My wife and I have lived in the Pacific Northwest for most of our married life. We love everything about living in Oregon; the climate, lifestyle, environment, and standard of living are beyond compare. While living and practicing here in Oregon I quickly became familiar with a disease unique to the water shed draining into the Pacific Ocean commonly known as Salmon Poisoning. The motivation for writing this article stems from a patient I recently treated for the disease.
My patient had been treated for lethargy, anorexia and fever by a clinic in a neighboring town. They had performed blood work, which had only revealed a low platelet count but no other abnormalities. She had gotten progressively worse and had started vomiting despite therapy with antibiotics and antiemetics. Since the original clinic doesn’t offer after hours services the owners paged me to reevaluate their dog.
I was concerned that the antibiotics were not effective because her condition was worsening, so I prescribed a tetracycline antibiotic called doxycycline and initiated IV fluid therapy. Fortunately she responded to my treatment and became progressively better. By Monday she had improved to the point that I was able to send her home although she had now developed diarrhea. At the time I released her, the owner mentioned that her husband had recently started fishing and had cleaned some Steelhead trout in their garage. They are from another western state in which salmon poisoning is not present and therefore had no idea the fish could make their dog ill.
Salmon poisoning is a bacterial infection contracted from eating raw trout or salmon. Cases of Salmon Poisoning have been diagnosed from Southern California up the Pacific coast to Alaska. The scientific name of the bacteria is Neorickettsia helminthoeca1. N. helminthoeca is closely related to the bacteria that causes Rocky Mountain Spotted Fever and Lyme’s Disease.
Any canid, including dogs, foxes, wolves and coyotes can contract Salmon Poisoning. Cats, humans, bears, mink and other animals are immune to infection. It only requires a minute amount of tissue or fluids to make your dog ill. Even if you are in an area where fish have been cleaned and your dog licks a rock contaminated with scales, blood or fluid it can cause your dog to become sick.
Diagnosis is based on compatible clinical signs coupled with observation of the eggs of a parasite called Nanophyetus salmincola in the dog’s feces. N. salmincola carries the bacteria in its body so that when dogs eat tissues or fluids that contain the parasite the bacteria begins to spread and cause the symptoms I have just described. In short, even though the parasite doesn’t cause salmon poisoning directly, it carries the bacterium that does and the presence of the eggs in your dog’s feces will consequently confirm the diagnosis for your veterinarian.
Treatment depends on the severity of illness. The longer your dog is sick the harder it will be to treat. If only mild clinical signs are present your dog may only need oral tetracycline antibiotics. Even though N. salmincola does directly cause the disease I prefer to also eliminate the parasite by administering a wormer. If patients are severely ill, hospitalization and IV fluids with IV antibiotics may be required. Salmon Poisoning can result in death if left untreated. Death usually occurs due to dehydration and kidney failure that can result from the high fever, vomiting and diarrhea.
There is no reason that you should suffer the loss of your pet from this potentially deadly disease. Prevention is most effectively undertaken by avoiding exposure to raw fish and to preclude access to any area where raw fish have been present. If your pet is exposed pursue veterinary care as soon as possible. The sooner you seek help the better chance your dog has of surviving.
1. Veterinary Parasitology Reference Manual by William J. Foreyt; Second Edition page 26