Heartworm Disease in Cats
On our previous program, we discussed heartworm disease in dogs. Previously, most veterinarians felt heartworm disease in cats was extremely rare. However, over the last few years, the number of cats diagnosed with heartworm disease has increased. Cats are not considered the normal host for the parasite, and infected cats usually have fewer worms than infected dogs. However, because cats have a small heart size, only 1 to 2 worms have proven to be fatal in a cat. Cats are infected by being bitten by a mosquito carrying the infective larvae, as are dogs. Male cats are reported to be more frequently infected. The most severe clinical signs occur in cats 5 to 6 months after infection with the arrival of 5th stage larvae in the pulmonary artery.
The cat's reaction to the worm causes an acute pneumonitis, which appears to be an asthmatic condition. Sudden death can also occur later with death of the worms. Chronic signs reported in cats are vomiting, coughing, labored breathing, weight loss, and anorexia. Diagnosis of feline heartworm disease is usually accomplished with a blood test, although radiography and ultrasound can be helpful in the diagnosis. Treatment of cats with heartworm disease is not an easy decision as it is in dogs. Treating cats with a drug to kill the adult worms is a high risk procedure, and is only recommended for stable cats. It is reported 1/3 of cats treated will develop thromboembolic complications, or blood clots, that can be deadly. It is recommended that if a cat with heartworms displays no clinical signs but has radiographic evidence of heartworms, it is prudent to allow time for a spontaneous cure to occur with monitoring by radiography.
Cats with lung disease can be treated with cortisone to decrease the inflammation. The best option is to use a once a month heartworm preventative tablet on your cats to prevent this potentially deadly disease.
Date Published: 1/18/2005
