Heartworm in Cats - Feline Heartworm

Heartworm disease is an infestation of the heart and lungs by the parasitic worm Diroflilari immitus. Heartworm can infect both dogs and cats. The first reported case of heartworm in cats was in Brazil,1921. Since then it has been reported worldwide. 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".

Transmission of Feline Heartworm Disease
Feline heartworm is transmitted by an infected mosquito bite. Cats are susceptible to hearthworm disease even when kept indoors, as mosquitoes can fly find their way into the house. When the mosquito bites the cat to take its blood meal, it introduces the heartworm larva into the cats bloodstream. These larval heatworms invade the blood vessels in the lungs. These larval heartworms are capable of reproducing within 8 months of developing as adults. As they grow into adults they lodge themselves into the lungs and heart of the cat. Cats tend to have lower worm population then canines, as they have a stronger immune system. The damage by these parasites is still severe in cats and can cause death.

Feline Heartworm Symptoms
The cat exhibits symptoms when the larval hearthworm reach the lungs or when the adult heartworm dies. Many chronic symptoms 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 Hearthworm
It is very difficult to diagnose heartworm in cats. The veterinarian may advise the following tests:

Antibody Test: This test is used to detect the antibodies made by the cat's immune system against the heartworm antigen. This test is not very reliable as it may test positive for a previous heartworm infection that has cleared up.

Antigen Test: This test helps in detecting presence of antigen in the blood. It may give false results as it detects presence of only female heartworm. It may test negative results if the cat is infected by male or immature worms.

Echocardiogram and Radiography: Ultrasound may help detect presence of heartworms. Radiography helps detecting enlarged pulmonary arteries and enlarged right side of the heart and lung changes due to presence of heartworm.

Microfilarial tests: Only 20% cats have microfilaria in their blood. This is because the cat may not have both male and female hearthorms which mate and produce microfilaria. The cat's active immune system may be destroying all the microfilaria present, thus giving a negative microfilarial test.

Feline Heartworm Treatment
There is no medical cure specific for feline heartworm. The available treatments are dangerous and a single dead heartworm can cause blockage in the pulmonary artery of the cats leading to pulmonary embolism. If the cat does not show any clinical symptoms, the vet may wait for the parasite to clear on it's own. A heartworm may live upto 2-3 years in a cat. The vet may monitor the cat's health every 6-12 months to see any signs of complications.

If the cat exhibits symptoms, then Prednisone may be recommended to reduce inflammation and reaction to the worm. Cats which suffer from severe symptoms may require supportive therapy like bronchodilator to open airways. The other therapy includes oxygen therapy and intravenous fluids.

You should carefully consider all the pros and cons involved in adulticide treatment. The drug used is Carparsolate, which kills all the adult worms. As mentioned earlier, it is quite dangerous and has risk of pulmonary embolism. 1/3rd of the cats undergoing adulticide therapy face life threatening complications.

Prevention of Feline Heartworm
Feline heartworm disease can be prevented by using several products available in the market that are administered monthly. The vet may recommend these products after testing your cat for heartworm. Heartgard, RevolutionTM and Interceptor are the various products used to prevent heartworm disease in cats.

It is always advisable to take your feline friend for regular veterinarian visits. Early diagnosis and treatment is always better than cure. You can always hope that the worm lives out it's lifespan within your cat without causing any major complications. A healthy cat is a 'purrrr..fect' pet.