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Vet Dermatol. 2009 Apr;20(2):111-4. doi: 10.1111/j.1365-3164.2008.00725.x. Epub 2008 Dec 18.

ABCB1-1 Delta (MDR1-1 Delta) genotype is associated with adverse reactions in dogs treated with milbemycin oxime for generalized demodicosis.

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Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.


Twenty-two dogs diagnosed with generalized demodicosis were treated with milbemycin oxime (MO) because of poor response to previous therapies or because the dog was a breed known to be susceptible to ivermectin toxicosis. Fifteen of the 22 dogs were herding breeds. Doses of MO ranged from 1.0 to 2.2 mg kg(-1) day(-1) per os. Cheek swab samples were obtained in order to determine each dog's ABCB1 genotype. Adverse drug reactions were recorded for each dog by the owners and/or veterinarians. The ABCB1-1 Delta genotype was significantly associated with the development of an adverse reaction (neurological toxicity) after treatment with MO. None of the 19 dogs with the wild-type ABCB1 allele experienced adverse reactions, whereas two dogs homozygous for the ABCB1-1 Delta mutation developed ataxia. Assessing the ABCB1-1 Delta genotype prior to MO administration may prevent neurological toxicity in these patients.

[Indexed for MEDLINE]

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