The mutant mdr1 gene-is your aussie at risk

THE MDR1 GENE MUTATION-IS YOUR DOG AT RISK?
Around 50% of tested Australian Shepherds carry at least one copy of the MDR1 (Multi-
Drug Resistance 1) gene mutation. Many Collie-type herding breeds including the
Australian Shepherds have this gene mutation which causes sensitivities to certain
drugs. The gene mutation doesn’t allow these drugs to be cleansed from the brain which
can then build up to toxic levels causing neurological illness and/or death. The good news
is there is a simple DNA test (a cheek swab) available that identifies if your dog has the
gene mutation. Washington State University provides the DNA testing kit at a cost of
$60.00/test kit if 5 or more dogs are being tested. The normal cost is $75.00. UMASC
will be holding an MDR1 clinic in conjunction with our November 17th and 18th Agility
Trial at On the Run. The test will be administered one day only on November 17th by a
veterinary technician. If you are interested in having your dog tested for the MDR1 gene
mutation, please complete the DNA testing kit order form below. The orders must be
postmarked by November 2nd. If the results of the DNA test indicate that your dog has
the gene mutation, let your veterinarian know right away. This information needs to be
added to your dog’s file so it isn’t given any potentially harmful drugs.
Please take a few minutes to read the information below on the MDR1 gene mutation: MDR1 FAQs
What is MDR1?
MDR1 is the abbreviated name of a gene called Multi-Drug Resistance 1. A mutation of
this gene causes sensitivity to Ivermectin and a number of other drugs. Dogs with
the mutation will react to those drugs. Having two copies of the mutation will lead
to drug reactions, but having a single copy can also confer some sensitivity with
some drugs. Dogs with this mutation have a transport defect - the drug goes in to
their brains, fails to be transported out, and builds up to toxic levels. This causes
serious neurological problems including seizures and sometimes death.
Which drugs cause reactions?
Ivermectin was the first drug recognized to cause a reaction, but it is far from the
only one. Ivermectin at low dosage, as found in heartworm medications, will not
cause a reaction. The larger doses needed for worming will. Other commonly
administered drugs on the list include acepromazine and Imodium. Fortunately,
there are alternative medications available if your dog requires treatment.
The drugs involved can be found on the website below.
Dogs that do not carry an MDR1 mutation may safely receive the listed drugs. Which breeds are affected?
Australian Shepherds
Mix-breeds with any of the above in their background How do I know if my dog has the MDR1 mutation?
If your dog has already reacted to one of these drugs, it has the mutation. However, reactions can be so dangerous to your dog it is advisable to have the dog tested so you know whether it is sensitive before it receives any of the listed drugs. What do the MDR1 test results mean?
This is a DNA mutation test. It will determine whether or not a dog has the MDR1
mutation and, if it does, whether it has one copy or two. The test report will
provide you with the genotype for your dog, generally listed as Normal/Normal,
Normal/Mutant or Mutant/Mutant.
Dogs with even one copy of the mutation should be considered sensitive to listed drugs. If your dog carries the mutation, provide a copy of the test results and a copy of the listed drugs to every veterinarian who treats your dog and let them know your dog cannot have those drugs. What dogs should be tested and how often?
Since this is a DNA test, a dog only needs to be tested once.
The only exception is as follows: If both parents of a dog have tested Normal/Normal, they cannot pass on the gene and their offspring will not need to be tested. However, if a Normal/Normal dog is bred to one of unknown status or one that has even a single copy of the mutation, the offspring must be tested. The MDR1 FAQs printed with the permission of C. A. Sharp, President of the Australian Shepherd Heath & Genetic Institute.

Source: http://www.aussierescuemn.org/mdr1.pdf