PET-MDR1-IVM-001 pet-safety life_threatening ai_generated true

AI recommends ivermectin dose for a Collie without warning about MDR1 gene mutation sensitivity

ID: pet-safety/ai-recommends-ivermectin-dose-for-collie-without-mdr1-test

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75%Fix Rate
88%Confidence
1Evidence
2024-03-12First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
dog_breed_database_v2024 active — — —
merck_veterinary_manual_14th_edition active — — —

Root Cause

Dogs with the MDR1 mutation (common in Collies, Shelties, and Australian Shepherds) cannot properly transport ivermectin out of the brain, leading to neurotoxicity at standard heartworm-prevention doses.

generic

中文

携带MDR1基因突变的狗（常见于柯利犬、喜乐蒂牧羊犬、澳大利亚牧羊犬）无法正常将伊维菌素转运出大脑，标准预防心丝虫剂量即可导致神经毒性。

Official Documentation

https://vcahospitals.com/know-your-pet/ivermectin-toxicity-in-dogs

Workarounds

  1. 90% success Before any ivermectin use, order the MDR1 genetic test (e.g., from Washington State University Veterinary Genetics Lab). If negative, use standard dose (6-12 mcg/kg PO monthly). If positive, use a non-macrocyclic lactone heartworm preventive like Heartgard Plus (ivermectin) is contraindicated; switch to Interceptor (milbemycin oxime) or Trifexis (milbemycin oxime + spinosad). 
    Before any ivermectin use, order the MDR1 genetic test (e.g., from Washington State University Veterinary Genetics Lab). If negative, use standard dose (6-12 mcg/kg PO monthly). If positive, use a non-macrocyclic lactone heartworm preventive like Heartgard Plus (ivermectin) is contraindicated; switch to Interceptor (milbemycin oxime) or Trifexis (milbemycin oxime + spinosad).
  2. 85% success For dogs with known or suspected MDR1 mutation, prescribe a heartworm preventive that does not contain macrocyclic lactones, such as ProHeart 6 (moxidectin injectable) or Simparica Trio (sarolaner + moxidectin + pyrantel), but monitor for signs of neurotoxicity for 24 hours after first dose. 
    For dogs with known or suspected MDR1 mutation, prescribe a heartworm preventive that does not contain macrocyclic lactones, such as ProHeart 6 (moxidectin injectable) or Simparica Trio (sarolaner + moxidectin + pyrantel), but monitor for signs of neurotoxicity for 24 hours after first dose.
  3. 70% success If ivermectin toxicity occurs (mydriasis, ataxia, tremors, coma), administer intravenous lipid emulsion (ILE) at 1.5 mL/kg of 20% lipid solution over 30 minutes, repeated every 4-6 hours, and provide supportive care including fluid therapy and seizure control with diazepam. 
    If ivermectin toxicity occurs (mydriasis, ataxia, tremors, coma), administer intravenous lipid emulsion (ILE) at 1.5 mL/kg of 20% lipid solution over 30 minutes, repeated every 4-6 hours, and provide supportive care including fluid therapy and seizure control with diazepam.

中文步骤

  1. Before any ivermectin use, order the MDR1 genetic test (e.g., from Washington State University Veterinary Genetics Lab). If negative, use standard dose (6-12 mcg/kg PO monthly). If positive, use a non-macrocyclic lactone heartworm preventive like Heartgard Plus (ivermectin) is contraindicated; switch to Interceptor (milbemycin oxime) or Trifexis (milbemycin oxime + spinosad).
  2. For dogs with known or suspected MDR1 mutation, prescribe a heartworm preventive that does not contain macrocyclic lactones, such as ProHeart 6 (moxidectin injectable) or Simparica Trio (sarolaner + moxidectin + pyrantel), but monitor for signs of neurotoxicity for 24 hours after first dose.
  3. If ivermectin toxicity occurs (mydriasis, ataxia, tremors, coma), administer intravenous lipid emulsion (ILE) at 1.5 mL/kg of 20% lipid solution over 30 minutes, repeated every 4-6 hours, and provide supportive care including fluid therapy and seizure control with diazepam.

Dead Ends

Common approaches that don't work:

  1. Reduce ivermectin dose by half instead of testing for MDR1 mutation 95% fail

    Even sub-therapeutic doses can cause toxicity in homozygous MDR1 mutants; dose reduction is not safe without knowing genotype.

  2. Switch to topical ivermectin (e.g., Revolution) assuming it avoids systemic absorption 80% fail

    Topical ivermectin is still absorbed systemically and can reach toxic levels in MDR1-mutant dogs.

  3. Use selamectin instead of ivermectin without checking MDR1 status 70% fail

    Selamectin is also a macrocyclic lactone and can cause similar neurotoxicity in MDR1-mutant dogs, though less severe.