EHRF Research Grants: 2014-2015

Is SAA a reliable marker for septic arthritis therapies?

Drs. Joe Bracamonte, Andres Sanchez-Teran and Hilary Burgess, WCVM; Dr. Luis Rubio-Martinez, University of Liverpool; and Brent Hoff, University of Guelph

Septic arthritis, which is caused by an infection within a joint, is a common condition that can end a horse’s career — or even its life. The disease results in inflammation, degeneration, pain and loss of function of the affected joint.

Treatment options include flushing out the joint using an arthroscope or “through-and-through” lavage using needles. Veterinarians often use the through-and-through option because it’s more economical and produces good results. But diagnosing and monitoring septic arthritis can be challenging because practitioners have no way to definitively assess the effectiveness of treatments. These therapies may also cause changes to conventional inflammatory markers.

Dr. Bracamonte’s research team has recently shown that serum amyloid A (SAA) — a protein that’s naturally found in blood — is a reliable marker to assess the efficacy of arthroscopic lavage. In this project, his research team will determine whether SAA is also a reliable marker following through-and-through lavage therapy in a group of healthy horses. If results substantiate this theory, the protein could eventually become a standard tool for diagnosing, treating and monitoring septic arthritis in horses.

Developing a minimally invasive technique to test, monitor and treat PPID

Drs. James Carmalt and Andrew Allen, WCVM; Dr. Hall Schott II, Michigan State University; and Dr. Han van De Kolk, Euregio Laboratory, The Netherlands

Pituitary pars intermedia dysfunction (PPID), also known as equine Cushing’s disease, is a common occurrence in older horses. As more horses live longer, the rate of PPID is becoming more prominent and the demand for treatment options is growing.

PPID is caused by a tumour of the pituitary gland (a structure found within the brain). Clinical symptoms of the disease include excessive hormone production (which can trigger excessive hair growth), laminitis, excessive drinking and urinating, weight loss and redistribution of fat stores. While there’s no cure for PPID, owners can manage the condition with daily drug treatments.

Dr. James Carmalt and his research group aim to develop and refine a process for accessing the pituitary gland in live horses. It’s based on a technique that scientists have previously used to investigate the pituitary gland blood in normal horses. The WCVM researchers plan to insert a small catheter into a blood vessel on the side of the horse’s face and direct it toward the pituitary gland in the brain.

The research team has gained direct access to the pituitary gland in live horses and obtained blood samples. Their ultimate goal is two fold: to perfect a sampling technique that may allow early detection of PPID, and to develop a more effective treatment for PPID-affected horses.

Do horses with heaves have different microbiomes than normal horses?

Drs. Katharina Lohmann, Julia Montgomery, Hilary Burgess and Janet Hill, WCVM

Heaves, or recurrent airway obstruction (RAO), is a chronic inflammatory airway condition in horses that can drastically affect their overall health and performance and requires lifelong management.

Researchers of similar conditions in people have suggested that changes in the microbes (bacteria) found in the airways may be responsible for chronic inflammation. More specifically, certain microbes may trigger the immune system and cause inflammation.

Based on these findings, a WCVM research group proposes that the presence of different microbe populations — microbiomes — might also be associated with the development of equine heaves. Microbiomes are the collective group of microorganisms that are found within living animals, and these populations often vary in composition during healthy and diseased states.

To test their hypothesis, researchers will take lung, tracheal and blood samples from healthy horses as well as horses diagnosed with heaves. Members of the team will then compare the microbe species colonizing the trachea between the two groups of client-owned horses, looking at the total number of organisms, diversity and presence of potential harmful bacteria (pathogens).

This project aims to highlight differences between the microbiomes in the airways of healthy horses and horses with heaves. These results will help researchers gain a better understanding of the disease’s development and progression. It may also open new avenues towards preventive, diagnostic and treatment strategies in the control of heaves.

Using hormones to identify previous exposures to stress

Drs. Fernando Marqués, Carolina Durán, David Janz and John Campbell, WCVM

While the number of animal neglect and abuse cases continues to rise every year in North America, many cases go unreported and undetected. Cortisol – a natural hormone released during times of anxiety, pain or injury – is a well known indicator of stress that correlates to trauma, abuse or poor living conditions.

Previous research has discovered that examining hair cortisol concentrations (HCC) is a reliable marker for long-term stress in live animals. In many species, hair provides a linear record of cortisol levels over a long period of time and can be used to determine when stressful events have occurred in an animal’s life. Veterinarians routinely use saliva tests in horses, but in comparison, these tests only provide information about immediate and transient stress levels.

Led by Dr. Fernando Marqués, a WCVM research team will undertake a novel research project to determine if HCC can be reliably measured in horses — a species that hasn’t been included in previous HCC research. During their study, researchers will conduct a segmental analysis of hair collected from the tails of castrated and non-castrated horses. This process involves dividing the horses’ hair into small sections based on the distance from the body.

By looking at horse hair growth rates and the dates of when the animals were castrated (a stressful event), the scientists aim to determine if cortisol levels are a conclusive indicator to identify past stressful events in horses. Findings from this study will hopefully establish a non-invasive and definitive method for monitoring abuse and neglect in horses.

Investigating the mechanism of hormone imbalances in equine PPID

Drs. Suraj Unniappan, James Carmalt and Andrew Allen, WCVM

Dr. Suraj Unniappan is leading a second WCVM study of equine pituitary pars intermedia dysfunction (PPID) — a disease that stems from a tumour developing in a horse’s pituitary gland. Although there has been ample research dedicated to understanding the development of PPID, equine veterinarians and researchers still don’t have a good understanding of the exact hormonal changes that lead to PPID.

Unniappan and his colleagues believe that PPID development may be caused by changes in proteins (enzymes) that regulate the production of pituitary hormones. This process, which happens at the genetic and molecular levels, is gradual and progressive. Timely detection of these changes may result in early diagnosis and treatment of PPID before the onset of severe clinical symptoms – especially laminitis.

This study will focus on detecting specific enzyme alterations at the cellular and molecular levels that may be responsible for PPID. With this information, researchers will attempt to develop an early-stage definitive assessment for PPID based on hormone based biomarkers.

A potential therapy for equine laminitis

Drs. David Wilson, James Carmalt and Kathryn Carmalt, WCVM

Laminitis is an extremely common condition in horses that carries a very poor prognosis. The disease is triggered by inflammation and results in the separation and degradation of the hoof wall. It’s a painful, progressive disorder with limited treatments. Previous studies have shown that the separated layers of the hoof are quickly repaired in the early stages of laminitis. But once rotation of the coffin bone occurs, there is little potential for healing.

Dr. David Wilson and his research team are hoping to develop a surgical therapy that will slow down the progression of laminitis. During this study, the researchers will develop and analyze a surgical approach that will stabilize and prevent rotation of the coffin bone.

So far, they have calculated the rotational forces that occur around the hoof and have designed a method that uses surgical screws to “anchor” the coffin bone to the hoof wall and limit movement between the bone and the hoof wall. This procedure may allow for better hoof repair in the early stages of laminitis — something they believe is key in stopping the progressive deterioration of the hoof.

The research team will conduct a number of trials in equine cadavers and live horses to optimize the surgical technique. If the proposed research is successful, the researchers hope that this relatively inexpensive procedure will be adopted by veterinarians and applied in clinical practice.