Dog’s Close Call with Salmon Poisoning Disease Shocks Owners but Raises Awareness
“Case of the Month” – March 2025
Ollie, a 7-year-old chocolate Labrador retriever, lives his best life with owners Sarah Christie and Dan York of Sacramento. He enjoys plenty of outdoor activities, especially on hunting trips with York or to the family’s second home in Del Norte County in northwest California. But a recent health scare with Ollie alerted Christie and York to a disease they never knew existed and will make their awareness of Ollie’s outdoor activities keener.
Recently, Ollie begged to go outside for an urgent and unexpected potty break. Later that day, Christie noticed he was lethargic and trembling. They took Ollie to an emergency veterinary clinic. His tests were inconclusive, but the veterinarians gave him antibiotics and advised to watch for vomiting, as Ollie’s intestines were full but not necessarily blocked.
“The next day, he wasn’t as eager on his walk and definitely appeared under the weather,” said Christie. “But it didn’t seem like anything was drastically wrong with him.”
Two days later, Ollie wasn’t eating well, and he vomited. Christie took him back to the veterinarian, who confirmed that Ollie was not blocked and gave him anti-nausea medication. He continued to decline and was not responding to the medication, so Christie decided to take him to the UC Davis veterinary hospital.
After initial evaluation and stabilization by the Emergency and Critical Care Service, Ollie was transferred to the Small Animal Internal Medicine Service.
“We discussed that Ollie spends a lot of outdoor time with my husband Dan, who is an avid hunter and fisherman,” said Christie. “When they knew this, the veterinarians asked if Ollie had gone swimming in any rivers lately or encountered any raw salmon. They seemed to have a good idea of what was happening.”
“Ollie presented with classic clinical signs of salmon poisoning disease – low platelet count, enlarged lymph nodes, and changes to his spleen,” said Dr. Emily Hirsch, a second-year resident and co-chief house officer of the hospital. “Knowing that his owner is an outdoorsman and Ollie might be around salmon in those situations, I was almost certain that was the case.”
When presented with this potential diagnosis, Christie recalled a recent trip to Del Norte County where Ollie was on a walk near the Smith River – one of the best salmon river systems on the West Coast. She told Dr. Hirsch that Ollie encountered a dead salmon on the riverside.
While Ollie had not bitten into the salmon, it was clear that he must have licked it and had enough of an encounter with it to be poisoned by the salmon’s parasitic flukes that contain the bacteria Neorickettsia helminthoeca.
“We had no idea this disease even existed when we heard that Ollie was diagnosed with salmon poisoning,” said Christie.
Salmon contract flukes by eating snails, but not all salmon have flukes, and not all flukes contain the bacteria. However, Dr. Hirsch warns that even raw salmon without flukes can be dangerous and cause other diseases in dogs that ingest them, like mercury poisoning.
“Dog owners should be vigilant about keeping them away from any raw salmon,” she said.
“UC Davis did a great job of diagnosing this, and that saved Ollie’s life,” Christie said. “The studies I read showed the disease to be fatal within two weeks in 90% of cases if not treated. And Ollie was on Day 10 when he got to UC Davis.”
“Typically, we have to take samples from the abdominal lymph nodes,” Dr. Hirsch said. “But in Ollie’s case, we were able to get samples from his enlarged peripheral lymph nodes, meaning he was heavily burdened by this infection by the time we saw him, which is why he presented so sick.”
Thankfully, salmon poisoning disease is easily treatable with the proper medication if caught in time. Ollie was prescribed the antibiotic doxycycline to clear the infection and then the dewormer praziquantel to clear the flukes from his system.
“One thing I appreciated the most about UC Davis was that the veterinarians take all the time needed to explain the situation and make sure the clients understand everything about what’s happening with their pets,” said Christie. “I asked a lot of questions, and they answered every single one.”
Ollie recovered within just a few days of taking his medication. Christie and York are happy to report that he is back to his fun-loving self and still enjoying the outdoors – just under a bit more of a watchful eye now.
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