Inheritance of rupture of the cranial cruciate ligament in Newfoundlands

Objective - To determine prevalence, level of inbreeding, heritability, and mode of inheritance for rupture of the cranial cruciate ligament (RCCL) in Newfoundlands. Design - Retrospective and recruitment study. Animals-574 client-owned Newfoundlands. Procedure - Medical records from January 1, 1996, to December 31, 2002, were evaluated for prevalence of RCCL. A pedigree was constructed by use of recruited Newfoundlands with RCCL status based on results of veterinary examination; level of inbreeding, heritability, and mode of inheritance were calculated. Results - Hospital prevalence for RCCL was 22%; dogs in the pedigree from the recruitment study had a mean level of inbreeding of 1.19 × 10^-4, heritability of 0.27, and a possible recessive mode of inheritance with 51% penetrance for RCCL. Conclusions and Clinical Relevance - Identification of a genetic basis for RCCL in Newfoundlands provided evidence that investigators can now focus on developing methods to identify carriers to reduce the prevalence of RCCL.