At God’s Little Aussies, we take the health and safety of our puppies seriously — not just in our breeding choices, but in how we educate their future families.
Protecting these lives isn’t about genetics alone. It’s about awareness. And that’s something we carry forward — for every puppy, every time.
✔️Understanding MDR1 and the Blood–Brain Barrier
One important gene we test for is MDR1 (also called the “multi-drug resistance gene”).
✔️What is the Blood–Brain Barrier?
Think of the blood–brain barrier as a security fence that protects your puppy’s brain. It allows the “good guys” like oxygen and nutrients to enter, while keeping out many harmful substances and certain medications.
✔️The Role of MDR1
The MDR1 gene produces a special “pump” protein (called P-glycoprotein) that works at this security fence. Its job is to push out medications and toxins that don’t belong in the brain, sending them back into the bloodstream where the body can safely handle them.
✔️Why MDR1 Mutations Matter
Some herding breeds, including Australian Shepherds and Collies, may carry a mutation in the MDR1 gene.
If a puppy has this mutation, the protective pump doesn’t work properly.
That means drugs that normally wouldn’t reach the brain can slip past the blood–brain barrier.
When that happens, even a routine medication may build up in the brain and cause serious side effects such as tremors, loss of balance, seizures, or in extreme cases, coma.
✔️Our Safety Policy
While testing is important, it isn’t the whole story.
There have been documented cases of drug reactions, injuries, and even deaths in dogs who tested negative for MDR1 mutations.
Because of this, we ask that all of our puppies be treated as if they are MDR1-affected, regardless of their genetic status.
This means veterinarians should always exercise caution with certain medications and dosages.
✔️A Word on Over-the-Counter Medications
Please never give over-the-counter medications, dewormers, or flea/tick preventatives without first discussing them with your veterinarian. Many common products that seem harmless can interact with the MDR1 pathway and lead to toxic effects in sensitive breeds like Aussies. Even natural or “safe for all dogs” products can pose risks if used without guidance. A quick conversation with your vet ensures your puppy gets the right product, dose, and timing for their individual needs.
✔️Our Commitment
All of our breeding dogs are DNA tested, and we are open about those results.
We provide families with clear information about MDR1 and a list of medications to avoid or use with caution.
Many dogs with MDR1 (and even those without) live long, healthy, happy lives—it just requires awareness and care.
✔️Our goal is not only to raise healthy puppies, but also to equip families with the knowledge to keep them safe for a lifetime.
GOD'S LITTLE AUSSIES 