain meeasurements on the hoof of as biomechanical indicators of the hoof track interaction.
Drs J. Thomason and A. Cruz
The general aim of this study is to make an initial comparison of the three surfaces (common track surface: dirt, turf and PolytrackTM), and to provide for future work, a practical and repeatable method for assessing whether high-speed exercise on specific track surfaces contributes to wastage, either catastrophic breakdown or by causing lameness. The first study objective is to investigate the potential of a method for quantifying aspects of hoof-track biomechanics in race quality Thoroughbreds as they train at speed. The method uses established technologies of accelerometry and hoof strain measurement in a novel combination, which is practical for use under relevant circumstances. The second objective is to compare three types of common track surface: dirt, turf and PolytrackTM. There is a move to the artificial surface in many North American jurisdictions, including major Ontario tracks. The consistent behavior of the synthetic surface around the track, and in all weather conditions are among its advantages.

Effects of intravenous furosemide administration on lung fluid dynamics in exercising horses.
Drs L. Viel and M.Vengust
Horses develop high pulmonary pressures during exercise, which may cause pulmonary capillary stress failure and rupture-induced extravasation of red blood cells (RBC) into the alveoli, commonly known as exercise-induced pulmonary haemorrhage (EIPH). Current knowledge does not provide solid information how treatment with furosemide prevents occurrence of EIPH and more so if it does at all. We have recently developed a method that can quantify fluid movement in the pulmonary vasculature. Therefore, the purpose of this study is to provide new and comprehensive evidence of in vivo fluid dynamics in lungs of horses with and without furosemide treatment before strenuous treadmill exercise.

Role of the embryonic capsule in the success of early pregnancy.
Dr. K. Betteridge
Our research is aimed at understanding how an early equine conceptus becomes immobilized ("fixed") in the uterus and how this process fails in mares that lose the conceptus before it is fixed. Until day 15, the normal conceptus is enclosed in a sialylated oligosaccharide capsule through which various transport proteins deliver nutrients to the embryo. After day 16, the normal capsule loses sialic acid and the proteins bound to the capsule change rapidly. These studies should enable us to identify the main proteins involved in the transport of nutrients to the embryo and attachment to the uterine lining during the establishment of early pregnancy in mares. Some proteins that are more or less abundant in failing pregnancy may be useful as diagnostic biomarkers of health or infertility, or may lead to treatments that prevent early embryonic loss in mares.

Laparoscopic ultrasound for imaging abdominal organs in standing sedated normal horses: evaluation and comparison with transcutaneous ultrasound.
Dr. L. Boure
Horses affected with abdominal diseases are a diagnostic challenge for the equine veterinary surgeon. Most of the currently available minimally invasive diagnostic tools such as rectal examination, ultrasonography, and exploratory laparoscopy are associated with limitations and/or complications. Over the past recent years, laparoscopic ultrasound imaging technique (LUS) has been used in people and it has improved clinicians' ability to diagnose and treat several chronic or occult abdominal diseases. The present study aims at both comparing trans-cutaneous ultrasound (TUS) and laparoscopic ultrasound (LUS) for the assessment of the abdominal cavity in horses and establishing laparoscopic ultrasound as a valuable minimally invasive diagnostic procedure for the assessment of the abdominal cavity in standing sedated horses.

Stem cell therapy to treat cartilage defects and injuries in horses.
Dr. D. Betts
In horses, it is generally recognized that cartilage lesions over a certain size do not heal spontaneously and no universal treatment of osteoarthritis (OA) or cartilage defects exists today. Equine models of cartilage repair utilizing bone marrow stem cells for transplantation and various other cartilage grafting techniques have showed promising results. The recent isolation and derivation of stems cells of embryo and umbilical cord origin in various species has generated renewed efforts in transplantation based therapies. The objectives of this study are to derive and maintain equine stem cell lines from in vivo-derived blastocysts and umbilical cord blood; and characterize the ability of these putative equine stem cells to differentiate into various somatic cell types, including the chondrocytic phenotype in vivo and in vitro.

Clara cell secretory protein in equine recurrent airway obstruction.
Dr. D. Bienzle
Recurrent Airway Obstruction (RAO) or inflammatory airway disease is a common lung disease of stabled horses. Affected horses are unable to race or perform as show horses. Current treatment options are limited for fully restoring performance. Despite recognition of the disease over centuries, precise understanding of the pathogenesis and effective treatment are lacking. This study will establish a robust experimental disease model that will allow reproducible aerosol challenge of animals with a standard mixture of microbial and particulate matter and secondly, it will assess treatment of affected horses with recombinant equine Clara cell secretory protein (CCSP), which has potent anti-inflammatory properties.

Methicillin-resistant Staphylococcus aureus (MRSA) colonization in equine practitioners: Prevalence and risk factors.
Dr. S. Weese
Methicillin-resistant Staphylococcus aureus (MRSA) is emerging as one of the most important bacteria in human medicine, and is becoming an important cause of disease in people in the community. MRSA infection of horses and horse personnel appears to be an emerging problem. Risk factors for MRSA acquisition by equine veterinarians are not known. A better understanding of this could help modify standard infection control measures to decrease the risk of veterinarians acquiring MRSA, and therefore decrease the risk of veterinarians developing disease or infecting other horses. This study aims to help characterize the prevalence and epidemiology of MRSA in equine veterinarians attending a major international equine veterinary conference.