Salmon Poisoning: A Threat to the Outdoor Dog Donna S. Dimski, DVM, MS Diplomate, American College of Veterinary Internal Medicine Mid-Willamette Fly Fishers, Corvallis, Oregon “Salmon poisoning” is a disease occurring in dogs exposed to salmon, trout, or other salmonid fish in the Pacific Northwest. Not really a poison at all, the disease is caused by an organism called a rickettsia, transmitted to dogs by an internal parasite carried in salmonid fish. The eggs of the parasite are passed to dogs when the dog eats raw fish, fish entrails, or fish blood. Therefore, dogs are at risk where fish are being cleaned or prepared for cooking, and when roaming streamside (particularly during salmon spawning season). Cooking and freezing destroy the organism, eliminating the risk of disease transmission. This disease should not be confused with Salmonella, a bacteria that can infect animals and people that is not related to fish. Salmon poisoning is a disease specific to dogs. People and other non-canine animals are not affected. Salmon poisoning occurs primarily in the western portions of Washington, Oregon, and Northern California, in coastal streams and lakes west of the Cascade Mountains. This distribution occurs because the parasite responsible for transmitting the disease-causing organism must spend part of its life cycle in a particular species of snail that occurs only in this region; thus, no snail, no disease. It is important for anglers and hunters traveling to this area to keep salmon poisoning in mind if they bring their dogs along on the trip. The first signs of salmon poisoning occur in dogs five to 14 days after exposure to infected fish. Early signs include decreased appetite, lethargy, and fever, progressing on to vomiting, bloody diarrhea, swollen lymph nodes, and dehydration. If the disease is not properly diagnosed and treated, it can be fatal within two weeks. Any dog owner who observes these signs following a possible exposure should seek veterinary care immediately, and should inform the veterinarian about the potential for exposure. The specific diagnosis is made by noting the history of possible exposure, observing clinical signs, and identifying the parasite eggs in a stool sample. In the early stages of the disease, oral tetracycline antibiotics (effective against salmon poisoning) may be all that is needed to cure an infection. The wrong antibiotic choice may delay recovery. As the disease progresses, a sick dog may require hospitalization for intravenous fluids and injections of appropriate antibiotics. Even with the best of care, extremely ill dogs with advanced disease may die, so rapid intervention is needed. There is no vaccination for salmon poisoning, and prevention requires minimizing exposure to infected fish. Dogs should not be allowed access to meat, entrails, or fluids associated with fish cleaning. The fish cleaning area should be thoroughly washed and disinfected after every use. During salmon spawning times, the risk of exposure is so great that taking along a canine companion to the stream is not advised. Once a dog recovers from the disease, it usually (not always) develops lifelong immunity to repeated episodes. Hunters and anglers that may be away from “civilization” for extended periods with their dog may wish to discuss with their veterinarian the option of bringing along appropriate antibiotics in the event exposure occurs.