Most cases of intestinal parasitism are occult, meaning that symptoms are not present although the parasites are. Some worms (roundworms, hookworms and threadworms) have migratory phases to their lifecycle whereby the larvae migrate through the tissues and thusly, can allow the dog to build up some immunity against the parasite. Younger dogs will tend to have heavier worm loads and show more symptoms of infestation than will older dogs. 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 dogs and especially puppies 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 occasionally coughing when larvae are migrating through respiratory tissues.

It is easier to prevent worms if dogs are kept on hard sealed surfaces such as concrete, which can be easily cleaned and disinfected. If the dogs are kept on grass or dirt, try to keep stools cleaned up daily; keep the lawn mowed to a short length, and irrigate as little as possible. Try to prevent your pet from having fleas or eating rodents or birds as these often act as the intermediate host for tapeworms. Bleach or Lysol can be used to disinfect runs, but these will not work well on grass or dirt areas. Regular worming may be needed in some situations as a method of control.

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 survive in the environment for months. When a dog contacts the eggs in the soil or on the grass, they are swallowed and pass into the intestine, hatch into larvae, migrate through the blood to the lungs, 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 older dogs some larvae may encyst in the body tissues, when, during pregnancy, they again become active (become worms again) and are passed through the placenta to unborn pups. Some larvae may also be passed to the pups in the mother's milk. For these reasons, many pups are born with roundworms, which cause severe malnutrition and intestinal obstructions. 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 are very small worms that "hook" on the inside of the intestinal wall and suck blood from the dog. Adult worms pass eggs out in the feces where they hatch into a larval form. The larvae are ingested, pass into the small intestine, mature into adults and the cycle repeats. Unborn pups can (rarely) become infested in the uterus but more likely will acquire the disease from the mother's milk. Also, on rare occasion, larvae can penetrate the skin and migrate through the tissues to make their way into the intestinal tract.

Hookworm larvae may also encyst in the tissues of the dog, then, during periods of illness or stress, become active and begin a new infestation. Larvae that penetrate the skin of the dog can cause a skin disease known as hookworm dermatitis. This may also occur in humans, causing a disease known as cutaneous larval migrans which is usually self-limiting. Since these worms draw blood from the dog as well as occupy the small intestine, signs of illness include weight loss, diarrhea, bloody stools and anemia. Malnutrition and anemia caused by hookworm disease in young puppies can be so severe as to be rapidly fatal. Treatment

Whipworms are a very long, slender worms which inhabit the cecum and colon of the dog. 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 Whipworm Colitis; dogs may have several bouts of illness before the diagnosis is made. Treatment

This small species of roundworm known as threadworms live in the small intestine. Adult worms pass eggs and larvae into the feces where they can be ingested, or they may penetrate the skin and enter the body. Larvae enter the circulation, pass to the lungs where they are coughed up and swallowed and develop into adults in the small intestine. Puppies that often suffer most due to heavy infestations will exhibit signs of pneumonia, diarrhea with blood and mucus, fever and weight loss. These young pups will often die before diagnosis and treatment can occur. Treatment

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 dog. Some tapeworms can grow to many feet in length and some dogs can have several tapeworms in their intestine. ((Tapeworms))

Dogs cannot and do not acquire tapeworms by eating the segments or the tiny egg packets; rather, a dog 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 dogs, even with heavy tapeworm infestations, do not have symptoms of illness, but weight loss, diarrhea and poor coat condition can occur. Treatment should be given to prevent intestinal damage from the physical presence of the worm. Treatment

Coccidia are a commonly seen parasite of dogs, most common in young puppies, and is more likely where conditions of poor sanitation, stress and crowding have occurred. Dogs will ingest the parasite, which reproduces itself inside 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 about 5-7 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. In cases where poor sanitation is ongoing, dogs may continually infest themselves. Coccidia are often also found secondary to roundworm infestations in some dogs. Treatment ((Coccidia))

Giardiasis seems to be an ever-increasing parasitic problem in domestic dogs and will also easily infect humans. The parasite has a unique shape and attaches to the lining of the intestine. There it disrupts the digestive process and causes irritation of the bowel. Infection occurs as a result of 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 the infection.

Infected animals may or may not exhibit signs of illness and some may harbor and even spread the disease without being ill themselves. Some dogs may carry the cysts, which can later become active in times of stress or other illness and then cause symptoms. Even with treatment, some dogs 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

While not a pure intestinal parasite, dogs can acquire toxoplasma organisms by ingesting infected soil (cat feces) or contaminated meat of intermediate hosts. The primary or definitive host for this parasite is the cat; the dog would be considered an accidental host. Often infected dogs will not show any clinical signs, with younger dogs most likely to have more severe symptoms if any. Symptoms will include fever, coughing, vomiting, diarrhea, weakness, signs of acute hepatitis and encephalitis. Transmission from mother to unborn pups is also possible. As toxoplasmosis is a hazard to pregnant women, whereby fetal birth defects can occur, avoidance of cat feces or animals known to be infected is very important. Serologic testing as well as fecal analysis can be used to diagnose this disease. Treatment

Babesiosis is an uncommon disease caused by the organism Babesia canis. It is not really an intestinal parasite, but included here with other one-celled organisms. This protozoan parasite is transmitted from dog to dog by several varieties of ticks, mostly in the Southern United States. The parasite attaches to and destroys blood cells. Clinical signs include fever, jaundice, pale gums, red-colored urine, and in some cases, neurologic symptoms and death. Diagnosis is based on history, physical examination, blood counts, serum chemistries and urinalysis. Treatment

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

CAPILLARIASIS: worms of the nose or urinary bladder; asymptomatic.

DIOCTOPHYMOSIS: kidney worm, may cause kidney damage.

FILAROIDIASIS: bronchial and lungworms, may cause cough, respiratory disease.

PARAGONIMIASIS: fluke, or flat worm, may infect lungs, intestines and liver.

SPIROCERCOSIS: esophageal worm, may cause recurrent vomiting, and trouble breathing.

STOMACH WORM: Physaloptera species, may cause vomiting.

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 dog ill and fail to resolve the problem. Older wormers can be very toxic and irritating to your dog and should be avoided. Most people commonly mistake any diarrhea as surely being caused by worms when many other causes may be present; 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 condition.

Dewormers are known as anthelmintics.

For Roundworms, Hookworms, Whipworms and Threadworms: 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 amprolium.

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

For Toxoplasmosis: sulfadiazine, trimeth/sulfa combinations, primor and clindamycin have all been used with variable effectiveness.

For Babesiosis: trypan blue, acaprin, acriflavin and several other drugs effective. Fluids and blood transfusions may be needed.

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