Heartworms - Sneaky Little Devils

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?

[ginger899]

No I haven't. I don't know very much about heartworms. I didn't know it was possible to just kind of 'outlive the worms'. I thought they always needed treatment...So they would just die given time?
Misty tested neg. for heartworms too, last summer, but this does make me wonder. I think (as she has a slightly sensitive digestive system too) -that the treatment would be hard on her too.

[Jaybay]

Bizarre, huh?  Guess I got a new wrinkle on my brain.  :-)

Our vet keeps a dog heart in a jar of formaldehyde in the exam room.  The heart is packed full of heartworms.  They're long, thin and the exhibit usually prompts clients to get their dogs on preventive meds when they initially resist spending the money.  A picture's worth a thousand descriptive words, yes?  :-O

[sk123]

You could try asking your question in the veterinarian forum for a second opinion. I've certainly never heard of this before!