Is Wormseed Mustard Poisonous to Dogs, Cats, Horses, and Livestock?

Wormseed Mustard on This Page Means Erysimum cheiranthoides

The Wormseed Mustard covered here is Erysimum cheiranthoides, a Eurasian annual or biennial mustard that has become widely naturalized in North America and other temperate regions. It is also called Wormseed Wallflower, Treacle Mustard, Treacle Wallflower, and Wallflower Mustard. The plant belongs to Brassicaceae, but the genus Erysimum is chemically unusual because it combines the normal mustard-family glucosinolate system with cardenolide cardiac glycosides.

The common name reflects former use of the seeds in preparations intended to expel intestinal worms. That historical use does not establish a safe medicinal dose for animals. The same plant contains compounds capable of causing gastrointestinal irritation and, after sufficient exposure, clinically important cardiac-glycoside poisoning.

Accepted Taxonomy and Synonyms

The accepted scientific name is Erysimum cheiranthoides L. Carl Linnaeus published the species in Species Plantarum in 1753. The plant has been placed historically in names such as Cheiranthus cheiranthoides, Cheirinia cheiranthoides, Cheiranthus aquaticus, Cheiranthus erysimoides, Erysimum japonicum, and Erysimum lanceolatum.

Older varieties and subspecies based on plant height, branching, leaf form, pod length, or geography may appear in floras, seed records, grain-identification documents, herbarium labels, and older agricultural references. These synonyms matter for search and identification, but the PAWS page should keep the accepted name centered so the plant is not confused with unrelated “wormseed” plants or ornamental wallflowers.

Native and Introduced Range

The native range extends from Europe across northern and central Asia to northern Japan. It includes much of northern, central, and eastern Europe, parts of the Balkans and Caucasus, Siberia, Mongolia, northern and central China, Korea, and Japan. The plant has moved widely through agriculture, trade, and disturbed-ground habitats.

It has been introduced across much of North America, including Canada and the United States, and is also recorded from regions such as Great Britain, Ireland, Italy, North Africa, southern Argentina, New Zealand, and other temperate areas. Its spread has been aided by contaminated crop seed, grain screenings, rail transport, road traffic, disturbed soil, flood movement, and agricultural machinery.

Habitat and Exposure Settings

Wormseed Mustard grows in cultivated fields, gardens, roadsides, railway corridors, waste ground, disturbed pasture, riverbanks, gravel bars, floodplain openings, dry streambeds, and other open or recently disturbed habitats. It often becomes established where soil has been cultivated, compacted, flooded, graded, or otherwise disrupted.

Agricultural exposure matters more than ornamental exposure. Mature seedpods can enter grain, hay, green chop, silage, screenings, and other harvested material. Dogs and cats may encounter the plant along field edges, farmyards, trails, gardens, and disturbed urban ground. Horses and livestock are more likely to receive a clinically meaningful dose through contaminated feed than by voluntarily grazing a few bitter plants.

Growth Form, Leaves, Flowers, and Pods

Erysimum cheiranthoides is usually an annual but may behave as a winter annual or biennial. Plants commonly grow approximately 6 to 40 inches tall and can occasionally become taller under favorable conditions. The stems are erect, ribbed, and usually branched in the upper portion. Fine, tightly pressed, star-shaped hairs cover much of the foliage and stem; these appressed branched hairs are useful in separating the plant from some similar yellow-flowered mustards.

The lower leaves may form a temporary basal cluster and often wither before the plant reaches full fruiting. Stem leaves are alternate, narrow, lance-shaped to elliptic, and commonly one to four inches long. Margins range from nearly smooth to shallowly or coarsely toothed. Leaves taper toward a short stalk or narrow base.

The flowers occur in a terminal raceme that elongates as the plant matures. Each flower has four yellow petals in the cross-like pattern characteristic of Brassicaceae, four sepals, six stamens, and one pistil. The flowers are small and may become visually overshadowed by the many developing seedpods beneath them. The fruit is a narrow, upright or strongly ascending silique that eventually splits into two valves, releasing numerous small yellow-brown, reddish-brown, or dark-brown seeds.

Why the Seeds Matter

Canadian grain-identification guidance describes Wormseed Mustard seeds as very small, roughly around one millimeter long, with a variable oblique outline, a prominent curved radicle ridge, and a granular or slightly greasy-looking surface. Their small size allows them to contaminate cereal grain and screenings. Once seeds are mixed into grain, meal, pellets, or screenings, animals cannot choose around them.

Seeds matter because historical livestock concern centered on seed-contaminated feed, and because seed and reproductive tissues carry high-value defensive chemistry. They are not the only poisonous part of the plant, but they are one of the most realistic routes for concentrated animal exposure.

Distinguishing Wormseed Mustard from Similar Species

Wormseed Mustard may be confused with Tall Wormseed Mustard, Small Wormseed Mustard, western wallflowers, tumble mustards, hedge mustards, yellow rocket, wild mustard, flixweed, field pennycress, and other yellow-flowered crucifers. Accurate identification matters because different mustard-family plants vary in glucosinolate chemistry, nitrate risk, seed toxicity, and whether they contain cardenolide cardiac glycosides.

Erysimum inconspicuum generally has larger anthers, longer sepals and petals, and longer pods than typical E. cheiranthoides. Wormseed Mustard typically has small bright-yellow flowers, relatively short anthers, narrow upright pods, appressed branched hairs, and a weedy annual or biennial habit. When livestock disease or feed contamination is involved, a complete plant specimen with pods and seeds is much more useful than a single leaf photograph.

“Wormseed” Is a Common-Name Trap

“Wormseed” alone is one of the most dangerous common-name shortcuts on this page. Epazote and American Wormseed commonly refer to Dysphania ambrosioides or Dysphania anthelmintica, which are unrelated plants with different chemistry. Levant Wormseed is associated with Artemisia cina, an aster-family plant historically used as a source of santonin.

Wormseed Mustard is Erysimum cheiranthoides. It is a mustard-family plant with glucosinolates and cardenolides, not an epazote, not a santonin plant, and not the same thing as every “wormseed” listed in herbal or historical references. Emergency identification should use the scientific name or a plant specimen, not the common name alone.

The Erysimum Genus Is Chemically Unusual

Most members of Brassicaceae rely principally on glucosinolates and their breakdown products for chemical defense. Erysimum retains that ancestral mustard-family system but has also evolved the ability to manufacture cardenolide cardiac glycosides. Modern comparative work has shown that most tested Erysimum species produce both toxin classes.

This dual chemistry means Wormseed Mustard should not be treated as an ordinary mildly irritating mustard. Gastrointestinal irritation may be the first and most visible effect, but a sufficiently large exposure can also create a cardiac-glycoside emergency. That distinction is the main reason this page needs more depth than a generic Brassicaceae stomach-upset entry.

Glucosinolates in Wormseed Mustard

The three principal glucosinolates reported in E. cheiranthoides are glucoiberverin, glucoiberin, and glucocheirolin. Modern work confirmed their predominance in the studied Elbtalaue accession and detected additional aliphatic and indole glucosinolates at lower concentrations. These compounds differ in side-chain oxidation and length, which affects their biological activity, odor, hydrolysis products, and role as feeding cues or deterrents.

Older livestock references often grouped mustard-family poisoning under “mustard oils” or isothiocyanates without resolving the precursor glucosinolate or exact breakdown product. Those descriptions remain useful clinically, but they should not override modern species-specific chemistry. Wormseed Mustard can produce irritating glucosinolate breakdown products, but allyl isothiocyanate should not be named as its established dominant toxin.

How the Glucosinolate-Myrosinase System Works

Intact glucosinolates and myrosinase enzymes are stored in separate cellular compartments. When an animal chews the plant, or when tissue is cut, ground, frozen, wilted, or digested, the compartments rupture and the enzyme contacts its substrate. Myrosinase removes glucose from the glucosinolate, and the unstable remaining molecule rearranges into an isothiocyanate, nitrile, epithionitrile, or thiocyanate depending on the original side chain and local chemical conditions.

These reactive products deter herbivores through odor, taste, mucosal irritation, and cellular toxicity. The animal may experience salivation, nausea, abdominal pain, vomiting, diarrhea, or feed refusal before enough plant material is consumed to create a systemic dose. Feed contamination bypasses part of this deterrent because the plant material is already mixed into something the animal wants to eat.

Cardenolide Cardiac Glycosides

Cardenolides are glycosides containing a steroid-like core and a five-membered lactone ring. Their principal molecular target is sodium-potassium ATPase, a membrane pump found throughout animal tissues and essential for maintaining cellular sodium and potassium gradients. Inhibition raises intracellular sodium and indirectly increases intracellular calcium. Cardiac contractions may become stronger but slower, while conduction through the heart becomes unstable.

The gastrointestinal tract and nervous system are also affected because sodium-potassium ATPase is not confined to the heart. Vomiting, diarrhea, weakness, depression, trembling, poor perfusion, collapse, and seizures may therefore accompany cardiac abnormalities. A poisoned animal may look like it has a severe gastrointestinal illness before the arrhythmia becomes obvious to the owner.

Lei and Colleagues’ Seed Studies

Zhen-Huan Lei and colleagues conducted a series of chemical investigations of Wormseed Mustard seed during the 1990s and early 2000s. Their work isolated numerous previously undescribed cardiac glycosides rather than merely detecting a nonspecific positive cardenolide reaction. In 1996, Lei and colleagues reported cheiranthosides I, II, and III together with known cardenolides.

In later studies, Lei and colleagues identified cheiranthosides VI and VII together with glucoerysimoside, then cheiranthosides VIII, IX, and X from the seeds. The 2002 Chemical and Pharmaceutical Bulletin study characterized glycosides based on strophanthidin and cheiranthidin through spectroscopic analysis. This work provides direct exact-species chemical support for the seed-toxicity concern.

Na⁺,K⁺-ATPase Inhibition

Lei, Kuniyasu, Tai, Nakayama, and Nohara also evaluated sodium-potassium ATPase inhibition by cardiac glycosides isolated from E. cheiranthoides. This work connected the plant’s isolated chemistry to the established molecular target of cardiac-glycoside poisoning.

Different sugars and aglycones alter a cardenolide’s absorption, tissue distribution, persistence, and binding characteristics. The complete plant therefore contains a mixture with potentially different pharmacokinetic and toxicodynamic properties rather than one compound behaving exactly like pharmaceutical digoxin.

Cardenolide Movement Through the Plant

Martin Alani, Gordon Younkin, Mahdieh Mirzaei, Pavan Kumar, and Georg Jander published work on acropetal and basipetal cardenolide transport in E. cheiranthoides. They detected ten cardenolides distributed among different tissues. Concentrations were highest in young leaves and reproductive tissues, consistent with the plant allocating strong chemical defense to actively growing and reproductively valuable structures.

Grafting and transport experiments showed movement both toward the shoot tip and toward lower portions of the plant. Leaves can produce or contain cardenolides that are redistributed to other tissues, so toxicity cannot be assigned only to seeds. Seeds are historically and practically important, but the whole plant should be treated as potentially toxic.

Younkin and Colleagues’ Herbivore Study

Gordon Younkin and colleagues published 2024 work showing that cardiac glycosides protect wormseed wallflower against some, but not all, glucosinolate-adapted herbivores. The researchers used genetic manipulation and feeding experiments to distinguish the protective effects of cardenolides from those of glucosinolates.

Removing or reducing cardiac-glycoside production made the plant more acceptable to certain specialist herbivores that ordinarily tolerate mustard-family glucosinolates. The work confirms that cardenolides are a biologically functional defense in living Wormseed Mustard, not merely trace chemicals isolated from old seed samples.

Historical Cattle and Swine Poisoning

Canadian livestock reports describe cattle becoming ill and pigs dying after feed was contaminated with enough Wormseed Mustard seed. John M. Kingsbury included the species in the 1964 reference Poisonous Plants of the United States and Canada.

The historical reports do not provide the complete analytical detail expected from a modern case series. No exact cardenolide profile, glucosinolate concentration, dose per kilogram, electrocardiogram, serum potassium result, or contaminant screen was documented in the available summaries. The reports remain important because they identify seed-contaminated feed as a realistic exposure route and demonstrate that the outcome can extend beyond temporary gastrointestinal irritation.

Why Swine Are at Particular Feed-Contamination Risk

Pigs consume prepared rations rapidly and may receive weed seeds ground or mixed into cereal grain. Once the seeds are incorporated into meal, pellets, or screenings, the animal cannot select around the bitter contaminant. Cardiac glycosides survive drying better than many volatile irritants, and grinding may increase digestive access to seed constituents by breaking the seed coat.

Vomiting, diarrhea, weakness, depression, irregular heart rhythm, collapse, or sudden death after a new grain or screenings source should prompt immediate preservation and testing of the feed. The remaining ration should not be fed to another animal as a test.

Cattle and Other Ruminants

Cattle usually avoid bitter mustard plants when adequate forage is available. Exposure increases during drought, overgrazing, confinement, feed shortage, or contamination of harvested forage. The rumen can alter glucosinolates and some of their breakdown products, but it does not guarantee detoxification. Cardenolides can remain active, and nitrate may create an additional hazard when plants have grown under accumulation-favoring conditions.

Salivation, feed refusal, diarrhea, weakness, reduced milk production, poor exercise tolerance, abnormal pulse, collapse, or sudden death warrants examination of the full ration and not merely the pasture. If multiple animals are affected, the event should be treated as a feed-source or environmental investigation.

Horses

Horses may encounter Wormseed Mustard in hay, pasture weeds, grain screenings, or contaminated bedding and feed. They cannot vomit, so gastrointestinal irritation may appear as feed refusal, depression, diarrhea, or colic. Because cardiac glycosides are also involved, a horse with colic and an abnormal pulse requires more than routine gastrointestinal observation.

Cardiac-glycoside effects may produce weakness, sweating, abnormal pulse quality, bradycardia, tachycardia, arrhythmia, collapse, or sudden death. Electrocardiography, electrolyte testing, and careful cardiovascular assessment are appropriate when exposure is meaningful or signs extend beyond mild feed refusal.

Dogs and Cats

Dogs may chew plants along field margins or ingest seed-bearing weeds, garden waste, or contaminated animal feed. Cats are less likely to consume a large amount but may nibble foliage or contact discarded plants. A small taste may cause only drooling, nausea, vomiting, diarrhea, or appetite loss.

Because the species contains cardiac glycosides, repeated vomiting accompanied by weakness, collapse, an abnormal heartbeat, cold extremities, trembling, or profound depression requires emergency assessment. No dependable safe amount has been established for dogs or cats. Body size, plant tissue, maturity, amount of seed, and chemical variation all affect the dose.

Environmental Contaminants Require Separate Evidence

A plant growing on treated agricultural land may carry pesticide or herbicide residues. A plant growing in contaminated soil may also contain or retain metals or other pollutants. These possibilities apply to many plants and do not establish that Wormseed Mustard is a special accumulator of every environmental toxin.

The clinical pattern should guide testing. Tremors, excessive secretions, pinpoint pupils, or respiratory secretions may suggest certain insecticides. Bleeding may suggest anticoagulants. Severe neurologic or renal disease may point toward metals, pesticides, mycotoxins, ionophores, another weed, or a ration error. Plant identification and contaminant investigation should proceed together when illness is broader than the expected glucosinolate and cardiac-glycoside syndrome.

Nitrate as a Conditional Forage Hazard

Nitrate is present to some degree in nearly all plants. It accumulates when root uptake continues while drought, frost, prolonged cloudiness, nutrient imbalance, herbicide injury, or another stress reduces photosynthesis and protein synthesis. Brassicas can accumulate clinically important nitrate under the right conditions. Species name alone does not establish the concentration, and no reliable evidence supports labeling every Wormseed Mustard plant as inherently high in nitrate.

Suspect hay, silage, green chop, or pasture should be sampled and analyzed, with the result clearly identified as nitrate, nitrate-nitrogen, or potassium nitrate and reported on a fresh- or dry-matter basis. Nitrate-associated methemoglobinemia commonly produces gray-brown mucous membranes, severe air hunger, and chocolate-brown blood. Cardiac glycosides more characteristically produce vomiting, weakness, hyperkalemia, and slow, rapid, or irregular heart rhythms. Mixed exposure is possible.

Diagnosis

Diagnosis begins with identification of the plant and confirmation of the exposure route. Bring the whole plant when possible, including flowers, pods, seeds, leaves, stems, and roots. Preserve the feed label, grain sample, hay, screenings, silage, ration, or pasture material involved.

Veterinary evaluation may include electrocardiography, continuous heart-rate monitoring, blood pressure, serum potassium and other electrolytes, kidney values, glucose, acid-base status, complete blood count, packed-cell volume, urinalysis, and hydration assessment. A veterinary digoxin immunoassay may cross-react with some plant cardiac glycosides, but a negative result does not exclude poisoning because individual Wormseed Mustard cardenolides do not necessarily react exactly like digoxin.

Feed testing may include botanical seed identification, nitrate analysis, pesticide screening, mycotoxin testing, ionophore screening, mineral analysis, and evaluation for other toxic weeds. Representative sampling is essential because weed seeds and contaminants may be unevenly distributed.

Important Differential Diagnoses

Other glucosinolate-containing forage plants include Wild Mustard, Black Mustard, Rapeseed, Canola, Turnips, Kale, Cabbage, Tansy Mustard, Flixweed, Field Pennycress, Wild Radish, and Wintercress. Their toxin profiles and likelihood of nitrate, sulfur, or glucosinolate-related disease vary.

Other cardiac-glycoside plants include Oleander, Foxglove, Milkweed, Lily of the Valley, Dogbane, Kalanchoe, Desert Rose, Yellow Oleander, and Star of Bethlehem. Rapid gastrointestinal and cardiac illness also requires consideration of yew, aconite, ionophore-contaminated feed, metaldehyde, organophosphate or carbamate pesticides, electrolyte disturbance, mycotoxins, cyanogenic plants, nitrate plants, and primary cardiac disease.

Veterinary Treatment

There is no Wormseed Mustard-specific antidote. Treatment depends on amount, plant part, time since exposure, current neurologic status, cardiac rhythm, serum potassium, hydration, and the suspected balance between glucosinolate irritation and cardiac-glycoside absorption. The source must be removed immediately.

A veterinarian may induce vomiting in a neurologically normal dog or cat after recent substantial ingestion when aspiration risk is low. Activated charcoal may be administered professionally and repeated in selected cardiac-glycoside cases because enterohepatic recirculation can prolong exposure. Gastric lavage is reserved for exceptional severe exposures under anesthesia with endotracheal intubation and a protected airway.

Intravenous fluids support circulation but must be selected and monitored carefully when significant cardiac dysfunction or hyperkalemia is present. Electrocardiography and serial electrolyte measurements guide antiarrhythmic and supportive treatment. Atropine or glycopyrrolate may be selected for clinically important bradycardia. Other arrhythmias require rhythm-specific medication rather than one universal cardiac drug.

Digoxin-specific antibody fragments can bind several plant-derived cardiac glycosides and may be considered in severe poisoning with dangerous arrhythmias or hyperkalemia. Availability, dose estimation, cost, and expected cross-reactivity must be handled by the treating veterinarian or toxicologist.

Prognosis

The prognosis is generally good after a small exposure producing only brief gastrointestinal irritation. Improvement should follow removal of the source and appropriate supportive treatment.

The outlook becomes guarded when persistent vomiting, severe diarrhea, dehydration, hyperkalemia, bradycardia, tachyarrhythmia, conduction block, hypotension, seizures, collapse, or delayed treatment develops. Animals that receive early monitoring, decontamination when appropriate, electrolyte management, and antidotal treatment when indicated have a better chance of recovery than animals first examined after severe cardiac instability has developed.

Prevention

Control Wormseed Mustard before it forms mature seedpods in grain fields, hayfields, paddocks, feed-crop margins, gardens, and disturbed farmyards. Inspect harvested grain and screenings for small reddish-brown mustard seeds. Do not feed contaminated screenings, rejected grain, weed-heavy hay, or unknown feed waste without botanical identification and professional evaluation.

Grinding and pelleting do not guarantee detoxification. Provide adequate safe forage so livestock are not forced to consume bitter weeds. Remove pulled plants and seed-bearing garden waste from animal areas. Test suspect forage for nitrate after drought, frost, prolonged cloudiness, heavy nitrogen fertilization, or herbicide injury, and investigate pesticide or other contaminant exposure separately rather than assuming that every abnormal sign originates from Wormseed Mustard itself.