Toxic plant suspected in horses' deathWhite snakeroot

grows in area groves

By FRITZ BUSCH

Journal Staff Writer

NEW ULM -- A toxic and often lethal plant, which is primarily found in other parts of the country, has turned up in area farm groves this year.

White snakeroot causes trembles when consumed by livestock, and it may be the cause of death of a number of horses near New Ulm this summer.

The plant is unusually abundant this year, according to Dr. Nancy Peterson of the New Ulm Regional Veterinary Center.

The University of Minnesota Veterinary Diagnostic Laboratory is studying one of the area horses that died this summer. It has not yet been confirmed that the cause of death was from white snakeroot.

Test results may not be known for a couple weeks. Samples were sent to another university, according to Peterson.

"The diagnosis is still presumptive, but it appears to fit," Peterson said. "We still have a boatload of white snakeroot out in those groves."

She is concerned that rural residents may bale hay with snakeroot in it. Such hay could be deadly. There is no known antidote for the illness.

The leaves, stems and possibly flowers of the plant are most dangerous. Roots have less toxicity.

Illness signs include trembling, sweating, depression, stiff gait, heart failure and jaundice. Animals that ingest white snakeroot could produce toxic milk. Onset of signs takes two days to three weeks. Death occurs within one day to three weeks. Horses usually die in one to three days.

Even if a horse doesn't die from the toxin, it may suffer permanent heart damage.

The toxic component is tremetol. It is cumulative. One large dose or several smaller doses can kill.

Humans who drink raw milk from affected animals can be poisoned, sometimes fatally. The disorder was called "milk sickness" in colonial times.

White snakeroot grows from fibrous, matted roots as a smooth, erect, perennial herb, 1 to 3 feet high with opposite, oval, pointed-tipped leaves with sharply-toothed edges.

Upper leaf surfaces are dull. The lower surfaces are shiny with three prominent main veins. Small white flowers in compound animal clusters are conspicuous in late summer.

White snakeroot is found in woods, damp and shady pastures, and occasionally in thickets and clearings (especially at the edges of wooded areas.

Wooded areas with white snakeroot should be fenced off. Herbicide treatment may make the plant easier to control. The objective is kill the plant. However, the problem may recur the following year.

Several weeks between spraying and animal access should be allowed.

(Fritz Busch can be reached at fbusch@nujournal.com).