Merck Manual

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Professional Version

Rupture of the Peroneus Tertius Muscle in Cattle


Paul R. Greenough

, FRCVS, Western College of Veterinary Medicine, University of Saskatchewan

Last full review/revision Sep 2015 | Content last modified Sep 2015

The peroneus tertius muscle can be forcibly avulsed from its insertion by accidents associated with mounting or, more frequently, by the inexperienced use of ropes to restrain a hindlimb.

The hock is abnormally extended, while the stifle remains flexed. The animal cannot advance the limb normally, the calcanean tendon is flaccid, and the hooves may be dragged. The site of avulsion may be painful to the touch. A specific diagnostic feature is that the limb can be pulled backward without any resistance from the animal.

The condition may improve slowly if the animal is confined in a stall (loose) for several months.

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