There are a few different things that you can try when treating your cat's diarrhea at home. One of them is changing her diet (although you will want to consult your vet first, as with all of these home remedies). Cat food often includes dyes and other artificial ingredients, which may make your cat's gut have to work harder to process them. Switching to a more natural brand can help clear up the current trouble and prevent future bouts. Watch out, though -- changing foods can also cause intestinal upsets, so do it gradually.
You may also consider giving your cat a bland home-cooked diet until the diarrhea subsides. Two parts cooked white rice mixed with one part boiled hamburger or chicken is easy to digest. Some cats balk at rice, so you can use plain mashed potatoes instead. Rice-based cat foods are also available at most pet supply stores.
Sometimes a 12 to 24 hour fast is enough to calm things down. If nothing at all goes in (except water), there's nothing to process and the diarrhea should go away. When you resume feeding, begin with the bland rice mixture, then slowly mix in regular food, reducing the amount of the rice mixture until the cat is back on a normal diet.
A bulk-forming laxative such as Metamucil (use the plain kind) seems to have a normalizing effect on cats with diarrhea. If your cat's stools are still a little soft during or after a couple of days of the bland diet, try adding about a half-teaspoon of the Metamucil laxative to each of his or her meals for a day or two.
It's important that a cat with diarrhea keeps drinking and has access to plenty of fresh water. Besides losing fluids, a cat with diarrhea is losing key nutrients called electrolytes that are essential for nerve function. To replenish them, you can give your cat unflavored Pedialyte, an electrolyte beverage designed for infants and children. Mix with his or her water, or give with a dropper.
Relaxation, stress reduction and gentle exercise (take your cat for a walk on a leash and harness, if she likes it) may be all that are needed to clear up an attack of loose stools. Avoid the temptation to use over-the-counter diarrhea products designed for humans, unless your vet specifically tells you to.
Hopefully, one or more of these home remedies will have everything moving normally again through your cat's colon -- making both of you happier.