I don't know what's in the sentinal, but if I were you with a collie breed, I would have the dog MDR1 tested as well, I believe the website for the info was posted previously..
If your vet isn't that 'up' on collie breeds how will you know in the future if he prescribes something that could literally kill your dog IF it carries the MDR1 gene in one form or another?
Ivermectin isn't the only "no no" drug there is a long list of drugs to stay away from, Immodium AD being another common drug.
My aussie tested out "mutant/mutant" for the MDR1 gene, my vet's had never heard of it in aussies and were grateful for the info I gave them and the listing of drugs for future reference. I give her next to nothing in regards to drugs because you never know what can affect them adversely.
I do use interceptor with all my dogs. No flea / tick repellants,
Diane
