Yes, I have the test done annually (starting once the pup is 6-7 months old) and keep everybody on preventative year round. (It's not unusual to put puppies younger than 6-7 months on preventative before the test is done). I'm assuming that since you apparently never tested any of your prior dogs that they still were all on HW preventative for life. Is that correct? If so, depending on where you live, you were very lucky. Heartworm (HW) is nothing to mess around with.
Search the forum for threads related to HW testing and treatment --- look especially for posts by Magwart (there was a thread just last week). Meanwhile, here's a link with some basic info:
Yep, Aly's right. I actually wouldn't test until sometime between 7-12 mo. old, as long as it's been on prevention, like yours has -- but you definitely need a test in the first year. You'll also get a prescription for a year's supply of the prevention of your choice then, so that you can keep your pup HW free.
The HW lifecycle is weird. A mosquito bites the dog, and deposits a microcopic larvae into the blood. That HW can be killed by most prevention for maybe a couple of months (indefinitely for Advantage Multi--it's the only one that kills older larvae and even adults). If it's not killed by prevention, that tiny larvae morphs into a bigger stage of larvae in the dog's blood. However, it's undetectable at this stage -- it's in there growing, but the test would still show "negative" (but it would be a false negative).
Only 6-7 mo. after the mosquito bite is the worm finally big enough to produce enough antigen for the test to detect. The dog may be a few months older though, esp. if it's first few months were during the winter.
As an example, I adopted a shelter pup that was 6 mo. old. She tested negative upon adoption. We put her on prevention. At my vets suggestion, we retested 6 mo. after adoption (since that shelter test was potentially a false negative, due to her young age). Now she was positive -- the worms she'd already had were now showing up.
Do it every year. It's my understanding that even if your dog is on heartworm treatment year round there are some areas of the country where heartworms are developing a resistance to some heartworm preventitives. Also, if you don't get your heartworm medications from a reputable source (think buying off the internet) it could be less or non effective do to poor storage effecting the potency of the medication. Another thing to consider is the type of test. My vet uses a snap 4dx which tests for heartworm and tick borne diseases. If you have ticks in your area you would want to test for tick borne disease. So testing annually should be done IMHO. Better safe than sorry.
Thanks for the info. Ozzy has been on preventative stuff since 9 weeks old will continue year round. I understand testing every year but at 5 mo old not sure I need to until 7mo or a year old.
Back in the day with other dogs they would get stuff 8 mo out of year then test in spring and start again. Never any issues but it’s been 8 yrs since having a dog and I know lots of changes since then.
BigOzzy2018, that used to be a very common recommendation -- the American HW Society now recommends year-round in the United States. There are some northern areas with VERY cold winters where you might be able to get away with it still, but if you end up having a warmer-than-normal winter, or an earlier than expected Spring with mosquitoes showing up early, it can lead to unexpected infection. I think that's what led them to change the guidelines.