Nightshade - Solanum nigrum, Carolina horsenettle - Bull nettle, Solanum carolinense - Bitter nightshade, Climbing bittersweet - Solanum dulcamara, (nightshade family).
TOXICITY RATING: Moderate. While the plant itself is very toxic, it is also unpalatable, and rarely does an animal consume enough to cause a serious or potentially lethal poisoning. Toxic risk is higher if the plant is included in processed feeds.
ANIMALS AFFECTED: All animals, including pets, may be affected.
DANGEROUS PARTS OF PLANT: All parts are potentially toxic, the berries are often higher in toxicity.
CLASS OF SIGNS: The nightshade plants cause problems with the gastrointestinal tract and can also affect the central nervous system. Signs can include abdominal pain, vomiting, diarrhea, incoordination, weakness, depression, apparent hallucinations, convulsions, and possible death.
PLANT DESCRIPTION: Black nightshade is a low-branching annual, 1 to 2 feet tall with triangular stems that bear oval, thin-textured, alternate leaves with wavy margins. The tiny white flowers, borne in drooping clusters on lateral stalks between the leaves, resemble tomato flowers. The berry fruit is green when immature, purplish-black when ripe.
Bitter nightshade resembles black nightshade except that the stems are climbing, the lower leaves are lobed at the base, the flowers are purple, and the ripe fruit is red.
Horsenettles are similar but have coarser, prickly stems, larger white to purplish flowers in loose clusters, and yellow fruits that look much like small tomatoes. All three species commonly grow in open woods, old fields, waste areas, pastures, along roadsides, and around farm buildings.
SIGNS: Clinical signs of poisoning in the nightshade family tend to reflect gastrointestinal irritation and/or effects on the central nervous system. The plant is not palatable and is eaten only when animals have no other forage available. The plant may be a contaminant in hay, where it will still cause toxicity. Pets may eat the green, red, or black berries and be poisoned. The major toxin is solanine, an alkaloidal glycoside, and along with other glycosides and atropine have numerous and powerful effects on the body.
Gastrointestinal signs can include: vomiting, poor appetite, abdominal pain, and diarrhea which may become bloody. Central nervous system signs can include depression, difficulty breathing, incoordination, weakness, collapse, convulsions, and possible death.
Chronic toxicity can also occure where the animal eats small amounts of the plants each day. These animals tend to present with general unthriftiness, depression, and diarrhea or constipation.
FIRST AID: If a large amount of nightshade plant was consumed, contact a veterinarian immediately, since emergency measures may need to be undertaken. In most cases the animals will avoid eating this plant, so clinical cases are rare. Curious or bored pets are particularly at risk, and a veterinarian should be contacted if these animals are seen eating a nightshade plant. Treatment is largely symptomatic until the clinical signs wear off (which can take a day or two, sometimes longer). Death is rare in animals, but has occurred in people who have abused these plants.
PREVENTION: Nearly all grazing animals will avoid eating plants in the nightshade family unless they are extremely hungry and there is little else to eat.
Pets may be attracted to and eat the berries, so always keep pets away from nightshade plants, especially if the pet is confined, bored or unattended.
NOTE: Other Solanum species contain the same poisonous principle. These include buffalobur (Solanum cornutum), the ornamental Jerusalem cherry (Solanum pseudocapsicum), and the common white potato (Solanum tuberosum). Sprouts and sunburned (green) or spoiled potato tubers also contain solanine. Vines of tomatoes (Lycopersicon esculentum, nightshade family) contain similar glycoalkaloids.
