Healing With Horsepower

During the Dec. 8 Sunrise Session “Healing With Horsepower,” presented by Zoetis, at the 2024 American Association of Equine Practitioners (AAEP) Convention, a panel reviewed recent study results on autologous blood-based products and their effects on equine joints and metabolic parameters.
APS—Disease-Modifying Effects?
Kyla Ortved, DVM, PhD, Dipl. ACVS, ACVSMR, associate professor of large animal surgery at University of Pennsylvania’s New Bolton Center, and colleagues investigated autologous protein solution’s (Pro-Stride® APS) effects on synovial fluid parameters and joint pathology scores in 18 horses with induced synovitis. The goal was to identify intra-articular (IA) therapies vets can use to intervene early in the progression of joint disease.
While APS didn’t alter treated horses’ synovial fluid parameters or decrease lameness or joint circumference compared to controls, it significantly decreased gross pathology and synovial membrane histopathology scores when compared to the normal joint.
“APS may have disease-modifying effects within the synovium that could have significant, long-lasting downstream effects on the joint,” said Ortved.
In a second study Ortved compared four autologous blood-based devices: Alpha2EQ (alpha-2-macroglobulin, or A2M), Pro-Stride APS, Restigen® PRP, and Arthrex ACP (autologous conditioned plasma). Her team sought to quantify A2M, immunomodulatory cytokines, and the growth factor TGFβ-1 for each in six healthy horses. They found APS had the highest A2M concentration and saw high concentrations of IL-1Ra, a potent anti-inflammatory cytokine, in APS and PRP but not the other products. They saw no significant differences between other cytokine levels in any products and found the highest concentration of TGFβ-1 in Restigen PRP, which she said isn’t surprising because it is high in platelets.
“This tells us that blood-based products do have different immunomodulatory and growth factor profiles, and that’s probably a reflection of the different concentration of platelets and white blood cells, and the different processing,” Ortved said.
APS and ACS Safe for PPID Horses
Will pituitary pars intermedia dysfunction (PPID) affect orthobiologics’ anti-inflammatory and, thus, beneficial properties? Valerie Moorman, DVM, PhD, Dipl. ACVS-LA, clinical professor in the University of Georgia College of Veterinary Medicine’s Department of Large Animal Medicine, and team compared pro- and anti-inflammatory cytokine concentrations from six PPID and six non-PPID horses before and after processing blood for APS and autologous conditioned serum (ACS). They found no statistically significant cytokine differences in any groups, suggesting PPID does not alter ACS and APS cytokine profiles, so they could be effective in PPID horses.
APS Has No Metabolic Effects
Intra-articular (IA) corticosteroids remain popular therapies for equine joint pain despite published research on their metabolic effects. Allen Page, DVM, PhD, assistant professor at the University of Kentucky’s Gluck Equine Research Center, and team recently investigated if orthobiologics could be a safer alternative.
They compared metabolic effects of IA triamcinolone acetonide (TA), APS, and a saline control on five metabolically normal horses and hypothesized that “compared to the saline and the Pro-Stride-treated groups, a single 9-milligram dose of IA triamcinolone will elicit changes in a variety of different parameters, including ACTH, cortisol, insulin, glucose, as well as some thyroid hormones,” said Page. “We also wanted to look at what the effects of those different treatments would be on the oral sugar test (OST) for insulin dysregulation and the thyrotropin-releasing hormone (TRH) test for PPID.”
They found TA had significant effects on ACTH, cortisol, glucose, and insulin levels; APS did not. They saw significant insulin increases even in normal horses.
“Use intra-articular triamcinolone with caution in insulin-dysregulated horses due to induced hyperinsulinemia,” Page said. “Pro-Stride might be a safer alternative for insulin-dysregulated horses.” He urged vets to perform OST and TRH testing before injecting IA corticosteroids.

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