A parasite is a plant or animal that lives upon or within another living organism. There are a variety of parasites that infect various organs or body systems. Parasites can be either internal or external parasites – living primarily on the skin (fleas), in the respiratory tract (lungworms), or in the blood vessels and heart (heartworms).
Some gastrointestinal parasites are microscopic, and the only way to diagnose them is by microscopic examination of your dog's feces for the eggs shed by the adult worms. Others are large enough to be observed in your dog's bowel movements or after he vomits. Moreover, some tapeworms produce proglottids
, which are the segments making up their body. These segments can be seen around the hair on the anus or in the stool, appearing as bits of moving "white rice."
Among the important gastrointestinal parasites of dogs are roundworms (Toxocara species), hookworms (Ancylostoma caninum, Ancylostoma braziliense and Uncinaria stenocephala), whipworms (Trichuris vulpis, T. campanula, T. serrata), stomach worms (Physaloptera spp.), tapeworms (Diplylidium caninum, Taenia pisiformis), and microscopic parasites Coccidia, Giardia and Strongyloides species.How Parasites Are Acquired Ingestion of eggs. Most infections are acquired by ingestion of microscopic eggs. This occurs when a dog licks areas where other dogs have defecated, like yards, parks or grass.
At birth. Many puppies are born with intestinal parasites (usually roundworms) that have been passed from the mother, where the parasite was in an encysted, quiet state.
From intermediate host. Tapeworms are transmitted by an intermediate host when a dog swallows a flea or eats a rabbit.
It should be emphasized that some parasites – especially roundworms and hookworms – can also affect people, especially children. For that reason, it is essential to prevent intestinal parasites in our pets and to treat any resultant infection.
Parasitic diseases range from trivial to fatal disease. Parasites can cause severe disease in immature puppies, sick or debilitated pets, or in pets with a suppressed immune system. Younger pets often get acute disease (vomiting, diarrhea, dehydration, and anemia) whereas older pets get chronic disease such as intermittent diarrhea.
What to Watch For
Because parasitism is easily confused with other debilitating conditions, diagnosis depends on the following:
Medical history and physical examination, including observations of worms in the stool or vomitus.
Fecal examination for microscopic eggs or larvae. This is the most common approach to diagnosis as most pets do not appear ill.
CBC – Complete blood count if anemia is suspected (as with a hookworm infection) or if the pet is showing symptoms of illness.
Other blood tests may reveal concurrent problems.
Treatments for intestinal parasites may include one or more of the following:
Routine deworming in puppies – This is the ideal approach. All immature pets should treated at the first veterinary examination and regularly dewormed during the first year. In general, every dog less than one year of age should be given an anthelmintic (anti-parasite drug) for ascarids regardless of fecal results. This is in part to protect the environment from contamination with microscopic eggs that might infect children.
A yearly fecal check and treatment is recommended for adult pets, especially if they are not taking heartworm preventatives that would prevent development of intestinal worms.
Other treatments may include fluid therapy for debilitated pets or blood transfusion and iron supplementation (if necessary for severe blood loss as with hookworm infections).
Home Care and Prevention
At home administer any prescribed medications and follow-up with your veterinarian for examinations and repeated fecal (stool) tests as needed.
Some microscopic eggs can live in the environment (such as the yard) for weeks to months and cause re-infection. Clean up yard weekly and minimize roaming of pets in places like parks where exposure and infection are possible.
Many health care specialists recommend a fecal sample from all adult animals at least yearly, a sample at each puppy vaccination visit, and a follow up sample at the appropriate interval after the last deworming medication has been given.
With primarily outdoor dogs, it may be advisable to evaluate stool samples every three to six months if risk of infection is high. One may also consider heartworm preventatives that also prevent intestinal parasites.