Two dogs stricken with salmon poisoning at Lake DavisDiana Jorgenson Portola Editor 12/8/2010
Two cases of salmon poisoning in dogs have been confirmed in the last two to three weeks; Beckwourth veterinarian Dr. Martin Schafer treated them.
The disease, traditionally found in uncooked salmon, is a regional thing, found from north of San Francisco to Oregon. Eating or licking raw fish infects dogs.
“This is a normal environment for this parasite, which is periodically found in fish in local lakes,” Schafer explained, adding the parasite causing the disease was not endemic to this area but had been transferred to the area in transplanted fish.
He stressed not all the fish in a restocking would have the parasite, and said he had not seen a case of salmon poisoning for a few years.
“Salmon poisoning” is really a misnomer as no toxins are involved and salmon are not the only fish that carry the parasite. Steelhead, trout, salmon and other freshwater fish may be infested.
Salmon poisoning disease, according to the University of California’s Division of Agricultural Sciences, is caused by a virus-like organism, Neorickettsia helmonthoeca, found in all life stages of a parasitic fluke that lives in the intestines of many fish-eating birds and mammals.
However, ill effects of the disease only appear in canines: dogs, foxes, coyotes and wolves. It is not harmful to humans.
Because of the notoriety of Lake Davis’ poisonings, locals may associate the SPD with recent events, but Schafer said they were unrelated.
If you see a fish with fungus or with parasites, that’s not it. Fish infested with the flukes look healthy on the outside. The parasites are microscopic said Schafer.
The intermediary host, the fluke that attaches to the intestines or liver, can be seen as a tiny white speck on the black kidney line when you gut the fish, according to William Cox, Department of Fish and Game (DFG) program manager for Fish Production and Distribution.
If the fluke is in the gill or inside the liver, you may miss it altogether.
According to DFG, “Salmon poisoning disease is present in the Pacific Northwest, including the southern Cascades and northern Sierras to the Feather River drainage.’
‘The distribution of the fluke, Nanophyetes salmincola, is roughly north of a diagonal line from Sausalito to Chico, and on the west slope of the Sierra/Cascade range.
“The DFG raises fish at three hatcheries where this fluke is present either intermittently or continuously: Darrah Springs, Crystal Lake and Mount Shasta.
“However, DFG only stocks fish from these hatcheries into waters where the salmon poisoning disease parasites have been present for decades,” reported the DFG press release advising dog owners to not let their dogs eat or lick raw fish.
Well known in coastal areas and in the Cascades, thousands of dogs get sick every year from the disease.
The Feather River drainage area is on the edge of the fluke’s range and people are not as aware of the danger of SPD.
SPD is a real danger and 90 percent of the dogs that get the disease and are not treated, die from it.
On the other side, treatment is relatively simple and effective, and sick dogs show dramatic improvement in a couple of days. Dogs that survive, either on their own or because of treatment, become immune to the disease thereafter.
Symptoms of the disease include vomiting, lack of appetite, fever, diarrhea, weakness, swollen lymph nodes and dehydration.
If you know the dog has ingested raw fish or see any of these signs, you should seek treatment for your pet.
Usually the signs appear suddenly, within five to seven days after eating infected fish, but may be delayed as long as 33 days.
If untreated, most dogs will die in 10 to 14 days after the first signs appear. Death is generally caused by dehydration and blood loss.
Cooking the fish or freezing it for at least two weeks kills the organism. Usually the disease is transmitted by ingestion of raw fish, but other less common but possible means of infection may occur if dogs eat feces from other fluke-infested dogs or fish-eating mammals such as skunks, raccoons, mink or bobcats.
To protect dogs from SPD, owners should not let their dogs run loose, especially along beaches and along rivers. Keep salmon, steelhead, trout and other freshwater fish carcasses away from dogs.
Gary Giovannetti, owner of one of the sick dogs, is concerned local dog owners are unaware of SPD. His dog, Bruno, survived SPD, but he’s not sure how his dog was infected.
“I live across the street from Lake Davis and I have not had any contact with the fish in the lake,” he said. “Something has to be done. California Fish and Game must come up here and post the dangers of this so that all fishermen and visitors can be safe and their dogs protected.”
Jeanne Graham, J & J’s Grizzly Store and Camping Resort, agreed and has posted a warning at her store.
She did not want to exaggerate the problem, but felt visitors and residents should be informed of the potential dangers.
“The fact is,” she said, “people tend to let their animals run free.”