heartworm question

Hummm . . . I think my vet would do the test.  But, I'm not sure how long the medication stays in the system.  I know it's longer than one month but they have us dose it monthly for convienence sake.  I'm sure someone will know. 
 
I have to ask this though, why did you miss so many months?? 

ORIGINAL: willowchow
I have to ask this though, why did you miss so many months?? 

 
I adopted her in May, and she was on heartworm meds when I got her. Unfortunately, when she got sick, I guess the whole thing got ushed into the back of my mind. (I know, it's so irresponsible.) Her foster mom went to India for a while, and I couldn't contact her until recently either. So now I'm giving her Heartguard again.

What?? Bailey had heatworms when I got him from the pound, and no one had any clue he did until they tested him. No signs at all, luckily he was a young dog (1-2 years old) So he couldn't have had it for that long & the vet fixed it.
She probably doesn't have it... but its possible. It's better to be safe and just test for it, incase she really does have it. The treatment is horrible, Bailey couldn't even walk after he got the shot.

My vet's policy is that if you miss one does, your dog needs to be tested before resuming heartworm preventive.  Missing a dose= missing a month.  If you're a couple of days late giving the preventive, that's OK.  I believe the meds stay in the system for about 40 days, but I'm not entirely sure.  The reason you need to have the dog tested first is if your dog is even mildly  HW+, the preventive could kill him/her.  If this were my dog, I'd definitely have him/her tested before resumming the HG.

My vet also recommends testing if you miss any doses. I have to agree, you need to get her tested. It's better to be safe than sorry!

A test wouldn't show anything right now anyway. That's a VERY long time to be off HW meds - that would kind of freak out my vet, I know. The way it works, the meds don't stay in the system - they kill anything younger than 45 days. So if you were less than 15 days late, you'd be ok, but you've gone over that by a lot. You could potentially have worms that slipped through. Especially since this is peak season - unless you are in the Southern Hemisphere or in a low risk area.

BUT the test won't be able to detect the worms until they get old enough to reproduce - about six months from the infection. Take the date of your first dose after the break, count backwards 45 days, and you should test six months from then.

Here's the good news. It is safe to keep giving the Hartguard, even though your dog may be HW positive. Your dog would be only minimally positive and it's possible that even if you get a positive test down the road, the vet may recommend simply staying faithful to the meds - a few worms won't hurt a healthy dog and the meds will kill all the babies they produce. You will have to be religious about meds until the worms die - anywhere from one to four years. I'd also continue to test every six months to make sure the worms aren't gaining ground.

Good luck! I feel your pain - years ago I found out one of my dogs was sensitive to Interceptor and had been quietly barfing up his pills behind the couch. I found FOUR pills under there - but it happened in the winter and our yearly test came up negative - whew.

Thanks for the answers. I will give the Heartguard then go for the six-months-after testing, at least there will be no false negatives then. Someone told me the Ivermectin stays in the body for up to 60 days max. If I'm not mistaken, the treatment for heartworm involves a chemical which is injected into the dog but can also harm the dog if the dog can't take it -- so how would heartworm be treated in a dog that is old or sickly? Or is there no hope? 

Heartworm is treated with antibiotics, but the medication can be harmful to the dog.  That's why it's so important to prevent rather than treat.  Also, after treatment, the dog should stay quiet except for bathroom breaks.  I was told ideally a treated dog should be crate kept, or at least as quiet as possible for 30 days as the dead worms can break off and cause problems in the heart if exercising wildly.
 
We had a rescue Mastiff here last year for a few months.  she had been treated for heartworm already and never really bounced back.  I took her to the vet and she was diagnosed with heart failure, enlarged heart and not a very good prognosis.  The heartworms had done a lot of damage to her heart, and it was a shame.  The vet kept her herself to treat with meds and take home with her.  I was so glad because the rescue group wouldn't pay for her meds (quite expensive) and her prognosis wasn't great.  The vet fell in love with her and didn't want to put her down just yet, so she kept her.
 
I would imagine if your dog is already sickly, the treatment would be hard on them, but of course your vet could tell you that in much more depth.