Parasites That Infect and Infest Domestic Animals

Learning Objectives

After studying this chapter, the reader should be able to do the following:

• Understand that many types of living “creatures” are capable of parasitizing domesticated, wild, exotic, and laboratory animals.

• Understand that the Linnaean classification scheme is an important tool for studying veterinary parasitology.

Key Terms

Parasitism

Monogenetic flukes

Digenetic flukes

True tapeworms

Alimentary canal

Tegument

Pseudotapeworms

Roundworms

Acanthocephalans

Leeches

Causal agents

Intermediate hosts

Vectors

Toxins

Venomous substances

Chapter 1 describes parasitism as an association between two organisms of different species in which one member (the parasite) lives on or within the other member (the host) and may cause harm. The parasite is metabolically dependent on the host.

In parasitology, the study of parasitic relationships, parasitic groups are classified according to the Linnaean classification system. This chapter presents the parasites that infect and infest domesticated animals, indicating their important characteristics and their place in the Linnaean system.

Monogenetic Trematodes (Monogenetic Flukes)

Kingdom: Animalia (animals)

Phylum: Platyhelminthes (flatworms)

Class: Trematoda (flukes)

Subclass: Monogenea (monogenetic flukes)

Monogenetic flukes are ectoparasites of fish, amphibians, and reptiles. They are rarely parasites of mammals. These flukes are seen most often as ectoparasites of the gills, skin, fins, and mouth of fishes and are rarely observed in a veterinary clinical situation. They might be seen by a veterinarian who specializes in diseases of aquarium fish. Also, some veterinarians may specialize in fish farming or some aspect of aquaculture. Under these conditions, monogenetic flukes may be frequently observed.

TECHNICIAN’S NOTE

Monogenetic flukes are ectoparasites that parasitize fish, amphibias, and reptiles. They are rarely seen in a veterinary clinic setting.

Digenetic Trematodes (Digenetic Flukes)

Kingdom: Animalia (animals)

Phylum: Platyhelminthes (flatworms)

Class: Trematoda (flukes)

Subclass: Digenea (digenetic flukes)

Digenetic flukes are important parasites of both large and small animals. These flattened, leaf-shaped flukes are primarily endoparasites of the gastrointestinal tract; however, digenetic flukes can also infect the lungs and blood vasculature. Regardless of the site of infection, the operculated eggs of these flukes can be identified in the feces of domestic animals.

TECHNICIAN’S NOTE