Salmon Poisoning Can Be Fatal to Dogs
What could be more fun than a day at the beach? While that may be true for most of our canine companions, dog owners all along the Pacific coast need to be aware of the infection referred to as salmon poisoning.
When this infection occurs, an important component to prompt diagnosis (and thus successful treatment) is identification of potential exposure.
And while treatment is successful in the majority of cases, without appropriate medication the disease is highly fatal.
Bacteria Causes Salmon Poisoning
Salmon poisoning is caused by a specialized type of bacteria, Neorickettsia helminthoeca, categorized as rickettsia. Exposure comes through a complex series of events.
Rickettsia-class bacteria are specialized in that they are not found out in the environment at large, but are always carried within some other organism (just as Lyme’s disease is carried by ticks). This particular bacterium is found within a fluke called Nanophyteus salmincola, which is a type of intestinal worm.
Fish and amphibians can be infected with this fluke. Dogs become infected with the fluke by ingesting some part of the fish (or less commonly, amphibian). As the fluke infection develops, bacteria are released into the body.
So in essence, salmon poisoning is a bacterial infection caught by a parasite (fluke) infection caught by exposure to fish.
Salmon Isn’t Only Cause
Salmon are the most common source of fluke infection, but trout as well as other amphibians can also carry it. These aquatic creatures are the typical sources of exposure for dogs: either at the ocean, or at estuaries and inland rivers where fish migrate.
A typical history involves a dog who found a fish carcass on the beach and was either carrying it around or rolling in it. Sometimes the history is just of being at the beach and subsequent development of illness, or of someone bringing raw salmon home and the pet getting into it.
There are even rare reports of dogs developing this illness from exposure to fishing equipment alone (boots, etc.). Cooking destroys the infectious potential, but raw or undercooked fish can harbor the fluke — in any tissues and even in the slime on fish skin.
Symptoms of Salmon Poisoning
Symptoms do not begin immediately after exposure. On average it takes 5-7 days to see initial signs, though this can also vary.
Many cases start with intestinal disturbance: diarrhea and sometimes vomiting. For some cases, intestinal signs are minimal. The infection progresses to fever (with pets showing lethargy and anorexia), then lymph nodes become enlarged.
Beyond this, patients will develop inflammation throughout their body (called vasculitis), which will lead to organ damage with its associated symptoms of organ failure. Eventually death can occur.
Diagnosis is typically made by identifying fluke eggs in the stool. Occasionally, advanced cases are identified by biopsies from their swollen lymph nodes.
Treatment is Usually Effective
The infection is treated with an antibiotic (typically doxycycline or tetracycline) and a dewormer to get rid of the fluke carrying the bacteria. More advanced cases need additional stabilizing treatments such as anti-nausea medication or fluid therapy.
Except for very advanced cases, the infection tends to be very responsive to treatment.
Fortunately, salmon poisoning is a rare occurrence. However, in the event that your dog becomes ill, it is important that exposure history be openly discussed with your veterinarian and a fecal sample evaluated promptly if salmon poisoning is a potential.
Awareness of this rare hazard is important for the health of any dog who enjoys frolicking along the beautiful shorelines of the Pacific Northwest.
Written by a Seattle Veterinary Associates Doctor
Seattle Veterinary Associates was founded in 1971 by Dr. Sanford Olson, Dr. Donald Canfield, and Dr. Stephen Jones. In 1971, the original practice opened its doors at the current location of Queen Anne Animal Clinic. Coupled with our considerate expansion and the advancement of our medical capabilities at all our hospitals, we are proud to be providing the highest quality veterinary care to pets and their families. SVA is comprised of four locations: Queen Anne Animal Clinic, Green Lake Animal Hospital, Ravenna Animal Hospital, and Northwest Veterinary Hospital.