RADIOGRAPHIC APPEARANCE OF THE FEET OF MAMMOTH DONKEYS AND THE FINDING OF SUBCLINICAL LAMINITIS

All feet of 10 clinically sound mammoth donkeys (Group I) were radiographed to determine the appearance of the distal phalanx. The distal phalanges had blunted to concave-shaped dorsal solar margins which varied in appearance from slight to pronounced. The distal phalanges of the forefeet were wider than those of the hindfeet, and also were positioned a greater distance from the dorsal aspect of the hoof wall. The greater distance between the dorsal aspect of the hoof wall and the distal phalanges seemed related to the presence of a periosteal-like bony proliferation on the dorsum of the distal phalanx. This bony proliferation occurred in those distal phalanges which also had radiographic findings consistent with pedal osteitis. Next, all feet of 5 additional mammoth donkeys (Group II) that were to be necropsied for various reasons, were examined similarly to Group I, necropsied and found to have laminitis. Only 2 of these 5 donkeys had been lame; only one had rotation of the distal phalanges (in the forefeet). Radiographic data from the 4 donkeys without rotation seemed most similar to that found in those Group I donkeys which had periosteal reactions on their distal phalanges. Conclusions from this study were that: 1) feet of mammoth donkeys have some anatomic differences from those of domestic horses, 2) subclinical laminitis and pedal osteitis can occur in mammoth donkeys, 3) rotation of the distal phalanx occurs in some, but not all laminitic donkeys, 4) laminitic changes may be more pronounced in their fore than in their hindfeet, and 5) additional studies of donkeys need to be done, examining both proven normal and confirmed laminitic feet.     

The incidence of bone lesions in the carpal and tarsal regions and the rate of physeal closure in weanling quarter horses

Sixty weanlings were maintained in dry lots without forced exercise and individually fed a diet consisting of 25% Bermudagrass hay and 75% balanced concentrate twice dally. Radiographs of the carpus, metacarpus and first phalanx, and other radiographs of the tarsal region, were taken initially at approximately 180 d of age and at approximately 236, 292 and 348 d of age. The radiographs were evaluated for the presence or absence of subchondral and/or cystic lesions in the carpal and tarsal regions and for closure of physes of the distal third metacarpus and proximal first phalanx. Physeal scores were: 1 = open; 2 -- partially closed; 3 = closed. Only 1.7% of the horses had subehondral lesions in the carpal region at 180 d, and none had those lesions at 236, 292 or 348 d. There was a 3.3% incidence of subchondral lesions of the tarsus at 180, 236 and 292 d, but only 1.7% at 348 d. Cystic lesions of the carpus were evident in 13.3% of the horses at 180 d, 16.7% at 236 d and 18.3% at 292 and 348 d. None of the hrses had cystic lesions oftbe tarsus at 180, 236 or 348 d, but 1.7% had them at 292 d. Physeal closure scores for the distal metacarpus averaged 1.5 and 2.6 at 180 and 236 d, respectively. At 292 and 348 d, all of the distal metacarpi were closed. Physeal closure scores for the proximal first phalanges were 1.5, 2.6 and 2.9 at 180,