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University Library, University of Illinois at Urbana-Champaign

Plants Toxic to Animals

J

Jack-in-the-Pulpit (Arisaema spp.)

Description 

Jack-in-the-pulpit is a stemless plant, 8 inches to 2 feet tall, that grows in the woods. It has one or two long-stalked, 3-parted leaves; and at the tip of its flowerstalk, which is not quite as long as the leaves, it has a peculiar flowering structure, tinted shades of green, greenish-white, and purple.

The leaves and flower stalks rise from an underground, perennial corm, hard and turnip-shaped. The fruit is a mass of brilliant red or scarlet berries, each containing 1 to 5 seeds. Emerging Jack-in-the-Pulpit

Distribution

Jack-in-the-pulpit is common to abundant throughout Illinois in open and dense, moist woods and may be seen also in woods clearings and occasionally in pastures and at the edges of pastures that were formerly woodland. Though commonly regarded as an early spring plant, it persists through the growing season and is conspicuous in late summer and fall by its dense clusters of red berries. 

Conditions of Poisoning

Animals, if grazed in wooded pastures in early spring when other forage is not available, may eat the root of this plant. Susceptible species are cattle, sheep, goats, and swine. Mature Fruit

Control

Cattle should not be grazed in wooded pastures at any time when jack-in-the-pulpit is one of the few green plants available. Although there is no satisfactory way of eradicating it, its numbers will be considerably lessened if it is consistently dug when seen. 

Toxic Principle

The corms of the plant contain an unidentified volatile acrid principle, calcium oxalate crystals, and possibly an alkaloid. The corms are gathered, dried, and sold by drug collectors. 

Clinical Signs

Cattle, sheep, goats, and swine are susceptible to this poisoning, but they seldom eat enough of the plant to cause trouble. The corms would doubtless affect any animal that ate them. Eating the corms causes an intense burning and biting sensation in the mouth, throat, and stomach; large doses may cause inflammation of the stomach and intestine. Affected animals show evidence of colic, and they attempt to cool the mouth and throat with water. 

Animals Affected

Cattle, sheep, goats, swine

Japanense Yew (Taxus cuspidata Sieb. & Zucc.)

Description

Japanese Yew is an evergreen shrub with dark green leaves. The leaves grow alternately, with stiff, flat and needle-like leaves. The leaves grow from 1/2 inch to 1 inch long. Japanese Yew's berries are bright red and egg-shaped. It is a very common oriental shrub across North America. The shrubs grow up to 20 feet tall.

Distribution

Though Japanese Yew was originally imported to the United States, it is now found throughout the country because of it being cultivated in both landscape architecture and design. In particular, the plant is found in the Northwestern United States and is widespread across the East Coast and throughout the Midwest. 

Conditions of Poisoning

Consuming Yew introduces several toxins into the body. All parts of the plant are toxic. The plant is toxic year-round, with a higher level of toxicity occurring at the end of the year because there's been time for the toxin to build up in the plant. Both fresh and dried yew is toxic. 

Control

Animals should not be allowed to graze near where Japanese Yew is growing. 

Toxic Principle

Japanese Yew has a wide variety of toxins, including Taxine A and Taxine B, and Oil of Yew. Both Taxins are found in all parts of the plant except the fruit. Oil of Yew is found in the Yew's sap, and is an intestinal irritant that is the cause of colic and diarrhea symptoms of yew poisoning.

Clinical Signs

There are two syndromes of Japanese Yew poisoning an animal can exhibit--Acute and Subacute. The primary symptom of Acute Syndrome is death, which usually occurs 1-3 hours after consuming the Yew. The symptoms of Subacute Syndrome include Ataxia, diarrhea, hypotension, colic, hypothermia, coma, seizures, weakness, respiratory failure, bradycardia and sudden death. Most animals usually die within 24-48 hours of consuming the yew. 

Animals Affected

All animals

References Used

http://poisonousplants.ansci.cornell.edu/yew.html

Jimsonweed (Datura stramonium L.)

Other common names: Jamestown Weed, Thorn Apple, Devil's Trumpet, Mad Apple, Stink Weed
Description

Jimsonweed is a stout, coarse annual herb 2 to 5 feet tall, with spreading branches. It has a pale-green stem and large, ovate, green or purplish, strong-scented leaves, coarsely toothed on their margins. Its flowers are large, white, and tubular, 2 to 4 inches long, and set on short stalks in the axils of branches. Its circular seeds, about 1/8 inch across, are contained in a hard, prickly capsule which, when ripe, splits lengthwise into four parts.

Distribution

Jimsonweed is sometimes grows in cultivated fields, overgrazed pastures, and waste lots. It prefers rich soil and may be found throughout Illinois as well as other states from New England to Texas and Florida.

Conditions of Poisoning

All parts of the Jimsonweed are poisonous, but because of its strong odor and unpleasant taste, animals rarely eat enough of the green plant to be poisoned. Poisoning in animals occurs primarily when hungry animals are turned into a Jimsonweed-infested area where better forage is absent. Most cases of animal poisoning result from a quantity of the dried plant being fed in hay, while poisoning in chickens is due to eating of the seeds. Occasionally Jimsonweeds are accidentally included when the silo is filled. When the silage is fed to the animals poisoning occurs.

Jimsonweed is also known as Jamestown weed because of the mass poisoning of soldiers in Jamestown, Virginia in 1676. Jimsonweed poisoning is more common among humans than in animals.

Control

Hungry animals should never be allowed to graze where there is Jimsonweed. In meadows where the plant grows, hay should not be made until after all Jimsonweeds have been removed. The custom of destroying this plant should be practiced on all farms. 

Toxic Principles

Tropane alkaloids:

  • Hyoscyamine = an isomer of atropine.
  • Scopalamine = L-hyoscine = epoxidized hyoscyamine. 
Clinical Signs

Early signs of poisoning include: rapid pulse, rapid breathing, dilated pupils, restlessness, nervousness, muscular twitching, polydipsia, frequent urination, diarrhea, depression, anorexia, and weight loss. In fatal cases the pulse remains rapid but weak, breathing becomes slow and irregular, body temperature becomes subnormal, urine may be retained, and convulsions or coma precede death.

  • In cattle: excitability, tremors, rumen atony, nervousness, bloat, tenesmus, and anorexia. Death occasionally reported.
  • In goats: Datura stramonium ingestion was accompanied by tachypnea, tremors, drowsiness, recumbency, and altered locomotion.
  • In sheep: Datura stramonium ingestion was associated with ataxia, inability to stand, tachypnea, reduced drinking and mild tremors.
Animals Affected

Cattle, goats, sheep

K

Kentucky Coffee Tree (Gymnocladus dioica (L.) Koch)

Description

Kentucky coffee tree is a large round-barked tree belonging to the legume family and reaches heights of 60 to 100 feet. Its short trunk, 1 to 2 feet in diameter, divides into several large branches that end in contorted, stout twigs. Twice-compound leaves are arranged feather-fashion in 3-7 pairs of leaflets which are more or less ovalish without marginal teeth and 2-4 inches long. The tree is most easily identified in fall and winter for its large depressed leaf scars. The leaf which emerges late in spring is made up of a hundred or more separate oval leaflets arranged on the branches of the rib.

The flower, which blooms in May, is inconspicuous, greenish-white in terminal racemes, and has a tubular base about 1/2 inch long. Male and female flowers are found on the same tree. The fruit is a thick, flat pod, containing 4-7 flat broad seeds with a sticky pulp between them. The pulp dries at maturity and the seeds become olive-brown, 1/2 - 3/4 inches in diameter. 

Distribution

The Kentucky coffee tree grows in moist woods, creek banks, and flood plains. It is mainly found in the Midwest from western Ohio to eastern Kansas and Oklahoma, southern Michigan to northern Alabama and Tennessee. The tree was much planted around farm houses and may now be maintained as ornamentals around newer buildings.

Conditions of Poisoning

The leaves, seeds and pulp are poisonous and have affected sheep, cattle, horses, and humans. Sprouts eaten in the spring have produced toxicosis. Pods and seeds on the ground eaten in the fall or winter have produced poisoning. Leaves, young sprouts and seeds with the gelatinous material around them contain the toxin. 

Control

Until spring grasses and herbage are abundant, animals should not be grazed in woods where the Kentucky coffee tree grows or where it has been cut and allowed to sprout. Since there are never more than a few of these trees in any woodland, sprouts can be grubbed out periodically, and thus poisoning from them can be prevented.

The pods cling to the tree through the winter and are shed in the spring. To prevent animals from eating the fallen pods, large fruiting trees can be fenced in. Although the tree has little commercial value, it is so rare that unnecessary cutting of it is not recommended.

Toxic Principle

The toxic principle of this plant is uncertain. It is possibly the quinolizidine alkaloid, cytisine, which acts like nicotine.

Clinical Signs

Clinical signs include rapid onset (within 1 hour) of intense gastrointestinal irritation, profuse diarrhea and straining, vomiting, hypertension, bradycardia, respiratory depression, muscle paralysis, and convulsions. Animals often display depression. Death usually occurs within a day after clinical signs appear.

Animals Affected

Sheep, horses, cattle

L

Lamb's Quarters (or Lambsquarters) (Chenopodium album L.)

Description

Lamb's Quarters is an annual weed with branched stems. The stems have purple or red stripes or marks. The leaves alternate and are green with a grey underside. The leaves growing at the base of the stem have more of a serrated edge than the leaves towards the top of the plant do. The leaves at the top of the plant are smaller. Flowers grow at the end of the stems and are grey-green. 

Distribution

Lamb's Quarters is found throughout North America.

Conditions of Poisoning

Animals are poisoned when they consume large quantities of Lamb's Quarters. The leaves and grains of the plant used as a food source in some areas, and can be safely consumed in limited doses.

Toxic Principle

Lamb's Quarters is a Nitrate Accumulator. It can acquire toxic levels of nitrates if grown in rich soil or if it's fertilized like it would be if grown in cropland. It can also accumulate toxic levels of Oxalates and Sulfates. All parts of the plant are toxic. 

Clinical Signs

Signs of nitrate poisoning include difficulty breathing and the mucous membranes of the mouth and vulva turning brown due to methemoglobin in the blood. Other symptoms are depression, weakness, tremors, weak pulse, and coma. Sudden death can occur due to respiratory failure because of methemoglobin forming. 

Animals Affected

Cattle, sheep, goats

References Used

Burrows, George E., & Tyrl, Ronald J. (2013). Toxic plants of North America. Hoboken: Wiley-Blackwell.

Lantana (Lantana camara L.)

Description

Lantana (yellow sage) is a native of tropical Americas and West Africa. In the northern states including Illinois, it is grown as a garden annual reaching 12-18 inches tall. In the south, from Florida to California, it grows as a perennial shrub of 3-6 feet tall. In the tropics, it may grow even taller. Leaves are opposite, ovate, 1-5 inches long and 1-2 inches wide, with very small rounded teeth, somewhat rough and hairy. Leaves are aromatic when crushed. Flowers are borne in dense clusters 1-2 inches across on the axils near the top of the stem. Each flower is tubular with 4 lobes flaring to about 1/4 inch, initially yellow or pink gradually changing to orange and deep red. Often, the different colored flowers are present on the same cluster. Fruit is fleshy, greenish-blue to black, and berry-like with each containing one seed.

Distribution

Lantana is commonly found along roadsides, fence rows, and in fields in Florida and southern California where it escaped cultivation. In the northern U.S., it is strictly a garden and greenhouse annual. 

Conditions of Poisoning

Animals in pastures with sufficient forage will often avoid Lantana, perhaps because of its pungent aroma and taste, but animals unfamiliar to the plant may ingest enough to affect them. Fifty to ninety percent of animals newly exposed may be affected. Foliage and ripe berries contain the toxic substances with the toxins being in higher concentrations in the green berries.

Toxic Principle

Lantana contains lantadene A and B (the major toxins involved in poisoning) as well as other structurally and toxicologically related pentacyclic triterpene acids, including reduced lantadene A, dihydrolantadene A, and icterogenin.

Clinical Signs

The major clinical effect of Lantana toxicosis is photosensitization, the onset of which often takes place in 1 to 2 days after consumption of a toxic dose (1% or more of animal's body weight). Jaundice is usually prominent, animals usually become inappetent, and they often exhibit decreased digestive tract motility and constipation. Other signs may include: sluggishness, weakness, and transient, sometimes bloody diarrhea. In acute cases, death occurs in 2 to 4 days. Subacute poisoning is more common and may result in death after 1 to 3 weeks of illness and weight loss. Raw photosensitized surface areas are susceptible to invasions by blowfly maggots and bacteria. In severely affected cattle, lesions may appear at the muzzle, mouth, and nostrils. Ulceration may be present in the cheeks, tongue, and gums, while swelling, hardening, peeling of mucous membranes, and deeper tissues occur in the nostrils.

Animals Affected

Cattle, sheep, horses, dogs, cats, guinea pigs, and rabbits

References Used

Ross, I. A. (1999). Medicinal plants of the world: Chemical constituents, traditional, and modern medicinal uses. Totowa, N.J.: Humana Press.

https://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants/lantana

Larkspur, Dwarf and Other Larkspurs (Delphinium tricorne Michx. and other species)

Dwarf LarkspurDefinition

Dwarf larkspur is an erect, little-branched herb 1 to 3 feet tall. Its leaves, alternately placed and slender-stalked, are deeply divided into 5 to 7 nearly separate lobes, each lobe itself again rather deeply lobed or toothed. Its stout stem ends in a flower-bearing part that carries several blue or white, spurred blossoms 1 to 1 1/2 inches long. Three short-pointed rather fragile, widely spreading pods about 1/2 inch long develop from each blossom. These pods contain numerous small, dark seeds.

The rocket larkspur (Delphinium ajacis L.), which is cultivated and sometimes escapes, may be recognized from the above general description. It is supposed, in common with all other larkspurs, to be poisonous.

Distribution

The dwarf larkspur occurs principally in the southern third of Illinois, where it is most often found in ravines and along streams in wooded sections. Northward it becomes less frequent and probably does not grow in the northernmost two or three tiers of counties.

The rocket larkspur, also, is most abundant in southern counties, where it is most often found in open woods and fallow fields.

Conditions of Poisoning

Larkspurs are among the early spring plants, blossoming in late April and May. Animals turned out to graze in woods in the spring may eat the plant, especially if other herbage is scant. Cattle are the animals most often poisoned. Horses are susceptible to the poisoning but generally avoid larkspurs. Sheep, although seemingly resistant, can be poisoned by large amounts. Fatal poisoning of an animal may result from a single day's consumption of 1 percent or less of the animal's body weight of larkspur plants.

Control

Animals, especially cattle, should not be grazed in woodland pastures infested with larkspurs until there is an abundance of other herbage for them to browse. Heavily infested pastures probably should not be used until the larkspurs have been destroyed. In woods, where it is hard to use chemical weed-killers, the only way to eliminate the plant is to dig it out by the roots. 

Toxic Principle

Although larkspurs contain several other alkaloids, the main poison is the glucoside delphinin. 

Clinical Signs

Symptoms of larkspur poisoning vary according to the amount eaten and the animal's tolerance of the poison. Small amounts may cause loss of appetite, excitability, staggering, or muscular incoordination, and constipation. Severe symptoms include slobbering, nausea, vomiting, colic, bloating, and convulsive movements. Fatal poisoning brings convulsions and paralysis of the respiratory system. Autopsies reveal inflammation, or at least congestion of the windpipe, stomach and small intestine, congestion of the superficial blood vessels, and dark, extremely congested kidneys.

Animals Affected

Cattle, horses, sheep, dogs, cats

References Used

https://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants/larkspur

Lily of the Valley (Convallaria majalis)

Description

Lily of the Valley is perennial that originally grew in Europe. The leaves are oval or oblong shaped and dull green in color. The plant has an arched stem with typically 5-18 white, bell-shaped flowers growing on it. Lily of the Valley does occasionally grow small, red berries. It is a popular potted house plant.

Distribution

While it is native to Europe, Lily of the Valley has been introduced in North America and has now become naturalized in some parts.

Conditions of Poisoning

Lily of the Valley is poisonous when eaten, though it's more common for children to get poisoned than for animals. There have been few reports of animals getting poisoned from consuming Lily of the Valley. 

Toxic Principle

There are 38 different cardenolides which have been identified in Lily of the Valley, with a large concentration of them found in the plant's roots. All parts of the plant, including the bulb and roots, are toxic. 

Clinical Signs

Vomiting, salivation, limited diarrhea, irregular pulse or decreased heart rate, seizures.

Animals Affected

All animals, people

References Used

Burrows, George E., & Tyrl, Ronald J. (2013). Toxic plants of North America. Hoboken: Wiley-Blackwell.

Lupine (Lupinus)

Description

Lupine is a herbaceous perennial, 12-26 inches tall. Leaves are alternate, palmately divided into 10-15 narrowly oblong leaflets. The leaflets are smooth or hairy above, and very hairy beneath. Bonnet-shaped flowers are born in racemes on a single center stalk 4-10 inches long. The flowers bloom in early to mid summer displaying their wide range of colors from deep blue, purple, light blue, lavender, rose, pink, yellow, and white. The fruit is a pod about one inch long containing several somewhat flattened seeds. The seeds are cream-colored and irregularly circular, and no more than 1/4 inch in diameter. 

Distribution

Lupines thrive in dry open fields and prairie/wooded areas. The horticultural variety of lupine has been a favorite of many gardeners for ages. Though Lupine in Illinois is most frequently seen in flower gardens, most of the approximately 100 native species are found throughout the U.S. and Canada, mainly in states west of the Rockies. A blue wild variety of lupine covers Texas open ranges in early summer, earning the rank of the State Flower. A different wild variety is also widely encountered in early summer by the visitors of the Olympic National Park in the State of Washington. 

Conditions of Poisoning 

Poisoning varies depending on the lupine species and varieties, and it is difficult to pin point to specific plant or animal since different animals become susceptible in different ways under varying range conditions.

Species and taxonomic differentiation between species are insufficiently characterized. Different lupines produce varying syndromes in a a given species of livestock. Seasonal variation in toxicity in a given species of lupine exist and many species are acceptable forage under range conditions. Plants which are in the preflowering stage of maturity are unlikely to be hazardous, under normal range circumstances, except in the case of L. leucophyllus which may cause toxicosis as a result of consumption of young plants. Alkaloids are not lost upon drying. Range hay may be highly toxic if the seeds are retained, and this occurs when the majority of the pods are immature; mature pods open when drying and the seeds are dropped as the hay is bundled. For many lupines, the time and degree of seeding varies year to year.

Most losses occur under conditions in which animals consume large amounts of pods in a brief period, such as trailing animals through an area where the grass is covered by snow but the lupine is not or when feeding podded lupine hay, which is apparently palatable. Most cases of serious poisoning therefore occur in the fall because lupine remains green after other forage has dried.

Toxic Principle

More than a dozen quinolizidine alkaloids, but some piperidine alkaloids and other types of alkaloids have also been isolated from species of Lupinus. These alkaloids are largely nicotinic in effect. The nitrogen oxides of some of these bases have also been detected in some lupines. The alkaloids are present in the foliage but the greatest concentration is in the seeds.

Clinical Signs

Signs include characteristic labored breathing (snores) in sheep, with depression, salivation, ataxa, clonic spasms, head pressing tremors, seizures and coma, and frequently death. Death may be preceded only by coma and no other signs or alternatively, preceded by violent attacks on other animals or objects. Signs may appear as early as one hour after ingestion or as late as 24 hours after consumption. Death may occur within one day or occur several days later and is a result of respiratory paralysis. Cattle under range conditions rarely display clinical signs. Consumption of the plant may also affect the flavor and odor of the milk produced by the poisoned animal.

Animals Affected

Sheep, cattle, horses

References Used

Knight, A. P., & Walter, R. G. (2001). A guide to plant poisoning of animals in North America. Jackson, Wyo.: Teton NewMedia.

M

Maple, Red (Acer rubrum)

Description

Trees are large and can reach heights of approximately 100 feet when mature. Leaves have three to five lobes and are simple and opposite with red petiole, shiny green topside and white/gray underside. Leaves turn red during the fall. 

Distribution

Red maple trees are common throughout most of eastern North America and south to Florida and Texas. They adapt to moist or dry areas and are often planted as ornamental trees.

Conditions of Poisoning

Poisoning usually occurs when horses consume wilted or dried leaves of the red maple. Most poisonings occur in the fall when the bulk of the leaves drop. 

Control

Maintain a good feeding program for horses and remove red maple leaves and fallen branches from horse enclosures. Do not plant red maple trees in or near horse enclosures.

Toxic Principle

Pyrogallol.

Clinical Signs

Consumption of the wilted leaves is known to cause oxidative damage to equine erythrocytes that may result in intravascular or extravascular hemolysis, Heinz body formation, and/or methemoglobinemia. After consumption, horses exhibit clinical signs within 1 to 2 days. Symptoms include destruction of red blood cells (anemia), weakness, dark urine, difficulty breathing, abortion, and death. The fatality rate after consumption has been reported to be between 50-65%.

Animals Affected

Horses, alpacas, zebras

References Used

Wilson, D. A., DVM. (2012). Clinical veterinary advisor: The horse. St. Louis, MO: Elsevier Saunders.

Knight, A. P., & Walter, R. G. (2001). A guide to plant poisoning of animals in North America. Jackson, Wyo.: Teton NewMedia.

Burrows, George E., & Tyrl, Ronald J. (2013). Toxic plants of North America. Hoboken: Wiley-Blackwell.

https://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants/red-maple

Mayapple (Podophyllum peltatum L.)

Description 

Mayapple is a perennial herb of the Barberry family. Leaves are umbrella-shaped and are about 8 inches wide with 5-9 lobes. Plants that have a single leaf do not flower, while those with two leaves develop a single flower in the axil of the leaf stalks. The flower appears at the end of the downward-curved flower stalk about 1 inch long. The flower, with 6 or more white petals and about 1.5-2 inches across, blooms in April to May, and is eventually replaced by a green ovoid fruit. The plant withers away by mid-summer.

Although the creeping, fleshy rhizome has been used to prepare medicine commercially, it is poisonous by contact. The green leaves and unripened fruit are poisonous but the fruit becomes edible as it ripens and turns greenish-yellow in color. 

Distribution

Mayapple is found throughout the eastern and midwestern states of the U.S., from New York to Georgia and as far west as eastern Kansas and northeastern Oklahoma. Mayapple grows in colonies in damp meadows, woodlands, pastures, and along roadsides, and is a familiar spring woodland plant in all counties of Illinois. 

Conditions of Poisoning

Poisoning of livestock occurs primarily in the spring, but the plant is usually avoided and seldom eaten in harmful amounts by livestock. The root is the most toxic part and handling of it may cause dermatitis or other skin problems in humans. 

Toxic Principle

The toxic principles include the bitter resinous substance podophyllin, which is extractable with alcohol and precipitated in water. Podophyllin is actually a mixture of at least 16 physiologically active compounds, which are divisible into two groups, the lignans and flavonols. One of the active lignans is podophyllotoxin.

Clinical Signs

General signs include purgation, catharsis, and other signs referable to gastroenteritis.

Affected cattle may show the following signs: hypersalivation, anorexia, lacrimation, diarrhea, and excitation which lasts about 1 day. The muzzle and intermandibular area as well as the eyelids may become swollen.

When swine consume mayapple shoots or leaves, death may occur after few signs.

Experimental studies with a podophyllotoxin from a plant in the same family, also termed mayapple, show evidence of degenerative changes in the liver, intestine, testis and pancreas in orally exposed animals. 

Animals Affected

Cattle, swine, dogs, cats

Milkweed, Common (Asclepias syriaca L.)

         

Description

Common milkweed is an herbaceous perennial that can grow from 2 to 6 feet tall, though typically only grows to 3-4 feet. The stems of the plant are stout and leaves are light green, simple, and oblong, and are alternate and opposite. Stems and leaves produce a milky juice when injured. Flowers are dusty pink or lavender and fragrant, and grow in domed, drooping umbels in the leaf axis. Seed pods are 2 to 4 inches long and have a warty appearance, and split open when ripe to release numerous silky-tailed seeds which are dispersed by the wind.

Distribution

Common milkweed can be found in all parts of the central to eastern United States. The plant can be found in fields, open woods, and by roadsides and railroad tracks.

Conditions of Poisoning

All parts of the plant are poisonous when eaten and toxicity is retained when dried.

Control

Milkweeds tend to grow singly or in small groups and can be controlled by digging out individual plants or selectively spraying an herbicide such as 2,4-dichlorophenoxyacetic acid (2,4-D). Care should be taken not to include milkweed when making hay, as toxicity is not reduced by drying.

Toxic Principle

Cardiac glycosides and resinoids. The cardiac glycosides affect myocardial conduction and contractility in the poisoned animal.

Clinical Signs

Signs of poisoning usually begin within 8-10 hours after ingestion and severity is influenced by how much of the plant was consumed. Symptoms include vomiting, stupor, weakness, spasms, and rapid and/or weak pulse.

Animals Affected

Milkweed species are known to affect sheep, goats, cattle, horses, domestic fowl, cats, and dogs

References Used

Knight, A. P., & Walter, R. G. (2001). A guide to plant poisoning of animals in North America. Jackson, Wyo.: Teton NewMedia.

https://plants.ces.ncsu.edu/plants/all/asclepias-syriaca/

http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=b480