Salmon Poisoning Disease and Elokomin Fluke Fever in Dogs

Salmon poisoning disease is a short-term infectious disease of dogs and related animals, like foxes, coyotes, and wolves. Bacteria are spread through a fluke (a type of parasite), and despite the name, no poison is involved. A related condition, Elokomin fluke fever, is similar but affects a wider range of animals, including dogs, ferrets, bears, and raccoons. Both diseases occur only in the Pacific Northwest of the United States, from northern California to Alaska, especially between northern California and Puget Sound. Fish and snails in these areas are needed for the life cycle of the parasite involved.

Salmon poisoning disease is caused by Neorickettsia helminthoeca bacteria. It is sometimes complicated by Neorickettsia elokominica, which causes Elokomin fluke fever. Dogs become infected by eating raw or undercooked trout, salmon, or Pacific giant salamanders that carry infected the infected fluke. The fluke itself causes little harm. Instead, the bacteria produce the disease. Dog-to-dog spread is rare.

In salmon poisoning disease, signs usually appear suddenly about 5–7 days after dogs eat infected fish, although this can take up to 33 days. Without treatment, up to 90% of affected dogs die within 7–10 days. Early signs include high fever followed by weakness and complete loss of appetite. Persistent vomiting often begins by day 4 or 5, followed by diarrhea, which can be bloody. Severe dehydration, weight loss, and enlarged lymph nodes can occur, along with secretions from the nose and eyes. Fever can later drop to abnormally low body temperature before death.

Elokomin fluke fever is generally milder. Severe digestive signs are less common, but lymph node enlargement is more frequent. Fewer dogs die (around 10% in untreated cases).

Diagnosis is usually made by finding fluke eggs in the dog's feces. If eggs are not found, the vet might examine lymph node samples under the microscope for the presence of the bacteria.

Prevention is based on avoiding feeding dogs raw or undercooked salmon, trout, or similar fish. Dogs that recover develop strong immunity to reinfection with the same bacteria, but they can still be infected by the other related bacteria.

Treatment involves early use of IV (intravenous) antibiotics and supportive care. Prompt treatment greatly improves survival. Without early medical care, death is often caused by dehydration and anemia (low red blood cell count). Supportive care includes injections of fluids, nutritional support, control of diarrhea, and sometimes blood transfusions.