Intestinal parasites are common in small animals. Although puppies and kittens tend to be affected with greatest frequency, any age animal can acquire intestinal parasites. It is important to understand the importance of parasite control, since parasites pose a threat to both pets and humans.

General Information:

There are literally thousands of internal parasites that can affect animals, and these parasites can differ in various locales. Some parasites may cause only mild symptoms, while others may prove fatal.

Intestinal parasites are not just limited to worms that are seen in the stool. Some are microscopic organisms that can only be diagnosed with a microscope. We recommend bringing in a fresh stool sample from all new puppies and kittens for analysis. This stool exam is usually performed in conjunction with your pet's first examination. We also recommend testing adult pets for intestinal parasites once yearly at the time of their annual exam. If any parasites are found, treatment can begin immediately. Bringing in a stool sample for analysis is the only sure way to ensure that parasites are found and accurately diagnosed.

Intestinal parasites can be somewhat stubborn to eliminate. Many intestinal worms have a "migratory phase" in their life cycle. This means that immature forms of the parasites may travel around to various organs of the body before taking up residence in the intestine. Intestinal dewormer medication will only kill the parasites that are inside the intestine, but not those located elsewhere in the body. It is often necessary to deworm pets two or even three times to eliminate all of their parasite load.

The symptoms you see in your pet depend on the type of parasite(s) involved. Hookworms, for example, attach to the lining of the intestine and suck blood. Affected animals may suffer from anemia; they may be lethargic and have pale-colored gums. Other intestinal parasites may cause diarrhea, vomiting, pot-bellied appearance, cramping, dull haircoat, or poor appetite. Some parasites do not cause any obvious symptoms.

Intestinal parasites of pets may also pose a hazard to humans. In some cases, symptoms may actually be worse in humans than in pets! For example, the eggs of canine roundworms are highly dangerous to humans — especially to children. Children should be discouraged from playing near areas where animals (both wild and domestic) may have defecated. Sand boxes should be kept covered when not in use. Hand washing should be emphasized after outdoor activity or after handling animals. Keeping wild animals such as raccoons and skunks as pets is highly discouraged, since the roundworms of these species are especially dangerous to people. Below are several links to the Centers for Disease Control website regarding transmission of animal parasites to people:

CDC: Tapeworm
CDC: Roundworm
CDC: Hookworm
CDC: Roundworm (Raccoon)
CDC: Toxoplasmosis

For more information on the importance of parasites and their control, visit Growing Up With Pets.


As stated above, a fresh stool sample should be brought in for analysis. If you are seeing worms in the stool or in vomit, please bring in the worm also. Tapeworm eggs are fragile, and often break up on their way out of the body. If you are seeing rice-like segments in your pet's stools or around its anal area, this is consistent with a diagnosis of tapeworm infection. You may bring in the segments for us to confirm. With all other common parasites, however, finding the eggs under the microscope is the basis for diagnosis.


Most of the commonly-used heartworm preventatives for pets will also kill or prevent at least some of the common intestinal parasites. Some of these products are better than others. We will take your pet's intestinal worm problems/history into account when recommending a heartworm preventative. Keep in mind that heartworms are not intestinal worms, but some medications for heartworm prevention have the added benefit of intestinal parasite control.


Most intestinal parasites require treatment that is repeated one or more times. It is very important to read the medication label carefully to ensure that you give the medication at the correct times. The medication that we select will vary according to the parasite(s) your pet is infected with.