If a cat has worms, the common clinical symptoms include diarrhea, visible worms in the stool, bloody stool, a bloated abdomen and weight loss. Other symptoms include vomiting, constipation, coughing, trouble breathing and visible worm segments near the cat's anus.
Although the common symptoms are the same for cats that have worms, other symptoms differ based on the type of worm infecting the cat as well as the location of the infection. There are four types of worms that typically infect cats: roundworms, hookworms, tapeworms and lungworms. The most common worm infection seen in cats is roundworms. Roundworms resemble spaghetti, and adult worms typically grow 3 to 4 inches long. Cats become infected by ingesting infected rodents or by coming into contact with the feces of other infected cats. The worms are also passed to nursing kittens through their mother's milk if she is infected.
Hookworms are less than an inch long, and they are primarily found in the small intestine of infected cats. Hookworms feed on blood, which often leads to life-threatening anemia in cats. Kittens are more susceptible to anemia caused by worms. Cats become infected with hookworms by ingesting infected food or through contact with the skin.
Tapeworms are long, segmented parasites that range from 4 to 28 inches in length. Cats become infected with tapeworms through ingestion of another host animal. Lungworms are found in the lungs of infected cats, although the majority of cats do not show any signs of infection other than a cough. Cats become infected with lungworms by eating infected host animals such as birds or rodents.