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  MDR1  genetics - information





DRUG SENSITIVITY IN HERDING BREEDS - Including Australian Shepherds

See the above link for detailed information,

multi-drug sensitivity in AUSSIES. The problem is due to a mutation in the multi-drug resistance gene (MDR1). This gene encodes a protein, P-glycoprotein, that is responsible for pumping many drugs and other toxins out of the brain. Dogs with the mutant gene can not pump some drugs out of the brain as a normal dog would, which may result in abnormal neurologic signs. The result may be an illness requiring an extended hospital stay--or even death.
PUppies can be tested to determine if they carry this "mutation".. but why take the chance.. ??


Problem Drugs

Drugs that have been documented, or are strongly suspected to cause problems in dogs with the  MDR1 mutation:

  • Ivermectin (antiparasitic agent) in HEARTGUARD
  • Selectin - Revolution
  • Loperamide (ImodiumŪ; over-the-counter antidiarrheal agent)
  • Doxorubicin (anticancer agent)
  • Vincristine (anticancer agent)
  • Vinblastine (anticancer agent)
  • Cyclosporin (immunosuppressive agent)
  • Digoxin (heart drug)
  • Acepromazine (tranquilizer) - used for neutering/spaying
  • Butorphanol (pain control)

Potential Problem Drugs

The following drugs may potentially cause problems when given to dogs that have the mutation. Biochemical studies have shown that this gene has the potential to act on over 50 different drugs.

  • Ondansetron
  • Domperidone
  • Paclitaxel
  • Mitoxantrone
  • Etoposide
  • Rifampicin
  • Quinidine
  • Morphine




DRONTAL= wormer - DO NOT LET your vet give drontal wormer within 1 wk prior or after or same day as SHOTS.

For some reason it "pisses" off the worms and causes what my vet termed "negative inter-reaction".. he had some more technical term..  I PERSONALLY lost puppies at 7-9wks from excessive internal bleeding/shock. only after worming with drontal and then giving the 2nd shot within the week.  My vet says the strongest reaction can be to the 2nd vaccine. For tape worms, use Panacur for 3 days.. much safer.

FORT DODGE BRAND VACCINES - PLEASE request that your vet DOES NOT use a FORT DODGE brand vaccine or before going in ask what brand they use. IF they use only Fort dodge, go to another vet..  my experience & my vets is this brand has the highest "vaccine reaction" rate..  including death - my vet won't use the brand. I had a HORSE die within minutes of getting a Fort dodge brand vaccine and the vet (still there and couldn't save the horse) said "oh, vaccine reaction".   It is the cheapest brand by a buck or two.. but may cost you $1000's in vet bills and/or worse-the  loss of pet.

PERSONALLY - Aussies can have a severe reaction to LEPTOSPORIS and CORONA virus Vaccines.  PLease request that your vet not use these unless you live in an area with a lot of Mice (lepto) or corona.