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Pets & Parasites

Parasites are worms that can live in your pet’s body and can affect your pet’s ability to absorb nutrients, damage the lining of its intestinal tract, and cause your pet to become very ill. Parasite control (or deworming) is an important way to safeguard not only your pet’s health, but also that of you and your family.

The "#2 Way" to Protect Your Pet—and Your Family—from Parasites

An annual fecal check for all dogs and cats is recommended and can be done as part of your pet’s health exam. Any pet at any age can be infected with parasites, which is why a yearly fecal exam is important.

To prevent infection, keep your pet away from other pets’ waste and dispose of your pet’s own waste quickly. Don't let waste sit in the yard or litterbox for several days. Parasite eggs can become infectious as soon as one day after being shed in pet feces, and, in turn, can contaminate the soil. And, of course, wash your hands after handling your pet's waste, as some parasitic infections can be transmitted to humans.

Symptoms of Infection

Symptoms may include: change in appetite, coughing, diarrhea, weight loss, and a rough or dry coat. However, some pets show no symptoms, so regular health exams with a fecal check are important.

Common Parasites


Adult roundworms are an intestinal parasite that resemble strands of spaghetti. Their eggs are shed through a pet’s feces and, while fresh feces are not infectious, the eggs become infectious over time as they sit in grass, soil or sand. This is why picking up pet waste promptly is important. Roundworms can cause vomiting or diarrhea. Children are more prone to contract roundworm as they are more likely to touch infected dirt or sand and then put their hands into their mouths. Do not let children eat sand or dirt. Children should wash hands thoroughly after playing in areas where pet waste may have been deposited. Keep sandboxes covered when not in use. In rare cases, roundworm infection can cause an eye disease that can lead to blindness; such infections can be more serious in children than adults. Gardeners should wear gloves and wash hands after working outside.


Your pet can contract tapeworms from eating fleas that can harbor the tapeworm in its larval stage or from eating an infected rodent. Segments of the tapeworm resembling bits of rice are often shed in the feces or found clinging to the hair near the rectum.

Hookworms & Whipworms

Hookworms attach themselves to your pet’s intestinal lining, and can cause dark feces or bloody diarrhea. Whipworms, found in the large intestine, can cause diarrhea also. If you notice blood in your pet’s stool, collect a sample and take it to your veterinarian.


Although less common than other worms, heartworm disease is a serious, life-threatening infection of the heart caused by the adult stage of the parasite Dirofilaria immitis. Heartworm is present in Oregon, even in the metropolitan areas. Mosquitoes are the carriers of heartworm disease. As a part of a regular health exam, your veterinarian may recommend testing and preventative medication for heartworm. Many heartworm preventatives also protect your pet against other types of worms.

Testing & Treatment

Kittens and puppies are commonly infected with parasites and should be tested as part of their early life care, which includes examinations and vaccinations. Typically, your veterinarian will ask you to provide a stool sample for testing. Sometimes, more than one test will be required to ensure that the parasites have been eliminated.

For kittens and puppies, or any pet you suspect may be infected, collect a fresh fecal sample within 12 hours prior to an examination. Keep the sample cool or refrigerated. Your veterinarian will examine the sample to identify the parasite. Different parasites will require different treatments, so proper identification is key.


An annual fecal check is recommended and can be done as part of your pet’s annual health exam. Preventative medication is available; talk with your veterinarian about whether this medication is appropriate for your pet. To prevent (re)infection, it’s best to keep your pet away from other pets’ waste and dispose of your pet’s own waste quickly.

Have your veterinarian treat your cat or dog regularly for worms, and wash your hands after playing with your pet. As with any health concern involving your pet, be sure to consult with your veterinarian if you think your pet may be infected with parasites.

Your Pregnancy

If you are pregnant, or planning to become pregnant, you may want to read these tips about staying healthy and avoiding infections such as toxoplasmosis.

Updated: January 16, 2020