Heartworms represent an increasingly recognized problem in cats. As in dogs, heartworms are transmitted by feeding mosquitoes and, once mature, take residence in the right side of the heart and the large vessels of the lungs. For cats, the prevalence of heartworm infection is directly related to the number of infected dogs in the area.

While infection rates in cats (not the typical host for heartworms) are lower than in dogs, studies have shown a prevalence as high as 10-14 percent in shelter cats. In most cases, the effects of heartworm infection in cats are more severe.

How will heartworms affect my cat?

Symptoms of infection are variable but most often are related to the respiratory system. A veterinarian may suspect that a cat has been infected in cases of coughing, wheezing, difficulty breathing, vomiting or weight loss; however, several tests conducted by your veterinarian may be necessary to determine whether or not your cat has heartworms.

The heartworm larvae, which enter the cat’s bloodstream after it is bitten by an infected mosquito, eventually migrate to the heart or vessels of the lungs. Here the larvae cause a severe reaction, resulting in lack of oxygen exchange and cough. Sudden death of the cat may occur and is typically associated with the death of a worm.

How do I prevent my cat from getting heartworms?

Heartworms are found in cats in all 50 states, so all cats are at risk, even those animals that live indoors. However, heartworms are preventable.

Ask your veterinarian about heartworm prevention. Preventive treatment should begin after a blood test has been conducted to determine if your cat has already been exposed or is infected.

Is heartworm disease treatable in the cat?

At the present time, there are no acceptable treatments for eliminating heartworms from infected cats. Your veterinarian may treat your cat’s symptoms if it is displaying signs of disease. Because of the potential for serious or fatal consequences of infection, and lack of approved treatment, preventing heartworm is the best strategy.

Can humans contract the disease?

Isolated cases of human infection have been reported. However, the heartworm is generally not considered a risk to human health.

• While heartworms are more common in dogs than in cats, cats can get heartworms too. They get heartworms by being bitten by a mosquito who has bitten an infected dog.
• Heartworms can cause your cat illness or death.
• There is no acceptable treatment for heartworm in cats, so prevention is key.
• Your veterinarian can provide a program for heartworm prevention.