Vet Blog

Is Heartworm Prevention Important

October 02, 2020

The short answer to this question is yes!

In La Porte, our warm, humid climate makes it a perfect environment for mosquitoes, the carriers of heartworms. In fact, the state of Texas leads the country in having the highest rate of dogs who test positive for heartworm disease. To protect our pets, we recommend year-round heartworm prevention for all dogs and cats in La Porte, TX.

What Are Heartworms?

Heartworms are internal parasites spread by the bite of infected mosquitoes. Mosquitoes pick up the larvae from biting an already infected animal and then pass it on to our pets with their next bite. Dogs are most susceptible to heartworms because they are the natural hosts, but cats can also be affected. Once an infected mosquito bites your pet, the heartworms then travel through your pet's bloodstream and lodge themselves in the blood vessels around the heart and lungs. There, they mature (in about 6 months) and multiply, gradually putting more and more pressure on your pet's heart and lungs.

Why Is Heartworm Disease Dangerous?

Heartworm disease is a dangerous illness that can cause a serious life-limiting condition and even death. While it is dangerous for all pets that can be infected, it can do cause some different illnesses depending on the type of pet you have.

Heartworm Disease in Dogs

In dogs, heartworms can cause lasting damage to the heart, lungs, and arteries, which can affect your dog's quality of life long after the parasites are gone. Unfortunately, the disease is difficult to diagnose by symptoms alone since most dogs have very few symptoms or even none at all.

Early, subtle signs of the disease include:

  • Coughing
  • Lethargy
  • Reluctance to exercise
  • Decreased appetite
  • Weight loss

These early signs usually only occur after the heartworms have been left to mature for over 6 months. If left untreated, the disease can go on to cause more serious problems including sudden blockages of blood flow within the heart, which can result in cardiovascular collapse. Because the disease is difficult to detect until it is further advanced, prevention is truly the best cure. It can even help avoid permanent damage to your pet's heart and lungs if administered in the earliest stages of the disease.

Heartworm Disease in Cats

Cats are atypical hosts for heartworm disease and most heartworms do not make it to their adult stages. Still, immature heartworms can cause quite a bit of damage, and sometimes, one or two heartworms do manage to make it to adulthood. Unfortunately, heartworms are very difficult to detect in cats, and there is no treatment available for them. If a cat does contract heartworms that are not eradicated by the cat's own immune system, these heartworms can cause heartworm-associated respiratory disease (HARD).

Signs of heartworm disease in cats may include:

  • Coughing
  • Asthma-like attacks
  • Periodic vomiting
  • Lack of appetite
  • Weight loss

More rare and advanced symptoms may include difficulty walking, fainting or seizures, or fluid accumulation in the abdomen. Sadly, the first sign of the illness can sometimes be collapse or sudden death. Since there is no treatment for cats, prevention is truly the best and only option for them.

Heartworm Testing

Heartworm testing is slightly different for dogs and cats. For dogs, the test is the only accurate way to detect the presence of heartworms. The test requires a small sample of blood, which is then examined for heartworm proteins. If your pet tests positive, we may require further testing to be sure of the diagnosis and fine-tune a treatment plan.

We recommend all dogs be tested annually for heartworm infection. We often conveniently perform this test at their annual pet wellness exam. Testing is recommended even for dogs for heartworm prevention to ensure the medicine is working and that there were no gaps in their administration.

Heartworm testing for cats requires an antigen and an antibody test to see if your cat has been exposed to heartworm larvae. Your veterinarian may also use X-rays and/or ultrasound to detect the presence of heartworms. Since there are no approved heartworm treatments for cats, they are usually only tested before and after they are put on prevention, in order to determine their exposure to risk as well as the medicine's effectiveness.

Heartworm Treatment for Dogs and Cats

If your dog tests positive for heartworms, treatment is available; however, it is expensive and complex. First, your veterinarian will restrict your dog's exercise to limit damage to the heart and lungs. As long as your dog is healthy enough to undergo the treatment, your veterinarian will begin it as soon as possible. Treatment involves several steps, yet many dogs with mild cases have a high success rate. Others with more severe infections can still be successfully treated; however, the risk of complications is increased.

After a successful treatment, your veterinarian will perform a heartworm test and then start your dog on heartworm prevention that should be given year-round for the rest of his life.

If your cat tests positive for heartworms, there is no direct treatment for the disease. However, since cats are not ideal hosts for heartworms, many infections do resolve on their own, although they can sometimes leave damage to the respiratory system. The goal of treatment is to stabilize your cat and determine a long-term management plan including monitoring and additional support if the disease becomes severe. In some cases, it may be possible to remove the heartworms via surgery. After the disease is resolved, our focus will be on prevention to avoid a re-infection.