Figure:  Microscopic parasite eggs found in dogs and cats feces

•  Coccidia: Protozoan ingested from contaminated feces or soil.  Causes diarrhea.
• Giardia​: Protozoan ingested from contaminated moist environments and water. Can cause diarrhea.
• Hookworms: Nematode passed directly from mother to her puppies through the placenta or milk, migration through the skin, or ingestion of contaminated feces or soil. Causes diarrhea and severe anemia in young and debilitated animals.
• Roundworms: Nematode ingested from contaminated feces or soil.  Causes stunted growth, pot  bellied appearance, and diarrhea in young or debilitated animals.
• Tapeworms: Flat, segmented parasites called cestodes that a dog or cat becomes infected with by ingesting an infected flea.  Generally, these appear like a small grain of rice in an animal’s stool or in the hair around the perineum.
• Whipworms: Nematode that is ingested from contaminated feces or soil.  Causes bloody, watery diarrhea, weight loss and general debilitation in animals.

Administering Anthelmintic Drugs (Dewormers)

It is important to know what type of parasite your pet has before administering an anthelmintic (parasite killing drug).  This is because different medications are needed for different parasites.  Unfortunately, anthelmintic drugs have been used indiscriminately and sometimes inappropriately, which has allowed the worms to develop resistance to the medications.  As a result, it is becoming more and more difficult to eliminate worm infestations.  You should only administer an anthelmintic after a positive diagnosis of intestinal parasitism under the direction of a veterinarian. It is also important to administer the medication in the correct dose and to repeat treatment at the correct interval to kill all worms. While the anthelmintic is a poison meant to directly target the parasites, pets weakened by a parasitic infection might be too fragile for the toxicity of the medication and an overdose is possible if directions are not followed.

How to control parasites

Parasites are known for their ability to continually re-contaminate their host. In order to control parasites, destroying the eggs and larvae or removing them from the environment before re-infestation is critical. To achieve this, pet owners must maintain clean and dry living areas for their pets.

Pets should be encouraged to defecate in areas that are easy to remove waste from, wash out, and keep clean such as cement or gravel. Dirt and grass should be avoided when possible. Pet waste needs to be removed daily, and fleas need to be exterminated.