Fishing can be wonderful recreation, but sharing the catch with your dog can be an act of kindness that kills. Salmon Poisoning Disease is a potentially fatal condition seen in dogs that eat certain types of raw fish. Salmon (salmonid fish) and other anadromous fish (fish that swim upstream to breed) can be infected with a parasite called Nanophyetus salmincola, a fluke that thrives in the waterways of the western Pacific Northwest. Overall, the parasite is relatively harmless. The danger occurs when the parasite itself is infected with a rickettsial organism called Neorickettsia helminthoeca. It’s this microorganism that causes salmon poisoning.

The story of how the bacteria infect a dog goes like this. There’s the fish, and then there’s a snail, and a fluke. The fluke infects the snail, and the fish eats the snail and gets the fluke. Inside the fluke’s some bacteria, and the bacteria is what infects the dog. Only salmon-type fish such as steelhead and trout – anadromous fish that swim upstream to breed – seem to provide a suitable home for the fluke.

If a dog eats a fish that contains the parasite, the fluke will release eggs that enter the animal’s intestinal tract, where they release the neorickettsia. Dogs that are infected will usually begin to show symptoms within one to three weeks, and symptoms typically include vomiting, diarrhea, swollen lymph nodes and fever.

“Salmon poisoning occurs most commonly west of the Cascade mountain range in Oregon, Washington, California, and British Columbia, Canada,” says  Dr. Bill Foreyt, a veterinary parasitologist at Washington State University’s College of Veterinary Medicine. He adds, “Canids (dogs, wolves, foxes, and coyotes) are the only species susceptible to salmon poisoning. That’s why cats, raccoons and bears eat raw fish regularly without consequence.”

Generally clinical signs appear within six days of a dog eating an infected fish.

Common symptoms of salmon poisoning include:

·        vomiting

·        lack of appetite

·        fever

·        diarrhea

·        weakness

·        swollen lymph nodes

·        dehydration

If untreated, death usually occurs within fourteen days of eating the infected fish. Ninety percent of dogs showing symptoms die if they are not treated.

Thankfully, salmon poisoning is treatable if it’s caught in time. A key to its diagnosis is telling your veterinarian that your dog ate raw fish. If you have a dog that wanders, or raids trashcans and you are unsure of what it’s eaten; consider the possibility of salmon poisoning.  Salmon poisoning can be diagnosed with a fecal sample or a needle sample of a swollen lymph node. Detecting the parasite’s eggs as they are shed in the feces confirms its presence. The rickettsial organism can be detected in a needle sample from a swollen lymph node. The combination of symptoms and the presence of parasite eggs or the rickettsial organisms are enough to justify treatment.

Given the severity of the condition, treatment is relatively simple. Your veterinarian will prescribe an antibiotic and a “wormer”. The antibiotic kills the rickettsial organisms that cause the illness, and the wormer kills the parasite. If the dog is dehydrated, intravenous fluids are given. Once treatment has been started, most dogs show dramatic improvement within two days.

Next time you are fishing or purchase raw salmon and you hear the familiar begging whine of your dog, ignore it. They may not understand it, but not sharing the fish is the best thing for them. This will save them from suffering salmon poisoning, and save you from a veterinary bill.