Abstract: The aim of this study was to investigate the feasibility and clinical significance of applying RT-PCR to the detection of the MDR1 mutation and establish a simple, economic, efficient method of genetic diagnosis. Genomic RNA was extracted from the blood of and ivermectin-nonsensitive collies. The MDR1 gene was amplified by RT-PCR, and then cloned and sequenced. The MDR1 mutation of Scotland Collies concerns an exonic 4 bp detection in the palindromic sequence GATAG and creates a nonsense frame shift at amino acid position 75 followed by a premature stop codon. RT-PCR is a simple, economic, quick, precise method of genetic diagnosis and was able to find MDR1 mutation in Scotland Collies in this study. It is helpful in clinical carries on the pharmacological treatment reasonably.

Key words: ivermectin; Collies; MDR1; sequence