damaged more readily, causing the area of fibrosis to enlarge to a point where it affects the horse’s gait. Generally, the lesion is palpable by the time the gait is affected. If the horse continues to exercise and the area of fibrosis is left untreated the fibrotic tissue will eventually calcify then in response to repeated strain and inflammation. Horses used for reining, for working livestock or for polo tend to injure the hamstring muscles. are predisposed to developing both the acquired and the congenital types of fibrotic and ossifying myopathy.
This condition tends to affect the muscle primarily, but the biceps femoris, semimembranosus and gracillis may also become involved as the lesions spread.
Clinically fibrotic and ossifying myopathy is seen as a unilateral, palpable thickening of the semitendinosus muscle associated with a characteristic lameness. The lameness is described as having a , stuttering cranial phase of the stride with a sudden retraction of the foot just before the foot contacts the ground.
Diagnosis of fibrotic and ossifying myopathy is through clinical signs and symptoms as well as through ultrasonography and radiography.
For mild or early cases of fibrotic and ossifying myopathy the recommended treatment is extracorporeal therapy and massage therapy, especially frictions, to break up fibrotic masses. In more advanced cases with larger lesions or ossification it is necessary to surgically remove lesions. To rectify gait anomalies, the surgical severing of the tendon of insertion of the semitendinosus on the stifle joint may be necessary. This will only be successful if there are no lesions in the semimembranosus or gracillis muscles. Prevention of fibrotic and ossifying myopathy may be achieved through the proper warm up and stretching of the muscles of the hamstring before engaging in exercise that involves sudden turning or stopping. This can be achieved through a prescribed warm up routine and stretching or may be done before the horse is tacked through the application of hot hydrotherapy, massage and stretching. Corks or grabs may be attached to the hind shoes to prevent the hind foot from slipping cranially if the horse is expected to exercise on slippery footing. Regular massage may be able to improve the resilience and elasticity of the hamstrings muscle there by reducing the instances of strain and scarring. Individuals affected with the congenital type of fibrotic and ossifying myopathy should not be used for breeding as there is evidence suggesting a breed and familial predisposition in the congenital for of this condition. Breed or familial predispositions are suggestive of a genetic link and of the heritability of congenital fibrotic and ossifying myopathy. Rupture of Peroneus Tertius The tendinous peroneus tertius muscle lies along the cranial aspect of the gaskin. Its action is to flex the hock joint while the stifle is flexed. The apparatus dictates that the
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