Can an indoor cat really get heartworm?
Heartworm arrives by mosquito, mosquitoes come indoors, and cats have no approved treatment for the adult worm — prevention carries the whole load.
Heartworm needs no contact with other animals — a single infected mosquito bite is the entire transmission chain, and window screens do not stop every mosquito. Cats are an atypical host, so they carry far fewer worms than dogs, but even one or two can inflame feline airways badly, and sudden collapse is a described first sign.
Why prevention is the entire strategy for cats
Dogs with heartworm can be treated with a drug that kills the adult worm; for cats no such treatment is approved, so veterinary care for an infected cat is limited to managing the disease the worms cause. That asymmetry flips the economics: a monthly spot-on or oral preventive, started and dosed under veterinary guidance, is cheap insurance against a problem with no clean exit.
Feline infection is also hard to confirm — test results in cats are less clear-cut than in dogs, another reason to keep the parasite out rather than hunt it later. Mosquito pressure differs by region and season, and each cat's risk profile differs too, so bring the question to a checkup and let your veterinarian set the product and calendar.
MediIndex articles are for general information only and are not medical advice, diagnosis, or advertising. Outcomes vary by individual — consult a board-certified specialist for personal decisions.