Heritable bone fragility, joint laxity and dysplastic dentin in Friesian calves: a bovine syndrome of osteogenesis imperfecta.

A lethal syndrome of bone fragility, joint laxity, translucent teeth and other connective tissue defects occurred in Victoria in 37 of 84 progeny of a clinically normal, registered Friesian bull between 1978 and 1981. Test matings to unrelated cows indicated that the syndrome was transmitted as an autosomal dominant trait. Affected calves were readily recognized at birth by pink teeth and abnormal posture. At birth 14 of 19 affected calves examined had rib fractures and 4 of these calves also had fractures of long bones. Spontaneous fractures of long bones also occurred in 5 of the 11 calves which survived for more than 10 days. Hypoplasia of dentin, tendons, and ligaments were observed in all cases at necropsy. Osteopenia was only observed at necropsy in older calves. Histological lesions of bone and teeth were similar to those reported in descriptions of osteogenesis imperfecta with dentinogenesis imperfecta in man. The syndrome is provisionally designated as "bovine osteogenesis imperfecta". Semen has been collected from the progenitor bull to enable further investigations of this heritable collagenous tissue dysplasia.