When your cat eats the fleas hitching a ride on his back, it may seem like a good way to avoid the cost of flea treatment. But scarfing down these bloodsucking parasites isn't as harmless as it seems, because he's most likely exchanging an external parasite for an internal one.
Fleas are the ultimate freeloaders. They help themselves to your cat's blood, and offer nothing but discomfort in return. And if your cat frees himself from his uninvited hitchhiker by eating the little bugger, the flea offers one more bit of unpleasantry. Flea larvae eat tapeworm eggs, and carry them through adulthood. When the cat grooms herself and eats the infected adult flea, the tapeworm egg hatches in the feline's intestinal tract, where it attaches to the wall and begins feeding and maturing. As it reaches reproductive age, segments of its body detach and exit through the cat's anus, to fall into the environment and perpetuate the cycle.
In most cases, you'll never know your cat has a squatter in his gut, as cats with tapeworms typically don't exhibit any outward signs of illness. The best indicator of a tapeworm infestation is the shedding of egg segments. Your cat may experience extreme itchiness around his behind, and you may notice, should you care to look, small white segments like grains of rice moving around on him or in his bedding or stool. Tapeworms steal the nutrients from your cat's food, so extreme infestations can cause your cat to lose weight and become weak and ill.
With tapeworm infestations, you get to play veterinarian and diagnose your cat yourself. Don't get too excited: the best way to determine the presence of tapeworms is to visually identify the egg segments. Sometimes these segments are found in the cat's stool, but not always, so you'll need to check your cat's behind and around his bedding and food dishes for the telltale little wiggling white rice-like pieces. Though they're only pieces of the parasite inside your cat, these segments can move on their own until they dry out, after which they look like sesame seeds. Be warned: you may need to collect them or a stool sample to show your veterinarian. Ah, the glamorous life of a cat owner.
Once you've verified that your cat is indeed playing host to an uninvited guest, call your vet. She may want to see your pet, or can offer you the proper tapeworm-killing medication without a visit. Deworming medications come in pill or injection form, and your vet can give you the best solution depending on your cat's medical history. The medication will kill all worms present, and the cat will essentially digest the dead worms (so you shouldn't see any long, segmented corpses in your pet's litter box). Keeping tapeworms out of your cat means eliminating their mode of transport, specifically the flea. Use flea prevention products, and thoroughly clean bedding and litter boxes, to keep your pet flea-free, and ultimately tapeworm-free.