What is Salmon Poisoning?
Salmon poisoning, also known as Salmon Poisoning Disease, is seen in dogs of all ages and primarily occurs in the northern Pacific portion of the U.S. and the Pacific costal areas of Canada. Salmon Poisoning is present on the Central Oregon Coast and we encounter this disease quite often in our veterinary practice at Grove Veterinary Clinic.
Salmon poisoning is an acute infectious disease of wild and domestic dogs caused by ingestion Neorickettsia helminthoeca, an infectious organism found in the tissues of raw freshwater fish, primarily salmon and trout. The infective agent is actually transmitted through the various stages of a fluke in a snail to fish to dog life cycle.
The name of the disease is misleading because there is no toxin involved. The disease is caused by the Rickettsial organism Neorickettsia helminthoeca, and is most often associated with eating raw fish containing N. salminocola, the trematode fluke (worm) that carries the infectious bacteria.
Exposure to a fresh brackish stream or beach and eating raw fish in an endemic area are risk factors. The fluke parasite is carried in the kidneys of infected salmon or trout. The fluke is passed to the dog after ingestion of the infected fish.
The fluke grows and matures in the dogs gastrointestinal tract at which time the fluke releases the rickettsial organism Neorickettsai helminthoeca. This organism is then taken up into the dog’s blood stream, blood cells and lymph nodes. This invasion of the dog’s body results in the clinic signs associated with this infectious disease.
Dogs do not have to be at the side of the river to be infected. In Lincoln County, many dogs have been exposed to the infectious organism by getting into garbage that contains salmon or trout trimmings. We also seen many cases of Salmon Poisoning, where the dog was exposed to raw trout from one of the many reservoirs that we have in Lincoln County.
What are the Common Clinical Signs of Salmon Poisoning?
- Fever and lethargy are the hallmark signs of Salmon Poisoning
- Lack of appetite (anorexia)
- Diarrhea (with or without blood)
- Enlarged lymph nodes
- Nasal and eye discharge may be seen in some dogs
How is the Diagnosis Made?
Fecal Examination in Dogs may reveal characteristic eggs of the carrier N. salminocola. This has been an extremely reliable diagnostic test in the diagnosis of Salmon Poisoning.
Baseline tests to include a complete blood count (CBC), biochemical profile, and urinalysis may be recommended in all patients, and are often within normal limits.
Lymph node aspirates are rarely needed, but may be utilized to diagnose this disease.
How is Salmon Poisoning Treated?
- Most of these patients are acutely (abruptly) ill and need hospitalization. Treatment to treat infection, control vomiting and maintain hydration is essential.
- Fluid and electrolyte therapy is recommended.
- Drugs to control vomiting are often needed.
- Monitoring for extreme elevations in body temperature and treating these fevers appropriately.
- Appropriate antibiotic administration may include Doxycycline or Tetracycline.
- Anthelmintics (dewormers) are effective against the fluke (carrier). Praziquantel is a drug commonly used.
What is the Prognosis?
The prognosis is good in pets that are aggressively treated with fluids, antibiotics and medications to control vomiting. Untreated dogs can die within 4 to 10 days, so prompt treatment is highly recommended.
Home Care and Prevention
- Administer all medication and diet as directed by your veterinarian. Overall prognosis is good if caught and treated early.
- Prevent animals from eating raw fish.