When people talk about worms in dogs and cats they are referring to intestinal parasites, of which there are several kinds. In our climates there are four common kinds of intestinal worms and one protozoan to be concerned about. To be sure, there are others than those we will discuss here, but these are the most commonly found intestinal parasites.
Parasites cause harm to their hosts generally in two ways--by damaging specific organs or tissues, and by robbing the host of vital nutrients. Classic signs that internal parasites have infected your pet include a dull, rough hair coat; a pot-bellied appearance; unthriftiness or poor growth; gastrointestinal disturbances ranging from diarrhea to constipation or vomiting; lack of energy; anemia, and in severe cases, death.
The proper treatment for intestinal parasites requires professional diagnosis of the types of parasites present, selection of a specific safe and effective dewormer, and repeated treatment according to the life cycle of the parasites.
Not all intestinal parasites are visible to the naked eye, so we must begin with laboratory examination of the feces. We do this routinely in all puppies and kittens under our care. When we check a sample we prepare it for microscopic examination by doing a concentration technique which separates any parasite eggs from the fecal debris. Each parasite has a characteristic egg recognizable under a microscope. Checking one sample is about 75% accurate. Checking two is 85% accurate.
Good sanitation practices and disinfection are often necessary to achieve adequate control of bothersome parasites. In addition, controlling fleas and other vermin that can transmit parasites is important for providing the optimum protection for your pet.
Pinworms are unknown in dogs and cats. If your children pick up pinworms, please don't blame the family pet. The life cycle of people pinworms is such that they can only infect other people.
Ascarids or Roundworms
Nearly all puppies are born with large round worms called ascarids.
Even though the mother dog may not show signs of ascarid infection, she
may have tiny, encysted larvae in her body that are activated during
pregnancy and infect the developing fetuses. Ascarid eggs are very resistant
to environmental and climactic factors as well as to many chemicals.
It is thought that ascarid eggs can stay alive in or on the ground for
several years. Puppies and kittens can also become infected by accidentally
eating these infective eggs.
Other commonly occurring parasites in pets are hookworms. Very young
puppies can become infected through their mothers' milk while nursing.
Dogs and cats of any age may be infected by consuming food or water contaminated
with infective larvae, or the larvae can penetrate the animal's skin
to establish an infection.
Dogs become infected with whipworms by ingesting infective whipworm
eggs. The eggs are very hardy, and can remain viable for long periods
of time in the environment. Once an area is contaminated with whipworm
eggs, dogs using the area are destined to be plagued repeatedly with
this parasite. Adult whipworms live in a portion of the dog's intestinal
tract called the cecum. Infected dogs are often troubled with bloody,
mucus-filled diarrhea, and are usually unthrifty. In many cases, whipworm
eggs cannot be found in the watery stool, making it difficult to make
a diagnosis. The whipworm parasite is a problem for older dogs, but not
This is the parasite most often missed on laboratory examination. It
is diagnosed by finding rice-like 1/2 inch segments in the feces, on
the hair under the tail, or in the animal's bed. Fresh segments of tapeworm
will move like an inchworm--squeeze up stretch out.
Coccida are protozoa. They attack the lining of the intestine causing severe digestive upsets. Proper sanitation is a most important factor in coccidiosis control. Coccidia seem to have little effect on adult animals who act as carriers and spread the disease to both young puppies and kittens. Coccidiosis starts with a slight diarrhea which gradually worsens until the feces are full of blood and mucus. The animal then becomes dehydrated and very sick. If left untreated it will soon begin to cough and have a discharge from the eyes and nose and a low grade fever. Occasionally an animal will survive without treatment, but most will start to have convulsions and soon after that, die. Kittens are less seriously affected than puppies. Effective treatment involves daily oral medication for several days.