Osteopetrosis
Dr John R Baker

Osteopetrosis is a rare disease of mammals and birds. The name means "stone bones" suggesting that the bones are even harder than normal although this is not always the case. While the disease has been diagnosed in various types of domestic poultry there appear to be no reports of it in cage birds.

The four budgerigars in which the disease was seen all belonged to the same fancier, and were from two clutches which also included some normal chicks. The condition was first noted when the birds left the nest boxes but may have been present before this.

The affected birds had difficulty in moving about but this varied in severity from bird to bird; one could only get about at all by hooking its beak into roughness on the cage floor, while another stood in a slightly crouching position, but could walk and fly, at least as far as the nearest perch. The birds had normal appetites and were in good bodily condition. Once the condition was diagnosed in the most severely affected bird the others were put down and two of the four bodies were examined post-mortem.