Objectives: To define the mode of inheritance of the dorsal ridge and investigate if the ridge predisposes to the congenital abnormality dermoid sinus in the Rhodesian ridgeback.
Methods: Segregation analysis was performed, including 87 litters (n=803) produced in Sweden between 1981 and 2002. Data were corrected to avoid bias in the segregation ratio. Chi-squared analysis was performed including 402 litters (n=3598) for the evaluation of a possible genetic correlation between the ridge and dermoid sinus.
Results: The ridge is inherited in an autosomal dominant mode and predisposes for dermoid sinus. The frequency of ridgeless offspring in the Swedish Rhodesian ridgeback population is estimated to be 5·6 per cent.
Clinical Significance: Rhodesian ridgeback dogs that carry the ridge trait are predisposed to dermoid sinus.