Beware of poisonous arrow grass in western states.

Poisonous arrow grass causes serious livestock losses in the western states. Each year these poisonous plants, of which the arrow grass is one, kill three to five percent of the cattle, sheep and horses on the range.

Poisonous arrow grass is found in all the western states and both sheep and cattle may be poisoned by it. The leaves contain hydrocyanic or prussic acid, a toxic substance. Cud-chewing animals may be severely affected if they eat a large amount of leaves in a short time.

Species of arrow grass that poison livestock are widely distributed in marshy pastures and native grass hay areas throughout the United States. It has fleshy, dark green, half-rounded, grass-like leaves that grow from the base of the plant. Although clumps of leaves are only 6-18 inches tall, slender flower stalks reach a height of three to five feet. Small green flowers appear close together along the upper part of the stalk early in the season. Later, the flowers develop into golden-brown fruits. The plant is a perennial in the arrow grass family.

As long as arrow grass has adequate moisture, it does not cause poisoning. When growth is stunted from lack of moisture or an early frost, plants become toxic.

Poisonous arrow grass grows best in soil covered with water. In such soil it may spread over large areas. In moist soil or near springs, it some times grows in small patches. Arrow grass starts growth in early spring.

How much arrow grass does it take to poison sheep or cattle? This depends on the toxicity of the plants and the rate at which the plants are eaten.

About 1/50 of an ounce of hydrocyanic acid of stunted arrow grass will kill a 600 pound animal. The toxic dose must be eaten at one time to cause death, because the poison is not cumulative. Death results from respiratory failure.

The best way to reduce losses is to keep animals off areas where growth of arrow grass has been retarded by dry weather or frost.

The action of hydrocyanic acid is so rapid that it is usually too late to treat an affected animal after the signs are recognized. The signs are nervousness, abnormal breathing--either very rapid or slow and deep, trembling or jacking muscles, blue coloration of the lining of the mouth, and spasms or convulsions continuing at short intervals until respiratory failure causes death.

Some poisoned animals may be saved by immediate treatment with an intraperitoneal injection. Use 20 cc of a 10 percent solution of sodium thiosulfate to which 10 cc of a 10 percent solution of nitrite has been added. For animals in advanced stages of poisoning give an intravenous injection of sodium thiosulfate and sodium solution. For further advice about treatment consult your local veterinarian.

Eradication of arrow grass is not practical.