Well it seems one of the dogs had heartworms break through the sentinel monthly preventive. I thought the test sent out had to be wrong. Had the vet do a second in house test the next week. It was positive too. I’ve never had a dog test positive, it’s a new experience for me. I buy all preventative through my vet, and have never miss a dose. I had them give her a proheart 6 injection, and a month of doxycycline. Retest her in 6 months. Just sucks that she’s going to miss the whole season.

I’ve heard of positive test result after regular use of ivermectin also. Guess the heart worms are becoming immune to some older, widely used medications.

I have always tried to stay away from the new and improved versions of meds. I like to wait a few years, just to see if there are any unknown side effects. With this happening, guess I will break that rule.

Parts of Texas and the Mississippi have ivermectin resistant heartworm. I happen to live in one of them and have had several dogs get heartworm on ivermectin. I now give a dose of ivermectin on the 15 th of the month and a dose of nexguard plus (moxidectin) on the 30th. Ask your vet about the severity of the infection — if he never missed a dose it is likely he only has one or two heartworms and could still work some, I get my dogs twice a year rather than the one recommended. If you live in the hill country or south of there you should consider Chagas testing.

Dang that is not good news. I have a friend from the Houston area who had the same thing happen about 3 years ago with one of his bird dogs. Makes me wonder if I should be giving my dog something different. Heartgaurd, which is ivermectin is what my vet gives me for them. I’m not that far north of the Houston area in Trinity co.

I’m in Spring, just north of Houston.

Hot and humid = higher mosquito count more chances of developing heart worm resistance

My buddy went through the same thing last year. He never missed a dose either, but his vet said she might’ve vomited that day after he gave her the pill. Just never know.

She’s in the house, so I would have known if she vomited. Best guess by one of the older vets there, was possibly the dog not chewing it, and basically swallowing it mostly whole. She said she’s seen heartgard heartworm pills fully intact in a dogs stool before.

Pro-heart is the way to go, 1 shot every 6 months or there is a 12 month version

"She said she’s seen heartgard heartworm pills fully intact in a dogs stool before."

I give my dogs Bravecto and I always chop it up really well for this reason. Mine get Ivermectin once a month. I'll have to rethink now if the worms have developed immunity. My feed store guy told me Ivermectin is very hard to find in the smaller quantities since it may be going presciption required in the near future.

I told my vet I'd seen that happen before and they just looked at me like it couldn't happen. I crush'em up and mix with peanut butter, dog eat's them up now.

There’s definitely some resistance to ivermectin in heart worms now. In good news, if you’ve been consistent as you say, the drug company should pay for treatment. Ask your vet.