# Age for heartworm test?



## CarolinaCasey (Jun 1, 2007)

6 months of age. You have to make sure he's negative in order to continue the preventative. For peace of mind, you should really do it. A 3DX or 4DX will also screen for Tick Borne Diseases. It only takes 3 drops of blood- I don't think Enzo will mind!


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## Enzos_Mom (Apr 8, 2010)

We've got the test scheduled for 2 weeks from tomorrow. I just wanted to make sure that this is really the time that he should be getting it and they're not just trying to get my money. =)


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## IowaGold (Nov 3, 2009)

We usually do the first one at around 6 months when we do pre-anesthetic bloodwork prior to spay/neuter. It's a bit ambiguous as to when to test the first time (with the whole lag time before testing positive, etc), but since it's just a blood test and not something that has the remotest chance of hurting the dog, I'd do the first one at around 6 months.


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## lgnutah (Feb 26, 2007)

Just wondering why they always say you have to test negative for heartworms in order to be able to take heartworm preventative.
What would the heartworm preventative do to an animal who already had heartworms?


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## mylissyk (Feb 25, 2007)

lgnutah said:


> Just wondering why they always say you have to test negative for heartworms in order to be able to take heartworm preventative.
> What would the heartworm preventative do to an animal who already had heartworms?


I'm wondering too. If rescue has a dog that does have heartworms, we continue to give them Heartgard Plus (specifically Heartgard Plus), to prevent the heartworms from increasing. The Heartgard kills the microfilaria (baby worms) that the adult worms in the heart are producing.


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## cubbysan (Mar 13, 2007)

lgnutah said:


> Just wondering why they always say you have to test negative for heartworms in order to be able to take heartworm preventative.
> What would the heartworm preventative do to an animal who already had heartworms?


Years ago it would have killed the dog.


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## cubbysan (Mar 13, 2007)

mylissyk said:


> I'm wondering too. If rescue has a dog that does have heartworms, we continue to give them Heartgard Plus (specifically Heartgard Plus), to prevent the heartworms from increasing. The Heartgard kills the microfilaria (baby worms) that the adult worms in the heart are producing.


If this same dog was given a heartworm test after taking Heartguard Plus, would you get a false negative? I was told the test only shows one stage of heartworm. Can't remember if it was the microfilaria or the adults.


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## IowaGold (Nov 3, 2009)

The test only shows adult females, so no the dog won't test false negative.

Yes, the old heartworm meds could/would kill an infected dog. The new ones are safe, that's why I said it was kind of ambiguous as to when is the exact best time to do the first test. It depends a bit on your vet and what their policy is. Like at my clinic, we do the test at 6-7 months. After that age, if the test isn't done, we consider it "overdue" and we won't sell you more heartworm pills until it is "current".


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