Both dogs and cats alike are commonly infected with intestinal parasites, particularly puppies and kittens. Parasites can be broken down into two categories, worms and protozoa. Common intestinal worms include (listed by common names) roundworms, tapeworms, whipworms, and hookworms. Two protozoan parasites that commonly affect dogs and cats are coccidia and giardia. Both protozoan and worm parasites have the potential to cause diarrhea, vomiting, anemia, ill-thrift, and even death if left untreated. Puppies and kittens are especially sensitive to parasite infection.
Roundworms, hookworms, and whipworms are transmitted on a fecal/oral cycle. Infected animals shed infective eggs in their feces that are ingested by routine sniffing behavior, direct ingestion of feces, or the sharing of a litter box. Tapeworms are most commonly transmitted by the ingestion of an infected flea. If tapeworms are present, a different wormer will be used. Not all worms respond to the same treatment and no single wormer works against all kinds of parasites. And some non-prescription wormers are quite ineffective in removing worms from the dog or cat. Your veterinarian will have available for you the best kinds of wormers for the particular type of parasite your pet has. Therefore, stool samples should be taken to the veterinarian for microscopic examination for the worm eggs if worms are suspected. Many veterinarians include the stool check as part of the annual health examination.
Prevention of intestinal parasites of dogs and cats is also very important because they are potential health hazards for humans, too. If hookworm larvae penetrate the skin they can cause “cutaneous larval migrans”, where potentially serious and scarring inflammation results. Ascarid (roundworm) eggs if ingested can cause a disease called “visceral larval migrans” where tiny worm larvae migrate through the human host’s intestinal wall and into the body tissues. They can then grow to larger size almost anywhere in the body. Ocular disease is a common sequel to “visceral larval migrans”. Thie form of the disease can cause blindness – children are at most serious risk especially if play behavior is in an environment where dog, cat, or raccoon feces may be present… such as in a sandbox. A single adult Toxicara canis female can shed up to 100,000 eggs a day which pass into the dog or cat’s environment with the stool. It is important that you take the worming advice of your veterinarian seriously and adhere to strict sanitation principles whenever pets and children are in close contact. Note… roundworms are not spread to people simply by close contact with dogs or cats (such as petting).The individual must ingest the infective stage of the roundworm eggs; since the eggs are primarily associated with feces, humans would somehow need to consume the egg contaminated feces for contagion to occur.
All of the aforementioned parasites are quite treatable with a variety of safe pharmaceutical products. With regard to tapeworms, however, in addition to medication, good flea control is a necessary component of the treatment. Yearly stool analysis as part of the yearly visit is an important component of making sure your pet is free of parasites.
Roger L. Welton, DVM
Founder and Chief Editor, Web-DVM.net
President, Maybeck Animal Hospital
Article updated 8/19/2012