The article that I read says that heartworm preventative is actually good for 60 days as a preventative for heartworms but only 30 - 45 days for intestinal worms. The manufacturers say to give it every 30 days so that when people miss a dose (which they almost always end up doing) they will, in fact, still be covered for the full 60 days if they go to the next month.

I have gone to 60 days apart in the winter and 45 days in the summer and my dogs always test negative. (The article was in Whole Dog Journal I think)

 

We have missed once or twice before...and gave it anyhow....and then changed the cycles on the calendar to reflect the new schedule....we have never had a problem in 15 years....were also on Interceptor...always fecal neg for HW.

 

Fecals won't find HW... I'm sure it was just a typo since you've had dogs for 15 years, but just a heads up to other members.

I also think Wallaby will be okay -- I have read similar articles about Interceptor lasting much longer than the 30 day mark...I will try to find them!

 

Thank you guys. I'll get him another dose tomorrow.

 

Ive always given preventative once every 60ish days. And I always HW test in the spring.

 

Ditto here. I HW test in March-ish and give every 45-60ish days through September.

 

Alrighty then, thanks Linsey. Yes we get cold winters here... Upstate NY winters are, well, pretty bad.

 

The maps in this article might help, they give the months you should start/end heartworm treatments by region:

Heartworm Region Map

My vet gave me something similar but I can't find it at the moment. I would use it as a loose guideline. In my area, I go by the general rule that once the weather stays above 60 degrees consistently for 2 weeks, I will start heartworm treatment 45 days afterwards.

ETA: By the way, the map is pretty conservative like it says...for instance, it says Maryland should dose June-December, but I just do July-October.

 

It is a fairly conservative map. It has us staring in June but by then we've had mosquito's for quite awhile. The only months I would really say we don't have mosquito's would maybe be Jan. and Feb. and we've had some really warm spells in those months so I wouldn't guarantee that even. They're tough little suckers down here!

It does mention the 45 days for dosing though.