Parasites Common to Cats

Death from parasites is still one of the most difficult health battles being fought for both animal and human populations worldwide. Still, the greatest progress in overall health for both humans and animals is due to improved sanitation practices and knowledge in the last 100 years. In areas lacking modern sanitation technologies, health statistics remain grim, due to parasite infestations.

When someone belittles the need to check their cats for worms, I have to sigh heavily for the likely outcome of a short life span for those cats. Most common on farms, where cats are regarded only as mousing machines, cats may live one or two years at best. If they are not killed by predators, or starvation because they couldn't find enough mice, they die from parasitic infestations. What most people with outdoor cats don't realize is that worms can quickly multiply and completely overtake a cat's system, resulting in death by starvation, respiratory failure, neurological problems, or cardiovascular complications. It's a big problem for any cats that must live outdoors.

For our cuddly home companions, the situation is more favorable, as most owners are responsible and take their kitties in for regular checkups and care. These are the lucky ones.

Here is an overview of the kinds of parasites cats can get, what the cat's fate can be, and how to recognize and treat some of the different parasites.

Most of the parasites listed here are in the worm category, though fleas and ear mites are very big issues, too. This list is by no means comprehensive, so if you need to know more, or suspect your cat has something not listed here, please consult your own veterinarian.


The most common worms seen in cats are the various roundworms. They may be white, and round, like spaghetti, and quite wiggly. Some are long (I've seen one 6 inches long that looked like a broken rubber band), and some are short, about a quarter to a half inch long, and they curl into a “C” shape or little ball. Worms may come out of the cat from either the front or the rear end. Some worms are vomited from the stomach, others are released with the cat's fecal material.

The large roundworm, Toxocara cati, is acquired by ingestion of host animals, such as by eating mice. Kittens infected with this worm do not thrive, have a dull coat, and appear pot-bellied. Untreated, kittens will die. Piperazine is the drug most often used for this one.

Tape worms are common, too, and their flat, short segments often can be found stuck to the fur on the cat's rear end. Looking somewhat like grains of rice, they are sticky and will adhere to the fur until the cat licks them off, thus reingesting the worms and starting the cycle all over again. Tapeworms are transmitted either by fleas or by eating infected carriers, such as mice. Praziquantel is used to treat adult worms but is not effective against the eggs. Check with your vet for proper treatment. Cleanliness is crucial, too, as these and other worms can be transmitted to humans – as in, children playing with infected animals or in their area.

Stomach worms occur worldwide in cats and are of the nematode group. Since they are acquired from eating the worm’s host – usually mice and frogs – it is a strong argument against allowing cats to be mousers. Indeed, allowing cats to roam outdoors opens them up to the risk of becoming infected by many kinds of parasites. The common worm medication, pyrantel pamoate, is effective against stomach worms.

The intestinal fluke, Nanophyetus salmincola, can be acquired by eating improperly prepared or undercooked fish that are infected with the organism, or by eating infected frogs or snails. It occurs more often among wild and free roaming animals, such as ferals.

Cats also can get eye worms, though this is not as common. They appear at the inner corner of the eyes and can be cleared by physical removal, or eye drops obtained from your vet. Cats, dogs and humans can get these from flies that are infected.

In some areas, cats may become infected with lungworms as well as lung flukes. If your cat coughs a lot and appears malnourished or lethargic, a veterinary exam should be sought immediately.

It's critical to have your vet identify the worm involved, because the wrong medication may not kill the infestation. So, get brave, get a plastic baggie, scrape up the worm(s) into the baggie and take it to the vet's office for identification. Usually, over-the-counter worming products are not sufficient, unless your vet tells you it's the correct formula for your cat.

Sanitation is very important with this. Keep the litter box clean! Clean it several times a day! When someone tells me they scoop the box "regularly," I press for how often. Some people only scoop once a week! Incredible! And they wonder why the cat stops using it! If there are worms involved, and your cat stops using the box, you're in bigger trouble than just having stains on the rug. If you have children and/or other pets, and the cat is leaving worm-infested piles in a corner, other household members also can become infested! Do your cat and your family a huge favor by keeping the cat's area clean, and by keeping the cat healthy, too.

The worm you won't see is the heart worm. It's not just for dogs. Cats get them, too. Check with your vet for the risk factor in your area. Some parts of the country are relatively clear of this one, but it doesn't hurt to keep an eye on your kitty's health. Heart worms are among the deadliest of them all, though, so getting treatment quickly is essential! Watch for coughing, depression, lack of strength or vigor, and loss of appetite. These signs are not absolute, but warrant an examination. You might need to ask your vet to specifically check for heart worms, too, as it is not common to do so.

Fleas and mites

These little invaders are extremely irritating to your cat, as well as to you! Fleas can infest your carpet and eat up your ankles as you simply walk around your own home. Our poor kitties can get these little blood-suckers all over their bodies, and go nuts from the itching and irritation. Worse, though, is the fact that some parasites, such as tapeworm eggs, can be harbored within the bugs and transmitted to the cat when she eats them off her skin.

While fleas are insects, mites are arachnids - the spider family. Mites are smaller and generally infest the ears. If your cat has ear mites, his ears will appear incredibly dirty. There is a blackish brown residue in there that looks a bit like soil, or dirt. This is the mite colony, held together and adhered to the ear canal by their own excrement in there. It looks terrible, but feels worse to the cat.

Signs of ear mite infestation include frequent scratching of the head (sometimes resulting in bloody sores), head shaking, and sitting with the head hanging down and one or both ears rotated forward or back, as if the cat is trying to close them off.

Many over the counter ear mite preparations are quite effective, so it's important to use something right away. Actually, for owners who prefer to use the natural approach, simply using olive oil can do the job, as it suffocates the mites. But it has to be repeated diligently every few days until the mites are gone and the ears pass inspection perfectly. Just drip a little oil (or ear mite medicine) into the ear, fold the outer ear down and massage it in, then clean out the ear canal with cotton swabs. (See above: You may need to wrap kitty in a towel to encourage cooperation.)

Repeat these applications until the mites are completely gone. Remember, however, that the mites' eggs will hatch within about 10 days, and the procedure will need to be repeated then.

Tick borne diseases

Rare in the U.S. and found sporadically in the southern states, it's a fatal disease caused by a protozoan organism called Cytauxzoon felis. It is spread by ticks, and the life cycle of the organism ends in a host cat. That’s because it kills the cat very quickly, in a matter of days. And there is no cure. Treatment may prolong the cat’s life, but there is little to no relief. The best course of action is to prevent exposure to ticks.

(Information for this page was found in the Merck Veterinary Manual.)

Copyright © 2014 - RJ Peters 
Dr. R.J. Peters, a retired physician, established an animal rescue shelter in 2002. She has worked with hundreds of dogs and cats and shares much of what she's learned, at The Problem Cat.