Triglochin maritima L. (USDA, ITIS)
Arrow grass prefers wet alkaline soils at most elevations. It flourishes in marshy ground and irrigated pastures, often growing in native meadows cut for hay.
Arrow-grass - Triglochin maritima
Cyanogenic glycoside triglochinin, which is hydrolysed in the rumen by microorganisms to produce hydrogen cyanide (HCN). All parts of the plant are poisonous especially if wilted or under water deprived situations. Levels are highest in newly initiated plant tissues. The cyanide blocks the action of cytochrome oxidase that prevents hemoglobin from releasing oxygen to the tissues. Death results rapidly from anoxia.
Perennial "grass like" plants with fleshy, half rounded, dark green leaves clumped at the base of the plant. Leaves are 6-8 inches long, linear, unjointed, and sheathed at the base. In cross section, the leaves are round with a flat or concave side. The inflorescence is a pediceled raceme up to 1 1/2 meters in length that appears as an unbranched, unjoined flower spike. The flowers are inconspicuous and numerous, with a greenish, 6-parted perianth. The fruits are made up of 3-6 celled capsules which turn a golden brown before splitting.
Animals may bloat or have increased salivation.
Animals may exhibit muscular twitching, staggered gait, or succumb to convulsions.
Without stressing the animal, sodium thiosulfate and sodium nitrite should be given intravenously. A mixture of 1ml 20% sodium nitrite and 3ml of 20% sodium thiosulfate should be prepared and given at the rate of 4 ml of the mixture per 100lbs body weight. Sodium thiosulfate should be given orally via stomach using 30gm dissolved in a gallon of water for an adult cow.
Sudden death may be the only presenting sign. A rapid heart rate, red mucous membranes, and cherry-red venous blood is highly suggestive of cyanide poisoning.
Animals exhibit rapid labored breathing, gasping.
Animals become anxious and excited because they are unable to breathe.
Sudden death with supporting evidence of cherry-red venous blood and absence of other diseases. Rumen contents or plant material can be tested for cyanide using the sodium picrate test. Commercial test kits for cyanide are available.
Ruminants are more susceptible to cyanogenic glycoside poisoning since the environment of the rumen favors the conversion to cyanide. Horses, pigs, and dogs are rarely if ever affected by plants containing cyanogenic glycosides as their digestive system does not readily convert the glycosides to free cyanide.
Majak W, McDiarmid RE, Hall JW, Van Ryswyk AL: Seasonal variation in the cyanide potential of arrow grass (Triglochin maritima). Can J Plant Sci 1980, 60:1235-1241.