Is Your Pet Protected From Heartworm?


For those of you who know me, I’m originally from Florida — AKA Heartworm Central, thanks to the warm weather and abundance of mosquitoes. But we also see the disease quite often here in the beautiful mountains of Virginia. As of late March, I’ve already diagnosed four pets with heartworm disease in the past three months.

A Single Mosquito Bite Can Ruin Your Pet’s Life

All it takes is one mosquito bite to transmit the larval stage of the heartworm parasite. From there, it grows and travels over the next six or so months to the heart, where it becomes an adult worm. In dogs, there can be numerous worms. Cats typically only get a small worm burden, but it is no less deadly.

As the worms grow, they interrupt blood flow to the heart and its function, leading to heart failure and, eventually, death. In cats, we usually see severe inflammation in the lower airways and respiratory distress. They can also act as emboli, or blood clots, causing strokes where they block blood vessels elsewhere in the body. It’s a truly devastating disease.

A Steep Cost for Treatment

It is treatable, if detected early enough before severe cardiac changes occur, but treatment can easily exceed $1000. It’s also a long, cumbersome process over several months. Much of this time requires strict restriction from exercise and activity, which can be frustrating for many high-energy dogs and their owners. The American Heartworm Society has detailed information on the treatment process.

Preventing Heartworm is Much Easier than Treatment

I know it may sound like we’re harping on prevention every annual exam, but it’s because we care! Preventing heartworm (and most other conditions) is so much easier on your pet’s health. It’s also much less expensive for you.

We recommend you give your pet a monthly tablet that kills any heartworm larvae a mosquito may have injected into your pet within the last month. But beware: If you miss a dose, those larvae grow up into more adolescent parasites that are not killed by the preventative. Hence why consistent monthly prevention is so important.

Indoor Pets Can Get Heartworm, Too

“But, my pet never goes outside,” you might say. Perhaps not, but mosquitoes get inside. They are pesky like that. If your door or window ever opens (you leave your house!), they can get in. Also, your pet could escape one day. It happens! The door opens as you get home and your pet sees something exciting outside and ZOOM! They’re running through the door before you know it. You never know when something can happen. Better safe than sorry!

Do I Really Need to Treat for Heartworm in the Winter?

Sure, it gets cold in the winter, and you don’t often see mosquitoes. But Blacksburg weather doesn’t always play by the rules. For instance, this past year we barely even had a winter! I was seeing ticks on patients all “winter” long. If the fleas and ticks haven’t gone away, mosquitos likely didn’t either. I myself had a couple bug bites over the winter.

People also travel with thier pets during the holidays — especially if you travel farther south, I can tell you from personal experience that the mosquitos only get worse! I usually go to Florida for Thanksgiving and I always come back as partially eaten mosquito food. Thankfully humans don’t get heartworms. My dogs are faithfully on their monthly heartworm preventatives, so they also lived to tell the tale.

Even Pets Taking a Monthly Preventative Need an Annual Test

There are circumstances that we cannot predict or necessarily know about that could interfere with our diligent monthly prevention. Or maybe you did just miss a month; we’re human, life gets busy. It’s no one’s fault–things happen! For these reasons, every pet should get an annual test.

Or, you can be as diligent as possible, but sometimes our pets have their own ideas! For instance, it is possible that your pet went outside after taking its preventative and ate grass or something else disgustingly delicious and vomited up its medicine.

Indoor pets occasionally vomit, too. You might not find this vomit for a while, and hence not make the connection that they upchucked their preventative. It is also possible that your pet has absorption problems in the digestive tract (such as IBD, food sensitivities, or worse), and is having a flare up that prevents adequate absorption.

You Should Get a Test Even if Your Pet Passed Last Year’s Heartworm Test

Tests only detect adult heartworms. And, because it takes a minimum of 6 months from infection to adult stage, the first test might miss an infection. If your pet is negative on its first test, then starts preventative and is diligent, he/she could still test positive the next year if infection occurred prior to starting the preventatives, and the worms were just too young to detect on that first test.

As a bonus, our heartworm test also tests for tick borne diseases. And those bad boys are horrible in this area! Annual screening for tick-borne diseases is also recommended.

Do Cats Really Get Heartworm?

Yes! But the disease affects them differently than in dogs. Cats typically only get 1 or 2 adult worms as opposed to the plethora that can grow in a dog. But, the disease is no less dangerous for felines. Cats are VERY sensitive. Heartworm disease typically causes severe inflammation in a cat’s lower airways, similar to a very severe case of asthma. This can put them into respiratory distress, leading to death.

Treating Heartworm in Cats is Difficult and Dangerous

Also, even just a few worms can cause a kitty to have obstructive heart disease and thrombosis/stroke. Unfortunately, the treatments we use to kill worms in dogs have a high risk of causing a severe allergic reaction in cats. We do not recommend it. We usually can only treat the symptoms with anti-inflammatories to ease the airway. Sometimes surgery (with a cardiologist) to remove the worm(s) is possible, but at great expense and risk.

Luckily, Revolution Plus is a great product for cats, especially outdoor cats, that prevents heartworms, intestinal parasites, fleas, ticks, and ear mites. Keeping your pet on this medication can save you a lot of money, and heartache.

Heartworm disease is a terrible, but preventable disease in both cats and dogs. All it takes is 1 tablet (or topical treatment) once a month plus annual tests!

– Dr. Kelly Lemkul, DVM

Companion Animal Clinic has been serving Blacksburg, Virginia and surrounding Montgomery and Christiansburg communities since 1974. We are an AAHA accredited veterinary hospital and provide quality, professional care for dogs, cats, exotics, and small mammals. Learn more about our amazing team.

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