Deworming Dogs and Puppies

Although nearly all dogs are infested with parasites at one time or another, most develop an immunity that keeps the parasite population in check. This immunity can break down, however, under conditions of stress or ill health. When that happens, the worms increase in number and eventually produce signs of intestinal infection, including diarrhea, weight loss, anemia, and blood in the feces.

Dogs develop the highest level of immunity to worms that have a larval phase that migrates in tissue. These are the ascarids, hookworms, and threadworms. Whipworms and tapeworms do not have a migratory phase and thus produce little immunity.

Deworming Puppies

Most young puppies are infested with ascarids. Other worm parasites may also be present, but they’re not as common. It is advisable to have your veterinarian check your puppy’s stool before deworming for ascarids, because if other worms are present, a broad-spectrum deworming agent may be recommended.

Puppies should be dewormed at 2 weeks of age (before ascarid eggs are passed in the stool) and again at 4, 6, and 8 weeks of age. Then, it’s prudent to put them on a monthly heartworm preventive for life that also protects the dog against other parsites, or at least continue monthly deworming for six months. This schedule kills all ascarids, whether acquired in utero, through infected mother’s milk, or by ingesting the eggs. Pyrantel pamoate (Nemex or Strongid) is an excellent choice for ascarids and can be safely given to 2-week-old puppies. It is available as a liquid suspension or tablet.

Worm medications can be harmful to puppies that are ill from a respiratory infection, chilled, crowded in unsanitary surroundings or abruptly weaned from their mothers. Stressful conditions such as these should be corrected before administering the dewormer. Do not deworm a puppy who has diarrhea unless your veterinarian has determined that the diarrhea is caused by the parasite

Deworming Adult Dogs

Most veterinarians recommend that adult dogs be dewormed only when there is specific reason to do so, such as when eggs or parasites are found during a fecal examination. Dogs can also be kept on a yearlong heartworm preventive that also protects against many of the intestinal parasites. All dogs should have a fecal examination done at least once a year.

Most dogs carry ascarids as encysted larvae, but intestinal infestation by the adult worm is rare in the healthy dog. Hookworms are likely to be a problem in adults only during periods of stress. Only milbemycin (Interceptor) is effective against encysted hookworm larvae.

Whipworms are a frequent cause of acute and chronic diarrhea in adult dogs. They are difficult to diagnose on routine fecal examination. Eradication requires the use of specific agents not commonly used for other worms.

Tapeworms are common in dogs but, fortunately, cause few symptoms. The worm segments are easy to detect in the stool. Threadworms are not common. Very few agents are effective against this parasite.
How to Control Worms

The life cycle of most worms is such that the possibility of reinfestation is great. To keep worms under control, you must destroy the eggs and larvae before they reinfest the dog. This means good sanitation and maintaining clean, dry quarters.

Dogs should not be kenneled with dirt runs, which provide ideal conditions for seeding eggs and larvae. A watertight surface, such as cement, is the easiest to keep clean. Gravel is a good substitute. It provides effective drainage and allows for easy removal of stools. Hose down each kennel or run daily and allow it to dry in the sun.

Remove stools daily from runs and pens. Lawns should be cut short and watered only when necessary. Stools in the yard should be removed every day

The table below show the different types of worms:

Hookworms 
In dogs reach 5-19 cm in length and can infect animals from the environment. This occurs when they are ingested or penetrate the skin of paws and legs. They can also be transferred to pups through their mother's milk.
Hookworms cause a variety of clinical signs, including weight loss, poor appetite, bloated abdomen, black tar-like diarrhoea, dehydration, enteritis and lethargy. Severe infections can be fatal.

Roundworms
Reach 9-19 cm in length. They can infect dogs by ingestion, across the placenta, or be transferred to pups through their mother's milk.
Roundworms cause a variety of clinical signs, including coughing, diarrhea, vomiting, bowel obstruction, pneumonia, a dull coat, and a swollen abdomen. Severe infections can be fatal.

Whipworms
May reach 4-7 cm in length, and can only infect dogs when worms are swallowed.
Clinical signs include abdominal pain, anorexia, pale eyelids and gums, dehydration, smelly bloody diarrhoea and weight loss. Infection in adult dogs is generally not as serious as infection in puppies, which can be fatal.

The Common Flea Tapeworm 
Grows to 50 cm in length, and infects dogs after ingestion of infected fleas.
This tapeworm causes irritation and itching around the anus but is not considered to be a major health risk.

The Hydatid Tapeworm 
Grows to 7 mm in length, and is found in areas where sheep and dogs (or foxes) are in contact.
While this tapeworm does not cause significant clinical signs in dogs, infection of humans can be life-threatening. Humans contract hydatids by swallowing eggs found on the coats and in the faeces of infected dogs.