In February of this year, Elle noticed a big orange tabby hanging around outside her
house. After a few days of the same routine, walking outside to see him waiting patiently for a meal, Elle decided to bring him in for a general check up, to make sure he was healthy before finding him a new home. “I’m not keeping him!” she proclaimed upon her arrival for his first exam. He received a clean bill of health, and the rest was history. “Rascal” had found his forever home.
This summer Rascal came back in because he had a very deep “croupy” sounding cough. On exam he was working hard to breath and had raspy lung sounds. X-ray were taken and showed changes consistent with Asthma or a severe bronchitis. Heartworms can cause the same changes in cats, so a heartworm test came back positive. Sure enough, he came back POSITIVE!
Heartworms are internal parasites passed by mosquitoes. A mosquito ingests the microfilaria, or baby heartworm, when it feeds from an infected animal. The microfilaria mature within the mosquito over the next few weeks. Then the mosquito feeds on a new victim and passes on the heartworm larvae from their saliva into the skin. The larvae mature and migrate to the main pulmonary artery over the next 6 months. Once there is an adult male and female they mate and the lifecycle continues.
When discussing heartworms, people commonly think of it as a dog disease, but cats can get heartworms too! Since cats are not the natural host, they tend to mount a pronounced inflammatory response to the parasite which is often more detrimental to the cat than the heartworm itself. In most cases, heartworms do not survive long enough to mature in a cat, but the resulting inflammation can be life threatening to the cat. Cats with heartworms often present with coughing or difficulty breathing. Many cats were previously diagnosed with asthma before we realized they could get heartworms too. In some cases chronic vomiting may be the only sign or sudden death.
Rascal was treated with oral steroids to reduce the inflammation which likely resulted as the heartworm was dying. He was also placed on an oral antibiotic to kill Wolbachia on any remaining heartworms . It is theorized that this bacteria-like organism has a symbiotic relationship with the heartworm and killing it weakens the heartworms. We do not actually treat cats with medications to kill the heartworms in cats because treatment can be more life threatening than the parasite itself.
Rascal was likely infected prior to his adoption into his new home. Fortunately, he has responded well to treatment and we are slowly weaning him off of the oral steroids. He will remain on Revolution monthly so that he does not get infected with additional heartworms. His owner will be diligent about monitoring for future episodes of difficulty breathing as there could still be some heartworms present that will eventually die. Rascal is loved by our hospital and all our staff, and we couldn’t be happier with his recovery. Keep your cats protected from heartworms with a monthly preventative such as Revolution!
