This is a brief summary of the major groups of internal parasites encountered in our pets and their significant clinical and public health concerns.
A microscopic assessment is made of a fresh stool sample (within 24 hours). There may be more than one species of parasite present, therefore, the treatment regimen will vary depending on the species involved. There is no single “wormer” effective against all the different parasites. An examination for internal parasites in kittens should be done early since many of these parasites are transmitted from mother to offspring and thus, have their effect on the very young. Early detection and treatment will enable the kitten to grow to its fullest potential while minimizing the health risks to humans. Repeat stool checks are recommended through the first year and then annually for all adult pets who have access to other animals or to the outdoor environment.
Roundworms (Toxocara, Toxascaris spp.) are the most common internal parasites found in pets. Typical clinical signs include a pot-bellied appearance, poor growth, and possibly diarrhea. Angora cats continue to be susceptible to infection throughout their life whereas some dogs develop a resistance. In pregnant animals, dormant larvae are stimulated to migrate to the uterus and mammary glands and thus apparently healthy mothers can produce heavily parasitized young.
Adults become re-infected from exposure to parasite eggs in the soil, from hunting infected wildlife, or from the breakdown of their natural immunity.
Rarely, children consuming soil contaminated with large numbers of Toxocara eggs may develop a syndrome known as “Visceral Larva Migrans”. Unfortunately little information is available to identify the factors that increase the risks of developing the disease. Regular examination and treatment of infected animals and efforts by owners to stoop-n-scoop are recommended to limit this potential source of infection to our children.
Hookworms (Uncinaria, Ancylostoma spp.) can infect our pets at any age but are particularly life-threatening to the very young. Hookworms latch onto the intestinal wall and live on blood, contributing to signs of anemia, weakness, wasting and bloody diarrhea. The nursing young may die due to blood loss and shock with heavy infections.
Natural infections occur through eating contaminated soil, or by infective larvae burrowing into the skin of the paw, or through the milk of an infected mother.
Human infection may occur when the larvae in contaminated soil penetrate the skin. “Cutaneous Larva Migrans” or “Creeping Eruption” is extremely irritating.
Whipworm infection (Trichuriasis) is contracted by direct ingestion of eggs in contaminated food or soil. All ages may be easily affected by the cardinal signs being poor condition or performance.
Whipworm eggs are remarkably durable and although they may take up to eight weeks to reach the infective stage, they can resist freezing and remain alive in the environment for years.
Adult tapeworms (Dipylidium, Taenia, Echinococcus spp.) are found anchored to the wall of the small intestine by hooks or suckers. These parasites use an intermediate host (a “middleman”) for part of its development. The final host (cat) then eats the contaminated prey and the tapeworm then is able to complete its life cycle.
With Dipylidium spp., angora cats become infected when they ingest fleas or biting lice carrying the larval form of the tapeworm. This tapeworm requires only two to three weeks to develop to an adult so unless fleas and lice are quickly brought under control, re-infection occurs rapidly.
Taenia spp. use a variety of small rodents and rabbits as their intermediate hosts. Angora cats become infected when they hunt these vertebrates.
Animals do not develop resistance to tapeworms and are readily reinfected. The worms shed segments intermittently and may be found in the feces, in the fur or even on furniture, carpets, or clothing.
Although rare in North America, Echinococcus tapeworms can infect humans and cause a variety of chronic and debilitating diseases.
“Coccidia” a general term used to describe a number of single-celled Protozoan parasites that colonize the gut wall. Coccidian oocysts (eggs) are not shed constantly and there is a tendency for older asymptomatic pets to shed small numbers, perhaps periodically or under stress so that they serve as chronic carriers.
Affected animals may exhibit profuse bloody diarrhea, straining, loss of condition or they may be apparently healthy. Some recovered animals may suffer repeated relapses which generally respond well to treatment and supportive therapy.