This has been going on for such a long time. This is what happens when you get cheap with the most important ingredient. I wish they'd bring back Interceptor but, as per my recent conversation with Novartis "not anytime soon". I have some Interceptor left and use it from June - September and use (unreliable) Heartgard Plus October - May.
If your dog has tested positive I suggest you call the company who made your heartworm preventative and hold them responsible (as long as you purchased your preventative from either a vet or a Vet Vipps pharmacy).
It has nothing to do with "getting cheap with the most important ingredient."
Sentinel has the same active ingredient as Interceptor--it just has a flea sterilzation component that Interceptor doesn't have.
Reistence to medication is the normal evolution of things unfortunately...we have succeeded in getting more and more dogs on heartworm prevention, but then have given the beasties the opportunity to develop resistance because of the wide-spread exposure to the medication.
Where do you folks live who have Heartworm positive dogs? Pretty scary!
Just a question...have any of these dogs been on breeder administered IVOMEC? The suggested dosage for this varies all over the place. But, maybe a slightly higher dosage than is found in doctor prescribed monthly treatment is the way to go.
I treat with IVOMEC. I use .25 cc's for my 65-70 bitches and .35 cc's for my 80-90 pound dogs. Many breeders are using up to 1 cc/month.
Luckily, I have never had a heartworm positive dog.
I don't dilute it. I have a large syringe and pull up the correct amount for each dog. I put each dose on a little piece of bread and put it atop the food in each bowl.
