Veterinarians Use MRI to Diagnose Navicular Injury

Clinicians at Washington State University recently published a case report about a mare that was referred to the university's veterinary hospital with chronic left front lameness. The mare's X rays showed her lame leg was clean, so veterinarians turned to MRI (magnetic resonance imaging), which told a different story--blunt force trauma.

The mare's owners said she had become acutely lame on her left forelimb while turned out in an arena one day. Radiographs taken by the referring veterinarian didn't reveal any fractures or fragments, and the mare was placed on stall rest for four months. She was referred to the hospital after failing to improve.

At the university, clinicians performed an MRI scan, which revealed bone density changes in the navicular bone that the radiographs couldn't identify.

Researchers said, "The most likely explanation is that the navicular bone in the affected limb was injured by blunt trauma, resulting in bone proliferation."

Because of the poor prognosis to return to soundness, the mare was euthanatized. When the researchers further examined the mare's forelimb, they discovered injuries consistent with blunt force trauma. However, the navicular bone was not fractured, which X rays can't easily detect

The researchers said their findings indicated that horses can sustain severe navicular bone injury even without fracturing the bone.

"Magnetic resonance imaging was important in making an accurate diagnosis and yielded evidence that navicular bone injury, even in the absence of radiographic evidence of a fracture, should be considered as a differential diagnosis for horses with acute onset of severe unilateral forelimb lameness originating from the heel."

The case study was published in the Sept. 1 issue of the Journal of the American Veterinary Medical Association.

About the Author

Chad Mendell

Chad Mendell is the former Managing Editor for TheHorse.com .

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