The Salmon Poisoning Disease (SPD) has previously been reported in North America only along the western coast of the U.S.A. Dogs and other animals become infected by ingesting trout, salmon, or Pacific giant salamanders. Infected fish are found in the Pacific Ocean from San Francisco to the coast of Alaska, but SPD is more prevalent from northern California to Puget Sound. It is also seen inland along the rivers of fish migration. The causative agent is Neorickettsia helminthoeca. This organism is transmitted to dogs in cysts of the fluke Nanophyetus salmincola salmincola within the tissues of the salmon or trout. Overall, the parasite is relatively harmless. The danger occurs when the parasite itself is infected with a rickettsial organism Neorickettsia helminthoeca, the causative agent of salmon poisoning disease. Owners can prevent salmon poisoning disease by not allowing their dogs to eat raw salmon or trout and similar freshwater fish or snails
Common signs of salmon poisoning include vomiting, lack of appetite, fever, diarrhea, weakness, swollen lymph nodes, and dehydration. Signs appear suddenly, usually 5-7 days after eating infected fish, but may be delayed as long as 33 days, and persist for 7-10 days before culminating in death in up to 90% of untreated animals. Body temperature peaks at 104-107.6°F (40-42°C) 1-2 days later, then gradually declines for 4-8 days and returns to normal. Persistent vomiting usually occurs by day 4 or 5. Diarrhea develops by day 5-7; it often contains blood and may be severe. Dehydration and extreme weight loss occur.
Appropriate treatment, including various sulfonamide drugs are effective, as are chlortetracycline, oxytetracycline, and chloramphenicol. Animals usually succumb because of dehydration, electrolyte and acid-base imbalances, and anemia. Therefore, general supportive therapy to maintain hydration and acid-base balance, while meeting nutritional requirements and controlling diarrhea, is essential.