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Measuring Arthritic Inflammation in Equine JointsBy Kentucky Equine Research Staff · December 27, 2016

Joint disease, including osteoarthritis, remains a leading cause of lameness and decreased quality of life among horses. Methods currently used to assess the overall health of a joint include physical and lameness exams and radiology. So far, there are no specific tests that can be performed on synovial fluid to facilitate a diagnosis of joint inflammation and disease.

According to a group of researchers from Spain*, haptoglobin may be just the metric horse owners and veterinarians need to track inflammation. Haptoglobin is a type of “acute phase protein” that increases in response to inflammation (e.g., following infection or injury). Haptoglobin is similar to serum amyloid A, which is widely used to diagnose a variety of inflammatory conditions in horses, such as pneumonia, but haptoglobin levels rise slower and remain elevated longer than serum amyloid A. This means that haptoglobin could be an excellent adjunct to serum amyloid A for diagnosing and monitoring inflammation over time.

To explore whether haptoglobin could be used for identifying inflammation stemming from joint disease, arthritis was induced in one knee joint in 12 Shetland Ponies. Serum and synovial fluid samples were collected at the start of the study, just prior to inducing arthritis, and again 15 days later. The researchers found:

  • Haptoglobin was measurable in both serum and synovial fluid;
  • Significant increases in haptoglobin were identified in both serum and synovial fluid following induction of arthritis;
  • Haptoglobin levels remained elevated for 15 days, which is longer than other acute phase proteins; and
  • Haptoglobin levels were lower in synovial fluid than serum at the start of the study, but no significant difference was identified at the end of the study. This indicated the increase in haptoglobin was larger in synovial fluid samples than serum, potentially making synovial fluid samples a more sensitive way of identifying inflammation.

Haptoglobin appears to be a useful tool to measure joint inflammation using either synovial fluid or serum; however, protecting joints from injury, disease, and ultimately arthritis serves as an alternative and more desirable, option.

To help achieve this goal, Kentucky Equine Research (KER) offers several joint supplements that not only help horses already diagnosed with osteoarthritis but also supports joints when offered prophylactically, prior to the onset of trauma or injury. Such products in the United States and Europe include KER•Flex, which contains high-quality glucosamine HCl and chondroitin sulfate; Synovate HA, a high molecular weight sodium hyaluronate liquid that helps maintain proper joint health and lubricates joints for frictionless motion, especially in high-motion joints; and even the omega-3 fatty acid supplement, EO•3. Australian horse owners should look for these research-proven products.

*Barrachina, L., A.R. Remacha, L. Soler, et al. Acute phase protein haptoglobin as inflammatory marker in serum and synovial fluid in an equine model of arthritis. Veterinary Immunology and Immunopathology. In press.