We adopted our dalmatian, Doc, in January of 2008. We have no real idea of how old he is or his prior history. A dal rescue group saved him from the needle at a county pound. At the time, he was heartworm negative. A year later, he was still heartworm negative. We are religious about keeping both our dogs on Sentinel, so imagine our surprise when Doc tested heartoworm positive a couple weeks ago.
Our vet tells us that there is an intermediate stage of development in heartworms that can go undetected by current testing methods. He suspects that the preventive meds kept any new ones from developing and that Doc is harboring one or two worms. Because he already has a twitchy digestive system and the treatment is very hard on the dog, we opted not to treat. The vet believes Doc will simply outlive the existing worms - in 3 or 4 years!
I had no idea this could happen, or that heartworms lived that long. Has anyone else ever come across this situation before?