D. E. Larsen, DVM
When I was growing up in Coos County one rarely encountered a Coyote, except on the high ridges. We didn’t think much about it at the time. That was just the way it was. I remember the first coyote I saw, on the top of Sugarloaf Mountain, on a cold morning Jeep ride with Uncle Robert.
Twenty years later coyotes had moved into the valleys and were heard regularly and encountered with little effort if hunting them. They had become a significant problem to sheep ranchers, and an occasional brave one would come close enough to the barnyard to snatch a chicken.
My Uncle Duke’s explanation for the change was probably the most accurate. I didn’t have a full understanding at the time but would later come to appreciate his wisdom. In my younger years, 1940s and early 1950s, all the creeks in the area were full of spawning salmon and steelhead in the fall and winter. Dead, spawned out, fish were present on the riverbanks and all the creek banks. Later in the 1950s and 1960s, commercial fishing for salmon moved from the steams to the ocean. Spawning fish numbers decreased and dead fish were only occasionally encountered on most streams.
Duke’s opinion was that when the streams were chuck full of fish the coyotes would have easy access to salmon and would die from the disease. The only viable populations thus existed on the high ridges far removed from the spawning streams.
Salmon Disease (or Poisoning) is a complex disease of all canines. It occurs approximately 7 days after a dog (or coyote) consumes infected raw salmon, trout or steelhead. The fish carry a larva of an intestinal fluke. The fluke causes only mild disease and can infect a number of species, but the fluke also carries a rickettsia. It is this rickettsia that makes all canines ill and is the cause of Salmon Disease.
Salmon Disease is treatable if it is caught in time. Ninety percent of dogs (and coyotes) will die within 7 – 10 of becoming sick if they are not treated. Survivors may be immune for long periods if not for a lifetime although there are exceptions to this immunity.
I was on a farm call, talking with Dick Rice. Dick owned a ranch on the Calapooia River. His ranch was one of the early pioneer ranches in the area.
“Doc, I have been having a heck of a problem with coyotes the last couple of years,” Dick said. “It seems to be the same coyotes most of the time. He has only three toes on one foot. He catches any lamb left out of the barn overnight. Can’t trap him, he is too wise.”
Dick was at his wits end on how to deal with this bandit. I related my Uncle Duke’s opinion on the shift of the coyote population into the Western Valleys. He listened with interest but just seemed to take it in as a story. I finished with the calf we were treating, loaded up and returned to the clinic.
I never gave the conversation much thought after that until I bumped into Dick outside of Thriftway one afternoon. Dick had hurried to catch up to me in the parking lot. It was apparent that he wanted to talk.
“Hi Doc, how have you been?” he said, a little out of breath. “I have wanted to talk to you about that Old Three Toes.”
“Aw, yes, I remember you talking about him,” I replied.
“You know, I got thinking about the story you told about Salmon Poisoning. One night after work, I stopped in here and bought a hunk of salmon tail. I have an old burn pit and garbage pile on the far side of the pasture behind the house. I took that salmon out there and put it on the edge of that pile. It was gone the next morning.”
“And Doc, that was a couple of months ago. I have had no more coyote problems, and Old Three Toes is gone. I have not seen his tracks anywhere. Can’t thank you enough for that story.”
“I’m glad it helped you, Dick. You can thank the observation skills of an old farmer for the information. I am not sure that I would have ever put that information together to come up with that conclusion,” I replied.
Photo by DAVID NIETO on Unsplash
Memoirs of a Country Vet 
Does Salmon Disease only affect canids?
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https://www.merckvetmanual.com/generalized-conditions/rickettsial-diseases/salmon-poisoning-disease-and-elokomin-fluke-fever-in-animals
I will comment more a little later this morning.
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Thanks for the link. I had not heard of EFF before.
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Salmon Disease, caused by the Neorickettsia helminthoeca, is restricted to canids (in my opinion). In the Pacific Northwest, Elokomin fluke fever is clinically insignificant. It probably exists at the same time as salmon disease, which is alluded to in the link. There have been some evidence of several strains of Neorickettsia helminthoeca, so theoretically, a dog could contract salmon disease 3 times. I don’t doubt that but most of the time, one infection give immunity for life. I would guess most dogs get all three strains at the same time. I have seen a dozen dogs with 2 confirmed diagnoses of salmon disease, and maybe 2 dogs with 3 diagnoses of salmon disease, but in both of those cases, at least one of the diagnoses was a clinical diagnosis and not confirmed.
Infections with the fluke, Nanophyetus salmincola, can cause clinical disease by itself in most carnivores, including man (I avoid sushi. I would be very careful about any salmon sushi. Years ago, when OSU had a veterinary parasitologist, I spoke with Dr. Gary Zimmerman about an autopsy OSU did on a malnourished cougar. He said the small intestine of the that cougar showed a massive infestation of Nanophyetus flukes.
I the last few of my practice years, it became popular to treat salmon disease dogs with medication to kill the flukes. I went along with that, but in all my years of practice, I have never identified a fluke egg in the stool of a dog who had recovered from salmon disease.
There was also a book published in Veterinary Clinics on parasites. It neglected salmon disease completely. There is very little written in Veterinary texts on salmon disease, and if you have a salmon disease dog in a clinic outside of the west coast, the diagnosis may be completely missed. I wrote a letter to the author, a professor in Virginia, critical of his oversite. My main point was the lack of awareness of the disease in the profession outside of the northwest. I contended that someone traveling through Oregon could be home in Virginai before their dog became ill, and the diagnosis could be delayed or missed. I never gave a thought to the fact that wild caught salmon could be shipped to other areas of the country where people would be complete unaware of the disease, and feed raw fish trimmings to their dog.
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Did the quiz on that side about non-infectious renal diseases in small animals. Let me tell you my result like this: Merlin is lucky I’m willing to drag him to the vet ever so often. He’d be gone by now if he had to rely on my “expertise”.
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