MDR1 · drug sensitivity
30 SECONDS · What it is
The ABCB1/MDR1 variant changes transport of certain drugs. A dog can be clinically healthy while needing lifelong medication precautions.
3 MINUTES · What to look for and do
What changes in the body
P-gp helps limit substances entering the brain and transport them in other organs. Reduced function can increase toxicity from particular drugs. This does not mean an allergy to every medication.
Understanding copy numbers
1 copy · Sensitivity is still possible
2 copies · Greater drug susceptibility
A negative result does not eliminate other adverse reactions. One copy needs caution; two do not prove the dog is currently experiencing toxicity.
Medication: an individual plan
The vet may choose alternatives, adjust doses or avoid combinations for the individual patient. Simply swapping any drug is insufficient: dose, route and interactions matter. Sedation, surgery, parasite control and cancer treatment also require checking the result.
Loperamide is an example to avoid in sensitive dogs. Ivermectin illustrates dose dependence: some authorised preventive formulations may be safe, while high doses can cause toxicity. Do not generalise between products or change treatment without the vet.
Three steps for the family
- Keep the report and copy number
- Inform the vet at every visit, operation or emergency
- Check every medication before administering it
EXPERT · Testing and breeding decisions
Is it exclusive to Aussies?
The variant occurs in several breeds, especially herding dogs, and in mixed breeds. Its presence elsewhere does not reduce individual risk.
Responsible breeding
It can pass to offspring. Planning with both parents’ results can reduce transmission while preserving diversity; automatic exclusion of every dog carrying the variant is not required.
From the guide to your Lunamar records
The library explains breed and health concepts. The private platform organises dogs and kennels, preserves evidence, explores pedigrees and records reproduction. Reading a guide does not create records, grant access or confirm a result.
In Health and genetics, preserve the dog’s report and review variant, copies, inheritance and page before marking it Documented. A genetic finding, clinical suspicion and diagnosis are different facts. Recording a result does not prescribe treatment or automatically approve a mating.
For an individual dog, discuss tests and family history with the veterinarian. The system does not diagnose or decide treatment, ovulation or insemination timing. Missing data must remain identified as pending information.
Open the private platform user guides
Application to Lunamar features reviewed on 22 October 2026. Each reading retains the scope of its clinical sources and review dates.