Salmon Disease.

After the recent heavy rains and resulting floods in western Washington, the Washington State Veterinary Medical Association sent a FAX to us members warning of increased risk of "Salmon Poisoning" in dogs.

The disease can be very serious, or even fatal. It is not common in our local area but many people from this area go on fishing trips to other parts of the Northwest and sometimes friends and relatives from other areas send or bring the fish here. A dog can become infected by eating raw or undercooked salmon or steelhead, even if it has been smoked or frozen.

It is a nasty disease but it is wonderfully complicated. The thing that makes dogs sick is a sort of bacteria, called a "rickettsia." The microscopic Rickettsia live in a fluke, which is an intestinal parasite.

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 get along amicably with the dog, or whomever they live with, 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, where they swim around until they meet the right snail.

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 the rickettsia that makes dogs sick. A goodly percentage - maybe millions - of those larvae hook up with a snail and live there for a while.

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. Most of them 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. In about a week the fluke larvae grow up into flukes, which live in the animal's intestinal tract. The flukes produce more eggs and the whole circle of fluke life starts all over again.

If your dog, or a coyote or wolf, eats the fish, they get flukes too, but other bad things happen. The flukes attach to the lining of the gut and that old rickettsia (bacteria) that's been living in the fluke eggs and larvae through all this will infect the dog and make him sick.

In about a week, maybe two or three weeks, the dog gets a fever, stops eating, may have runny nose and eyes, vomiting and severe, eventually bloody, diarrhea. Most dogs die if not treated.

These symptoms are very similar to parvovirus. Many dogs with parvovirus will recover with good supportive care, and so will most dogs with salmon disease, but with salmon disease it is very important to use the right antibiotics, given by injection. It's a lot better to prevent the disease. Don't let your dog eat raw salmon, steelhead, or any kind of fish, to be safe. The disease is most common near the northwest coast, but there are probably many scattered small areas along any tributary to coastal rivers where infected flukes may be found. Very few dogs die of "salmon deficiency" so, the way I see it, why take a chance?