Heartworm Disease in Dogs

Is your dog on a monthly heartworm prevention medicine? Heartworm disease is very easy to prevent, with a pill once a month or a shot twice a year. If your dog is not on heartworm prevention medicine, there is a high risk that he will get heartworms sometime during his life. Heartworm disease can be fatal to dogs and treatment is difficult, so prevention is very important!

heartworm disease in dogs

Pin It

What Causes Heartworm Disease?

Heartworm disease is caused by a parasite called Dirofilaria immitis, also called the heartworm. It is transmitted by mosquito bites, and can not be transmitted from one dog directly to another. When a dog is infected with heartworms, he has tiny larvae (baby heartworms), called microfilaria, in his blood. If a mosquito bites an infected dog, the mosquito will ingest some of these microfilaria. In the mosquito, the baby heartworms mature to teenage heartworms (infective larvae). When this mosquito bites another dog, the infective larvae will be transmitted to the new dog. Once inside a dog, the infective larvae grow into adult heartworms.

heartworm disease is transmitted by mosquitoes

Pin It

 {Image from Diagnostic Imaging Atlas.}

The adult heartworms live inside the dog’s heart and the main arteries that give blood to his lungs. The adult worms interfere with normal heart function, and make it very difficult for the heart to pump enough blood to the dog’s body, especially his lungs. These adult worms will continue to make microfilaria (baby heartworms), and can spread heartworms if they are bitten by another mosquito.

What are Signs of Heartworm Disease?

Most dogs will not show signs of heartworm disease until they have been infected with adult heartworms for at least 2 years. It takes this long for the worms to grow big enough to cause problems that you can see in your pet. Some signs you might notice are coughing, weakness, lethargy (tiredness), or getting more tired than normal with exercise. Some dogs may even faint during or right after exercise. In addition to the signs you can see, your dog has also had damage to his lungs, liver, and kidneys because of decreased blood flow. When the heart can not pump enough blood (because of heartworms in the way), these organs get damaged and don’t work as well as they should. Your veterinarian can do a simple blood test to determine if your dog has heartworm disease.

Can My Dog Get Heartworm Disease?

Any dog can get heartworm disease, even if he spends most of his time inside. No matter how little time your dog spends outside, he can still be bitten by a mosquito. Mosquitoes are everywhere, especially during the warm, humid summer months. Just a short trip outside to go to the bathroom can be long enough to get a mosquito bite. And mosquitoes can find their way inside your house, too! They can squeeze through holes in screens or can fly in when you walk in the door. Dogs with long hair or thick coats can get heartworms. While mosquitoes usually will bite dogs where their hair coat is thinner (like on their belly), mosquitoes can bite anywhere. A hungry mosquito can work very hard to find some skin to bite, even through a thick hair coat. A dog that has had heartworms in the past (and been successfully treated) can get heartworms again – they do not develop an immunity to the worms. It is very important to keep your dogs on heartworm prevention medicine, even if they have had heartworms in the past.

Is your dog on heartworm prevention medicine? If your dog isn’t on heartworm prevention medicine year-round, it is time to start up againCall us or come in to ask about the options we have available. We have different types of chewable pills that are given once a month, topical medicines that are applied once a month, or we have a shot that is given twice a year. We can help you decide which of these options will be the best for you and your dog.

Check out our Heartworm Disease Resource Page for even more information about heartworms.

Comments are closed