Dehydration and salt toxicity? Cows dying in Saskatchewan

Ann Hui of The Globe and Mail reports that for decades, cattle farmers have sent their livestock to graze on the sprawling Shamrock pasture, about 80 kilometres south of Chaplin in southwest Saskatchewan. Shamrock is where Russ Coward, a fourth-generation cattle farmer, has for years raised nearly a quarter of his cattle. It’s the same place Mr. Coward’s father sent his cattle.

But some time between last Monday and Friday, the cows and calves at Shamrock began to die. It’s not known whether the deaths happened all at once or slowly over the course of the four days. But by the time the manager arrived on Friday afternoon, 200 of the approximately 680 cattle in a single field were dead.

The president of Shamrock Grazing Ltd., Glenn Straub, called Mr. Coward, who raced out to the field. He was met with a gruesome scene. “We seen a tragedy,” he said. “We simply seen a terrible sight.”

Other ranchers soon joined him, about 31 in total who have cows and calves there. “We all had the same feelings – how did this happen? How did this happen?”

Since Friday, provincial authorities as well as the local RCMP have been trying to piece together the mystery. The cause is still being determined, but the prevailing theory is dehydration and salt toxicity.

The area has been subject to drought in recent weeks, said Saskatchewan’s chief veterinary officer, Betty Althouse. Officials believe this may have led to evaporation at the water source, resulting in higher concentrations of salt in the water.

“An analogy would be someone shipwrecked in the ocean,” Dr. Althouse told reporters this week. “They’re thirsty, they’re craving water, so they’re going to drink the water. But ultimately the salt water will kill them.”

Many of the dead cows and calves were found clustered around one “dugout” in particular – the pools of collected rain and runoff where they drink. Investigators at the Western College of Veterinary Medicine in Saskatoon who were called in to assist have collected samples from the dugouts. Results are expected some time this week.

From Promed: E. coli O157 in Africa, 1992

The Epicore Global Surveillance Project reports that in 1992, a large outbreak of bloody diarrhea caused by Escherichia coli O157 infections occurred in southern Africa.

Swaziland-Bucket-BrigadeIn Swaziland, 40,912 physician visits for diarrhea in persons aged 5 years and older were reported during October through November 1992. This was a 7-fold increase over the same period during 1990-91. The attack rate was 42 percent among 778 residents we surveyed. Female gender and consuming beef and untreated water were significant risks for illness.

E. coli O157:NM was recovered from 7 affected foci in Swaziland and South Africa; 27 of 31 patients and environmental isolates had indistinguishable pulsed-field gel electrophoresis patterns. Compared with previous years, a 5-fold increase in cattle deaths occurred in October 1992. The 1st heavy rains fell that same month (36 mm), following 3 months of drought. Droughts, carriage of E. coli O157 by cattle, and heavy rains with contamination of surface water appear to be important factors contributing to this outbreak.

Early in November 1992, physicians arriving for duty at a small hospital on a sugar plantation in Swaziland found over 100 persons sprawled on the ground in front of the casualty department. Many had bloody diarrhea, and almost all were suffering severe abdominal pains. The next day, the number of patients with the dysenteric illness nearly doubled, yet stool specimens sent to local laboratories did not yield common parasitic or bacterial pathogens, including Shigella spp. With the etiologic agent still unknown into the 2nd week of the outbreak, specimens were forwarded to a reference laboratory in South Africa, where a surprising discovery was made: E. coli O157 had emerged in Africa.

An outbreak of E. coli O157 infections was heretofore unheard of in Africa or, for that matter, anywhere in the developing world. E. coli O157 had been isolated only once before in southern Africa, from an elderly man undergoing surgery for lower gastrointestinal bleeding in Johannesburg in 1990. Carriage of E. coli O157 by cattle, cattle deaths secondary to drought, and heavy rains that resulted in contamination of surface water were important factors contributing to the emergence of E. coli O157 in Africa. Given that drought and heavy rains will likely recur in Africa, the possibility that E. coli O157 will once again emerge to cause a major regional outbreak cannot be excluded. Clinicians need to be aware of this so that delayed diagnosis and inappropriate treatment resulting in loss of lives can be avoided.