{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,7,30]],"date-time":"2025-07-30T16:36:34Z","timestamp":1753893394316,"version":"3.41.2"},"reference-count":22,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,5,29]],"date-time":"2025-05-29T00:00:00Z","timestamp":1748476800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Vet. Sci."],"abstract":"<jats:p>Certain dog breeds, particularly herding breeds like Collies, are predisposed to drug sensitivity due to the <jats:italic>ABCB1-1\u2206<\/jats:italic> (previously known as <jats:italic>MDR1<\/jats:italic>) mutation, which disrupts P-glycoprotein (P-gp) function. This mutation impairs drug efflux at the blood\u2013brain barrier, leading to increased susceptibility to neurotoxic effects. While adverse reactions to P-gp substrate drugs such as macrocyclic lactones and chemotherapeutics are well documented, opioid sensitivity remains poorly understood. This case report documents a Collie that developed severe neurotoxicity, including profound sedation, ataxia, hypersalivation, and seizures, following a single 0.2\u202fmg\/kg dose of butorphanol. Symptoms persisted despite supportive care, requiring continuous naloxone administration for approximately 40\u202fh before significant improvement. Neurotoxicological effects may have been exacerbated by metoclopramide and maropitant, known P-gp substrates. This case underscores the need for further research into opioid pharmacokinetics in <jats:italic>ABCB1-1\u2206<\/jats:italic> mutant dogs and highlights the importance of genetic screening in veterinary practice. To enhance patient safety, integration of automated alerts within electronic medical record systems is recommended to flag high-risk drugs for at-risk breeds, providing real-time warnings, dosing adjustments, and monitoring guidance. These measures could reduce adverse drug reactions and improve clinical outcomes in genetically susceptible dogs.<\/jats:p>","DOI":"10.3389\/fvets.2025.1603375","type":"journal-article","created":{"date-parts":[[2025,5,29]],"date-time":"2025-05-29T05:26:18Z","timestamp":1748496378000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Case Report: Adverse reaction to butorphanol in a Collie homozygous for the ABCB1-1\u2206 (MDR1) mutation"],"prefix":"10.3389","volume":"12","author":[{"given":"Tyler S.","family":"Nelson","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Heather 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