Yes, you read the title correctly. Primarily when we talk about heartworm, it’s in relation to dogs, but heartworm can and does affect cats and it affects cats quite differently. In a dog, a natural host for heartworm, a dog can primarily coexist with heartworm (in small doses). For a cat, as a resistant host, a cat’s body instantly reacts and the inflammatory response is much more severe. (Being a resistant host simply means that heartworm is intended to infect canines but it will settle for a feline body.) The heartworm parasite is found everywhere throughout North America. Keeping your cat strictly indoors isn’t necessarily going to stop the spread of feline heartworm, as mosquitos (the carriers of heartworm) can carry the infective blood indoors.
Diagnosing a canine with heartworm is relatively easy. For felines, not so much. The same test that is quite reliable for dogs will time and time again produce false negatives in felines. Dogs are also usually rife with heartworm, but it can take as little as one heartworm to infect a cat. If you or your vet suspect a heartworm infection, he will likely perform an “antibody” test screen (though the results can’t show whether the infection is active or from a previous infection) and x-ray the chest. What to watch for? Heartworm disease mimics feline asthma. Your cat will probably be coughing or wheezing. In fact, if your cat has been diagnosed as asthmatic, get a heartworm check done too. Many cats are misdiagnosed.
There are no approved feline treatments for feline heartworm disease. Treatment will include supportive care with steroids to control the inflammation. It may include bronchodilators and/or antibiotics. Treatment will also include prevention of further infection or re-infection by administering a heartworm preventive medicine. Treatment for your cat will likely span several years as you’re going to have to wait for the heartworms to die of old age.
The best way you can help your cat avoid lung damage or death from a heartworm infection is to prevent it in the first place. When you’re taking your dog in for his heartworm prevention, take your cat too. Heartworm in felines is more common than we all think.