Mark Revenaugh, DVM, of Northwest Equine Performance, in Mulino, Oregon, offered his perspectives during the 2022 American Association of Equine Practitioners (AAEP) Convention, held Nov. 19-22, in San Antonio, Texas. He has set up a small laboratory in his clinic to make PRP in-house and has nearly 15 years of experience using this therapy.

Practitioners and labs prepare PRP by separating liquid and solid parts of blood, which produces a product with a platelet count above that of whole blood.

Basic considerations when choosing a conventional PRP system include:

• Does it fit in your truck?
• Is it durable?
• Whether it’s a closed system, which is important for preventing infection in the field.
• The cost of the system and its kits.

Then Revenaugh posed additional questions:

What does the system produce? What are the PRP values, and are they consistent? “A few years ago, my colleagues and I started measuring the values our respective systems were producing and were quite dismayed to find the numbers advertised were seldom actually represented by our measured values,” he said. “Furthermore, some systems were highly inconsistent. On one horse you might have a high concentration, and on another horse you’d have a low concentration. This was an alarming discovery.”

Does PRP work? The research into PRP’s efficacy is conflicting. Revenaugh said the main reason is there are many types of PRP preparations (e.g., red-blood-cell rich, leukocyte-rich, platelet lysates, etc.) available. Plus, the doses used in PRP studies aren’t consistent, so a lower dose might produce a markedly different response than a higher dose. “If we don’t know the correct dose for platelet treatments, it is not possible to discuss its efficacy,” he said. “It’s a little like concluding that penicillin does not work because in some studies it was not effective at an ultra-low dose.”

What platelet numbers is the system producing? The total volume of the blood you’re harvesting will affect this figure, said Revenaugh. “If you’re harvesting a larger volume of blood, there are more platelets to capture. It’s quite simple that way,” he said. So if you have a system that concentrates well but only accepts a small amount of blood, you’re inevitably going to have a small number of platelets in that system.

Do we know an optimal PRP dosage? The literature also has conflicting information on dosing. Even though veterinarians have been using PRP for more than a decade, the industry still hasn’t developed standard protocols and dosing.

“It’s still a new field,” said Revenaugh. “We’re really young in this process, and we need to stay vigilant if we want to move the field forward. We need to do our homework, we need to figure out the correct dosage, frequency, and indications of the products were using. This process can be surprisingly challenging but will ultimately lead us to better outcomes.”