TEHRF research grants: 2017-18

The Townsend Equine Health Research Fund (TEHRF) has allocated more than $80,000 to five equine health research projects at the Western College of Veterinary Medicine (WCVM). All of the research work will be conducted by WCVM scientists and their collaborators over the next 24 months. Read the following research summaries for more details about each study.

Can veterinarians eliminate “roaring” in horses by removing tissue?

David G. Wilson, Michelle Tucker and James Carmalt, WCVM

Recurrent laryngeal neuropathy (RLN) or “roaring” affects 20 per cent of thoroughbred racehorses and other performance horses as well as 30 per cent of draft horses. RLN is a condition where part of the larynx collapses into the airway during exercise. This affliction limits a horse’s performance by making it difficult for them to breathe. In the racing industry, a horse affected by RLN means significant losses for its owner. A diagnosis of roaring alters an affected horse’s sale value and shortens its career on the racetrack.

Dr. David Wilson is a part of a research team responsible for the design of a new therapeutic procedure that has the potential to improve breathing in horses affected by recurrent laryngeal neuropathy. Photo by Debra Marshall.

Veterinary surgeons treat RLN by performing a prosthetic laryngoplasty, a surgical procedure that uses a permanent suture to pin (or abduct) the affected arytenoid cartilage out of the airway. However, about 17 per cent of equine patients require more surgeries after this procedure to correct over-abduction or loss of abduction. A larger percentage of treated horses also experience other complications — including wound infection, coughing, aspiration and pneumonia.

WCVM equine surgeons Drs. David Wilson and James Carmalt have designed a new therapeutic procedure that has the potential to improve an affected horse’s breathing ability while avoiding these surgical complications. By completely removing the collapsing portion of the larynx, the proposed procedure eliminates the need for a prosthetic and reduces the risk of infection.

In this study Dr. Wilson and a team of researchers will use cadavers to test this new treatment. If the proposed therapy shows promise, the next step will be to eventually test the surgery in live horses under race conditions.

Can stem cells from the umbilical cords of ponies speed up wound healing in horses?

Spencer Barber, Suzanne Mund, Ali Honaramooz, Bruce Wobeser, Daniel MacPhee, John Campbell

Skin wounds in horses heal more slowly than in ponies, and horses’ leg wounds are more susceptible to developing proud flesh (exuberant granulation tissue) that’s difficult and expensive to manage. The reason for this is that ponies’ initial inflammatory response to wounds is much greater than in adult horses. The result: ponies’ wounds heal faster and their leg wounds don’t develop proud flesh.

Dr. Spencer Barber and a team of WCVM researchers believe that if the inflammatory response of an adult horse can be manipulated to mimic that of a pony it will increase the rate of healing in that horse. Their theory is based on previous WCVM studies that investigated the behaviour of equine cord blood stem cells (multipotent mesenchymal stromal cells or MSCs) once they were injected into the jugular veins of horses participating in the research. Based on the team’s preliminary analysis of skin wound biopsies from the animals, it appears that injected stem cells do migrate to equine wounds. The team also identified b-arrestin 2, a protein that plays an important role in regulating inflammation.

In this prospective study, Barber and his team will continue their analysis of the wound biopsy tissues collected in their clinical study. Other researchers have already proven that stem cells promote healing in laboratory animals, but the WCVM team’s stem cell work with live horses is the first of its kind. Once their analysis is complete, WCVM researchers hope to determine whether stem cell injection can positively influence the quality of wound repair and speed up the healing process in horses’ wounds.

Researches Dr. Spencer Barber (left) and Dr. Suzanne Mund (right) believe stem cells from the umbilical cords of ponies can increase the healing rate of adult horses.

Can dexmedetomidine infusions reduce stress for horses undergoing surgery?

Tanya Duke, Masako Fujiyama, WCVM

Anesthesia and surgery cause significant stress for horses, and the rates of morbidity and mortality in horses are higher in comparison to companion animals. Problems such as low blood pressure, a lack of adequate oxygen and the fact that opioid drugs cause excitement in horses instead of sedation are contributing factors to the problem.

Previous research has shown that surgical stimulation and poor pain management in horses increases the release of stress hormones such as cortisol, increasing the length of time it takes for equine patients to heal after surgery. Cortisol concentrations are three times higher in anesthetized horses undergoing surgery than in horses that are only anesthetized and not having surgery.

In this study, Dr. Tanya Duke will investigate the ability of dexmedetomidine, a sedative drug given intravenously, to relieve pain and reduce stress in horses under anesthesia. The research team will test the drug’s effects on equine surgical patients both alone and alongside infusions of other pain-relieving drugs such as butorphanol (an opioid drug), remifentanil and with a ketamine/morphine control group. In all cases, the researchers will monitor the horses’ stress hormone response to the introduction of dexmedetomidine during surgery. The WCVM team hopes that results from this study will help to reduce surgery-related stress in horses and improve equine patients’ recovery after surgery.

Is doxycycline an effective alternative for treating infection in horses?

Patricia Dowling, Joe Rubin, Fabienne Uehlinger and Ronan Chapuis, WCVM; Scott Weese, University of Guelph

Today trimethoprim/sulfadiazine (TMPS) is the only antibiotic drug approved for oral administration in horses. When it comes to treating infections like Streptococcus zooepidemicus, the most common pathogen found in horses in Western Canada, a drug like penicillin is powerful, but its usefulness in treating infections is limited because it can’t be taken orally. The drug must be administered intravenously or through other parenteral routes — making it very difficult to treat infections in horses’ joints, tendon sheaths, internal lymph nodes and other secluded sites.

WCVM veterinary pharmacologist Dr. Patricia Dowling and a team of researchers will test the use of doxycycline (DXC), a common antibiotic drug used in human medicine. Previous studies have shown that DXC is clinically effective in horses (reaches high enough concentrations in cells and tissues). But so far, no one has tested its effectiveness in treating infection.

In this study, the researchers will use tissue cage models implanted on the necks of 10 healthy adult horses to develop an experimental S. zooepidemicus infection. The primary objective of this study is to understand how DXC moves through the horse’s body, and to determine its potential usefulness in treating this type of bacterial infection. As well, the researchers will assess DXC’s effect on the fecal microbiota of treated horses.

Does equine papillomavirus hold the key to preventing equine skin disease and cancer?

Bruce Wobeser, Sarah Greenwood, Dale Godson and Tasha Epp, WCVM

Papillomaviruses can cause certain cancers in certain species — including people and horses. Equine papillomavirus (EcPV) is connected to the development malignant skin tumours on horses’ genitals. Partial or complete amputation of the diseased genitals is the only treatment available, and it’s often unsuccessful.

Researchers know very little about when and how these viruses are transmitted between horses. Even less is known about how EcPV causes cancer. Previous research has identified seven types of EcPV and only one (EcPV-2) is known to cause cancer.

Over the next two years, WCVM veterinary pathologist Dr. Bruce Wobeser will lead a team of researchers as they conduct four prospective studies with integrated goals. The first study examines equine cancers — apart from genital cancers — for evidence of papillomavirus bodies. The second study will determine how common EcPV-2 infection is among Western Canada’s healthy horse population. The third study will examine connections between a horse’s PV status and the treatment it received. In the fourth study, the research team will characterize molecular interactions between proteins in the virus and proteins in the virus’ host (the horse).

The primary goal of this multi-phase study is to learn more about how EcPV develops so scientists can work on the next steps: learning how to prevent the virus and developing more effective therapies for horses diagnosed with cancer caused by EcPV-2.