Grasses

>Arrowgrass has prussic acid in its leaves and can have a high cyanide content, depending on the location and conditions under which it's grown. It's recorded to be potentially lethal to animals at .5 percent of their body weight. Signs of poisoning:Symptoms o f arrowgrass poisoning are typical of cyanide poisoning: excitement, rapid respiration, weakened pulse, tachycardia, salivation, voiding of urine and feces, staggering, collapse, bright-red mucous membranes, convulsions, and death.

>Dallis grass Paspalum dilatatum-Poaceae,Grass Family Similar species:Rye Grass;Lolium perenne(withErgotfungus,Clavicepsspecies). Description:Dallis grass is a common perennial grass that may grow as tall as 40 inches under the right conditions. The blades are flat, coarse, and have pointed ends. Little hairs grow at their base, and dozens of tiny oval seeds grow up the stem. Rye grass is a coarse green annual or perennial grass with a spiked end, similar to dallis grass, but it grows only to about 25 inches tall. Its seeds, which grow up the side of the plant, are somewhat flatter and less sparse than those of the dallis grass. Frequently, a parasitic fungus invades the flower heads, producing "honey dew." Insects are attracted to the secretion and help in transmitting the fungus. This fungus produces lysergic acid derivatives, ergotamine, and ergotoxine, affecting animals that ingest it. The endophytic fungus (Acremonium lolii) that invades rye grass produces a tremorgenic toxin that induces muscle tremors. Signs of poisoning:Symptoms include nervousness; trembling; staggering; abortion; convulsions; blood-vessel restriction causing nerve damage in the tail, ears, and other limbs; lameness; and gangrene. These symptoms occur within several days to several weeks of ingestion. Cattle are more commonly involved in dallis or rye grass poisoning, but other animals, including horses, may also be susceptible.

Fescue Festucaspecies-Poaceae,Grass Family Description:Chewings fescue,Festuca rubra, grows to three feet tall and has round, wiry leaves that grow in tufts at the base of the plant. Nematode galls are often found in the seed and have produced toxic symptoms in horses after they ingest either the seed or the grass. Coryne toxins are the toxic principle. Tall fescue,Festuca arundinacea,is a drought-resistant, coarse perennial grass that thrives in wet areas and is often grown for forage. It has a long, flat, ribbed, dark-green blade, and can grow up to four feet. It bears many small flowers on one-foot spikes. The plant contains alkaloids, perloline, and halostachine. An endophyte fungus is known to infect fescue and is important to the development of toxicity to animals grazing the grass.Signs of poisoning:With chewings fescue poisoning, muscle trembling, ataxia, staggering and falling, abortions, and death have all been noted, with degeneration of liver and kidneys in chronic cases. Tall fescue poisoning occurs after several days to several months of grazing endophyte-infected fescue. Symptoms may vary depending upon the time of the year: In winter, lameness, diarrhea, anorexia, rough haircoat, and possible gangrene of the tail, hooves, and ears may appear. Poor growth rates and weight loss may occur. In summer, animals may have elevated temperatures, and females have little milk for their young. Stillbirths, abortions, prolonged gestations, retained placentas, and infertility are frequent in mares. Foals may have very long hooves if they survive birth due to the prolonged gestation. Fescue infected with the endophyte Neotyphodium coenophialum (formerly known as Acremonium coenophialum) is known to produce many ergopeptide alkaloids. Most of the toxic effects of fescue are now attributed to ergovaline, a specific ergopeptide alkaloid.

Johnson Grass Sorghum halepense -Poaceae,Grass Family Similar species:Columbus Grass; Sorghum;Sorghumspecies; Sudan grass;Sorghum vulgare.Both Johnson and Sudan grasses may contain hydrocyanic acid (prussic acid) and sometimes toxic levels of nitrates. Toxicity is highest in young plants and lowest when the plant is yellow, more than two feet tall, and forming fruiting heads. The levels of cyanide increase when the plant is stressed, for example during drought or frost. Leaves have a higher concentration of cyanide than stems.

Kleingrass Panicum coloratum-Poaceae, Grass Family Similar species:Panicum vitgarum. Description:Kleingrass is a perennial with narrow blades and looks similar to coastal grass (the hay of choice in Texas). Look for bunches of small seeds at the tops to help identify it. Kleingrass grows up to four feet tall and bears small spiklets on its tops at maturity. The toxic principle is believed to be saponin, but it's not found in the same quantities in all plants. Although the grass has a strange smell, it may be eaten by hungry horses when no other forage is available. Kleingrass hay is also toxic. The seed provides a good food source for game birds and the foliage provides cover and shelter for small game birds such as quail and dove.

Squirreltail Grass Hordeum jubatum-Poaceae, Grass Family Also known as:Foxtail Grass, Wild Barley. Signs of poisoning:The grass may pierce the skin on the animal's ears, neck, face, or mouth, causing abscesses, ulcers, possible blindness, and the inability to eat. It may cause colic and impaction in horses.

Yellow Bristle Grass Setaria Lutescens -Poaceae, Grass Family Also known as:Foxtail Grass; Pigeon Grass. Yellow bristle grass doesn't contain toxins, but it's a poor forage for animal consumption. It has little spikes and wiry bristles with tiny barbs on the ends that cause mechanical injury to an animal's oral tissues.

Yellow oatgrass or golden oatgrass, Trisetum flavescens, is a species of grass in the Poaceae family. It is native to Europe, Asia, and North Africa. It can be found elsewhere, such as sections of North America, where it was introduced as a rangeland grass for grazing. It now exists in the wild as a common weed. In Austria and Germany, T. flavescens is a common component of alpine pasture and is associated with the onset of signs about 18 months after cattle are put onto the infested pasture. Resident cattle show clinical signs at about 3 years of age. The grass is most toxic when it is young, and the clinical signs are worse when the cattle are at pasture. Pathogenesis The glycoside ingested in the plant is hydrolyzed by rumen microbes, intestinal mucosal enzymes, and bone cells to form the vitamin D3 analog. Absorption of the active substance results in a dramatic increase in the uptake of calcium from the diet. Blood levels of calcium are markedly increased, and this is followed by deposition of calcium in soft tissues.
The mode of action of the glycoside is similar to that of 1,25-dihydroxycholecalciferol. Recent studies have confirmed that the toxin is in fact Vitamin D3. Trisetum flavescens, has joined a list of plants now known to contain active VD3. Science direct This plant and other plants containing calcinogenic glycosides are unlikely toxic to captive birds if fed at less than 10% of a balanced diet. The effects of VD toxicity is described here Vitamin D Properties and Metabolism

Horsetails Equisetum arvense -Equisetaceae,Equisetum Family Also known as:Foxtails; Scouring Rushes. Description:Horsetails have windswept-looking whorls of thin, grasslike leaves at the ends of the many tall, green, segmented hollow stems, resembling a horse's tail. They're reported to be poisonous to all classes of livestock, although horses appear to be most susceptible. The plant contains toxic aconitic acid, palustrine, and thiaminase. Horses have shown various degrees of poisoning after consumption, and young horses are more likely to succumb than older horses. Toxicity is higher in green plants than in aged plants.