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Heartworm in Cats

Heartworm in Cats

Recent studies have revealed that the heartworm disease, which was thought to be a canine disease, affects cats as well.
CatAppy Staff
The first reported case of heartworm disease in cats came from Brazil in 1921. Since then, it has been reported worldwide. In fact, the American Heartworm Society states that feline heartworm disease has been found in each of the contagious 48 states, Hawaii, Puerto Rico, U.S. Virgin Islands and Guam.

Feline Heartworm Disease

Transmission
Feline heartworm is transmitted by an infected mosquito bite. Cats are susceptible to heartworm disease even when kept indoors, as mosquitoes can fly find their way into the house. When the mosquito bites the cat, it introduces the heartworm larvae into the cat's bloodstream. These larval heatworms invade the blood vessels in the lungs. As they grow into adults, they lodge themselves into the cat's lungs and heart. Cats tend to have lower worm population as compared to dogs owing to their stronger immune system, but the damage caused by these parasitic worms is severe enough to cause their death.

Symptoms
The cat exhibits symptoms when the larval heartworm reach the lungs, or when the adult heartworm dies. Some of the chronic symptoms associated with the condition include ...
  • Asthma-like symptoms
  • Rapid breathing
  • Vomiting
  • Gagging
  • Coughing
  • Weight loss
  • Lethargy
  • Lack of appetite
  • Fluid in chest
Sometimes in acute feline heatworm diseases, cats may show the following symptoms ...
  • Fainting
  • Diarrhea
  • Convulsions
  • Blindness
  • Sudden death
Diagnosis of Feline Heartworm
It is very difficult to diagnose heartworm in cats. The veterinarian may recommend the following tests:

Antibody Test: This test is used to detect antibodies produced by the cat's immune system to fight the heartworm antigen. It is not very reliable, as it may test positive for a previous heartworm infection which has already cleared up.

Antigen Test: This test helps in detecting the presence of antigen in the blood. It only detects the presence of female heartworms, which means it will come negative if the cat is infected by male or immature worms.

Echocardiogram and Radiography: While ultrasound will help in detecting the presence of heartworms, radiography will help in detecting physiological changes, like the enlargement of pulmonary arteries or the right side of the heart, in response to the presence of these worms.

Microfilarial Tests: These tests are conducted to detect the presence of live microfilariae in the cats blood. As microfilariae are only produced when heartworms mate, the cat's blood will be devoid of them, unless it has both, male and female worms. Interestingly, only 20 percent of cats have microfilariae in their blood. Additionally, the test will also come negative if the cat's active immune system is destroying microfilariae on its own.

Treatment
While treatment options are available, one needs to understand that there is a significant risk involved. A single dead heartworm can block the cat's pulmonary artery and lead to pulmonary embolism. If the cat does not show any clinical symptoms, the vet may wait for the parasite to clear on its own. Now that may take up to 2 to 3 years. In the meanwhile, the vet will monitor the cat's health after every 6 to 12 months to check for clinical symptoms of this condition.

If the cat exhibits any symptoms, the vet may prescribe Prednisone to reduce inflammation and reaction to the worm. Cats which suffer from severe symptoms may require supportive therapy, like a bronchodilator to open airways, as well as oxygen support and intravenous fluids. You should carefully consider all the pros and cons involved in adulticide treatment. Studies reveal that one-third of the cats undergoing adulticide therapy face life-threatening complications.

Prevention
Feline heartworm disease can be prevented by using any of the several preventive medicines available in the market; Heartgard, Revolution, and Interceptor are a few to name. (Note: It is always better to consult a vet before you administer any such medication to your pets.)

It is always advisable to take your feline friend for regular veterinarian visits. You can hope that the worm lives out it's lifespan within your cat without causing any major complications, but opting for the treatment of this condition is definitely a better option. After all, a healthy cat is a 'purrrr ... fect' pet.