Roundworms or Tapeworms in Dogs & Cats

By Jayne Adams

Two of the most common internal parasites in dogs and cats are tapeworms and roundworms. Both live in your pet's intestinal tract where they steal important nutrients from the food that passes by, thereby threatening your pet's health. Knowing which worm (or both) has infected your pet is an important step toward administering the correct treatment.


Tapeworms are long, segmented worms that live in your dog's or cat's intestines. They attach by burrowing their heads into the intestinal wall and absorbing nutrients through their bodies. The most common kind of tapeworm is made up of segments, each of which contains its own reproductive organs. The segments, which resemble grains of rice, break off and can be seen in a dog's or cat's feces. Adult tapeworms can reach lengths of about 28 inches.


Roundworms look like pieces of spaghetti and are very common in puppies and kittens. Roundworms live in the digestive tract of dogs and cats where they feed on passing nutrients and irritate the linings of the intestines. Large numbers of roundworms can cause blockages and diarrhea. Infected puppies and kittens may exhibit a dull coat, appear listless and develop a pot-bellied appearance if the infestation is severe. Roundworms can grow to about 7 inches in length.


Tapeworms are mainly transmitted when dogs and cats consume fleas that were harboring the larva or by eating rodents that were infected. Tapeworms can be transmitted to humans, most commonly to children who might ingest an infected flea.

Roundworms can be transmitted from the mother to her puppies or kittens through nursing or in utero, by animals of any age walking through infected fecal matter or by consuming a small animal that is carrying the worm larva.


Tapeworm segments can be seen in the feces of dogs and cats and are often the first sign your pet is infected. Since tapeworm eggs generally do not pass with the feces, diagnosis is usually made visually. Large infestations may cause diarrhea and vomiting in which case larger sections of the worm could possibly be seen.

Roundworms are usually diagnosed through a fecal flotation exam, a process in which a sample of feces is submerged in a substance that causes the eggs to rise and be seen through a microscope. Adult roundworms rarely show up in feces but occasionally may be revealed through vomit.


Checking and then treating infected puppies and kittens when they're very young can rid them of the worms that would steal important nutrients from growing bodies. Since any deworming program doesn't kill all stages of the worms, your veterinarian will probably suggest a step plan that will catch each life stage of the worms as they develop into adults.

Following eradication, prevention is the best method of control. Many monthly flea and heartworm treatments will also control roundworms. Tapeworms most often will need a specific treatment to eradicate them, and then keeping litter boxes and yards clean of feces and controlling rodent pests should help prevent reinfestation.