Dear Christopher Cat
My cat has been having difficulty breathing. After my veterinarian performed chest x-rays and a heartworm test, he diagnosed a condition called HARD, heartworm-associated respiratory disease. How common are heartworms in indoor cats like mine? Please explain HARD.
Heartworms are carried by mosquitoes, which I’ve seen inside my own house.
Sadly, your experience is consistent with the findings of a recent study which documented that 27 percent of heartworm-infected cats lived exclusively indoors. They contracted heartworm disease in the presumed safety of their own homes.
Heartworm-associated respiratory disease, which mimics asthma and chronic bronchitis, can cause breathing difficulties, coughing, lethargy and vomiting.
HARD develops after immature heartworms invade a cat’s lungs and blood vessels -– and then die. Thus, the larvae don’t have to mature into adult heartworms to cause severe damage.
National studies show that 12 to 16 percent of pet cats have antibodies to heartworms, meaning they’ve been exposed to heartworms and are susceptible to HARD.
Treatment focuses on controlling the cat’s overactive inflammatory response to the immature heartworms, usually with prednisone. In addition, other supportive medications, such as bronchodilators to expand the breathing passages, are prescribed.
Despite aggressive treatment, feline heartworm disease is sometimes fatal.
As usual, the best defense is prevention. Preventive medication is safe and effective, and most products protect against additional parasites. Options include a chewable monthly tablet or a liquid applied to the skin every month.