Study Indicates New Standards Needed for Evaluating Blood Clotting in Horses
Two Illinois faculty members who are boarded in veterinary emergency and critical care recently published their findings showing that the blood of horses differs substantially from that of humans and dogs when a diagnostic tool called thromboelastometry is used to assess the status of blood flow and coagulation. Their work should improve clinicians’ ability to use thromboelastometry effectively in the care of critically ill horses.
Through hemostasis, the body essentially forms an organic band-aid. Factors such as disease, medications, and other conditions can affect hemostasis, which is why doctors need ways to evaluate the status of this process in the patient (animal or human).
In horses, common diseases such as colic, colitis, endotoxemia, and sepsis are associated with alteration of the hemostatic pathway, leading to coagulation abnormalities in these horses. It is critical in these patients to have the ability to assess their current blood clotting situation for successful treatment.
Dr. Maureen McMichael and Dr. Pamela Wilkins, who is also boarded in large animal internal medicine, directed a study in order to further evaluate thromboelastometry for clinical use with horses. Dr. Stephanie Smith, a faculty member at the College of Liberal Arts and Sciences, as well as Dr. Tanya Rossi, a veterinary intern, also contributed to this study. Thromboelastometry is a method that allows kinetic observation, in real time, of clots forming and dissolving.
“There has been very little, if any, standardization of how this test is conducted,” says Dr. McMichael.
Thromboelastometry is useful for looking at the interaction of coagulation factors, anticoagulant drugs, blood cells, and platelets during clotting and fibrinolysis, the breakdown of clots. It uses conditions to mimic the flow of blood in veins in order to provide more precise results. Unfortunately there have not been dedicated parameters set for methodology and reference ranges in horses for this test.
In the study, Drs. McMichael and Wilkins determined how much of the clotting pathway occurs in citrated equine whole blood, and what effects this has on results of the thromboelastometry. Citrate is a compound added to blood to prevent clotting from occurring since often the time between taking the blood sample and conducting the test is delayed. When the time comes to run the test, the blood is recalcified so that it can clot again and be tested. The effect of the holding time, which is how long the sample is actually kept before conducting the test, was also evaluated.
The research team found that there were significant increases in the likelihood of the blood to coagulate as the holding period time was lengthened. They also found that there was a significant increase in pro-coagulant factor activity after a 30-minute holding time, and that there was a strong activation of the coagulation pathway during this time.
“Our study shows that horse blood is stimulated to clot much more quickly outside the blood vessels than is the blood of dogs or humans. Horse blood has a very strong contact activation, which may partially explain why very sick horses are prone to clot quickly with some diseases,” says Dr. Wilkins.
Conclusively, with this research it was determined that in order to achieve the best results for thromboelastometry studies, a profound outside stimulation was needed when using recalcified blood. Without some sort of stimulation, the recalcified blood should not be used to study the system of hemostasis in horses.
“Our study showed that a strong trigger will help minimize the differences present in many cases,” says Dr. Wilkins.
“We believe we have set a standard to allow comparison across research institutions,” adds Dr. McMichael.
Their findings, published in the February 2015 American Journal of Veterinary Research, will provide clinicians and researchers with a better set of data for use with this method of testing, resulting in more appropriate treatment and ultimately a better level of care for critical equine patients.
Horse Rehab Similar to Sports Therapy
What happens when an athlete is sidelined with an injured tendon, ligament, or a chip fracture of a carpal bone? Surgery may or may not be part of the treatment, but rehabilitation therapy most likely is—whether the athlete has two legs or four.
“Physical therapy and rehabilitation play an important role in performance enhancement, injury prevention, and restoration of full function during recovery from injury,” says Dr. Santiago Gutierrez-Nibeyro, an equine surgeon at the Veterinary Teaching Hospital. He is boarded in equine surgery and is a diplomate of the American College of Veterinary Sports Medicine and Rehabilitation.
“Similar to high-performance human athletes, performance horses frequently encounter musculoskeletal injuries of various severities. Restoration of functional limb movement is the key to recovery from these sports-related injuries,” says Dr. Gutierrez-Nibeyro.
Typically, a horse must be rested after an injury, and this period of inactivity causes “disuse atrophy”—a decrease in the size of a muscle, cartilage, ligaments, and so on. Inactivity also leads to decreased range of motion of the joints as well as shortening and decreased range of motion in the muscles.
Most horses that have been rested in a stall due to an injury have shortened limb excursion, lack of agility, and visible signs of discomfort once they are moving again. When horses undergo rehabilitation as their musculoskeletal system heals, these deficits can be lessened or prevented.
“The goal of rehabilitation is to restore the normal function of the musculoskeletal apparatus following injury while reducing the symptoms of injury and restoring range of motion and stretch,” explains Dr. Gutierrez-Nibeyro. “People board certified in equine rehabilitation understand the science behind the treatment: biomechanics, musculoskeletal and nervous systems function, and sports medicine.”
Many therapies are used to rehabilitate performance horses, he says, and they are essentially the same as those used in people during physical therapy or athletic training: the use of heat and cold, extracorporeal shock waves, electricity, laser, ultrasound, hydrotherapy, massage, acupuncture, stretching, chiropractic, hyperbaric oxygen, pools, under-water treadmill, and controlled exercise.
These therapies enhance normal limb and vertebral spine function, decrease soft tissue pain and inflammation, allow the animal to regain normal limb proprioception (awareness of body position), and restore normal muscle tone and elasticity, among other functions, just as they do in human patients.
“Unfortunately, scientific literature documenting the efficacy of the different physical therapies in horses is limited. However, published reports and clinical data are growing because physical therapies and rehabilitation are an active area of clinical research in veterinary medicine,” says Dr. Gutierrez-Nibeyro.
The horse’s caregiver often plays an important role in the rehabilitation treatment plan, he adds.
“Horses with involved caregivers tend to improve more rapidly. The caregiver may work with the injured horse at home to restore normal range of joint motion or limb movement by performing simple exercises or movements on a daily basis.”
Faculty Spotlight: Annette McCoy, DVM, PhD, DACVS
Annette McCoy, an assistant professor of equine surgery, joined the Veterinary Teaching Hospital in January 2015. Her research focuses on genetic susceptibility and risk factors for orthopedic diseases in horses.
What is your favorite thing about being a veterinary equine surgeon?
I really enjoy the variety of different cases we see—both lameness/orthopedic and soft tissue problems. I also love that surgery gives us the opportunity to really get in and “fix” certain things—it’s not that way for every case we see (sometimes we can only try to help improve things), but I really enjoy it when it happens.
What are you speaking on or publishing about?
I have two major areas of research right now. One is the investigation of genetic risk factors underlying orthopedic disease in the horse, specifically osteochondrosis (a developmental orthopedic disease), and the other is the investigation of genetic factors underlying the ability of horses to perform alternative gaits (such as the pace in Standardbreds or the running walk in Tennessee Walkers). Both of these projects currently use Standardbred horses as a model population, so I’m excited to be in an area where Standardbreds are popular.
What one thing do you think equine practitioners should be most aware of regarding your profession?
We’ve known for a long time that genetics play an important role both in the development of disease and in economically important traits (i.e., speed and other performance characteristics) of the horse. We are now reaching the point where we have the tools and resources to really start digging deeply into the genetic factors that influence these complex traits. The results of this work could have profound impacts on breeders, owners, and practitioners. However, our ability to do research in this field is driven by the sample sets that we can compile—thus, I am always on the lookout for individuals willing to contribute DNA samples for ongoing projects. Participation is as simple as collecting a single blood or hair root sample from horses that meet study criteria.
>> If you haven’t visited it for a few months, check out our revamped College of Veterinary Medicine website: vetmed.illinois.edu. We have a special section for referring veterinarians right on the homepage called “DVM Resources.” You’ll find links to our clinical specialists and referral services, continuing education, the Veterinary Diagnostic Lab, and more.
>> Anesthesiologists, join our highly productive and dynamic group dedicated to excellence in comparative research, resident instruction, and the practice of cutting-edge medicine for companion, production, and zoological species. We have an opening for a full-time clinical assistant, associate, or full professor in veterinary anesthesia and pain management. See more details and other veterinary positions at jobs.illinois.edu.
>> The Veterinary Teaching Hospital is conducting a new study to look for a better way to detect cardiac blood clots in cats. Computed tomography (CT) may prove a quicker, less stressful, lower cost procedure than echocardiograms and X-rays for cats with suspected heart disease. Cats that have heart disease and have been suspected to have a cardiac clot may be eligible to take part in the study and may receive a free echocardiogram and computed tomography scan. Call radiology resident Dr. Kyle Vititoe at (217) 649-6338 for inquiries or veterinary cardiologist Dr. Ryan Fries at (217) 333-5311 for an appointment.
More news: vetmed.illinois.edu/news
More clinical trials: go.illinois.edu/trials
TAGteach Seminar: Collaborating with Veterinary Professionals
Would your practice benefit from training that fosters staff consistency and communication while improving your patients’ and clients’ experience?
Dr. Kelly Ballantyne, a faculty member and a veterinarian whose practice is limited to behavior, is copresenting a cutting-edge seminar introducing the TAGteach methodology for low-stress patient handling and how it can enhance the overall experience for patients, clients, and staff in the veterinary environment.
Sunday, May 31
9 a.m.-5 p.m.
Medical District Veterinary Clinic at Illinois, Chicago
Learn more and register: http://tagteach.com/event-1906676
Executive Veterinary Program in Swine Health Management: Module 5
June 11, 2015
Fall Conference for Veterinarians
September 17-18, 2015
iHotel, Champaign, Ill.
Microsurgery Training Lab
September 28-October 2, 2015
Learn more: vetmed.illinois.edu/vet-resources/continuing-education