Disease Du Jour: Immune System’s Role in Equine Osteoarthritis 

In this episode, Dr. Erica Secor discussed her ongoing research into equine osteoarthritis.
young horse with equine osteoarthritis
Young horses with developmental issues or joint trauma would likely benefit from a different treatment than the old horse with degenerative disease. | Getty Images

In this episode, Erica Secor, DVM, MS, Dipl. ACVS-LA, joined us to discuss her ongoing research into equine osteoarthritis. She talked about her studies on the immune system’s role in osteoarthritis as well as her work toward improving diagnostic capabilities and understanding how arthritis varies among individual horses. 

Immune System and Equine Osteoarthritis 

While we often think of our immune system as being responsible for battling illness, Secor said it also plays a role in maintaining nonpathogenic issues, such as osteoarthritis. She said many types of white blood cells and immune cells reside within joints, where they help maintain normal joint mechanics and joint fluid composition.  

“When we have insult to those joints, those immune cells both can try to help and heal whatever the insult was but can also shift and start contributing to worsening of that kind of pathology,” Secor explained.  

Secor’s research is focused on learning more about the interplay of how these immune cells function in health, what happens to them in disease, and how they contribute to osteoarthritis development in horses.  

Improving Diagnostic Capabilities for Equine Osteoarthritis  

Osteoarthritis tends to be a catch-all term. Horses have painful joints and characteristic cartilage thinning. “But there are a lot of different things that can actually incite that development of osteoarthritis,” Secor said.  

On one end of the spectrum, older horses often have cartilage degradation after years of use. On the other end of the spectrum, young horses with developmental issues or joint trauma can also experience osteoarthritis. “Ultimately, we characterize all of these as the same osteoarthritis, but the inciting factors can be very different,” Secor said.  

She is currently researching whether any diagnostic markers early in the development of the disease might pinpoint the exact mechanisms contributing to osteoarthritis. This would help veterinarians better tailor treatments to individual patients, since the young horse with joint trauma would likely benefit from a different treatment than the old horse with degenerative disease.  

Biomarker Discovery Using Synovial Fluid Proteomics 

Secor recently co-authored the paper “Biomarker Discovery Using Synovial Fluid Proteomics For Equine Osteoarthritis.” She discussed this study further in the episode.  

“One of the big hindrances we have in studying horses, and all equine researchers can appreciate this, is our lack of available testing,” Secor said. Therefore, many diagnostic tests and research methods rely on antibodies. In human or rodent research, you can find antibodies to pretty much anything, but horses are much more limited in what researchers can measure.  

“This proteomic-based approach is a relatively new method, and it’s really fascinating because there’s no species-specific reagents needed,” Secor said. “It’s really opened up what we can look at and discover.” 

The other interesting thing about the proteomics-based approach is researchers don’t need to go in with one marker in mind, Secor said. “We don’t necessarily need to go in and say, ‘I’m going to measure concentrations of Protein A in osteoarthritis horses and healthy horses,’” she explained. “We can say, ‘I’ve got a group of osteoarthritis horses and a group of healthy horses, and I want to know all the things that are different in the protein composition between these two groups.’”  

In their study, Secor and the other researchers used this approach to evaluate a group of horses with naturally occurring knee arthritis and a group of healthy control horses. Some of the proteins they picked up were expected, but others were novel and hadn’t been described in horses with osteoarthritis before. They can now examine these proteins further to see how they might be useful as diagnostic markers and further fine-tune the different mechanisms and pathways that might be involved in osteoarthritis.  

Future of Equine Osteoarthritis Research and Treatment 

“This is an area that so many people are researching, and one of the big reasons there’s so much research in osteoarthritis is cartilage doesn’t do a very good job at repairing itself and definitely doesn’t do a very good job at regenerating,” Secor said. “We can Band-Aid it and make joints feel better, but we have no way of reversing the changes that we see with osteoarthritis. And most of the time we don’t even do a very good job at slowing it down.” 

That’s why many humans with bad osteoarthritis consider joint replacement, an option that’s not available for horses. So, current research is focused on altering some of the pathways involved in osteoarthritis to slow down or even possibly reverse those changes. Researchers are also interested in altering the function of those cells so they start working in our favor instead of contributing to osteoarthritis.  

“I unfortunately think we’re several decades out still from having the golden bullet for curing osteoarthritis,” Secor said. “But there’s a lot of groups working on trying to improve both our diagnostic and our disease-modifying therapeutics.” 

About Dr. Erica Secor 

Erica Secor, DVM, MS, Dipl. ACVS-LA, grew up riding and training horses in Vermont. She completed her undergraduate degree and veterinary school at Cornell University and completed her residency at the University of Illinois. After residency, she worked as a staff surgeon in private practice before returning to Cornell in 2021 for her PhD. She currently studies the immune system’s role in osteoarthritis and is working toward improving diagnostic capabilities and understanding how arthritis varies among individuals, with the goal of identifying how to better tailor osteoarthritis treatment to individual cases. 

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