Toxin concentrations in the plant vary and are greatly influenced by environment. Arrowgrass that has adequate moisture does not cause poisoning. When growth is stunted from lack of moisture or frost, plants quickly produce and accumulate hydrocyanic acid. Arrowgrass and chokecherry both contain hydrocyanic acid. The toxic dose must be eaten over a short time as the toxin is not cumulative.
Death results from respiratory failure.
How to Reduce Losses Keep animals off areas where the growth of arrowgrass has been retarded by drought or frost, and regrowth following harvest of hay. Harvested forage may be toxic if not properly cured. The action of hydrocyanic acid is so rapid that it is usually too late to treat affected animals after the signs of poisoning are recognized. Commercial solutions for treatment of prussic acid poisoning are available. Always consult your veterinarian regarding both drugs and treatment.