Heartworm in Cats – More than just a curiosity

Joan Henderson
Although feline heartworm disease was identified in 1921, for many years cat lovers, veterinarians, and scientists did not recognise heartworm as a problem in cats. It was only after a lot of research that veterinary parasitologists were convinced that heartworm infection may cause serious disease in the cats.
 
Cats are naturally more resistant to infection than dogs. But any cat can develop heartworm diseases if they are infected by the larvae. The infection rate in cats is lower than that in dogs. In cats heartworm can occur everywhere, whereas in dogs it is endemic.
 
How it spreads?
Heartworm infection spreads through mosquito bite. When a mosquito bites a cat after taking in blood from an infected dog, the infection spreads. After living under the skin for about three months the immature worms find their way to the pet’s heart and lungs via blood vessels. When the worms reach the small blood vessels of the lung they cause a reaction in the lungs which may lead to serious aftermath and in severe cases it can be fatal.
 
Signs and symptoms
The most common signs are respiratory in nature. Clinical signs can be sudden in onset or chronic and intermittent. Common symptoms include: Coughing, Breathing Difficulties, Fainting Spells, Lethargy/Lack of Energy, Increased Heart Rate, Convulsions, Vomiting and Weight Loss. These symptoms can be associated with other disease/infections, like one-worm infections in cats.
 
Diagnosis
To determine if a cat has heartworm infection a blood test can be done. But unfortunately, these tests are not as accurate in cats as they are in dogs. But in areas where heartworm occurs in dogs, it is advisable to test before they start in heartworm prevention. Cats who survive the initial effects of heartworm infection, become susceptible to inflammatory lung disease and bronchial asthma. It is best to ask your vet for medications and lifestyle changes to help your pet lead a healthy life.  As I have said often, the wisest thing is to keep your cat indoors. A cat who is well loved and perhaps taken outside for some fresh air and exercise on a cat leash can still enjoy the outdoors under the supervision of their loving pet parents. Cats are more inclined to wander—jump over the fence—and get up to mischief much more than our dogs do and therefore, it is up to us to make sure they are well protected and cared for at all times.
(Joan Henderson is based in Australia and she has judged furry felines in many other countries including USA, Bermuda, Malaysia, South Africa, Hong Kong, Philippines and New Zealand)