Radiographs are an often overlooked but indispensible tool for assessing a horse's feet and developing a hoof care plan that will maximize his soundness. At a recent in-depth seminar titled "The Foot from Every Angle," Randy Eggleston, DVM, of the University of Georgia's School of Veterinary Medicine, described how to optimize use of radiography.
"It is important to assess the relationship between the coffin bone and the hoof wall," Eggleston advised at the event, which was held during the 2012 American Association of Equine Practitioners (AAEP) Convention, held Dec. 1-5 in Anaheim, Calif. Radiography allows the equine veterinarian to do this and formulate advice for the farrier; he or she can measure sole depth, solar angles, and foot balance, as well as evaluate the health of the coffin bone. He stressed that the information obtained is only as good as the quality of radiographic technique and images produced. In addition, Eggleston said, "The clinical interpretation has significant impact on the success of therapeutic farriery."
Another element to consider is the dynamic nature of the foot. Eggleston reminded practitioners that foot conformation changes during a typical eight-week trim cycle. As the toe grows out, it increases coffin joint extension, which adds tension to the deep digital flexor tendon (DDFT), the structure that attaches to the underside of the coffin bone.
Because the hoof can conform to the stresses it incurs on impact with each footfall, a visual exam helps the practitioner evaluate it for distortions and abnormalities that might develop over time due to hoof imbalances. Eggleston recommended using radiography if the veterinarian observes abnormal hoof and/or distal limb conformation; if he or she observes abnormal growth patterns or hoof distortions; and/or when distal (lower) limb anesthesia blocks out lameness.
To achieve good-quality images, the handler should square the horse up as best as possible on a firm surface, with his head and neck aligned straight; any twisting will distribute weight unequally between the feet. "Only a small amount of weight redistribution will cause incongruities in the coffin joint," Eggleston noted. He recommended placing positioning blocks of similar height beneath each hoof.
Hoof hygiene is another key element to getting quality films, and Eggleston noted that the hoof wall and frog sulci (the grooves next to and in the middle of the frog), in particular, should be cleaned well. Applying radio-opaque markers to the dorsal hoof wall and the bottom of the hoof allows the veterinarian to see these surfaces and angles on the radiographs and make accurate measurements and assessments. For images that require the frog sulci to be packed, he highly recommended placing the horse's foot in a water bath since this technique is ideal to remove artifacts that can make it difficult to read the X rays.
Eggleston suggested that in addition to radiographing the hoof using a lateral-medial (or side to side) view, the veterinarian should also obtain a horizontal dorsal-palmar (front to back) view aiming the X ray beam parallel to the bottom of the foot, about 1.5-2 cm above the weight-bearing surface. With these multiple radiographic views, the veterinarian can obtain quantitative measurements to best plan trimming and shoeing strategies for the individual horse and facilitate good communication with the farrier to execute these recommendations.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.