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Don't stop your pet's parasite prevention in the fall!

It's fall and all of the autumn traditions are making themselves seen across the city and the Internet. I have seen pictures of the magnificent colors spread across the Aspen trees of the Rocky Mountains and I have seen WAY too many pictures of Pumpkin Spiced (fill in your favorite food here).

I also received an email bulletin today from the American Heartworm Society reminding me to not "fall" back on heartworm vigilance. At first, I was certain that this was a play on words to coincide with the upcoming "falling" back of the clocks to end daylight savings time, but then I realized that many of our pet owners still think of Autumn ("the Fall") as a time to put up the monthly preventives until March or April. Why is it that so many people are reluctant to continue parasite prevention through the winter months?

I am sure that my readers will say something like "well, Tom, mosquitoes aren't out in the winter time, so why should we spend money on prevention?" I certainly can't disagree with the fact that winter snows are coming for much of the country, but as I type this today, it's 81 degrees Fahrenheit in Indianapolis! We are still dealing with mosquitoes AND, much more importantly, the heartworm larvae coming from those mosquitoes that are biting today are not affected by last month's pill. To put it more plainly, if you have already given October's prevention, that medication is generally out of your pet's system in about 48 hours or so. Our forecast locally is calling for temperatures in the 80s for the rest of the week. If you aren't planning on giving prevention in November, your pet runs the risk of being heartworm positive by next April or May. Furthermore, almost every winter I see a picture from a veterinarian in a northern state showing a live mosquito found in their house in February!!

You can also check heartworm statistics at even have a map showing prevalence in your area, down to the county! Right now, nationwide, 1 in every 78 dogs is testing positive for heartworms! It's a number that seems to grow each year despite safe and effective prevention!

Remember that most heartworm preventions work "backwards", that is, they are de-worming your pet from heartworm larvae picked up in the previous month. It takes about 45-60 days for the infective larvae of the heartworm (the ones from the mosquitoes) to work their way through our pet's connective tissues and into the bloodstream. At this point, the monthly preventives are less effective and the chance of a larva growing up to be a fully functioning and reproducing heartworm adult increases greatly.

It's just not worth the risk!! You won't save that much money by stopping prevention in the winter time and it only takes one of those "winter" mosquitoes to infect your furry friend. Then, you are looking at hundreds to thousands of dollars in diagnostics and treatment to rid your pup of these deadly worms. It's also important to note that most of our monthly preventives also work to control several of the intestinal parasites, like hookworms and roundworms. These nasty worms can be spread at anytime during the year (especially at dog parks and other dog hangouts) AND they have the potential to infect your two-legged family too.

So, let's stay on track this year and keep our pets safe from this preventable disease. Don't let the changing colors change your commitment to keeping your pup heartworm free! For those of you that do stop each year, care to share why? After reading this, are you giving second thoughts to year-round prevention?


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