Gastrointestinal Parasites in Cats
little kitten playing on the grass close up
If I cannot see any "worms" in my cat's stool, then he or she can't have any, right?
There is a lot more to determining gastrointestinal parasites presence in your cat than looking at stools for actual worms. You will rarely see worms in stools and not all parasites in the intestinal tract are nematodes (worms).
Cats may have protozoan parasites, pathogenic bacteria, and worms. When a fecal float and direct stool test is done at St. Louis Cat Clinic, we are looking for microscopic worm eggs, microscopic protozoa, and microscopic bacteria. All of these are not visible to your eyes without great magnification via use of a microscope at different magnification powers. A gram stain is sometimes also necessary to look for specific pathogenic bacteria and the mixture of types of bacteria.
Worm eggs, bacteria, and protozoa do not always shed in the stools every day; so several stool samples need to be done to find parasites many times.
There is not one universal "worm" medication that will kill every species of worm, every protozoan parasite, or every pathogenic bacteria.
Purchasing a "worm" medication in a pet store may not solve anything if you are treating with an older medication that works poorly or a medication that does not kill the type of parasite that your cat has. It is also important that you know how to prevent re-infestation to the cat/cats or transmission from one cat to another when you have more than one cat.