A seven-month-old black female setter-retriever cross was found to have a modal chromosome number of 77 and an apparent centric fusion of two autosomes. Extensive clinical examinations were performed, and the findings were all within normal limits. Similar cases have occurred in man and dogs, suggesting that chromosomal aberration may occur without a change in phenotypic expression and that the presence of congenital disease in dogs with chromosomal centric-fusion may be coincidental.