Why This Calculator Uses "Multiples of Normal Dose"
Different wormer active ingredients have very different margins of safety. Praziquantel and pyrantel, common in all-wormer tablets, are generally well tolerated at several times the labelled dose. Macrocyclic lactones like milbemycin and moxidectin, often found in heartworm-combination products, have a narrower margin, and MDR1-sensitive dogs can react at levels far below what's safe for other dogs. A single "mg per kg" number can't capture this difference — but comparing the amount consumed to the product's own normal dose gives a more consistent way to gauge concern across different products.
Frequently Asked Questions
A genetic test is the only way to know for certain, but breeds with herding dog ancestry (Collies, Australian Shepherds, Shelties, Old English Sheepdogs, and many mixed breeds) have a much higher chance of carrying the mutation. If you're unsure of your dog's breed background, it's safest to select "Yes" and treat any overdose with extra caution.
Different products use completely different active ingredients with different safety margins. A vet or poisons line can only give you an accurate risk assessment if they know exactly what your dog consumed, not just that it was "a wormer."
A single normal dose given slightly ahead of schedule is generally low risk for most registered products, which are tested with a wide safety margin above the labelled dose. The main concern is when a dog consumes multiple doses at once, such as getting into a whole packet or box.
Call your vet or the Animal Poisons Helpline anyway and describe the product as best you can — colour, shape, where it was purchased. They may be able to identify it, and can advise based on general risk even without the exact name.