Canine multi-drug resistance-1 mutation prevalence: A South African perspective

Abstract

The multi-drug resistance (mdr-1) gene mutation is a phenomenon well known to current veterinary practitioners. The mutation causes a predisposition for, amongst other phenomena, macrocyclic lactone-induced neurotoxicosis in affected canines, a condition that can be fatal. Various herding dog breeds can be heterozygous or homozygous for the mutation, and prevalence differs only slightly in dog populations between geographical regions. This report provides prevalence data of the canine mdr-1 mutation in 306 South African dogs.

Prevalence of the MDR1 gene mutation in herding dog breeds and Thai Ridgebacks in Thailand

“…Although the population of Rough Collies in the current survey was relatively small, as it is an unusual dog breed in Thailand, the current results are similar to those from large-scale studies in the USA, where the mutation frequency was 54.6-56% [ 15 , 16 ]. Moreover, our findings agree with those from several studies from Japan [ 17 ], Brazil [ 18 ], South Africa [ 19 ], Australia [ 20 ], Germany [ 14 , 21 , 22 ], France [ 23 ], the UK [ 24 ], Belgium [ 25 ], Italy [ 26 ], and numerous European countries [ 27 ], where the mutation frequency was estimated to be 50-71%. In Israel, however, a lower mutation frequency of approximately 27.5% was found [ 28 ].…”

“…Moreover, a wide range of mutation frequencies, from 7% to 24.2% [ 26 , 27 ], has been reported in several other European countries, with the lowest frequency being found in Italy [ 26 ] and the highest in Poland [ 27 ]. Interestingly, the occurrence of this mutation in White Swiss Shepherds has also been published in countries located outside the European zone, including South Africa [ 19 ] and Israel [ 28 ], where the mutation frequencies were 7.69% and 16.7%, respectively. As mentioned above, the population of White Swiss Shepherds in this investigation was very small, because this breed is not popular in Thailand.…”

“…However, a higher mutation frequency and wide variation have been reported in various other countries, which may be attributed to the different sample sizes of those studies. As stated in large-scale MDR1 genotyping surveys, the mutation frequency was approximately 19.50-22% in Germany [ 21 , 22 ] and 29% in the USA [ 16 ], and a mutation frequency of approximately 25-46% has been reported in the small-to-medium-scale populations investigated in Israel [ 28 ], Japan [ 17 ], South Africa [ 19 ], Australia [ 20 ], and several European countries [ 24 , 26 , 27 ]. In terms of the universal distribution of MDR1 nt230(del4), the second most affected breed is most likely the Australian Shepherd.…”

“…Other than these surveys, a low mutation rate has also been observed in some European countries, including Germany [ 21 , 22 ], Italy [ 26 ], and the UK [ 24 ], with mutation frequencies of 1-3.5%. In addition, the presence of this mutation has been reported in South Africa [ 19 ] and Israel [ 28 ], with frequencies of 2.13% and 4.8%, respectively. On the basis of a herding breed genealogy study, the ancestor of Border Collies is speculated to have separated from the rest of ancestral population of old working collies in the UK and Ireland before the emergence of MDR1 nt230(del4) [ 15 ].…”

“…This result is similar to those from previous investigations in the UK [ 24 ], Belgium [ 25 ], and Italy [ 26 ]. However, the existence of the MDR1 nt230(del4) has been observed in some countries, including the USA [ 16 ], Israel [ 28 ], South Africa [ 19 ], and Brazil [ 29 ], with low mutation frequencies of 0.6-7.14%. In addition, we also investigated the MDR1 nt230(del4) in White Swiss Shepherds.…”