Genotypic and allelic frequencies of gene in dogs in Italy.

Background: A mutation in the canine multidrug resistance gene (also referred as ), encoding for the multidrug resistance () P-glycoprotein (P-gp) transponder, causes a pathological condition known as 'ivermectin toxicosis'. The causative mutation, known since 2001, has been described to affects sheep herding breeds related to collie lineage. The present study is a retrospective investigation of the presence of mutated allele in Italian dog populations in a 5 years' time lapse. The aim of the research is to offer a deep knowledge in allelic and genotypic frequencies in canine breeds and populations raised in Italy.

Methods: Genotype data for the 4-bp deletion (c296_299del4) in gene from 811 dogs belonging to 32 breeds/populations were collected.

Results: The mutated allele has been found in 9 out of 31 breeds: Rough Collie, Smooth Collie, Border Collie, Bearded Collie, Shetland Sheepdog, Australian Shepherd, White Swiss Shepherd, Old English Sheepdog, Whippet and also in crossbreed. The breeds with the highest allelic mutation frequency are Smooth and Rough Collies with 75 per cent and 66 per cent of mutant allele, respectively.

Conclusions: The results support the usefulness of this genetic analysis to optimise medical care in dogs at risk of multidrug resistance and to create an objective basis in breeding programme definition and in the risk evaluation in different breeds.