Clinical and morphological studies on spontaneous rupture of the gastrocnemius tendon in broiler breeders.

1. Clinical and morphological studies were performed in 8 broiler breeder flocks (one hybrid) originating from two different farms in Bulgaria, with an incidence of lameness in female birds between 3 and 4% on one farm and 7 and 8% on the other. Clinical and morphological studies were performed. 2. Ruptured gastrocnemius tendons were observed in 78 broiler breeders, 24 to 31 weeks old with signs of lameness, selected for pathoanatomical study from different flocks. Unilateral ruptures predominated, over 80%. 3. A histological study of 20 samples from one farm and 8 samples from the other revealed that lesions varied between birds. In about 50% of them, haemorrhages, dystrophic and necrobiotic changes in tendons were present. In the other 50% of cases, the resolving haematoma and ruptured tendon were surrounded by fibrous tissue growth. No inflammatory changes were detected.