Fleas do not need a cat to go outside. They need a warm host and a few weeks, and that is why indoor cats get them more often than owners expect.
How fleas reach an indoor cat
Cornell's Feline Health Center notes that a flea can jump about seven feet and that wildlife in a yard seeds it with fleas, and that an animal going outside carries a few inside. The CDC says fleas prefer animal hosts but bite people when animals are unavailable, and UC IPM warns that used carpets and upholstered furniture can carry them in. The same sources describe dogs as the usual link in a mixed household.
Why one flea becomes many
Cornell says a flea's life cycle lasts about a month, and that one female can lead to about 20,000 new adult fleas in 60 days under ideal conditions. UC IPM adds that, in cooler weather, pupae can stay in cocoons for months and emerge later. So a house can look clean for weeks and then show fleas again.
How to check your cat
- Run a flea comb through the fur over the lower back, belly and near the tail.
- Tap the comb onto white paper. Small black specks that turn reddish when wet are flea dirt.
- Watch for scratching, excess licking or crusty bumps on the lower back and neck.
- Ask your veterinarian for a product made for cats. Some dog products are toxic to cats, and permethrin should never go on a cat.
Fleas and a boarding stay
Happy Paws asks pets to arrive flea and tick free, and flea prevention is on the recommended list. If a problem is found after drop-off, the pet is bathed at the owner's cost. A prevention product started a few weeks before the trip avoids the question. See flea and tick prevention before boarding. A cat condo is $35 a night on the 2026 rates.