Merck Manual

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Flukes That Infect Dogs

Flukes That Infect Dogs

Class

Species (Common Name)

How Contracted

Signs

Intestinal flukes

Nanophyetus salmincola (Salmon poisoning fluke), found in northwestern US, southwestern Canada, and other countries in the northern Pacific Rim

Dogs eat intermediate host (raw or improperly prepared salmon and similar fish)

Heavy infection causes intestinal inflammation. Infection is compounded by rickettsial infection carried by flukes (salmon poisoning disease).

Alaria species, found in North America, Europe, Australia, and Japan.

Dogs eat intermediate hosts (frogs, snakes, mice)

Heavy infection can cause bleeding in the lungs or inflammation of the intestines (enteritis).

Heterobilharzia americana, found in southeastern US

Dogs are infected by a stage shed into water by snails (the intermediate host)

Heavy infection can cause lethargy, weight loss, vomiting, and diarrhea. “Water dermatitis” may be seen where parasites enter the skin.

Liver flukes

Opisthorchis species, found in eastern Europe, parts of Asia; Clonorchis sinensis is closely related

Dogs eat intermediate hosts including certain snails and fish

Longterm presence causes thickening and fibrosis of bile and pancreatic duct walls. Severe cases have been associated with cancer in the liver or pancreas.

Metorchis species, found in North America, Europe, former Soviet Union

Dogs eat intermediate hosts (certain raw or undercooked fish and snails)

Seldom causes disease.