HEREDITARY ACHONDROPLASIA IN THE RABBIT

Abstract

The variation of lethal achondroplasia of the rabbit arose in pure bred Havana stock which had been studied for 10 yrs. The stock also carries a normally proportioned diminutive form which has not been supplanted by the new form. The abnormal condition is detd. by the expression of a simple recessive unit factor, affected individuals being homozygous for the factor. Of 788 total births contained in 132 litters, 228 were achondroplastic animals, an incidence of 28.9%. Rabbits heterozygous for the factor as detd. by appropriate breeding tests have a perfectly normal appearance at birth and in later life. The condition appears to be detd. solely by the genetic constitution of the animal. Although the development of the achondroplastic form proceeds to birth at term, death regularly occurs at the time of or very shortly after parturition. Possible explanations for the cause of death are discussed.