Commonly asked questions about heartworm in dogs

by | Dog Care |

Heartworm is a serious health condition that can result in severe lung disease, heart failure, and sometimes, even death for dogs. It can be difficult and time-consuming to treat. In this blog we’re going to answer commonly asked questions about heartworm in dogs – signs, causes, treatment and more. 

Heartworm in dogs 

You’ve found the perfect dog who is looking for a loving forever home – but she is recovering from heartworm. Or maybe you’ve heard of this illness and worry about your furry friend getting sick. 

Did you know that heartworm is both preventable and is often treatable? Prevention of heartworm is always preferable to treatment as it is safer, simpler, and less costly. 

How does a dog get heartworm? 

Mosquitoes play a critical role in the transmission of heartworm disease.  Risk is especially high during mosquito season and along waterways where mosquitoes frequent. 

A mosquito feeds on an infected animal (such as another dog) and picks up an immature stage of heartworm called microfilaria. This immature stage matures within the mosquito to an infective stage. The mosquito then goes on to bite a dog and pass along this infective stage, which matures further over six to seven months into adult heartworm within that dog. 

Adult heartworms can live for up to five to seven years in a dog. Dogs can be re-infected even if they already have heartworm, which means that they can have more and more heartworms build up in their body if not treated. 

What are the signs of heartworm disease? 

Clinical signs of heartworm disease can include cough, shortness of breath, exercise intolerance, lethargy, reduced appetite, and weight loss. Severe cases may result in heart failure, which can present as a swollen belly and legs, due to fluid buildup. 

It’s important to note that just because a dog with heartworm disease may not be showing clinical signs, it does not mean they don’t have significant disease and damage present. Contact your veterinarian if you have any concerns about your animal’s health. 

Can it be passed to other dogs? To me? 

Heartworm disease is not spread directly from dog-to-dog or from dog-to-human. Heartworm disease in humans is rare. 

Do dogs ever fully recover from heartworm? 

Dogs can be successfully treated for heartworm. However, there is a risk of long-term damage to their heart, lungs, and blood vessels. Other vital organs, such as their liver and kidneys can also be affected if heartworms have blocked blood flow and oxygen delivery to these areas. Some recovered dogs may also require supportive therapy through the form of medication and diet, for life. 

What’s involved in treating heartworm? 

There are a number of stages involved in heartworm treatment, which will depend on the treatment plan recommended  by your veterinarian. Your veterinarian will stage your dog’s heartworm disease using various tests, such as blood work and x-rays. A specific treatment plan tailored to your dog will be developed by your veterinarian, with the aim to stabilize your dog and reduce treatment complications. 

Heartworm treatment traditionally involves a monthly heartworm preventative in the form of an oral or topical medication. The purpose of which is to kill immature heartworms and help to prevent new heartworm infections. Bacteria within the heartworms that helps heartworm survive and reproduce will be killed using a specific antibiotic prescribed by your veterinarian. 

heartworm in dogs

Your veterinarian will administer a series of injections of a specialized drug to kill your dog’s adult heartworms (immiticide) over a number of months. A steroid is often prescribed alongside these immiticide injections to support your dog as the heartworms are killed and broken down in your dog’s body. Your veterinarian may recommend that your dog stay at the clinic for close monitoring after these injections. This is so additional supportive therapies can be administered if needed. 

An absolutely essential component of heartworm treatment is exercise restriction before, during, and in the weeks and months after heartworm treatment is complete. Exercise can worsen heartworm damage and complications can also arise as your dog’s body works to clear dead heartworms.  

There is currently no vaccine available to prevent heartworm disease. However, there are monthly topical or oral preventatives available. There’s also an injectable preventative that can provide protection for up to six months. Consult your veterinarian for the best prevention plan for your companion animal. 

I’m thinking about adopting a dog with heartworm. What should I know? 

Consult your veterinarian before considering adopting a dog with heartworm disease to make sure you understand the commitments involved. 

Did you know? 

Cats can also get heartworm disease, so should be on prevention as well. There is also no cure for heartworm disease for cats, and as little as 1-2 worms can kill them. 


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