What is Salmon Poisoning in Dogs?

Salmon poisoning is a potentially fatal condition seen in dogs who have eaten raw or undercooked salmon, trout, steelhead or other fish found in the Pacific Northwest This article will explain what causes salmon poisoning, what the symptoms are, and how it is diagnosed and treated

What Causes Salmon Poisoning?

Salmon poisoning is caused by a bacterial infection transmitted by a parasite Here is how it happens

Certain raw fish like salmon, trout, steelhead and others that live in coastal streams and rivers can be infected with a parasite called Nanophyetus salmincola This parasite itself does not make dogs sick However, the parasite can be infected with a bacteria called Neorickettsia helminthoeca.

When an infected raw fish is eaten by a dog, the parasites in the fish carry the bacteria into the dog’s intestines. Here the parasites release the bacteria, which spreads through the bloodstream to the liver, lungs, brain, and lymph nodes. The bacteria multiplies rapidly, causing damage and the symptoms of salmon poisoning.

Where is Salmon Poisoning Most Common?

Salmon poisoning occurs most often in the Pacific Northwest, from Northern California up to Alaska. It is especially prevalent along coastal rivers and streams where the fish host of the parasite is found.

The states with the highest rates of infection are:

• Washington
• Oregon
• Northern California
• Southern British Columbia

However, salmon poisoning has also been reported sporadically in other parts of North America, when conditions allow for the parasites’ lifecycle to be maintained.

What Are the Symptoms of Salmon Poisoning?

Salmon poisoning causes many of the same symptoms as other bacterial and gastrointestinal infections in dogs. Symptoms usually start about 5-7 days after a dog eats infected raw fish. They include:

• High fever – often over 104°F
• Lethargy and depression
• Loss of appetite
• Vomiting
• Bloody or mucoid diarrhea
• Weight loss
• Enlarged lymph nodes
• Discharge from eyes or nose
• Increased heart rate
• Rapid breathing rate
• Muscle tremors or seizures

Without treatment, salmon poisoning is 90-100% fatal within 14 days of eating the infected fish. However, with prompt veterinary treatment, most dogs can make a full recovery.

How is Salmon Poisoning Diagnosed?

Diagnosing salmon poisoning requires testing to confirm the infection. If a dog shows symptoms after eating raw fish, the veterinarian will suspect salmon poisoning. They will ask about the dog’s potential exposure to raw fish.

To help confirm the diagnosis, the vet will check the dog’s stool for eggs of the Nanophyetus parasite. Finding the eggs supports salmon poisoning as the cause of illness.

The vet will also run blood tests to check organ function, electrolyte levels, and look for anemia. Enlarged lymph nodes may be aspirated with a needle to look for bacteria inside the cells. Or a PCR test can detect the bacteria’s DNA.

How is Salmon Poisoning Treated?

The main treatments for salmon poisoning are:

• Antibiotics – to kill the Neorickettsia bacteria. Doxycycline is most often used.

• Anti-parasite medication – to kill the Nanophyetus parasites and prevent reinfection. Praziquantel and fenbendazole are often prescribed.

• IV fluids and hospitalization – for dogs that are dehydrated or vomiting. This provides fluid and electrolyte support.

• Anti-nausea medication – to control vomiting.

• Nutritional support – with a bland, easily digestible diet as the dog recovers.

With aggressive treatment, most dogs show improvement within 3-5 days and can make a full recovery within a few weeks. Dogs that do not receive treatment typically die within 14 days.

Are There Any Long-Term Effects?

Most dogs that survive salmon poisoning and receive proper treatment make a full recovery without any long-term effects. They usually develop an immunity to future infection from the same strain of bacteria.

However, salmon poisoning can sometimes cause permanent damage to the nervous system, kidneys, or liver if the infection was severe. Dogs that develop seizures or kidney failure may need lifelong medication and care.

How Can Salmon Poisoning Be Prevented?

Since eating raw, infected fish is what exposes dogs to salmon poisoning, the best prevention is avoiding feeding raw fish to your dog. Other tips include:

• Cook fish thoroughly to kill any parasites before feeding it.

• Freeze fish for at least 2 weeks before feeding to also kill parasites.

• Prevent access to raw fish, such as when cleaning fish after fishing or disposing of fish parts.

• Always discard fish garbage in secure, covered trash cans.

• Keep dogs leashed around rivers, lakes or beaches to avoid scavenging.

• Use monthly heartworm prevention medication that also treats for common intestinal parasites.

Dogs can get salmon poisoning by eating raw or undercooked salmon, trout, steelhead, or Pacific giant salamanders that are infected with a parasitic fluke called Nanophyetus salmincola. This fluke carries a rickettsial bacteria, Neorickettsia helminthoeca, which causes the disease.