EHRF Research Grants, 2013-14

Photo: Myrna MacDonald

Is fine needle aspiration an option for diagnosing equine skin disease?
Drs. Bruce Wobeser and Hilary Burgess

Skin disease, including both skin cancers and inflammatory conditions, is common in horses. Fine needle aspiration (FNA) is a technique commonly used to diagnose similar conditions in companion animals. It involves inserting a needle into the skin and extracting cells for microscopic observation. Although FNA is quick, effective and requires no anesthesia or sedation, it’s rarely used to diagnose equine skin disease.

Using 10 years of data from Prairie Diagnostic Services Inc. (PDS), Drs. Bruce Wobeser and Hilary Burgess will retrieve information regarding all equine skin FNA samples and surgical skin biopsies. They will then compare the frequency of use, the variability in use according to the suspected disease and the final diagnoses. A similar investigation will compare the frequency of FNA versus surgical biopsy in companion animals over the same period.

Wobeser and Burgess will also survey western Canadian veterinarians to determine their preferred method for diagnosing equine skin disease and their reasons for choosing or not choosing the FNA technique. The researchers will use results from this pilot project to develop.

How is equine herpes virus able to survive in cells?
Drs. Marko Kryworuchko and Katharina Lohmann

Equine herpes virus (EHV) infections are a major cause of disease in horses and have a huge economic impact on the horse industry worldwide. EHV is the cause of many respiratory and neurological disorders and can also cause abortions and deaths in newborn foals. Current statistics show that outbreaks of EHV are on the rise in North America and Europe.

Transmission of EHV is through respiratory secretions (droplets from coughing or snorting) and the virus is very hardy. Once infection is established, animals can harbour the virus in a dormant form for life. Current treatments for EHV aren’t particularly effective, likely because researchers have a limited understanding of how the virus is able to infect and divide inside horse cells.

In this study, WCVM researchers will investigate how EHV replicates in cells and how it may seize control of an immune defence mechanism called autophagy. Cells normally use this process to degrade and eliminate invading viruses and bacteria.

To complete their studies, researchers will measure and manipulate autophagy in equine respiratory epithelial cells that are infected with EHV in the laboratory. The research team will obtain tissue samples for this work from WCVM Veterinary Medical Centre patient donations.

If this team is successful in their research, the information they gather may help to improve current EHV treatments as well as to help develop new and more effective therapies in the future.

What tests can we use to detect tick-borne disease in horses?
Drs. Katharina Lohmann, Gili Schvartz, Hilary Burgess and Tasha Epp (WCVM) and Neil Chilton (U of S Department of Biology)

 The incidence of tick-borne diseases in horses appears to be increasing in Canada. The potential risk may increase as climate changes help to expand the tick species’ geographical range.

Equine granulocytic anaplasmosis (EGA) is caused by Anaplasma phagocytophilum bacteria while Lyme borreliosis (LB) is caused by Borrelia burgdorferi bacteria. Both are tick-borne diseases that are diagnosed more frequently in Canada. The bacteria causing EGA and LB are transmitted by Ixodes ticks are already present in some parts of Canada and can also be carried into Canada from the United States on migrating birds.

Current testing methods for EGA and LB may not be completely reliable: results from home tests and from a commercial laboratory have shown significant disagreement. While veterinarians diagnose EGA by examining a blood smear or through molecular methods in a lab, diagnosing LB is more difficult. Clinicians must rely on visible symptoms and blood tests in order to make a diagnosis of LB.

In this study, researchers from the WCVM and the U of S Department of Biology will examine the accuracy of some blood tests by comparing results obtained from different laboratories based on the same blood sample. They’ll also compare the management of horses that have or have not been exposed to EGA or LB to pinpoint scenarios in which horses may be at greater risk for tick-borne illnesses.

Results from this research project will give veterinarians more information about the accuracy of different testing methods for tick-borne diseases. This will ultimately help to improve the interpretation of EGA and LB data so disease exposure risk levels can be better monitored.

In the face of a drug shortage, how else can horses be anesthetized?
Drs. Tanya Duke, Barbara Ambros and Joe Bracamonte

When anesthetizing horses for surgery, veterinarians use a combination of drugs to improve results. Current protocols involve the use of the drugs ketamine and dexmedetomidine along with a muscle relaxant such as diazepam. Diazepam works to reduce muscle rigidity and excitement and improve the quality of the procedure. Ketamine is used to initially induce the anesthesia, and dexmedetomidine can be used to help maintain the anesthesia’s effect.

North American veterinarians are facing a shortage of the drug diazepam and that situation has forced practitioners to use alternative drugs such as propofol and alfaxalone. Initial anesthesia results from these two drugs look promising, so researchers at the WCVM plan to investigate whether propofol and alfaxalone could be used as a permanent replacement for diazepam.

Drs. Tanya Duke, Barbara Ambros and Joe Bracamonte will study the effects of propofol and alfaxalone combined with ketamine as a viable alternative for inducing anesthesia. They’ll also investigate whether propofol and alfaxalone can be combined with ketamine and dexmedetomidine for the improved maintenance of anesthesia.

WCVM researchers ultimately hope to replace the standard diazepam with propofol or alfaxalone. They plan to develop a protocol in which these two drugs can be used as part of a totally injectable anesthetic technique and to improve the quality of recovery from anesthesia. Results from this study will improve current equine anesthesia procedures and assist veterinarians during this drug shortage.

Photo: Myrna MacDonald

Can horses benefit from current human liver disease treatments?
Drs. Ahmad Al-Dissi, Andy Allen and Santhi Sridharan

Chronic liver disease (CLD) is a major cause of death in horses. The ability to treat CLD depends on how well liver function deterioration can be controlled. In humans, a protein called metallothionein (MT) is used in liver disease treatments to improve liver function and to prevent future injuries to the liver.

In humans MT reduces inflammation, decreases fibrosis (thickening of connective tissues) in the liver and promotes liver regeneration. Unfortunately little is known about liver defence mechanisms in horses, preventing veterinarians from using MT as a form of CLD treatment.

In this study, WCVM researchers will compare MT levels in normal and diseased horse livers to see if they correlate with the severity of the animal’s CLD. Their overall goal is to better understand the mechanisms of liver disease in horses.

If MT is proven effective in treating equine CLD, this will open doors for future liver disease treatments and give horses the chance to benefit from therapies already used in humans.

Can plant oil therapy prevent early pregnancy loss in mares?
Dr. Claire Card

Early pregnancy loss affects more than 10 per cent of mares, leading to frustration and economic losses for horse owners. In mares, a complex series of events must occur for pregnancy to be maintained. This entire process is referred to as maternal recognition of pregnancy (MRP).

The corpus luteum (CL), a hormone-secreting structure that develops on the ovary after an egg has been ovulated, releases progesterone (P4). P4 is necessary for the maintenance of pregnancy. If the mare isn’t pregnant, her uterus secretes prostaglandin F2α (PGF2α), a hormone that destroys the CL. During pregnancy, the embryo will secrete factors blocking the release of PGF2α, allowing the CL to be maintained and pregnancy to continue. But in some cases, PGF2α release isn’t accurately blocked, resulting in loss of the pregnancy.

MRP is not completely understood, but new reports have shown that administering plant oils into the uterus of a mare can suppress PGF2α secretion and assist in pregnancy maintenance. Plant oils contain a special type of fatty acid that may have effects on PGF2α synthesis.

During this three-year study, WCVM equine reproduction specialist Dr. Claire Card will investigate the effects of plant oils and the mechanism by which they act to maintain pregnancy on a group of healthy mares. Their results will be compared to other untreated mares in the study’s control group.

If researchers can better understand the processes associated with MRP, they can develop better therapies for prevention of pregnancy loss. This new information will assist in the overall care and reproductive health of horses.

What can be done to improve the outcome for horses with septic arthritis?
Drs. Joe Bracamonte, Andres Sanchez-Teran, Steven Hendrick, Hilary Burgess and Tanya Duke (WCVM), Luis M. Rubio-Martinez (University of Liverpool) and Brent Hoff (University of Guelph)

Septic arthritis is specific type of arthritis caused by an infection of a joint. It’s a very serious condition and can threaten the performance career and life of an infected horse. Up to 15 per cent of adult horses and 38 per cent of foals infected with septic arthritis won’t survive. Over half the affected horses won’t return to previous athletic activity.

For treatment to be successful, septic arthritis must be diagnosed as soon as possible and monitored closely. Veterinarians must rely on microscopic examination of joint fluids to determine whether disease agents are present in the joint. Administering antibiotics and repeatedly draining and flushing fluid from the joint (arthroscopic lavage or AL) are two important components of septic arthritis treatment and both cause microscopic changes to the joint fluid. The challenge is that these changes are similar to those caused by disease agents, making test results unreliable.

Recently the use of serum amyloid A (SA-A), a type of plasma protein, has been evaluated for use in diagnosing septic arthritis. SA-A increases significantly during sepsis and it could be used as a marker for septic arthritis in horses. Researchers from the WCVM, University of Liverpool and University of Guelph will be studying whether arthroscopic lavage has an effect on SA-A levels in horses with septic arthritis.

If the arthroscopic lavage treatment doesn’t affect SA-A levels, the protein could serve as a new, more reliable marker for evaluation of sepsis in a joint. This will help veterinarians to diagnose and treat septic arthritis more effectively and lead to better outcomes for infected horses.

What are normal reference ranges for respiratory tests?
Drs. Julia Montgomery, Katharina Lohmann, Hilary Burgess, Stephen Manning and Tasha Epp

Airway inflammation is a frequent cause of poor performance and exercise intolerance in horses. Early detection and treatment can prevent chronic respiratory problems.

Veterinarians base treatment decisions on cytology tests and bacterial cultures of airway samples obtained through two common tests:  tracheal wash (TW) and bronchoalveolar lavage (BAL). However, no one has scientifically established reference ranges characterizing healthy versus diseased airways nor has anyone determined a range of “normal” values based on age. This information is critical for diagnosis and treatment as well as for future research.

During this study, WCVM researchers will arrange healthy, client-owned horses into three age groups of 10 to 15 animals each: young horses (one to two years old), adult horses (three to seven years old) and mature adult horses (over seven years). Each animal will initially undergo a complete physical examination (including a re-breathing test where clinicians have the horse breathe several breaths into a plastic bag). If all signs point to a normal, healthy animal, researchers will conduct additional tests including the TW and BL tests.

Team members will evaluate the cytology of BAL and TW samples, analyze bacterial cultures on TW samples and group cytology results according to age. The study’s results will provide invaluable baseline for future projects. The project will also help researchers identify the next steps for future investigations of equine airway diseases.

More information about the study and its requirements for horses can be found on the WCVM’s website.