Heartworms are parasites that are exactly as they’ve been named. They are foot-long worms that find their way into the heart, lungs, and nearby blood vessels of your pets. While these parasites inhabit the vital organs of your pets, they will cause a litany of serious, and often fatal, health conditions including heart disease and lung disease that will need to be treated by a veterinarian. The presence of heartworms can even cause severe damage to other organs in the body of your pet which will lead to the development of a myriad of other serious diseases.


Unfortunately, the symptoms of heartworms in the early stages of the disease are benign or nonexistent. It isn’t until the heartworms have had an ample amount of time to grow and infect your pet that it will begin to show symptoms of an underlying health condition. The most common symptoms that may develop as the heartworm disease begins are:

  • Fatigue after common activities
  • Refusal to exercise or be active
  • A cough that won’t go away
  • Noticeable weight loss
  • Loss of appetite

Once the heartworm disease worsens and it begins to affect your pet in a more severe manner, the symptoms of the disease will worsen as well. The two main symptoms of severe heartworm disease to watch for are the development of heart failure and the swelling of their bellies as fluids begin to collect in their abdomen. The signs of heart failure in your pets can include fatigue, loss of appetite, coughing during sleep or rest, and the discoloration of their gums.

If heartworms are left untreated, they can grow to enormous sizes. Since heartworms take up residence within the heart, lungs, or blood vessels of your pet, this can cause a clog or blockage in your pet’s vital organs and/or circulatory system. This clog or blockage can cause a fatal medical condition known as cardiovascular collapse or caval syndrome. Pale gums, dark urine, bloody urine, or labored breathing are signs of caval syndrome. This is a life-threatening medical condition that requires immediate surgery from a veterinarian.


Believe it or not, mosquitos are the main cause of heartworms. Heartworms develop mostly in wild animals such as wolves, coyotes, and foxes. An adult female heartworm will release microscopic worm offspring into the bloodstream of an infected animal. A mosquito will then bite the infected animal and take in a large dose of that animal’s blood along with the heartworm babies, called microfilariae.

The microfilariae will mature into infective larvae in a process that can take between 10 to 14 days. The mosquito will then bite another animal and transmit the larvae through the bite wound. Once inside of a new host, the larvae can take up to six months to mature into an adult heartworm. As an adult, it can live up to seven years inside of a dog and three years inside of a cat. Your pet can contract a new set of heartworms every year during mosquito season. Because of this, it’s important to get your pet examined by a veterinarian every year to check for heartworms.


The best way to treat heartworms is to put your pet on a heartworm prevention treatment plan. This includes providing your pet with a monthly heartworm medication and taking your pet to see a veterinarian every year for testing. Before you begin your pet on a heartworm prevention treatment plan, consult with your veterinarian to ensure that your pet is old enough and healthy enough to be placed on the medication.

The entire team of professionals at Eastside Animal Hospital is dedicated to improving the quality of life and health of your pet. Dr. Spears and her medical staff provide our clients and their pets the most knowledgeable, informed, and compassionate veterinary care available today. We specialize in wellness and preventative care for both dogs and cats. Eastside Animal Hospital is located in Muskogee, Oklahoma and serves the surrounding communities.

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