FRACTURES
Fractures have a distinctive appearance both in the skeleton and on x-rays, making them among the easiest of all lesions to detect. Rolf’s skeleton shows two: The first is a healed fracture of the 16th rib of the left side. Fractures of the rear ribs in horses are fairly common because ribs are thin bones that are, at the same time, exposed to kicks. Rolf was, of course, pasture-bred and lived with a herd yearround. This can be a pretty rough-andtumble experience for the stallion as he approaches, sniffs and licks each mare to determine whether she is in season. Far more surprising is the partiallyhealed fracture of Rolf’s left ischium (the ischium is the bone that structures the rear third of the pelvis). The photo below (A) shows Rolf’s whole pelvis in top view; yellow arrows mark the line of fracture. Guidelines show that both the fore and hind parts of the pelvis are somewhat asymmetrical; this much is within normal limits as no mammal is perfectly symmetrical left to right. However, the fracture of the left ischium has displaced it forward.
The enlargement (B) is a view directly from the side: Note the sharp, raw edges and that the fragments seem to be only minimally adhering to each other by the deposition of new bone (blue arrow). This indicates that the fracture occurred less than two months before Rolf was euthanatized, as the minimum time for complete bone healing is eight to 10 weeks. In actuality, we know that the fracture occurred shortly before Rolf’s death. The break occurred as the result of a direct and forceful kick to the hindquarters, probably by a mare. The fracture was very painful and reduced Rolf’s mobility to near-zero, so the determination was made almost immediately to euthanatize the old stallion.