MRI for Confirming DDF Tendonitis

Tendonitis of the deep digital flexor tendon (DDFT) in horses is a newly recognized cause of foot pain. Radiography and even ultrasonography have failed to detect abnormalities in this tendon, especially as it travels within the hoof capsule and attaches to the pedal or coffin bone. In an effort to improve the ability of practitioners to diagnose DDFT lesions within the foot, a study was performed to determine the incidence and types of DDFT injuries in horses with a history of lameness localized to the digit.

A group of 75 horses undergoing MRI for investigation of foot pain with no radiographic abnormalities was investigated by Sue Dyson, FRCVS, of the Center for Equine Studies, Animal Health Trust, Newmarket, U.K., and colleagues, in an effort to describe the lesion in light of the response to nerve blocks as well as ultrasonographic and nuclear scintigraphic findings.

MRI examinations identified 46 horses (61%) with lesions of the DDFT that could be considered a major contributor to lameness. Thirty-two horses (43%) had primary DDFT injuries, and 14 (19%) had a combination of DDFT and navicular bone problems. Information such as breed, type of work, and diagnostic findings was also gathered and analyzed. Findings were compared to those in horses with other types of lameness or poor performance.

No breed predilection was identified, but horses used for jumping tended to have lesions more often than horses of other disciplines (48% versus 36% of horses in other disciplines affected).

Ultrasound examination did not prove effective at detecting DDFT lesions at the pastern, which was an unexpected finding. Dyson explains, "If you believe that ultrasonography should be able to detect any lesion in an accessible tendon or ligament, as many do, then you should expect to see lesions of the DDFT that extend into the pastern." The effectiveness of nuclear scintigraphy was mixed, with positive results for only 16 of 41 total horses (40%) with DDFT lesions.

The authors concluded that DDF tendonitis is indeed a significant cause of forelimb lameness of the digit in horses. Dyson adds, "DDF tendonitis is the most common injury seen in horses with foot pain that have no detectable radiological abnormalities."

Dyson is currently validating the MRI findings for this and other injuries by examining the feet of horses euthanized for persistent foot-related lameness and horses destroyed for unrelated reasons using MRI and post-mortem examination. She is also investigating other lesions of the foot, how they relate to clinical lameness, and how they are best treated. Visit to learn more.

Dyson, S; Murray, R; Schramme, M; et al. Equine Veterinary Journal, 35 (7): 681-690, 2003.

About the Author

Susan Piscopo, DVM, PhD

Susan Piscopo, DVM, PhD, is a free-lance writer in the biomedical sciences. She practiced veterinary medicine in North Carolina before accepting a fellowship to pursue a PhD in physiology at North Carolina State University. She lives in northern New Jersey with her husband and two sons.

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