By now it's no secret that MRI is the gold standard in diagnosing pain in the rear (palmar) portion of horses' feet. However, many owners still choose to have less-reliable radiography performed on their heel-sore horses due to MRI's high cost and inconvenience.
Tracy Turner, DVM, MS, Dipl. ACVS, ACVSMR, of Anoka Equine Veterinary Services, in Elk River, Minn., believes there's a more effective diagnostic option for owners hoping to avoid MRI: navicular bursography. He explained how veterinarians can perform and interpret this procedure during the 2013 American Association of Equine Practitioners' Convention, held Dec. 7-11 in Nashville, Tenn.
With navicular bursography, veterinarians inject a contrast material into the horse's navicular bursa (the fluid-filled sac cushioning the navicular bone from the deep digital flexor tendon [DDFT] that slides over it) and then radiograph (X ray) the area.
Practitioners originally used this technique to confirm accurate injection of anesthetics (pain relievers) into the bursa. They soon learned they could also use it to evaluate the navicular region when normal radiographs fail to pinpoint the problem.
"By adding dye, you get 60% more information on the X ray," said Turner, who has performed 344 navicular bursographies.
He said the most frequent finding he sees is cartilage thinning or erosion—a common navicular disease pathology. Other radiographic changes include:
- Cystlike lesions in the flexor surface of the navicular bone;
- Uneven areas in the DDFT with juxtaposing cartilage loss;
- Distal annular ligament (which function to maintain tendon alignment across joints) injuries;
- Bursa tears;
- Enlargement of the collateral sesamoid ligament that attaches the navicular bone to the proximal (upper) end of the short pastern bone; and
- Shrinking of the proximal joint capsule pouch.
"Navicular bursography is a simple technique that can be used to confirm injection into the navicular bursa and can also give valuable new information regarding pathology in the region of the navicular bone," Turner said. "Changes seen by means of contrast navicular bursography represent stages of pathologic damage and allow a more timely therapeutic intervention, more targeted management, and more accurate prognostication."
He concluded that bursography offers owners another effective diagnostic option for palmar foot pain when MRI is not in the cards.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.