INTERNAL PARASITES (INTESTINAL PARASITES)

Most cases of intestinal parasitism are occult, meaning that symptoms are not present although the parasites are. Younger cats will tend to have heavier worm loads and show more symptoms of infestation than will older cats. Some worms have migratory phases to their lifecycle whereby the larvae migrate through the tissues and thusly, can allow the cat to build up some immunity against the parasite. Not all intestinal parasites, however, are "worms". Coccidia and giardia are two very common single-cell intestinal parasites.

As many cases of parasitism are occult, and as it is rare to see the worms in the feces, all cats and especially kittens should have regular fecal exams to detect these even if there are no signs present. During the fecal analysis, your veterinarian will be able to detect worm eggs or these single-cell organisms, make an exact diagnosis and prescribe the proper treatment. Sometimes, several tests may be needed as the eggs or organisms are not present in every bowel movement. Common symptoms of intestinal parasites can include weight loss, vomiting, diarrhea, inappetence and abdominal distention.

It is easier to prevent worms if cats are kept on hard sealed surfaces such as tile, which can be easily cleaned and disinfected. Outdoor cats will become infected more often. Litter pans should always be kept clean. Preventing cats from having fleas or eating rodents or birds is important as these often act as the intermediate host for tapeworms. Bleach or Lysol can be used to disinfect rooms and litter pans, but these will not work well on outdoor areas. Regular worming may be needed in some situations as a method of control.

 

WORM PARASITES

ROUNDWORMS (Toxocara species)

Roundworms live in the small intestine and in larger numbers can cause intestinal obstruction. Female roundworms can lay hundreds of thousands of eggs in a day, which pass in the feces and can live in the environment for months. When a cat contacts the eggs in the soil or on the grass, they are swallowed and pass into the intestine, hatch into larvae, migrate through the liver, enter the lungs where they are coughed up and swallowed and return to the small intestine to develop into adults where the cycle starts again. ((Roundworms))

In nursing females the parasite may be passed to kittens in the mother's milk. One species of Toxocara can infect rodents, which, when eaten, provide another source of infection for the cat. Clinical signs are most common in younger cats and include weight loss, abdominal distention, vomiting, diarrhea, poor appetite and a shabby coat. These worms can on occasion cause a human disease known as visceral larval migrans, which can cause serious illness, especially in young children. Treatment

 

HOOKWORMS (Ancylostoma and Uncinaria species)

Hookworms are very small worms that "hook" on the inside of the intestinal wall and suck blood from the cat. Adult worms pass eggs out in the feces where they hatch into a larval form. Some cats become infected when the larvae penetrate through the skin and migrate into the gut. Most commonly, the larvae are ingested, pass into the small intestine, mature into adults and the cycle repeats.

Hookworm larvae may also encyst in the tissues of the cat, then, during periods of illness or stress, become active and begin a new infestation. Since these worms draw blood from the cat as well as occupy the small intestine, clinical signs of illness include weight loss, diarrhea, bloody stools and anemia. Malnutrition and anemia caused by hookworm disease in young kittens may be so severe as to be fatal. Treatment

 

WHIPWORMS (Trichuris species)

Whipworms are a very long, slender worm which inhabit the cecum and colon of the cat. Adult worms pass a football-shaped egg which, when ingested orally, hatches into a larvae, develops into an adult worm and attaches to the colonic wall of the animal. Signs of illness will often be minimal in light infestations, but if enough worms are present, diarrhea, often with blood and mucus and a loss of weight may occur. Your veterinarian may diagnose this as a Whipworm Colitis. Infection by whipworms in cats, however, is quite rare. Treatment

 

TAPEWORMS (Taenia and Diphlidium species)

Tapeworms are very long, segmented worms which live in the small intestine. Each worm has a head known as a scolex, which anchors the worm to the intestinal wall with hooks and suckers. The segments after the head each contain egg packets that are passed at variable and unpredictable intervals in the feces. Often, these segments can be seen around the anus of the cat. Some tapeworms can grow to many feet in length and some cats can have several tapeworms in their intestine. ((Tapeworms on Anus))  ((Tapeworms))

Cats cannot and do not acquire tapeworms by eating the segments or the tiny egg packets; rather, a cat must ingest fleas or raw meat from birds, rodents, fish or other mammals. These are called intermediate hosts and are essential to the life cycle of the tapeworm. Many cats, even with heavy infestations, do not have symptoms of illness, but weight loss, diarrhea and poor coat condition may all occur. Treatment should be given to prevent intestinal damage from the physical presence of the worm. Treatment

 

FLUKES

Flukes are unusual flat worms that can inhabit the intestines, liver or lungs of the cat. The unique nature of flukes requires several intermediate hosts be involved before they may infect a susceptible cat. For instance, once an infected cat passes fluke eggs, a snail often carries the next larval form, then a fish will carry a cystic stage and when a cat eats this fish and becomes infected, the life cycle is completed.

Three common intestinal flukes include Cryptocotyle, Alaria and Nanophytes species. Present in large numbers, intestinal enteritis may occur. The fluke Platynosomum can infest the liver and bile ducts of cats. Although uncommon, the condition is seen in Hawaii and south Florida causing hepatitis and cholangiohepatitis. Another fluke, Paragonimus kellicotti, can infect the lungs of cats that ingest infected crayfish in a few areas of the United States. The fluke Eurytrema procyonis has be shown to cause pancreatitis in cats. These cats may show signs of bronchitis or mild pneumonia. Treatment

 

PROTOZOAN PARASITES (One-cell organisms)

COCCIDIOSIS (Isospora and Sarcocystis species)

Coccidia are a commonly seen parasite of cats, most common in young kittens and is more likely to be seen where conditions of poor sanitation, stress and crowding have occurred. Some sources indicate that most every cat will become infected by coccidia at some point in their life. ((Coccidia))

Cats will ingest the parasite from any source that has been contaminated by infected cat feces or by ingestion of infected rodents or other meat sources. These organisms reproduce themselves inside the lining cells of the intestinal tract. As the new organisms emerge from these host cells, the intestinal cell is killed in the process. This life cycle takes only a few hours to a few days and new organisms are again passed in the feces.

Clinical signs include weight loss, weakness, dehydration and diarrhea with possibly blood and/or mucus being present. Kittens or otherwise weakened cats will have more severe symptoms. Older and generally healthy cats may exhibit no symptoms whatsoever. In cases where poor sanitation is ongoing, cats may continually infest themselves. Coccidia are also found secondary to roundworm and tapeworm infestations in cats. Treatment

 

GIARDIASIS (Giardia species)

Giardiasis seems to be an ever-increasing parasitic problem in domestic cats and will also easily infect humans. The parasite has a unique shape and attaches to the lining of the intestine, disrupts the digestive process and causes irritation of the bowel. Infection occurs by ingesting infected food and water sources that contain an encysted form of the parasite or the actual live organism. Crowding and stress increases the spread of this parasite.

Infected animals may or may not exhibit signs of illness and some may harbor and even spread the disease without being ill themselves. Some cats may carry the cysts, which can later become active in times of stress or illness and then cause symptoms. Even with treatment, some cats will continue to carry the organism, having recurrent bouts of the disease. Clinical signs include acute, chronic, or intermittent diarrhea, often with heavy mucus production, weight loss, poor appetite and weakness. Treatment

 

TOXOPLASMOSIS (Toxoplasma and Hammondia species)

While toxoplasmosis can affect many different species, it is the cat that is the primary host for the disease and thus, the source of infection for all other species. Cats become infected either by eating feces-contaminated materials, directly from an infected mother to unborn kittens and most commonly by the cat eating the meat of other infected animals. (rodents etc.) Once inside the cat, the organism reproduces in the intestinal tract, eventually to be passed out again in the feces where the infection can continue to spread.

Most cats can harbor and pass the parasite without ever becoming ill. In some cases, however, the parasite may pass through the intestinal barrier, spreading first to lymph nodes, then to other internal organs including the liver, lungs, brain, eye, heart and adrenal glands. When the organism reproduces in these abnormal areas, organ damage and subsequent clinical signs occur.

Clinical signs will vary with the organ(s) affected but can include loss of appetite, lethargy, trouble breathing due to pneumonia, uveitis, fever, vomiting, yellow gums, diarrhea, neurologic disease, behavioral changes and abdominal enlargement. Disease will often be worse in kittens, kittens infected before birth and in cats with FeLV, FIP, FIV, hemobartonellosis and other infections. Diagnosis is based on history, physical examination, fecal exam, serologic testing for toxoplasmosis, blood counts and serum chemistries and biopsy of infected tissues.

Toxoplasmosis is a hazard to humans, especially to pregnant women. If a woman becomes infected, the parasite can be passed to her fetus and cause severe birth defects. Pregnant women should not handle raw meats or clean litter pans. Soil, where cat may have defecated should also be avoided. Vegetables grown in home gardens should be thoroughly washed and all meat should be properly cooked. Serologic testing as well as fecal analysis can be used to test household cats as an aid in the prevention of human illness.

TREATMENT OF TOXOPLASMOSIS

Clindamycin seems to be the most promising drug available to treat this illness. Sulfa drugs and tribrissen have also been routinely used. Supportive care and good nutritional maintenance will help most cats recover. Many cats will develop immunity if they do recover from the illness.

 

CRYPTOSPORIDIUM (Cryptosporidium species)

Cryptosporidia are the smallest of all coccidia-type parasites and attacks the intestines of cats and most other warm and cold-blooded animals. Many cats become infected but few show clinical signs. Most cats with actual cryptosporidial illness will be FeLV positive or otherwise weakened. Usually, the primary symptom of infection is chronic, persistent and watery diarrhea, weight loss and a poor appetite. Humans can become infected by cats and vice versa which is the most serious aspect of this type of infection. There currently is no known effective treatment.

 

UNCOMMON INTERNAL PARASITES

AELUROSTRONGYLUS: cat lungworms. May cause mild respiratory disease.

AMEBIASIS: common in few areas, single cell organism causing diarrhea.

CAPILLARIASIS: worms of the lungs and windpipes. Often causes no illness.

OLLULANIASIS: rare stomach worm, passed by cats licking infected vomit

STOMACH WORM: Physaloptera species, may cause vomiting. Rare.

STRONGYLOIDES: small worm that may cause nodules in the large intestine.

TRICHOMONIASIS: one-celled organism similar to giardia, causes diarrhea

 

TREATMENT OF INTESTINAL PARASITES

As a general principle of treatment, proper identification of the organism(s) present is most important. The use of old medications, now commonly sold over the counter, often will make the cat ill and fail to resolve the problem. Older wormers can be very toxic and irritating to your cat and should be avoided. Most people commonly mistake any diarrhea as surely being caused by worms when many other causes may exist, thus, a proper diagnosis is paramount to good treatment.

Modern wormers are among the safest and most effective drugs your veterinarian will have on his/her shelf. However, these medications are often very specific so a "one size fits all" approach is no longer acceptable. Also, if other problems secondary to a parasitism have occurred, such as dehydration, worming alone will not cure the patient.

Dewormers are known as anthelmintics.

For Roundworms, Hookworms and Whipworms: fenbendazole (panacur), mebendazole (telmintic) and vercom are most recommended. Other wormers that may not have as broad a spectrum but include canopar, nemex, piperazine, DNP, ivermectin, milbemycin and styquin.

For Tapeworms: droncit and vercom are most advised; cestex, scoloban and panacur are sometimes used.

For Coccidia: albon is most commonly used, some vets use tribrissen and other sulfa agents.

For Giardia: flagyl, quinicrine, panacur, albendazole and furazolidone are all commonly used.

For Flukes: fenbendazole, albendazole and droncit at increased doses may all be effective.