Gastrointestinal Parasite Infections

Gastrointestinal (GI) parasites are worms and protozoa (one-celled organisms) that take up residence in your pet’s stomach and intestines. Depending on the cat’s age, her level of immunity, and the number of parasites present, the infection can range from unnoticeable to life-threatening. Symptoms include diarrhea, vomiting, weight loss, and a failure to grow and thrive.

Risk Factors
    A pet’s age, health, and exposure to parasites determine her risk of infection. Kittens are at high risk because their immune systems are immature, and they often live in a contaminated environment before weaning. Also, their small size means fewer parasites are needed to cause symptoms of disease.

Stresses such as injuries, illnesses, and pregnancy raise the risk of infection at any age. Adult pets develop some resistance to roundworms and hookworms but not to other parasites.

GI parasites thrive in warm, moist climates, because the parasite eggs and cysts can survive the winter and the larvae can live longer, giving them more opportunities to become infective. These climates are also perfect for fleas, which transmit tapeworms. Because pets transmit some parasites through their feces, areas such as parks, kennels, and breeding farms can be sources of infection. Pets who roam outdoors freely are most likely to contract GI parasites.

Here are some of the most common parasites:

Roundworms and hookworms. Nursing cats transmit roundworms and hookworms to their offspring through their milk. The mother can pass on worms because she likely had the parasites when she was young. Some of the larvae migrated in her body and some developed into worms in her GI tract. As she matured and was dewormed, she cleared the worms in the GI tract, but the larvae that migrated stayed in her muscle tissue. Pregnancy may activate the larvae, which she passes to her offspring. Kittens can develop some resistance to roundworms and hookworms as the larvae migrate through their tissues, activating the immune system. Juvenile and adult pets can also contract infections by ingesting eggs or larvae from the environment or eating rodents infected with roundworms.

A large number of roundworms in the intestines will interfere with nutrient absorption and can lead to an unhealthy pet with a poor coat, abdominal enlargement, diarrhea, and occasional vomiting. The diarrhea and vomit may contain spaghetti-like roundworms. Infection can also cause coughing and pneumonia when roundworms and hookworms pass through the lungs during larval migration. In young animals, a large roundworm burden can create a life-threatening intestinal obstruction.

Hookworms cause intestinal damage by attaching to the lining and sucking blood. Once they detach and move to a new spot, the old wound still oozes blood and protein, which can cause anemia. Pets with hookworms display many of the same signs as pets with roundworms. Also look for anemia and black, tarlike stools, which result from digesting blood. Pets of any age can become infected because hookworm larvae can burrow into the skin.

Tapeworms. Tapeworms are common in cats, but despite what you’ve heard, they don’t cause severe weight loss. The infection actually causes little damage. You probably won’t see the diarrhea, vomiting, unhealthy appearance, and weight loss seen with other GI parasites. Adult tapeworms live in the intestines and pass worm segments in the feces. This may cause anal itching, and your pet may scoot her rear across the floor (similar to anal gland impaction). You may notice 1/4-inch white worm segments on your pet’s feces or on the fur around the anus. They look like tiny moving pasta segments or grains of rice.

Pets can get tapeworms from eating infected fleas, rabbits, and rodents. Since larvae don’t migrate throughout the body, cats don’t develop immunity against them. So pets can become reinfected each time they eat a carrier.

Whipworms. Whipworms are most prevalent in the South, where the environment is moist and warm. Pets become infected from ingesting the eggs in contaminated animal waste, soil, or grass. Whipworms live in the large intestines, causing diarrhea, protein loss, and occasionally anemia and weight loss. The worms are 2 to 3 inches long and resemble a whip, with one end thick like a handle. Pets can become reinfected because whipworms don’t migrate throughout the body, so the immune system isn’t stimulated.

Giardia. This protozoan parasite lives in standing water, so pets with access to streams and ditches – or the water collecting in your own yard – are at risk for infection. Giardia occasionally colonizes the small intestines of cats. It causes foul-smelling diarrhea that can be watery, bloody, or the consistency of cow manure, and it occasionally causes weight loss.

Coccidia. This protozoan parasite commonly infects kittens when they ingest the cysts from their environment. A potentially debilitating infection, coccidia causes diarrhea (occasionally with blood), dehydration, and sometimes vomiting. It can mimic the signs of panleukopenia in kittens.

Detection
    Your veterinarian should thoroughly examine all pets with signs of GI parasite infection to help rule out other causes of GI disease, such as feline panleukopenia and foreign body obstruction. Your veterinarian will examine a fecal sample for parasite eggs or cysts. Tapeworm eggs don’t appear on a fecal test unless a segment breaks open, releasing individual eggs. Sometimes the segments are passed in the feces, and they’re visible to you and your veterinarian.

Your pet will pass whipworm eggs and Giardia only intermittently, making these infections particularly hard to diagnose. Your veterinarian may perform blood tests to detect a high number of eosinophils, a type of white blood cell that increases in pets with parasitic infections. Blood tests may also reveal anemia and low protein levels, especially with hookworm infections.

Prevention and Treatment
    Preventing GI parasites is as simple as practicing good hygiene and using common sense – like cleaning up the feces in your yard and minimizing your pet’s exposure to contaminated areas.  Because prenatal transmission doesn’t occur in cats, treatment of kittens can begin at 6 weeks of age and be repeated at 8 and 10 weeks. This de-worming protocol should continue with monthly treatments until your pet is at least 6 months old.

Many heartworm preventives also control intestinal parasites, and flea control reduces the chance for tapeworm infection. Ask your veterinarian about the new Giardia vaccine and whether it’s right for your pet.

Treatment varies, depending on the type of parasitic infection, so regular fecal examinations to identify the parasite are important. If the fecal test result is negative but your veterinarian still suspects a particular infection, he may treat your pet anyway to see if the symptoms disappear. In general, over-the-counter

Some GI parasites can be transmitted to people. Children can accidentally ingest roundworm eggs from playing in the yard or eating soil, resulting in larva migrans, an uncommon but serious infection.

Though GI parasites are a common problem in pets, they’re easily treated. But it’s better to prevent pets from contaminating the environment and spreading infection by using de-wormers and monthly preventives. This strategy will help protect you, your children, and your pet from infection.