If your cat is indoor, can he or she have intestinal parasites? If your cat is old, can she or he have intestinal parasites? If you don't see any worms in the stool or in your cat's litter box, can she or he have internal parasites? If your cat does not have diarrhea, can he or she have intestinal parasites? The answer is yes, yes, yes, and yes.
If your cat is indoor, it may have intestinal parasites because it came with them when you adopted him or her. The doctors at St. Louis Cat Clinic always ask for a stool sample yearly for newly adopted cats, stray cats, outside cats, indoor/outdoor cats, and indoor cats. Cats and kittens are usually "wormed" by rescue organizations with pyrantal pamoate which only kills Roundworms and Hookworms. That worm medication does not kill protozoan parasites or pathogenic bacteria. Stool samples must be done to check for worm eggs, protozoa, and pathogenic bacteria. A fecal float will not be adequate to test for everything. Sometimes a Giardia Antigen test is necessary to identify cats with the protozoa, Giardia.
An "indoor" cat is not always indoor only. Sometimes an indoor cat will escape outside and be exposed to parasites. Some of the escaped cats have been outside for several months before they come home. New cats are often brought into a household and bring parasites inside with them. A friend may stay with you with their cat and bring parasites into your home with their pet cat. Cats may get outside during house fires and burglaries.
Insects and rodents can carry and spread internal parasites. Cats catch and eat flies, cockroaches, crickets, as well as other bugs that get into homes. Many insects feed on feces and carry parasite eggs, protozoa, and pathogenic bacteria.
If your cat is old, it can have intestinal parasites. The cat may have had parasites for a very long time and shown no symptoms. An old cat can get internal parasites in all of the same ways as indoor cats.
If you do not see "worms" in your cat's stool, it can still have internal parasites. It is not common for cats to defecate or vomit worms. When a veterinarian does stool tests, she or he is looking for microscopic worm eggs, microscopic protozoa, and microscopic pathogenic bacteria which cannot be seen without a microscope. Stool samples are prepared for viewing in special solutions, centrifuged to separate out eggs and protozoa, and some stained with special stains.
Not all cats with internal parasites will have diarrhea or vomiting symptoms. Not all cats with vomiting and diarrhea symptoms will have internal parasites.
Testing cats for internal parasites and treating them so that they are parasite free is very important for your pets, you, your children and family. Pet parasites can infect people. The Companion Animal Parasite Council is an excellent source of information. You can google it.