Salmon poisoning disease in Dogs(SPD) is not caused by any poison, but by a bacterium that gets transmitted to the dogs when they eat infected fish such as salmon. This disease mainly affects the animals of the canine family which include wolves and foxes too. A fluke or flat worm carries the bacterium named Neorickettsia helminthoeca responsible for the disease as it passes through different stages of its life as a parasite in salmon and other freshwater fish.
Flukes spend part of their life cycle inside freshwater fish such as salmon and trout or in amphibians like the Pacific giant salamanders, forming cysts containing their larvae. Neorickettsia helminthoeca may be present in these larvae. When the dogs eat the raw fish, the cysts reach their stomachs and release the rickettsia infected larvae, causing severe gastrointestinal infection.
Within a week of ingesting infected flesh, symptoms of SPD begin to appear, even though it may take up to a month in some cases. High fever for one or two days is followed by lethargy and total lack of appetite. By the fourth or fifth day, severe vomiting, and diarrhea with bloody stools appear. The dog becomes rapidly dehydrated. Considerable weight loss, enlargement of lymph nodes and discharges from the eyes and nose are other symptoms. Within a week or 10 days of the symptoms appearing, the dog may succumb to the disease. Subnormal body temperature preceding death is often noticed. 90% of infected dogs die of the disease unless immediate treatment is given.
Elokomin fluke fever in dogs (EFF) is another rickettsial infection similar to salmon poisoning disease, but it is milder in comparison. The gastrointestinal disturbances characteristic of SPD are not usually encountered in Elokomin fever. Lymph node inflammation is more common, but the flukes do not cause much tissue destruction in the intestinal wall. Consequently, the fatality rate is much less too, with only 10% of infections that go untreated resulting in death. Neorickettsia elokominica is the causative agent of this fever that affects not only dogs but several other species of animals such as bears, ferrets and raccoons.
Both the diseases are limited to the coastal areas of the US Pacific Northwest stretching from the San Francisco to Alaska. When these infections are suspected, examination of fecal matter usually shows the eggs of the fluke. They are yellow-brown, and oval in shape, with a rough outer surface. If the eggs are not detected in the feces, the veterinarian may order an examination of lymph which may reveal the bacterial infection. Early identification of the disease is important, especially in the case of SPD as delayed treatment is often not effective.
Both the diseases have to be treated with a number of drugs, but initiating the treatment early enough is important to ensure good outcome. Severe dehydration due to diarrhea, accompanied by electrolyte imbalance, is the main cause of death. Anemia due to intestinal bleeding and disturbances in acid-base balance too contribute to it. Hence, fluid and electrolyte administration as well as food supplementation is an important part of the treatment. Medications to control diarrhea are required too. The dog may need blood transfusion in some cases.
There are no vaccines against these diseases. The only preventive measure is avoiding uncooked freshwater fish such as salmon, steelhead and trout. Dog to dog transmission of the infection rarely occurs. Dogs which overcome the infection acquire strong immunity against the disease which will protect them from future incidents for a very long time. But immunity against SPD does not offer any protection against Elokomin fever, or the other way around, as the two diseases, though similar in many respects, are caused by two different species of rickettsiae.