Salmon Poisoning in Dogs
Salmon Poisoning is often a fatal disease in dogs. It is caused by a rickettsial infection, Neorickettsia helminthoeca. Salmon poisoning has not been reported in cats but can affect dogs, bears, and coyotes. It is most commonly seen in the Northwest US from Northern California to Washington. Continue reading to learn about this complex infection, symptoms, testing, and treatment.
What is salmon poisoning and how would my dog contract it?
The infectious rickettsial agent and its friend the fluke (trematode), must pass through a snail and fish before dogs can become infected.
There is a trematode, or fluke, called Nanophyetus salmincola that has a symbiotic relationship with the rickettsial organism. N. helminthoeca (the rickettsial agent) is present throughout the trematode’s development and does not harm the trematode. The eggs of N. salmincola are passed in infected dog and coyote feces. The eggs then hatch and infect a water snail. The trematode continues to mature in the snail and is released as a larval form. The larvae swim around the water and infect fish and salamanders. The trematode continues to mature in the next host.
When the dog, bear, or coyote ingests the fish or salamander that is infected, the parasite continues to develop and moves into the intestinal tract of the mammal. Once in the intestines, the trematode parasite attaches to the wall of the intestines and passes along the rickettsial bacteria.
Within 5 to 7 days post-ingestion, the rickettsial organism causes GI inflammation, allowing the parasite to enter the bloodstream and move through the body, often infecting the lymph nodes, spleen, tonsils, liver, lungs, and brain. This is when clinical symptoms are seen.
Symptoms of Salmon Poisoning in Dogs
Symptoms can range and be variable from dog to dog. Since the infectious agent targets multiple organs, symptoms can differ in each pet.
- Vomiting with or without blood
- Diarrhea with or without blood
- Weight loss
- Rapid or abnormal breathing
- Rapid heartbeat
- Abdominal pain
- Fever or low body temperature
- Enlarged lymph nodes
- Neurologic symptoms
- Discharge from the eyes and/or nose
What tests may be recommended to help diagnose salmon poisoning?
Since the symptoms can vary, most vets start with a complete physical exam and blood work to assess the internal organs and red and white blood cell levels. Abnormal electrolyte levels, low calcium, low albumin, and elevated liver and kidney enzymes are commonly found. Many dogs are also anemic and have abnormal white blood cell levels.
A fecal flotation test may detect the trematode parasite eggs. These eggs can often be found 5-8 days after infection. Just because these eggs are present does not guarantee your dog has the rickettsial infection.
Aspiration and cytology of enlarged lymph nodes or spleen may show the rickettsia organism in the cells.
There is also a PCR test available, but it does not detect every infection.
Treatment Options for Dogs with Salmon Poisoning
Antibiotic treatment with doxycycline, tetracycline, or oxytetracycline are all potential options to kill the rickettsial organism. Treatment is often continued for 5 to 14 days.
Deworming with praziquantel for 3 to 5 days in a row is needed to treat the trematode infection.
Supportive care, such as IV fluids, anti-nausea medications, and antidiarrheal medication may also be needed to help your pup feel better. Most dogs need to be hospitalized on IV medications and fluids for a few days before they feel well enough to go home on oral medications.
Dogs typically start feeling better within 1-3 days of starting treatment.
If treatment is not begun within 7-10 days of developing symptoms, it can be fatal.
To avoid salmon poisoning, do not allow your dog to eat raw or undercooked fish.
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