Cats are relatively low-maintenance pets, which is a strong part of their appeal. They groom themselves, don't need to be house broken and generally eat when they feel the need. However, this isn't to say that they aren't completely free of complications. Cats still need to be treated for fleas and their diets can potentially need to be adjusted to prevent diarrhea.
Preventing fleas from calling your cat home is always easier and preferable to trying to get rid of them once they've moved in. Regular flea treatments from your vet are the best way to ensure that your cat remains flea free. Restricting outside excursions also works, but it would be cruel to keep a cat inside if it regularly seeks outside time. Keeping your carpet and furniture regularly vacuumed is a huge help, as well.
If, despite your best efforts, your cat becomes infested with fleas the best course of action is flea treatment from the vet. At the very worst, your cat will be subjected to a flea dip. However, milder treatments are available and it's recommended that you exhaust these possibilities before harsh chemical treatment. Modern flea collars and flea powders aren't quite as awful as they used to be, but only cause fleas to relocate. Often, this means your carpet and couches, so keep them vacuumed daily while you're treating for fleas.
Diarrhea and the Proper Diet
Cats' digestive tracts can be tricky. While cats will certainly eat a lot of things, they certainly don't digest them all well. Cats, just like people, can have a wide range of food intolerances or outright allergies. If you made any changes to your cat's diet prior to them getting diarrhea, consider switching back to the old food. Food allergies can also develop over time. If your cat has started getting diarrhea and you have't changed the food, consider changing it and seeing if the diarrhea goes away.
Diarrhea and Parasites
Younger cats are more prone to intestinal parasites than older cats, but that doesn't mean older cats can't get them. Make sure that you keep your cat up to date on its current vaccinations and worm medications to make sure that they don't contract any infectious diseases or nasty worms that would cause diarrhea. As much as possible, also limit their contact with untreated animals or strays. If your cat should be unlucky enough to contract a disease or parasite, they can be treated, but testing will be needed to determine exactly what treatment is needed.
Diarrhea and Toxins
Diarrhea can also be caused by toxins that your cat has ingested or come into contact with. While there isn't a whole lot you can do in the realm of prevention, if you suspect some sort of toxin take your cat to the vet immediately. Toxins can be deadly and can act quickly. You can help prevent contact by utilizing pesticides, slug baits and other vermin-killing devices far away from where your pet will normally go. Although it is highly improbable that you can prevent contact with toxins in today's society, you can help limit the chance of exposure.