Heartworm Disease In Pets

By Dr. Lindsay Lane, Managing Veterinarian

Guess what? April is Heartworm Disease Awareness month!! And I apologize for starting off with a super nasty picture, but they say a picture is worth a thousand words and I am hoping that this picture will make your heartworm prevention efforts worth their weight in gold! Especially because heartworm prevention doesn’t cost much at all and more importantly, folks – HEARTWORMS KILL!!

I talk about this particular subject so passionately because it is true – heartworm disease can be extremely deadly. The most frustrating thing about it for me as a Veterinarian is the reality that the preventatives (pill, topical, or injection) we have available for your dogs and cats are 100% effective when given appropriately! By given appropriately we mean – every 30 days, or even every 28 days (because earlier is fine too), or an injection every 175-180 days or every 355-360 days (depending on the specific injection).

It may come as a surprise, but being late with heartworm preventatives by sometimes just a few days or weeks or months can change your dog or cat’s protection to this nasty disease. This is why we ask if you have missed any doses when you refill your heartworm preventatives; it’s not to be mean or difficult, it’s because heartworm larvae can mature to an infective stage in as little as 2 months, at which point your heartworm preventatives are ineffective!

So, let’s go through the basics. What are heartworms and how does your dog or cat get this terrible disease? Below is an image from the American Heartworm Society on how transmission occurs and roughly how long it takes for worms to either be unaffected by your preventative or how long before they become a problem in the host (your animal). They are transmitted through the bite of a mosquito and then those larvae travel in tissues through the bloodstream and end up in the animal’s heart where they can mature (like the picture above). Severe heartworm infections cause sometimes permanent lung and heart muscle damage and be so severe that the animal can die from these preventable changes.

Depending on the type of prevention (pill, topical or injectable), you must administer medication on regular intervals to kill young larvae before they become older, at which point the larvae are unharmed by the prevention. This means ALL YEAR LONG PROTECTION!!!!!! Folks, we live in Maryland! We do not live in the Northeast. Our winters are either fleeting or nonexistent and for those of you who stop your prevention efforts in November/December and restart in March/April, you are doing it wrong!

In this portion of the East Coast, we recommend all year long/365 days of protection against this disease.  This goes for all dogs and technically all cats! We know the prevalence is extremely low for indoor cats, especially compared to dogs but the scenario of “my pet stays indoors” does not mean your home is mosquito proof. Heartworm prevention should therefore be a definite for all cats and dogs.

Keep in mind, there is a treatment for dogs but THERE IS NO treatment for cats! And you have heard an ounce of prevention is worth a pound of cure? Well, that is 100% true here; figure anywhere from $1500-$3500 to treat this disease in your dog, if found early, vs between $70-$150 per year to prevent it!! That seems like pretty darn simple math to me.

If a dog is found to be heartworm positive, Rocky Gorge follows the recommended treatment protocol put forth by the American Heartworm Society, because that is what has been proven and studied to be the most effective and safest way to clear a dog of adult worms.

Bottom line, I hate heartworm disease and you should too! Let’s work together to get your pets the best protection that is appropriate for their case. Talk to your Veterinarians NOW, before it’s too late! Your pets deserve it!

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