Another summer is starting to wind down, and here comes autumn in all its golden larch glory. These are great months for longer hikes – water is more plentiful, the temperatures are a little cooler and the trails are a bit more open. With summer hiking well behind us, you’ve probably already composed your dog hiking pack. You’ve packed extra potable water, extra dog food for the strenuous hikes and ensured you have bandaging material in case of paw pad tears. You may even have tied a bear-bell to your dog’s collar (a great way to ensure they don’t sneak up on and surprise a foraging bear).
You likely know all about our giardia contaminated water. But as you relax by the river and enjoy watching our migrating salmon leap, you may not be aware of the danger these beautiful fish can harbor.
Dogs that eat raw or undercooked salmon can become infected with a parasitic worm called Nanophyetus salamicola. This worm can also infect non-salmonid fish and even salamanders! The end result is a condition called salmon poisoning. This disease is rare, but when seen is specific to the Pacific NW, and the Cascade Mountains. This is because in order for the worm to continue to mature and infect the fish, it must be first infect a very specific snail: Oxytrema silicua, which is native to our region.
When dogs eat the fish, they ingest the worm as well, which carries bacteria called Neorickettsia helminthoeca. As the worm matures inside the dog, it attaches itself to the inside of the intestines, irritating and inflaming the sensitive intestinal tissue. This allows the bacteria to migrate to the bloodstream, where it then spreads to the spleen, lymph nodes, liver, lungs and brain.
It takes approximately five to seven days after ingestion for dogs to start showing the initial symptoms, which can include diarrhea, vomiting, reduced appetite, fever and lethargy. Immediate interventional treatment is required. If untreated, the illness can progress and intensify resulting in death.
Salmon poisoning is most frequently seen in our sporting and retriever dogs, likely because of their increased exposure to raw or undercooked fish. The best treatment is prevention! Don’t feed your dog salmon, especially the organs. If fishing, ensure you’re disposing of your offal properly to prevent ingestion.
If you notice your dog showing clinical signs after a recent camping trip, ensure you visit your veterinarian promptly. Most dogs will need to be hospitalized for fluid support, intravenous antibiotics, and medications to control the vomiting and diarrhea. The majority of dogs affected by salmon poisoning recover nicely, but only if treatment begins in a timely manner.
Liz Spencer, BSC, BVMS
Northwest Veterinary Hospital