There are numerous toxicities that can be caused by consumption of certain plants. Goats are generally not as susceptible to plant toxicities as other livestock because of their grazing habit. Goats are browsers and normally consume a wide variety of forage species daily thereby avoiding overconsumption of any one plant. For a plant to be poisonous it must be consumed in sufficient quantities to cause illness in a natural grazing setting. In goats this may happen when forage is limited, such as during drought, and goats are forced to overconsume plant species not normally eaten. Some ornamental plant species can also cause toxicity.

Plant toxicities can cause a variety of signs and symptoms from mild irritation to central nervous system disorders to abortion and death. Most do not respond well to treatment and prevention is best. Activated charcoal given to adsorb toxins is recommended for many toxicities. Others can be treated by chemicals that usually only a veterinarian would carry. Most plant toxicities can be avoided by supplying hay or grain during drought, not overstocking pastures, and preventing access to ornamental plants and clippings. Examples of plant species causing various toxicities are listed.

Azalae, rhododendron, laurel poisoning

Azaleas, rhododendrons, and laurels are members of the Ericaceae family. These plants contain a toxin which causes anorexia, salivation, vomiting, abdominal pain, weakness, staggering, and death. Death usually occurs after several days of illness. Affected goats typically vocalize and vomit. Relatively small doses of these plant species are effective in causing clinical signs. For a mature goat, a cupful of leaves would be toxic. Goats that have consumed and recovered from eating these plants may repeatedly ingest them in large and often fatal quantities. Treatment is non-specific in nature. Mineral oil and activated charcoal may be given orally to adsorb residual unabsorbed toxin. Fluids and relief of pain are given as needed.

Fescue toxicity

Fescue toxicosis is caused by consumption of tall fescue infected with the endophyte Acremonium coenophialum. Affected animals show poor growth. In cooler months, the mycotoxin can cause gangrene or death of extremities like the tail and feet. Goats appear to be less sensitive to fescue toxicity than cattle. Do not feed tall fescue to pregnant animals. If feeding to other classes of animals, dilute with other forage.

Hydrocyanic acid poisoning

This condition is most commonly associated with Sudan grass, Johnson grass, sorghums, and white clover. Under conditions of drought or frost the plants release cyanide. Cool growing conditions and use of nitrate fertilizers are also implicated. Animal symptoms include muscle tremors, labored breathing, and sudden death, often within minutes of consuming a fatal dose. The blood of affected animals is bright red as the cyanide prevents hemoglobin from releasing oxygen. Prevent by limiting access to pastures in the conditions listed above. Plants can be most toxic during early regrowth. Sorghum at least 2 feet tall is generally safe. Some plants found on range or pasture such as choke cherry and oleander can also cause this problem. Contact a veterinarian for treatment.

Nitrate poisoning

Nitrates are essential for plant growth and normal concentrations are not high enough to cause problems. However, the increased use of nitrogenous fertilizers has raised the potential for nitrate poisoning to occur from not only nitrates in plants, but through contamination of water supplies. Nitrate poisoning is usually associated with sorghums and Sudan grass but can also occur when grazing sugar beet tops, kale, Italian ryegrass, white clover, and oats. Drought, recent fertilization, and retarded plant growth can cause nitrates to accumulate in plants. Highest nitrate concentrations are found in stems and leaves in the cool, early morning. The nitrate does not allow the blood to exchange oxygen. Signs include weakness, tremors, increased heart rate, collapse, and sudden death. Contact a veterinarian for treatment.

Selenium toxicity

Certain plants can accumulate high levels of selenium. If an animal consumes a large amount of these plants, acute poisoning can occur with damage to the liver, kidney, and lungs. Animals become weak, have difficulty breathing, experience bloating, and can die from respiratory failure. Some plants that accumulate selenium include broomweed, desert aster, princess plume, and saltbush.

Photosensitization

Photosensitization is a condition where photodynamic chemicals accumulate under the skin and react to sunlight on unpigmented areas of the skin. Capillaries in the skin are damaged resulting in skin death and sloughing. Liver damage can also occur in some instances. Skin around ears, eyes, and muzzle is usually affected and becomes red, swollen, and irritated. Secondary infections can occur. Remove the plant causing the photosensitization and protect the animal from the sunlight. Prevent or treat secondary infections. Some plants known to cause photosensitization include St. John’s wort, buckwheat, wild carrot, Lantana, ragwort, rape, and kale.

Abortions and fetal defects

Some plants contain toxic substances called teratogens that can cross placental membranes and cause fetal deformities, fetal resorption, abortion, or stillbirth. Teratogens may cause different defects depending upon the stage of gestation and amount consumed. The first trimester of pregnancy is when the fetus is most susceptible. Usually, restricting pregnant animals from pastures containing these plants during the first third of gestation is sufficient; however, plants such as milk vetch and locoweed should be avoided throughout pregnancy. Other plants known to have these reproductive effects include broomweed, lupine, tobacco, desert tobacco, and Veratrum californicum called false hellebore, skunk cabbage, or corn lily.

Liver damage

The liver can be vulnerable to toxicosis due to its role in detoxifying substances in the body. Some plants consumed in excess can cause liver damage. Signs are usually non-specific and overlap with signs of other toxicities and include vomiting, diarrhea, and going off-feed among others. Some plants that can cause liver damage include cocklebur, crotalaria, Lantana, sneezeweed, bitterweed, rubberweed, St. John’s wort, blue-green algae, horsebrush, oak, rhubarb, castor bean, and mistletoe.

Kidney damage

Kidneys can be damaged due to plant toxicosis with renal failure resulting in extreme cases. Signs are non-specific and include depression, off-feed, going down, and death. Plant species implicated include lambsquarter, pokeweed, Russian thistle, pigweed, rhubarb, oak, and Ponderosa pine.

Central nervous system effects

There are many plant toxicities that have central nervous system signs. These signs differ for different plant species but include one or more of the following: paralysis, muscle convulsions, tremors, incoordination, vomiting, depression, weakness, coma, and death. Plants causing these symptoms include locoweed, larkspur, Indian hemp, milkweed, lupines, Jimson weed, water hemlock, poison hemlock, nightshade, false hellebore, death camus, sneezeweed, greasewood, horsebrush, rubberweed, rhodendron, mountain laurel, azaleas, castor bean, and horse chestnut. Treat animals that have consumed these plants with one pound activated charcoal to adsorb the toxin.

Aflatoxins

Aflatoxins are produced by a number of fungi that contaminate grains and soybeans. Affected animals will go off feed, may experience bleeding, tremors, weakness, and death. Abortions and liver damage can also occur. Drought or excessively warm and moist conditions are factors in occurrence. Identify toxins in feed and feed toxin-free diets.

Next
Module Home
Certification Table of Contents
Browsing Table of Contents