Navicular Disease Treatment Easier for Horses and Vets

Instead of injecting the steroid triamcinolone acteonide directly into the navicular bursa, which can be technically demanding, veterinarians can instead inject the coffin joint and still potentially manage horses affected by navicular syndrome, researchers recently reported.

"Good short-term success rates have been reported after injecting the navicular bursa with corticosteroids and hyaluronan," relayed Mary Boyce, DVM, MS, from the College of Veterinary Medicine at the University of Minnesota. "The problem is that injecting the navicular bursa is difficult, produces inconsistent results, and radiographic (X ray) guidance to verify correct needle placement is advised by experts. This limits the clinical use of bursal injections for many veterinarians."

It is widely speculated by veterinarians that triamcinolone will diffuse from the coffin joint to the navicular bursa, thereby precluding the need to inject the bursa itself to effectively treat horses with navicular syndrome. To test this hypothesis, Boyce and colleagues injected one forelimb coffin joint with 10 mg triamcinolone and 20 mg hyaluronan and the contralateral forelimb coffin joint with 10 mg triamcinolone and 2 ml saline. They then collected synovial fluid from both forelimb navicular bursae and one hind limb navicular bursa (for control) six hours after the injections.

"Triamcinolone concentrations were detectable in all navicular bursae and triamcinolone levels were higher in the forelimb bursae compared to the hind limb bursae. This indicates that while there is some systemic diffusion of triamcinolone (as seen by the presence of triamcinolone acetonide in the hindlimb bursae), the majority of steroid diffusion from the coffin joint to the navicular bursa occurs locally," said Boyce.

These results support the hypothesis that triamcinolone does diffuse from the coffin joint to the navicular bursae with or without the simultaneous use of hyaluronan.

Boyce noted, however, that this study used horses that did not have navicular syndrome.

"Since the included horses were normal, pathologic changes associated with navicular syndrome such as bursitis, capsulitis, or deep digital flexor tendonitis can potentially affect diffusion of the steroid," she said. To investigate the effects of navicular syndrome on steroid diffusion, Boyce and colleagues are currently conducting a similar study using horses that have navicular syndrome.

The study, "Evaluation of diffusion of triamcinolone acetonide from the distal interphalangeal joint into the navicular bursa in horses," was published in the February 2010 edition of the American Journal of Veterinary Research. The abstract is available for free on PubMed.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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