Orthobiologics have become popular in equine veterinary medicine, but there is some confusion. In this episode of the Disease Du Jour podcast, we chat with Kent Allen, DVM, ISELP Certified, about orthobiologics for horses.
The first topic we discussed is the difference in orthobiologics and regenerative medicine. It seems that orthobiologics are a part of regenerative medicine. However, orthobiologics are substances that come from the same animal they are used on. Some regenerative medicines come from donors or other sources aside from the horse they will be used on.
How Do You Choose?
We asked Allen—who has used orthobiologics and regenerative medicines on top-level horses since they appeared on the veterinary scene—how he chooses what to use on a case.
“There’s an algorithm we use that includes owner economics, the experience of the user, the science behind the product, issues, ease of use and other alternatives,” explained Allen. These can include platelet-rich plasma (PRP), bone marrow aspirate concentrate (BMAC), IRAP (interleukin receptor antagonist protein), and adipose-derived mesenchymal stem cells (cells from body fat).
Allen also noted that the science is growing with some products. “IRAPO was 1.0 when I first started using it,” said Allen. “Then there came other generations.”
Changes have not only been in better understanding the science, but in the production of some of these products. Some had to be obtained from the horse (bone marrow or blood), then taken to a laboratory for processing. That has changed today, with some products being stall-side and others being able to be frozen and thawed on-demand.
Allen said choice of product can depend on if you want to use it that day or come back in a week or two. Also, some products need to be produced in a more sterile environment than a barn.
He noted that some procedures—such as with the back and neck (a subject of another Disease Du Jour podcast with Allen)—work best using a specific centrifuge in a laminar flow hood in the clinic.
Allen said for out-of-clinic use he often selects leucocyte-rich PRP.
In the podcast, Allen described the variety of PRP products that are available to equine veterinarians today. He noted that with RBC-poor or WBC-poor PRP, you can generate a large amount of product. “That’s an advantage if you need to do a lot of injections,” stated Allen.
“There are 10,000 articles on PRP in human medicine, and less than 200 on PRP in horses,” stated Allen. “Some of the information is high-quality, and some is low-quality. And some is mixed!”
Allen advised veterinarians to understand that if PRP is being sourced from a young horse verses an old horse, the product might not be as good.
“It matters how you generate it and where you put it, in the clinic or not in the clinic,” stated Allen. “We use a ton of PRP.”
Regenerative Medicine 3.0
Allen discussed the different types of stem cells, how they are harvested, processed and used. He discussed bone marrow, fat-derived, dental pulp and allogenic” The latter two don’t have to come from the same horse.
He said one of the problems with the length of time it takes for labs to process products is that “the case might have changed in six weeks. The tendon might not have as much of a hole in it.”
Allen warned that he has had “flares” (non-infectious inflammation in a joint) because the horse’s body doesn’t recognize the things being injected.
Allen also discussed how the knowledge has changed of what is actually happening when you inject these products into a horse. “We call them signalers,” he said. “They ‘call out’ to the horse’s body to bring in stem cells.”
Regenerative Medicine 4.0
Alpha2 macroglobulin is an attempt to take PRP and fractionate it to only inti-inflammatory factors, explained Allen.
“PRP has anti-inflammatory and inflammatory factors,” he explained. “Sometimes you want inflammation to scar the tissue.”
Alpha2 macroglobulin is a natural product produced by the liver that is found in low concentrations in joints, explained Allen. Osteoarthritis creates a lot of proteases, so an anti-protease is good.
“For our use, it is as useful as corticosteroids,” said Allen. “It a nice anti-inflammatory product without the problems. Alpha2 macroglobulin is cartilage-friendly and it gets rids of inflammation. We can use it every six months on a horse with chronic inflammation in a joint, and you can freeze the remainder (of the product harvested).
He reminded veterinarians that PRP is “not freezer-friendly” and that amnion is dried.
Education and Use of Orthobiologics
Allen said while researchers and veterinarians don’t yet understand how some of these regenerative and orthobiologic products work, there have been breakthroughs in human medicine. “Vets have a couple too many choices, but that’s not a bad thing,” said Allen. “Each has its strengths in cases and areas (of the body).
He encouraged veterinarians to read literature, talk to colleagues and attend meetings where regenerative and orthobiologic medicines are discussed.
“They are all tremendous tools if they are put in the correct category and used in the correct case,” stated Allen.
About Dr. Kent Allen
Kent Allen, DVM, is the owner of Virginia Equine Imaging in Middleburg, Virginia. He received his DVM from the University of Missouri in 1979, and he has been practicing equine medicine ever since. Allen opened Virginia Equine Imaging in 1996 after selling the practiced he formerly owned in Arizona. Virginia Equine Imaging became the first privately owned and operated equine diagnostic imaging specialty clinic in the world. He had a vision to establish a practice that provides advanced diagnostic and sports medicine focused on the equine athlete in a way that had never been done before.
During his transition from Arizona to Virginia, Allen served as the head veterinary services coordinator at the 1996 Olympic Games in Atlanta.
Since moving to Virginia and establishing Virginia Equine Imaging, Allen has served as Chairman of the USEF Veterinary Committee, the USEF Drug and Medication Committee, and the Medication Sub Committee for the FEI. He served as the FEI Foreign Veterinary Delegate for the 1999 Pan American Games in Winnipeg, Canada, the 2000 Olympic Games in Sydney, and the 2012 Olympic Games in London. Allen also was the 2010 World Equestrian Games Official Veterinary Coordinator.
Allen is currently certified by the International Society of Equine Locomotor Pathology (ISELP) and serves as its vice president and executive director. He also serves as the volunteer chairman of the United States Equestrian Federation (USEF) Veterinary, Drug, and Medications Committees and on the FEI Veterinary and List Committees. Allen continues to see patients and impart his knowledge to veterinary interns and clients on a day-to-day basis, striving the share his knowledge with the equine industry both in his local community and around the world.