How the heartworm lifecycle starts in pets, symptoms to look for, and treatments to consider

These days, especially in the south where it can feel like summer for 6 months out of the year, it’s common to hear veterinarians remind us of the safety of heartworm prevention during our pet’s annual visit.

Some pet owners don’t think cutting the cost of heartworm prevention will mean anything serious to their pet. Unfortunately, this just isn’t true, and heartworm disease is extremely serious. It can be fatal if not treated appropriately.

Prevention is less costly than having to handle treatment should your pet become infected. Being pro-active wins over retro-active options.

So, what exactly is heartworm and why is it dangerous?

Heartworm Disease 101:

Heartworms are comprised of foot-long worms that can survive in the heart, lungs and contributing blood vessels within an infected animal.

Dogs and cats become infected with heartworms only if they are bitten by a mosquito that is already carrying immature worms ripe for infestation and growth. There is no distinction between a non-carrying mosquito versus an infected one. Which is why it’s important to monitor your pet outside during months when mosquitos are in full force.

Most common myth de-bunked: Dog’s cannot pass the disease to another dog. The heartworm infection is only caused by an infected mosquito bite. So let’s put this rumor to bed.

Heartworm Lifecycle in Dogs:

Mosquitos become infected from biting a dog that is already infected from a previously infected mosquito. Hence, why mosquitos continue the cycle of producing the disease from one dog to the next. A dog that is heartworm positive carries microfilariae within their bloodstream, which are picked up by other mosquitos, ultimately maturing into infective larvae within the insect.

While carrying the infective larvae, a mosquito will bite a dog and spread the larvae to the animal’s bloodstream, where the dog will serve as its host while the heartworms grow. It takes close to 7 months before this larvae will turn into mature heartworms. Once grown, the heartworms mate and release their offspring into the dog’s bloodstream. This is where heartworms continue to grow and expand, which is the most dangerous part of the life cycle. It can take years, but as the worms grow and expand, they begin to affect the heart and other vital organs as space within the dog’s inner-structure become limited.

While dogs can harbor hundreds of worms before extreme issues happen, the disease will cause life-long damage and other diseases if the worms are not treated.

In most extreme cases, blockages of blood flow within the heart can cause cardiovascular collapse. At this point, worms must be surgically removed through the dog’s neck and must be done immediately. 

What Symptoms To Look For:

In the beginning, there are little to no signs of any infection. As the infection lingers and the worms grow, symptoms will increase. Below is a list of most common signs to look for:

  • Mild persistent cough
  • Limited energy/ Constant fatigue
  • Low appetite
  • Weight loss

In some cases, a dog’s abdomen will swell due to increase in fluid.

An annual exam of your pet will help monitor any of these issues and test for heartworms routinely.

Heartworm Lifecycle in Cats:

Heartworm in cats is less severe of a lifecycle. Cats are an atypical host for heartworms, meaning the worms typically do not survive to adulthood. While dogs can sustain hundreds of worms, cats with adult heartworms typically just have a few worms.

While this may not seem like an immediate concern, damage can still be done. HARD (heartworm respiratory disease) can develop without any medical treatment. Although not as many worms are growing, it’s critical preventable treatment is maintained up front.

What Symptoms To Look For:

Cats will range in symptoms shown. Most typical signs are as follows:

  • Coughing
  • Raspy Breathing
  • Respiratory Issues (such as vomiting)
  • Treatment Options: 

Treatment options are different for dogs and cats. Never share the same treatment option for pets, as each preventative is created specifically for each breed.

There are various types of heartworm preventions on the market. From topical to chewable, or a 6 month shot administrated by your vet. There are multiple choices to choose from. See our recommended list of top medications below: 

Depending on your pet’s lifestyle, size and activity will factor into which prevention is best for their needs. The best first step is to talk with your vet to find what makes sense.

Our veterinary team at Emancipet is here to answer any of your heartworm questions, please feel free to reach out to our team here.