The manifestations and course of an hereditary disease of the rabbit are reported. The condition is present at birth and is invariably fatal, generally in the 4th and 5th weeks of age. Retardation and eventual cessation of growth with marked reduction in size are conspicuous characteristic symptoms.
The condition, which first occurred in the backcross progeny of a pure bred Dutch male rabbit, is inherited. It is determined by the expression of a simple recessive unit factor, affected individuals being homozygous for the factor. Rabbits heterozygous for the factor are identified only by appropriate breeding tests. The condition is not sex-linked.
The disease has a remarkable resemblance to osteopetrosis or marble bone disease of infants and children with respect to signs and general course and also, as may be stated in anticipation of later discussions (5, 6), to the characteristic abnormal condition of the skeleton.