The Most Common Worms in Cats

When to worry, when not to.


First the scary news. Roundworms infect many cats in the United States. One possible route of infestation is through mother’s milk, which is why it is recommended that all kittens be administered medication at four different intervals to kill any of the worms that might be lurking in their small intestine; roundworms put very young cats at risk for life-threatening complications The standard recommendation for de-worming medication is 2, 4, 6, and 8 weeks of age.

Unfortunately, that recommendation often isn’t followed to the letter because “many owners don’t see their veterinarian for the first physical exam until about 8 weeks of age,” notes Tufts veterinary medical internist Michael Stone, DVM. But the good news is that even starting that late will go a long way to keep a kitten from throwing up or having diarrhea, becoming anemic or dehydrated, and developing other life-threatening symptoms because of roundworms.

If the kitten goes on to live his entire life indoors, he doesn’t need to be on year-round preventative medications for roundworms despite what some websites suggest, Dr. Stone says. Roundworms are more of an issue for indoor/outdoor cats who might ingest prey that harbor them or who end up licking worm eggs from scat that other animals have deposited outside.

Still, all indoor cats should have a fecal analysis to check for roundworms (and other parasites) at their wellness exams. You could track some larvae into the house on your shoes (which is how a pregnant indoor cat might end up with them).

Fortunately, if the fecal exam shows roundworms are present, they are easily disposed of with medication and generally will not make an adult cat ill — especially if they are caught early.

Other worms that can cause cats harm

After roundworms, Dr. Stone says the three other most common worms that live in cats and can potentially make them sick are tapeworms, lungworms, and heartworms.

Tapeworms. As with roundworms, cats can get tapeworms by eating prey such as rodents. Flea infestation is another transmission route. Tapeworms live in fleas as well as typical cat prey, so if fleas end up in your home, your cat can have a worm infestation in addition to a flea infestation. You might not always know the fleas are there. Some cats are very good at grooming them away by swallowing them.

Whereas roundworms float around in the small intestine, tapeworms hook onto the intestinal wall. Fortunately, tapeworms generally do not make adult cats very sick, but the worms still need to be killed with medication if they are found, either on a routine exam or because you notice worm segments in your cat’s stools. The more the worms are allowed to proliferate, the greater the chance for illness.

Tapeworms in feline stools look like grains of cooked rice or tiny seeds. Fleas in your home should also make you suspect their presence.

Lungworms. Lungworms, like the other types of worms, present a greater risk for cats who spend time outdoors. You will know something is wrong if your cat has them, and the signs should not be ignored. They include coughing (often in fits), persistent difficulty in breathing, and general malaise or lethargy. It should be noted that worms that take up residence in a cat’s lungs are not usually life-threatening, but they can make a cat miserable nonetheless. Take your pet to the doctor if you notice any of these problems, especially since they overlap with many other illnesses. The veterinarian will have to conduct various screenings to arrive at a correct diagnosis to insure proper treatment.

Heartworms. People tend to think of heartworms as a dog thing, but cats can get them, too, although much less commonly than their canine counterparts. In cats, these parasites can cause something known as heartworm associated respiratory disease (HARD). Symptoms of feline heartworm disease range from subtle (lack of appetite) to sudden and dramatic (fainting, seizures, sudden collapse).

Unfortunately, the medicine that works for dogs can’t be used on cats. If a cat ends up with heartworm disease (via a mosquito bite), supportive care with oversight by a veterinarian is the best bet for getting him through; it will help stabilize the situation.

The American Heartworm Society recommends that cats be tested for heartworm disease once a year.



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