Multidrug Sensitivity (MDR1 Mutation)
A genetic mutation in the MDR1 (ABCB1) gene causes Collies to be highly sensitive to certain drugs, leading to neurotoxicity and potentially fatal reactions.
Detailed Description
The MDR1 gene encodes P-glycoprotein, a transporter that pumps drugs out of the brain. The mutation results in a non-functional protein, allowing drugs like ivermectin, loperamide, and some chemotherapy agents to accumulate in the brain, causing toxicity.
Common Symptoms
- Neurological signs such as ataxia
- Tremors
- Seizures
- Coma
- Death (after drug exposure)
Management Options
- Avoidance of contraindicated drugs
- Supportive care if toxicity occurs
Frequently Asked Questions
Which drugs are dangerous for Collies with MDR1 mutation?
Ivermectin, loperamide, certain chemotherapy drugs, and others.
Can I test my Collie for MDR1?
Yes, a simple cheek swab DNA test is available.
Is the MDR1 mutation curable?
No, but it is manageable by avoiding certain drugs.
Can carriers (heterozygotes) be affected?
They may show mild sensitivity; homozygotes are at highest risk.
Is this mutation unique to Collies?
No, but prevalence is highest in Collies and related breeds.
Condition Details
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Typical Age of Onset
Any age upon exposure to triggering drugs
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Testing Available
Yes
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Diagnosing Methods
Genetic testing; Clinical history of drug exposure and acute neurological signs
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Preventative Measures
Genetic testing before drug administration; Owner and veterinarian education
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Related Conditions
Other causes of acute neurological toxicity