If you live in the Pacific Northwest, you might be aware Salmon Disease or Salmon Poisoning. If you’re not aware of it, you might want to read on.

In the Northwest, salmon and other fish that swim upstream to breed can be infected with a fluke or intestinal parasite. When ingested, the adult flukes live in the intestinal tract of dogs, as well as other fish-eating animals, such as bears, raccoons and certain birds. The flukes themselves normally don’t cause any issues with the dog and generally don’t make their hosts ill. The fluke eggs that they produce come out with the dog poop. These invisible little fluke eggs hatch into invisible little fluke larvae and some of the larvae find their way into streams and rivers.

There is a particular species of snail (called Oxytrema silicula) that lives in the rivers and streams along the Pacific Northwest coast. Every year, billions and billions of fluke larvae hatch out; many of them – perhaps a billion – become infected with Neorickettsia helminthoeca, a rickettsia that makes dogs sick.

When the fluke larvae grow up a little into another stage they leave the snail and swim around until they stumble onto a salmon, steelhead, or maybe some other fish. They burrow into the fish and find their way to the kidneys but they can live in other parts of the fish.

Bears, raccoons or birds don’t get sick even if they eat the fish, and the fluke larvae it carries. But if your dog, or a coyote or wolf, eats the fish, the flukes attach to the lining of the gut and the rickettsia that’s been living in the fluke eggs and larvae will infect the dog and make him sick.

Common symptoms of salmon poisoning include:

  • vomiting
  • lack of appetite
  • fever
  • bloody diarrhea
  • weakness
  • swollen lymph nodes
  • dehydration

These symptoms are very similar to parvovirus and ninety percent of dogs die if not treated.

“Salmon poisoning occurs most commonly west of the Cascade mountain range,” says Dr. Bill Foreyt, a veterinary parasitologist at Washington State University’s College of Veterinary Medicine. He adds, “Canids (dogs) are the only species susceptible to salmon poisoning. That’s why cats, raccoons and
bears eat raw fish regularly with out consequence.” Generally clinical signs appear within six days of a dog eating an infected fish….

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. …“

Freezing any salmon before feeding it to your dog will kill any dangerous organisms. If you live in the Pacific Northwest however, you will want to be aware of this potential danger if you walk your dog where he is able to scavenge dead salmon. If you take your dog fishing, by all means, give him the heads and trimmings of your catch – but make sure you freeze it for a week or so first.