Evaluating the Effectiveness of Selective Breeding and Corrective Surgery on Entropion in Labrador Retrievers From a Guide Dog Program.

Abstract

OBJECTIVE: To evaluate the outcome of implementing a selective breeding strategy to reduce the incidence of entropion in a guide dog program. ANIMALS STUDIED: Labrador Retrievers born at Guide Dogs for the Blind. 2106 whelped between July 2013 and October 2016 prior to selective breeding, and 1958 whelped between May 2020 and December 2024 after selective breeding for a total of 4064 puppies. PROCEDURE: Retrospective review of medical records. Bayesian logistic regression modeling was used to calculate the heritability of entropion and compare the risk of entropion diagnosis for dogs before and after the implementation of a selective breeding strategy. RESULTS: Prior to selective breeding, the incidence of entropion was 6.46%. After selective breeding, the incidence of entropion was 3.12%. Of the 197 puppies diagnosed with entropion (median age at first diagnosis 6.7 weeks), 181 had a recorded surgical repair procedure (median age at first repair 7.9 weeks). Repair was corrective in 164 cases (90.61%) with no recurrence of entropion. Dogs whelped in the pre-selection cohort had 1.96 times greater risk of entropion diagnosis than dogs whelped in the post-selection cohort. Heritability of entropion (h) in this population is estimated to be 0.80. CONCLUSION: These results provide evidence that in a population of Labrador Retrievers where the heritability of entropion is high, selective breeding can greatly impact the incidence of entropion, and surgical repair is an effective form of treatment at a young age.