If your dog loves water, you should be aware of salmon poisoning, which is a bacterial infection that can affect dogs in the Pacific Northwest. Our Roosevelt Animal Hospital team prioritizes empowerment, and we believe the best way to empower you is to educate you about issues that can affect your four-legged friend. Here, we provide important information about salmon poisoning and explain how you can protect your furry pal. 

What is salmon poisoning in dogs?

Salmon poisoning is a bacterial infection that affects dogs who eat raw or undercooked anadromous fish (e.g., salmon, trout, lamprey, redside shiner, shad, sturgeon, candlefish, large-scale sucker, and steelhead) or Pacific giant salamanders that contain the Nanophyetus salmincola fluke. The disease, which is most common in Washington, Oregon, northern California, and southern Vancouver Island, can also affect dogs inland, along rivers where infected fish migrate. Dogs also can be infected if they swim in lakes or rivers contaminated by cercaria (i.e., the fluke’s free-swimming larval stage).

N. salmincola is typically harmless, except when infected by a rickettsial bacteria called Neorickettsia helminthoeca that is carried in all life stages of the fluke. When a dog ingests an infected fish or salamander, the flukes mature and attach to the intestinal mucosa, and the rickettsia can enter the intestinal cells. The rickettsia are then spread through the dog’s lymphatic system to the liver, lungs, brain and lymphoid tissues, causing necrosis, hemorrhage, and hyperplasia. N. helminthoeca can also replicate in immune cells called macrophages and cause an inflammatory response in the stomach, lymph nodes, intestines, and spleen.

What are salmon poisoning signs in dogs?

Signs typically occur about five to seven days after a dog eats a parasitized fish or salamander and include:

  • Inappetence
  • Vomiting
  • Diarrhea, which may be bloody
  • Fever
  • Weakness
  • Swollen lymph nodes
  • Weight loss
  • Ocular and nasal discharge
  • Increased respiration and heart rate
  • Muscle tremors and seizures

If not treated properly, most infected dogs die in two weeks.

How is salmon poisoning diagnosed in dogs?

Salmon poisoning signs are not specific to the disease, and the problem typically is identified using diagnostics that include:

  • History — We will ask for a detailed history to determine if your dog may have had access to parasitized fish or salamanders in the last two weeks. Tell us that your dog ate a fish or salamander or if they could possibly have been exposed. 
  • Physical examination — Our team will assess your dog from nose to tail looking for abnormalities such as fever, enlarged lymph nodes, and increased respiration and heart rate.
  • Blood work — Blood work is helpful to evaluate your dog’s overall health status, hydration, blood cell counts, and organ function.
  • Fecal examination — Fluke eggs can often be found in the dog’s fecal sample, supporting the diagnosis.
  • Polymerase chain reaction (PCR) — A PCR test can detect the bacteria’s DNA in an aspirate from your dog’s lymph node and confirm the diagnosis.

How is salmon poisoning treated in dogs?

Treatment should begin as soon as possible since the disease is life-threatening. Potential treatments include:

  • Fluid therapy — Intravenous fluid therapy to replace fluid deficits and electrolyte imbalances caused by vomiting and diarrhea is extremely important.
  • Antibiotics — Antibiotics to combat the bacterial infection are necessary.
  • Antiemetics and antidiarrheals — We may prescribe medications to help control your dog’s vomiting and diarrhea.
  • Blood transfusions — In severe cases where your dog is hemorrhaging excessively, they may need a blood transfusion.
  • Anticestodals — We may prescribe medications to kill the parasitized flukes.

What is the prognosis for salmon poisoning in dogs?

Prognosis is directly related to early diagnosis and the instigation of appropriate supportive care and antibiotics. Most untreated dogs die about 6 to 10 days after clinical signs manifest, but dogs treated appropriately usually recover in about 24 to 72 hours. Dogs who survive salmon poisoning are immune to reinfection with that strain, but can be infected with an alternate strain because no cross-protection occurs.

How is salmon poisoning prevented in dogs?

Tips to protect your four-legged friend from salmon poisoning include:

  • Ensuring your dog doesn’t eat fish or salamanders when near natural water sources
  • Leashing your dog at the beach or the river so you can monitor what they eat
  • Wrapping fish entrails securely when fishing, and disposing of them in closed containers
  • Never feeding your dog raw or undercooked fish

Salmon poisoning is a concerning issue, but you can easily protect your dog from disease by ensuring they do not eat raw fish or salamanders. But, if you suspect your dog has salmon poisoning, contact our Roosevelt Animal Hospital team, so we can start supportive care and appropriate antibiotics as soon as possible.