# My dog just tested positive for heartworms even though he was on Heartguard



## ozzy (Sep 29, 2007)

Hey all, just writing to vent. My poor Ozzy just had two weak positive tests for heartworms. I am not sure what weak positive means but I hope it means it hasn't advanced very far. He has been on the monthly preventative Heartguard but apparently just missing it by a few days can cause it to fail. I may have even missed a dose in the last year, I don't think I did but there is no way to no for sure so I have been racking my brain trying to figure it out. Since Jan. I have gotten engaged, bought a house with my fiance and moved, rented out my condo and planning a wedding so it has been a crazy year.

He has no symptoms and is very healthy otherwise so I pray this treatment and recovery will go well. Since the tests were weak positive my vet is sending it out to the lab that makes the test to verify one last time but I think he must have it.

My wedding is in October and then I am taking a 10 day honeymoon and I am just not sure how this is all going to work out with keeping him quiet. Normally he stays with my parents when I travel but there is another dog there and they love to play. 

Has anyone made it through this and have any tips? Waiting another week for the final test sucks and I just want to start the treatment asap. Knowing he has this in him is making me sick with worry. He has still be on Heartguard all this time though so I am hoping it just has not advanced very far.


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## DJsMom (Jun 6, 2008)

I'm sorry this is going on for you. And I'm afraid I can't give you any info, but I did want to comment because this is so scary & something I wouldn't want my dog to have to go through. But it also seems like I've heard about a lot of dogs testing positive lately. 
I'm curious - if he had no symptoms why was heartworm tested for? I've missed a few days in the past & not had any problems. In fact, I thought I had read once that heartworm meds only NEED be give every 45 days, rather than 30 or 31 as in a normal month. But, myabe that's just a certain brand of preventative. 

I sure hope that everything goes well for Ozzy!


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## Pai (Apr 23, 2008)

> He has been on the monthly preventative Heartguard but apparently just missing it by a few days can cause it to fail.


Actually, none of those medications have 100% efficacy (though the failure rate is very tiny). Sometimes things get through. =/

Though it takes around 4 months after infection for heartworm larva to grow up and enter the heart (the HW test measures hormones from adult worms), so if he's been on medication all that time... I'd almost wonder if the medication batch was defective somehow? Or perhaps it's a false positive, you never know.


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## grab (Sep 26, 2009)

DJsMom said:


> I'm curious - if he had no symptoms why was heartworm tested for?


Here they test yearly even if you use preventative


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## DJsMom (Jun 6, 2008)

grab said:


> Here they test yearly even if you use preventative


Oh, I see. That does make sense & that probably is what happened in the op's case, which is a good thing since they found it early.


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## ozzy (Sep 29, 2007)

Yes it was a routine yearly exam when they tested him. I almost forgot to bring him in since they did not remind me and he seems perfectly healthy but made the appointment and went on in earlier this week. I had no idea this was waiting for me. 

I am very concerned about how the treatment is going to go because usually they use heartguard and an antibiotic for the first month to kill off bacteria and the baby worms and then they start the hardcore treatment where he has to be kept perfectly quiet and still 24/7. That would be starting at the beginning of October when I have family coming in, my wedding and my honeymoon so it just seems impossible that we could keep him quiet. I might discuss it with the vet this week and see about pushing the hard treatment to after I am back from my honeymoon. Trust me I don't want to delay this at all but I want to be able to devote all my time and attention to him once I am back. Whatever she says I will go with though.

I really have no idea how he got it or when. I am aware that the adults worm must be 4-6 months old for the positive test so maybe it was last fall? I just have no idea.


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## Pai (Apr 23, 2008)

ozzy said:


> I really have no idea how he got it or when. I am aware that the adults worm must be 4-6 months old for the positive test so maybe it was last fall? I just have no idea.


That's why I'm thinking that perhaps the batch of medicine was faulty... perhaps contact the manufacturer so they could maybe do a test. There might be other bad batches out there.


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## ozzy (Sep 29, 2007)

Well I have an update..

Since the two tests that the vet gave my dog came back weak positive she decided to send out his blood to be analyzed at a lab. I believe it is the lab that makes the test but I am not positive. The snap test at the vet tests for the heartworm antigen produced by the adult female heartworm and the lab test was going to measure for that plus the antibodies that the dog produces in respone to heartworms.

Well the last test came back negative for both antigens and antibodies. I don't know what to make of it. Of course I hope that somehow the two snap tests were false positives but how likely could that be? I mentioned that to the vet and she seemed perplexed as well. She thought that he may just be very very early in the infection and the snap tests picked that up but the other didn't. That seems weird too though because the other test was supposed to be better? I don't know it's confusing but at this point she wants me to continue giving him heartguard each month and test again in December. So I guess I can relax a little now, we will not be doing any treatment soon. It still makes me very very nervous that he might have this but I guess we have to wait and see at this point.


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## DJsMom (Jun 6, 2008)

Thanks for update. I'm glad to hear you can relax for awhile anyway - I hope that everything will turn out OK


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## Willowy (Dec 10, 2007)

I have heard that SNAP tests have a high percentage of false positives. But 2 in a row. . .that's rare. Hopefully that's what happened and everything is fine.


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## ladyshadowhollyjc (Oct 28, 2008)

I know the SNAP tests will come up in a "positive" result if let to sit too long. Maybe this is the case both times your dog was tested?


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## ozzy (Sep 29, 2007)

ladyshadowhollyjc said:


> I know the SNAP tests will come up in a "positive" result if let to sit too long. Maybe this is the case both times your dog was tested?


That's what I am hoping! More and more I am feeling that maybe he doesn't even have this. It never added up since he always gets his prevenative and he is indoors almost all the time. I know it's possible though so we will be testing again in early December. Even if he does have it this shows it is most likely a very early infection which should make the treatment less risky. I am just feeling a lot more positive about it all now then I was when I first heard the diagnosis and read all the scary HW literature.


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