Shetland Sheepdog

Also avoid: Simparica Trio, moxidectin, ivermectin

Sarolaner alone (Simparica, not Trio) is safe in MDR1 breeds

Also avoid: Heartgard, ivermectin, moxidectin

Use Interceptor (milbemycin) with caution — also MDR1-substrate at higher doses; preventive doses generally safe but verify