Ask the Edmonds Vet: About dogs and raw fish

By Dr. David Gross

Is it true that my dog can be poisoned by eating raw salmon?

One of my professors once told me, “…any day you don’t learn something new is a day wasted.” Today was not wasted. Until today, I didn’t know about salmon poisoning disease.

Dogs and other canids — such as wolves, fox and coyotes — that eat RAW anadromous fish (fish that are born in fresh water and spend most of their life in the ocean, then return to fresh water swimming upstream to breed) are susceptible. Examples of anadromous fish are salmon, some species of trout, smelt, shad, striped bass and sturgeon. The Pacific giant salamander has also been incriminated, but your dog must be very special to catch and eat one of these.

This is another disease, like Lyme disease, caused by a parasite vector — in this case a fluke named Nanophyetus salminicola. These flukes can be infected with a nasty bacteria known as Neorickettsia helminthoeca. If your dog eats raw fish infested with these flukes, they attach to the dog’s intestine and release the bacteria. If the flukes do not harbor the bacteria, the dog usually shows no sign of a problem.

Cats, raccoons, bears and maybe even sushi-loving humans can eat raw fish containing the parasite with the bacteria but don’t get sick. However, the same fluke can also harbor Neorickettsia elokominica. This bacteria causes a similar disease known as Elokomin fluke fever in canids, bears, raccoons and ferrets.

Dr. Bill Foreyt, a veterinary parasitologist at Washington State University’s College of Veterinary Medicine, says that in the state of Washington, salmon poisoning occurs more commonly west of the Cascades. Signs of salmon poisoning are vomiting, lack of appetite, high fever, diarrhea, weakness, swollen lymph nodes and dehydration. Some or all of these signs appear within six days after your dog eats infected raw fish.

The bad news is that 90 percent of dogs with salmon poisoning die within a week or two if they are not treated. The good news is that treatment is usually straightforward and successful, if diagnosed early. The key is telling your veterinarian that your dog ate raw fish.

Veterinarians make a positive diagnosis by finding the eggs from the parasite in your dog’s feces and/or finding the rickettsial organism in a needle sample from a swollen lymph node. The treatment involves killing the parasite in your dog’s gut and treating the bacterial infection with an appropriate antibiotic. If the dog is seriously dehydrated, fluid therapy may be indicated.

So, Fido gets no sushi! You, my friend, are on your own.

Dr. David Gross graduated from Colorado State University’s veterinary school in 1960 and was in private practice for ten years. He enrolled in graduate school at Ohio State University earning a M.Sc. degree in 1972 and a Ph.D. degree in 1974. He retired in 2006 as Professor and Head of Veterinary Biosciences, at the University of Illinois, Urbana-Champaign. Dr. Gross is a Fellow of the Cardiovascular Section of the American Physiological Society. During his academic career, he published over 90 papers in refereed scientific journals and over 100 abstracts in proceedings of scientific meetings.

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