When should I stop HW meds?

[Kat09Tails]

Kind of a goofy question I know...

I'm getting a dog from a heartworm bearing area and moving them to here which is a non heartworm bearing area. How many months should I be using HW treatment once he gets here?

 

[Beanie]

I think Heartgard says to give heartworm meds for a month after "mosquito season" ends... so maybe an additional month? It takes six months for the baby worms to grow into adult heartworms and be detected on a blood test - you could do an additional six months, test, and if the dog is heartworm negative at that point, stop at that point.

 

[Kat09Tails]

Hmm... an additional 6 months wouldn't kill me - I'll see if my vet will write me a script when I see him. I'm not really worried about him being infected with adult worms since he's been on monthly control pretty much his whole life.

 

[CharlieDog]

I'd do what Beanie suggested as well. Our dogs go off HW meds 45 days after the first freeze we get. Then they go back on in the spring. It's worked for us, for 5+ years.

 

[Southpaw]

I would do an additional month, to kill whatever he was possibly infected with. Since heartworm "prevention" is actually a treatment. So the dose you give in August kills what they may have been infected with in July. Then test in 6 months just to be sure.

 

[GlassOnion]

There's not really any reason to wait 6 months. 6 months is the entire cycle, from microfilarid in the original infected host to a reproducing, adult heartworm. It has to go through a mosquito somewhere in between there.

45 days is about what you need, because that's the time period between when the L3 enters the host, molts to an L4 and when the L4 stage is still susceptible to treatment, give or take a few days.

We just say monthly because it's easier for clients to remember, and gives a lot of breathing room for prevention of what's otherwise an expensive condition to treat.