ClinQuiz: Answer 5B
Incorrect. Although effective against Sarcoptes scabiei, 14 the parasite found in this patient, high-dose ivermectin is not labeled for this purpose in dogs. Also, because of the potential side effects that can develop in dogs that lack a complete multidrug resistance 1 (MDR1) gene, 15 ivermectin is not recommended to be used at this elevated dose, particularly when safer, labeled options are available. Although the MDR1 gene mutation is more common in certain breeds, such as collies, both the mutation and ivermectin sensitivity have been reported in other dogs including mixed breeds.16