Cats can be infected with the potentially fatal heartworm disease. The disease is not exclusive to dogs.
Heartworms, according to Ernest Ward as updated by Catherine Ward in VCA website, are a “blood-borne parasite called Dirofilaria immitis that reside in the heart or adjacent large blood vessels of infected animals.”
Heartworm disease, Ward said, is more common in dogs than in cats. The disease may be present when the pet has heart and respiratory diseases.
“Cats are relatively resistant to heartworm infection when compared to dogs, with the infection rate in cats reported to be 5-20% of the rate in dogs in the same geographic location, however infection can still occur. Typically, cats have fewer adult worms than dogs, usually less than six. Many pet owners are surprised to learn that approximately 1/3 of infected cats live indoors only, “ Ward said.
A cat is infected through a mosquito bite.
There are several ways to diagnose heartworm in cats. These are not 100 per cent reliable though. Thus, a combination of methods is strongly recommended.
1) Clinical signs
There are no specific clinical signs. But the most common, Ward said, is when your cat suddenly develops coughing and rapid breathing which are also symptoms of other diseases.
The other signs are weight loss and vomiting.
Sometimes, a cat that looks healthy or normal may be found dead, or suddenly has a respiratory failure.
“Sudden death is thought to be due to a reaction within the lungs to the young heartworms, or to a reaction to dead or live heartworms entering the pulmonary arteries and obstructing the flow of blood to the lungs,” Ward said.
The signs, Ward said, are:
Collapse
Coughing
Dyspnea
Vomiting
Convulsions
Diarrhea
Vomiting
Lethargy
Blindness
Anorexia
Tachycardia
Weight Loss
Sudden Death
Please bring your cat to the vet immediately.
2) Blood Tests
There are two kinds of blood test to check if you cat has heartworm.
a. antibody test
b. antigen test
“The heartworm antibody test determines if the cat's immune system has been exposed to heartworms. A positive test may indicate that an active infection is present. However, cats who have had heartworms but whose heartworms have died will also have antibodies for an unknown time. Currently, it is believed that the antibodies persist for two to four months after the heartworms have died, “ Ward said.
He added: “Cats with late stage larvae that are not yet adults, and cats with adult heartworms in places other than the heart, may also test positive with the antibody test. This test is very sensitive, so it is used first. If it is positive, the next test is performed.”
On the other hand, the heartworm antigen test “detects the presence of adult female heartworms. It is very specific, but not as sensitive as the antibody test. A positive test indicates that heartworms are present, but a negative test does not mean that they are absent. Because the cat must have at least two adult female worms present to make this test positive, a negative test may mean that the cat may only have a small number of worms or that all the worms present are male. The low worm burdens often seen in infected cats results in a high number of cats testing false-negative on antigen tests,” Ward said.
When both tests are positive, the diagnosis of feline heartworm infection is confirmed, Ward said.
“In summary, a diagnosis of feline heartworm infection is confirmed when both the antibody and antigen tests are positive, but not all infected cats will test positive on both tests, “ Ward said. DC
(To be continued next week)