EHRF puts equine research teams to work

Grey horseThe Equine Health Research Fund has allotted more than $106,000 to six research projects that will ultimately help to improve veterinary health care for horses across Canada. The research will be conducted by researchers at the Western College of Veterinary Medicine (WCVM) over the next 18 months. As the work progresses, watch for more updates about some of these projects in future issues of Horse Health Lines

How do stem cells affect wound healing?
Drs. S. Barber, H. Sparks, A. Allen, V. Misra, J. Decoteau, S. Hendrick and J. Gordon
Wounds are a common, costly problem in horses that can lead to complications and diminished performance. Stem cell treatments may offer benefits including faster healing and better quality of repair.

This summer, a WCVM research team will work with two horses to test the healing effects of stem cell treatments. On one front leg of each horse, researchers will create a vertical row of six skin wounds in a standard size and location on the metacarpal area. Once they’ve completely healed, researchers will create similar wounds on the horses’ other front legs (the treatment wounds). Throughout this process, horses will receive pre-operative and post-operative antibiotics and phenylbutazone (bute).

Researchers will treat the horses’ first set of wounds with saline on the first day and then again on the fourth day following the procedure. The second set of wounds will be treated with 50 million autogenous mesenchymal stem cells (MSCs) at similar times after the procedure. The team will take photos of the top wounds on the horses’ front legs at standard intervals to record the rate and nature of wound closure. Other wounds will be biopsied once at four, seven, 10, 14 or 21 days post-surgery. Researchers will analyze the biopsies using histological and immunohistochemical tests as well as molecular assays that will characterize the nature of the inflammatory response and the effect of MSC on healing.

Tyrosine: potential treatment for equine recurrent uveitis (ERU)?
Drs. B. Bauer, L. Sandmeyer, B. Grahn, G. Forsyth, R. Bellone and Ms. Sheila Archer
Equine recurrent uveitis (ERU), an autoimmune disease that produces recurring inner eye inflammation, is the leading cause of equine blindness and is found most frequently in Appaloosa horses. TRPM1, the gene responsible for Appaloosa spotting patterns (LP status), is also essential to neural transmission in the retina and may affect susceptibility to ERU.

This study will evaluate the prevalence of ERU in Appaloosas and investigate its connection to accelerated coat de-pigmentation, a possible risk indicator for ERU. Using WCVM records, researchers will locate Appaloosas previously diagnosed with ERU to study their coats and assess the recurrence, severity and progression of ERU. The team will examine another 150 Appaloosa horses across Canada and conduct DNA testing to determine if LP status is significant.

Using 40 Appaloosa horses sorted by LP status and divided into two groups (control and treatment) researchers will conduct a clinical trial of tyrosine — an amino acid that helps produce the pigment responsible for hair and skin color. Results will show whether tyrosine supplementation improves the clinical signs of de-pigmentation and ERU.

What’s the best position for transcortical pins to repair fractures of long and short pasterns?
Drs. J. Carmalt and I. Roquet
Fragmented fractures of the long pastern (P1) and short pastern (P2) bones in horses are complicated to treat and often require the use of an external skeleton fixation device as a sole treatment or in conjunction with internal fixation techniques. Equine surgeons have successfully used transfixation pin casts to treat pastern (phalangeal) fractures, and most clinicians recommend replacing the transcortical pins as distal as possible on the horse’s limb.

Since no in vitro or in vivo biomechanical studies have been conducted to objectively evaluate these recommendations, this WCVM study will be the first to evaluate the optimal number and location for transcortical pins in the cannon bone. Using three groups of forelimbs from 15 equine cadavers, researchers will mechanically test three different placements of transfixation pin casts (using different numbers of pins) and two different breaking strengths. The team will take radiographs before and after mechanical testing to assess where the construct failed.

Findings will allow clinicians to decrease the complications associated with the number of pins used and their positioning along the cannon bone. The hope is that this information will potentially improve the prognosis of horses suffering from phalangeal fractures that have been managed with a transfixation pin cast.

Can Endo Stitch™ simplify laparoscopic surgery for nephrosplenic entrapment?
Dr. J. Bracamonte and T. Duke
Nephrosplenic entrapment of the large colon (NSELC) is a condition in horses with a high recurrence rate that requires surgery. The recommended treatment, minimally invasive laparoscopic surgery, is technically challenging and limited to equine surgeons with advanced laparoscopic skills.

An endoscopic suturing device (Endo Stitch™) has unique features that facilitate knot typing and intracorporeal suturing and would allow equine surgeons with basic laparoscopic skills to perform the procedure. They could routinely use laparoscopic closure as a preventive technique for horses with recurrences of NSELC or as a prophylactic procedure after the initial surgical correction.

Researchers will perform a standing left flank laparoscopy on four healthy mature horses using one laparoscope portal and two instrument portals. Using the Endo Stitch™ they will close the nephrosplenic space using a simple, continuous suture pattern. The research team will monitor the horses every six hours for the first 24 hours and then twice daily. One month later, surgeons will perform a second-look laparoscopy to evaluate the success of the procedure.

Is acupuncture a treatment option for horses with navicular syndrome?
Drs. S. Manning, K. Robinson, J. Bracamonte and T. Silver
Navicular syndrome, a debilitating, progressive disease, is a common cause of forelimb lameness that causes lesions of the navicular bone and its supporting/surrounding soft tissues. Since several structures within the heel may be involved, there are a number of recommended treatments including corrective shoeing and surgery, but they all have limited success. Although acupuncture, a non-invasive, drug-free solution, has been used for pain control, there is currently no scientific evidence to confirm its effectiveness.

The study includes 30 client horses diagnosed with navicular syndrome and placed into either the treatment or the control group. Prior to the trial, all horses will be evaluated using radiographs, clinical lameness evaluations and force plate analysis. A farrier will trim their feet, and they will remain barefoot throughout the trial. The treatment group will receive a total of eight treatments – electro-acupuncture (EA) and dry needle acupuncture (A) for 20 minutes twice weekly. All animals will receive lameness evaluations and force plate analysis during the study and then again two weeks after its completion, at which time they’ll also be radiographed.

What changes in endometrial and luteal tissues are associated with pregnancy?
Dr. Claire Card
Early pregnancy loss in mares is a costly and frustrating problem in the equine industry. Scientists believe a significant cause may be a breakdown in the critical process that triggers maternal recognition of pregnancy (MRP) and ensures continued endometrial support for the embryo while preventing the mare from going back into heat.

This study will use a novel ultrasound biopsy technique to investigate two essential tissues involved in MRP, the endometrium and the corpus luteum (CL). Using treatments proven to influence the endometrium’s receptivity (meclofenamic acid) and prolong the lifespan of the CL (oxytocin), researchers will compare tissue responses in six healthy mares over four treatment cycles: untreated cycling mare, untreated pregnant mare, meclofenamic-treated cycling mare and oxytocin-treated cycling mare.

The treatment mares will receive meclofenamic acid or oxytocin daily from day seven after ovulation until day 15. Researchers will determine pregnancy status on days 11 to 15, and they’ll biopsy luteal tissue at days 12 and 15 and endometrial tissue at day 15 in order to compare tissue responses.  By understanding the processes associated with MRP, scientists can develop better therapies for preventing early embryonic loss.

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