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A DNA test for Multidrug Resistance (MDR1) in Collies.
What is MDR1?
In the normal healthy dog, the brain tissue and central nervous system are
protected against high concentrations of drugs circulating in the vascular
system. The "Multidrug Resistance gene 1" (the MDR1 gene) plays an
important role in the barrier between blood capillaries and brain tissue.
It encodes a large transmembrane protein, P-glycoprotein, which is an integral
part of the blood-brain barrier. P-glycoprotein functions in a protective
capacity to transport a variety of drug substrates, including Ivermectin,
from brain tissue back into capillaries.
The phenomenon of "Ivermectin toxicity in Collies" was first described in
1983. Ivermectin (an antiparasitic agent) causes neurologic toxicity in some,
but not all Collies, at doses that are 1/200th of the dose required to cause
toxicity in other dogs. Neurologic manifestations of Ivermectin in susceptible
dogs include hypersalivation, ataxia, blindness, coma, respiratory compromise,
and death.
Dogs suffering from oversensitivity for Ivermectine have been documented to be
susceptible to neurotoxicity induced by many other drugs as well.
A DNA test for MDR1
"Dangerous drugs" for oversensitive dogs
Breeds at risk
Breeding policy
Testing for MDR1
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