2009-2010 Projects

Evaluation of Two Sedation/Analgesia Protocols to Assist Ventilatory Support of Critically Ill Equine neonate
Dr. C. Kerr

This study will be the first step to objectively developing ventilatory strategies and other novel therapies, such as exogenous surfactant therapy, for the critically ill foal in the future.

As in critically ill human and small animal patients, premature and/or critically ill foals often have respiratory failure that requires prolonged ventilatory support to improve their chance of survival.

In order to receive ventilatory support, animals may require sedation or general anesthesia depending on their underlying disease. Unfortunately, considerable variation in the efficacy and safety of different sedative/analgesic agents exist between species and age groups within a species. These differences make extrapolation of information regarding these drugs from the human or small animal literature to the foal difficult. To date, no controlled investigations evaluating different strategies for ventilatory (including surfactant therapy) and sedative/anesthetic management of foals requiring prolonged mechanical ventilation have been reported.

The specific objective of the current investigation is to evaluate two different sedative/analgesic protocols with the goal of optimizing the ability to provide ventilatory support and to improve the survival rate in critically ill foals.

At the present time, the Ontario Veterinary College is the only veterinary hospital that can provide prolonged ventilatory support of small animals in Ontario. While we are currently successful at providing prolonged ventilatory support for critically ill small animal patients in Ontario, at this time, no guidelines or protocols exist for the management of critically ill foals in our hospital.

Expression of cytokines following extracorporeal shockwave treatment in the horse
Dr. J. Koenig

Shock wave treatment has been shown to have beneficial effects on wound and tendon healing in horses. The exact mechanisms by which shock waves influence healing remain unknown, but alteration in the production of inflammatory mediators and cell substances such as transforming growth factor (TGF) ?, leading to new vessel growth and tissue regeneration, have been demonstrated.

Horses have a weak and prolonged inflammatory response after trauma, which is thought to be responsible for excessive scar tissue formation in horses. Currently, bowed tendons are shockwave treated 4 weeks after the injury, once the inflammatory phase is over; however, in people the current recommendation is to shock wave treat tendon injuries early, because the quality of repair is better.

It is unknown how shockwave exerts its action in horses, therefore we want to evaluate if shockwave treatment increases the levels of inflammatory cell substances in equine skin cells. This will allow us to better direct shockwave treatment in cases of tendon injuries or wound healing.

The use of intravenous lidocaine with field anaesthesia and analgesia practices for castration in horses
Dr. M. Sinclair

This study is relevant to the equine practitioners in Ontario as they typically perform field surgeries. Overall it is relevant to the equine industry to compare current equine field anesthetic techniques and promote optimal and safe anesthetic and analgesic practices for horses overall.

Field anesthesia in horses is used to permit minor surgical procedures. Typical anesthetic field injectable techniques includes; pre-medication with an alpha2-agonist followed by ketamine and diazepam intravenously. Under these anesthetic regimes horses may still respond to surgery necessitating additional injectable doses of the anesthetics, which may be difficult to administer quickly by the sole field veterinarian performing the surgery.

The ideal anesthetic and analgesic technique for the field situation has not yet been defined to reduce the need for additional injectable doses and maintain safety. Other attempts by the practitioner to provide analgesia and supplement the field anaesthetic regime include butorphanol administration, intra-testicular local anesthetic injection and non-steroidal anti-inflammatory administration.

In a veterinary hospital setting, lidocaine single boluses and/or constant rate infusions are commonly administered during inhalant anaesthesia to lower inhalant concentrations, stabilize the anesthetic depth, promote or maintain gastro-intestinal motility, and potentially supplement analgesia. The benefits of using lidocaine with injectable anesthesia for field surgeries, has not been fully explored.

Further research is warranted to determine the full advantages and disadvantages of systemic lidocaine as an anesthetic and analgesic adjunct in field conditions, impact on recovery quality, ideal dose of lidocaine, and plasma levels of lidocaine with an injectable anesthetic regime and other common field anesthetic techniques.

Devising a method for examining limb mechanics under racing conditions: a pilot study
Dr. J. Thomason

The aim of the present proposal is to identify potential measurements under laboratory conditions, and to validate and calibrate them against other informative measurements that cannot be made on the track.

High-profile breakdowns such as those of Barbaro and Eight Belles have raised the preexisting concerns of the racing industry and regulatory organizations to new heights. A great deal of research effort is being expended to identify risk factors and causes of such breakdowns with the goal of preventing, or at least minimizing the occurrence, of catastrophic injuries. Many of the risk factors relate to activities of the horse before it reaches the racing track, but it cannot be avoided that catastrophic injuries occur during races.

The long term aim of our research is to be able to make measurements on horses during races (or high intensity training) that may help explain the mechanical circumstances under which such injuries occur.

From the results of this pilot study, we would develop electronic equipment for use in the field that would make measurements related to the forces acting on bones and muscles under conditions of high performance. The benefit to the racing industry in Ontario and other jurisdictions is the hope for reduction in the frequency of fatal or debilitating injuries during intense training or races.

Identification of bacteriophages for elimination of Streptococcus equi and methicillin-resistant Staphylococcus aureus (MRSA)
Dr. S. Weese

This study will screen various sources for the presence of bacteriophages with effects against MRSA and S. equi. Bacteriophage therapy could be very important for the equine industry by providing a completely safe yet effective means of controlling these two bacteria, thereby decreasing the impact of infections, reducing carriers that are sources of infection and speeding response to outbreaks.

Methicillin-resistant Staphylococcus aureus (MRSA) is a drug resistant bacterium ('superbug') that is an important cause of disease in horses and humans. Streptococcus equi is the cause of strangles, an important and highly contagious equine disease. Control of both of these bacteria can be difficult and both are widely dispersed in healthy horses internationally. Methods to eliminate carriage of these bacteria from healthy horses, which are important sources of infection, are important aspects of infection control, but can be difficult.

Further, non-antibiotic approaches to treatment of these diseases are desirable because of the potential for adverse effects (i.e. severe diarrhea) and antibiotic resistance, which can be associated with antibiotic use in horses. One approach is the use of bacteriophages; viruses that only infect bacteria. While harmless to animals, certain bacteriophages have the ability to rapidly kill different bacteria.

If bacteriophages that are effective against MRSA and S. equi are identified, they could be a useful treatment measure for elimination of carriage of MRSA and S. equi, as well as treatment of active infections and killing of these bacteria in the farm environment.

Effect of local anesthetic deposition into structures of the foot on subsequent magnetic resonance images
Dr. N. Cribb

Our project will scientifically determine how long to wait, and ensure that false findings are no longer made nor are incorporated into theories on disease processes, which will ultimately delay time in finding a prevention or cure for conditions of the foot.

Ninety percent of forelimb lameness is in the foot and magnetic resonance imaging (MRI) provides the gold standard for diagnosing foot problems. Because MRI is so detailed, small anatomical variations are seen and their significance can only be interpreted with nerve and joint injections.

Nerve and joint injections of local anesthetic must be performed prior to the MRI to localise the lameness and allow the correct MR images to be taken. However, the injection itself or inflammation caused by the injection is seen on MR images if performed too soon after the lameness exam and these artifacts (or false findings) can be incorrectly diagnosed as the cause of lameness.

Such artifacts can also be seen on radiographs, ultrasounds and bone scans. Research already performed investigating artifacts on bone scans has given us clear guidelines on how long to wait between injections and bone scan. We do not know, however, how long to wait between performing a detailed lameness examination and doing an MRI examination.

Veterinarians are currently at risk of either making false findings on MRI if we do not wait long enough, or causing a horse unnecessary suffering, or taking precious time out of work and training if we wait for too long.

Diffusion of Cryoprotectants into equine embryos
Dr. T. Chenier

This research proposes to continue this investigation of the relationships between placental morphology and breeding history and management. This will benefit the Ontario Horse Industry by determining if there are breeding practices that contribute to umbilical cord torsion or other placental conditions in the mare. A reduction in the rate of fetal losses would be of economic benefit to all horse breeders.

Early embryonic death, abortion and stillborn fetuses represent significant losses to the equine breeding industry. Approximately 18% of early confirmed pregnancies result in embryonic death or abortion, and 4-5% of mares checked pregnant in October (at 5-7 months gestation) fail to produce a live foal the following spring.

The most common non-infectious cause of abortion in mares is umbilical cord torsion. This pheonomenon is associated with excessive umbilical cord length. Most breeders would assume that cord torsion is not preventable, however a preliminary study by investigators at the University of Guelph found significant association between cord length and placental blood vessel pattern, fetal cross-over during pregnancy and pre-breeding status of the mare.

Twin pregnancy often ends in abortion and for this reason one twin is usually crushed at 14-18 days of age. However, having a twin crushed may result in aberrant blood vessel patterns in the remaining placenta supplying the remaining embryo.

Continuing Projects:

Mechanisms of maintenance and loss of early pregnancy

Investigator: Dr. K. Betteridge

Magnetic resonance imaging evaluation of SPIO labeled equine mesenchymal stem cells and in vivo tracking SPIO labeled equine stem cell therapy in tendonitis model

Investigator: Dr. R. Cruz

Equine rhinitis A virus (ERAV). Molecular characterization and pathogenesis in the airways of experimentally infected pony foals

Investigator: Dr. L. Viel

Functions of equine clara cell secretory protein

Investigator: Dr. D. Bienzle

Arrythmia involvement in poor performance

Investigator: Dr. P. Physick-Sheard

Proliferate potential, tri-linage potency and allogenic immunogenic evaluation of equine cord blood stem cells

Investigator: Dr. D. Betts

Comparison of cardiovascular function in isoflurane-anesthetized horses administered lidocaine and medetomidine constant rate infusions during elective and emergency surgery

Investigator: Dr. A. Valverde

Determination of the presence of opioid receptors on bone tissue in horses and their binding to morphine

Investigator: Dr. A. Valverde