ACCESSORY SPLEENS IN DOMESTIC RABBITS (ORYCTOLAGUS-CUNICULUS) .1. FREQUENCY, DESCRIPTION, AND GENETIC FACTORS

Accessory spleens in 2 separate necropsy series of 1848 randombred rabbits and 21,802 inbred and partially inbred and 880 hybrid rabbits were described and illustrated. The overall frequency in the randombred population (8.9%) was comparable to that in unselected human necropsy series (10%). The predominant locations of accessory spleens in the rabbits (adjacent to the splenic hilus, the gastrosplenic ligament and the tail of the pancreas) arranged in descending order, were comparable to their locations in human beings. The inbred rabbits had an overall frequency of at least 1 accessory spleen of 22.5%, similarly located, and ranged from 1-50%, depending on the strain. It was shown by crosses of high- and low-frequency strains that the presence of accessory spleens was due in part to genetic factors and that a high frequency of accessory spleens was probably a recessive characteristic. The latter interpretation was also supported by the fact that the low or normal strains had an overall frequency of at least 1 accessory spleen of 8.8% which was in accord with both the randombred rabbit population and human necropsy findings.