Bracken Fern

Thiaminase - Ataxia, muscle tremors

Horsetail

Thiaminase - Weight loss, ataxia

Rhubarb

Oxalates - Kidney failure

Halogeton

Oxalates - Hypocalcemia, renal insufficiency, uremia

Dock

Oxalates - Low levels; poisoning rare

Dumbcane

Proteolytic Sap - Burning in mouth

Caladium

Oxalates and Proteolytic Enzymes

Philodendron

Oxalates and Proteolytic Sap

Jack in the Pulpit

Calcium Oxalate Crystals - Burning when embedded in mucous membranes

Skunk Cabbage

Calcium Oxalate Crystals

Milkweed

Depression, weakness, staggering, tetanic seizures

Rosary Pea

Phytotoxin - Gastroenteritis, purging, ulceration

Castorbean

Phytotoxin Ricin - GI irritation, vomiting, bloody diarrhea

Black Locust

Phytotoxins - Depression, nausea, diarrhea, irregular pulse

Poinsettia

Irritant sap, emesis, catharsis

Sensitive Fern

Liver failure with hepatic encephalopathy (ataxia, icterus)

Water Hemlock

Cicutoxin (Neurotoxin) - Violent convulsions and death

Ponderosa Pine

Isocupressin - Premature, weak, stillborn calves

Pigweed

Nitrates - Asphyxia, methemoglobin, brown blood

Lambsquarters

Nitrates - Methemoglobin

Oats

Nitrates - Methemoglobin

(Grass tetany and photosensitization)

Corn

Nitrates - Methemoglobin

Vulvovaginitis in swine fed moldy corn

St. Johnswort

Primary Photosensitization - Liver Undamaged

Buckwheat

Primary Photosensitization

Lantana

Secondary Photosensitization - Metabolic product accumulates because of liver dysfunction

Horsebrush

Secondary photosensitization/Severe liver damage

Trifolium

Slobbers when infected with Rhizoctonia (black patch disease)

Photosensitization

Alfalfa

Foamy bloat

Occasionally photosensitization

Birdsfoot Trefoil

Possibly contains hydrogen cyanide

 Quercus (Oak)

Tannins - Gastritis, nephritis, edema, depression

Cocklebur

Anorexia, depression, vomiting, dyspnea, convulsions, nephritis, hepatitis 

White Snakeroot

Excreted in milk (milk sickness) - vomiting, trembling, thirst, delirium, ataxia, ketosis, fatty liver

Poison Ivy (Toxicodendron)

Dermatitis (Allergy - requires sensitization)

Poison Sumac (Toxicodendron)

Dermatitis (Allergy - Requires sensitization)

Poison Oak (Toxicodendron)

Dermatitis (Allergy - Requires sensitization)

Horseradish

Mucous membrane irritation

Brassica (Rape, Kale, Cabbage, Brocolli)

Gastroenteritis 

Red Baneberry

GI Upset

Marsh Marigold

GI Upset

Christmas Rose

GI Distress

Buttercup

Gastroenteritis 

Ground Ivy

Salivation, sweating, dyspnea, and death in horses

Iris

Purgative, gastroenteritis 

Daphne

Corrosion of oral mucosa, vomiting, stupor, convulsions, bloody diarrhea

Aesculus (Horsechestnut, Buckeye)

CNS signs

Mellilotus (Sweetclover)

Coumarin changed to dicoumarol in moldy hay

Internal bleeding and anemia

Sweet Vernal Grass 

Coumarin - Internal bleeding, anemia

Moonseed

Gastroenteritis 

Mayapple

Catharsis, purging, gastroenteritis

Allium (Onions, Chives)

Heinz bodies, hemolytic anemia, hemoglobinuria, icterus 

Elderberry

Alkaloid - Purgative

Corn Cockle

Sapogenin - Gastroenteritis

Bouncing Bet

Saponin - Gastroenteritis 

Pokeweed

Saponin/Alkaloid - Purginig diarrhea, nausea 

Tung Tree

Saponin - Bloody Diarrhea 

Foxglove

Cardiac Glycosides - GI distress, cardiac irregularities, twitching, sweating

Dogbane

Cardiac Glycosides

Lily-of-the-Valley

Cardiac Glycosides

Vomiting in Cows

Oleander

Cardiac Glycosides - Cariac signs, colic, vomiting, diarrhea, tremors, paralysis

Datura (Jimsonweed, Angel's Trumpet)

Atropine Poisoning - Red, dry, blind, mad, hot

Belladonna

Atropine - Red, dry, mad, hot, blind

Henbane

Atropine - Red, mad, hot, blind, dry

Taxus (Yew)

Cardiac depressant - Death

(Not toxic to deer)

Akee

Hypoglycin - Severe hypoglycemia, vomiting

Box Elder

Hypoglycin - Hypoglycemia, vomiting

Pasture-associated myopathy

Mistletoe

Lectin - Smooth muscle stimulation with no characteristic symptoms/lesions

Senecio

Pyrrolizidine Alkaloids - Liver disease, icterus, photosensitization, CNS signs, straining, and prolapsed rectum

Fiddleneck

Liver Cirrhosis

Walking Disease of Horses - Unthriftiness, aimless walking, sleepiness, delirium

Rattlebox

Pyrrolizidine Alkaloid - Liver disease, icterus, photosensitization, CNS signs, prominent hemorrhage

Poppy

Opium - Excitement, ataxia, gastroenteritis, addiction

Prickly Poppy

Alkaloids - Dilated capillaries, edema, experimentally-induced glaucoma 

Dicentra (Bleeding Heart, Squirrel Corn, Dutchman's Breeches)

Poppy Alkaloids - Salivation, colic, trembling, convulsions, down (looks like grass tetany)

Celandine

Sap causes severe gastroenteritis 

Bloodroot

Poppy Alkaloids - Capillary dilation, edema

(Used to make paste that treats horse sarcoids)

Larkspur

Hypersensitivity, tremors, collapse, coma

Secondary bloat or vomition 

Lupine

CNS excitement or depression

Crooked calf syndrome - Arthrogryposis

Golden Chain

CNS Excitement or Depression

Hairy Vetch

Posterior paralysis, scoliosis, aneurysm

Dermatitis, pruritus, conjunctivits, diarrhea, granulomas in many tissues 

Can be fatal

Crown Vetch

Toxic to monogastrics

Star of Bethlehem

Bulb is poisonous - depression, salivation, bloating, death (sheep)

Wisteria

Gastroenteritis, vomiting, diarrhea

Poison Hemlock 

Excitement, ataxia, then depression

Mousy odor in breath and/or urine

Lobelia 

Vomiting, sweating, paralysis, feeble pulse, coma, death

(Purple = Great Lobelia)

(Red = Cardinal Flower)

(White = Indian Tobacco)

Tobacco

Shake, stagger, vomit, staring

Limb deformities in piglets

Climbing Nightshade (Solanum)

GI irritation, nervous signs, drowsy, trembling, weak

Black Nightshade (Solanum)

GI irritation, nervous signs, drowsy, trembling, weak

Horse Nettle (Solanum)

GI irritation, nervous signs, drowsy, weak, trembling

Buffalo Bur (Solanum)

GI irritation, nervous signs, weakness, drowsiness, trembling

Veratrum

Cyclopian lambs if eaten on 14th day of gestation

Hypotension, weakness, ataxia, nausea

Death Camas

Steroid Alkaloid - Salivation, nausea, ataxia, dyspnea, GI hemorrhage

Locoweed

Excitable, irritable, abortion, congenital malformation, blind staggers 

Yellow Jessamine

Depression, respiratory failure, mydriasis

Spicebush

Tremors, ataxia, hypersensitivity, tetanic seizures, 3rd eyelid prolapse

Mountain Laurel

Salivation, colic, vomiting, collapse, and death - Cattle, sheep, and goats

Rhododendron

Depression, nausea 

Azalea

Depression, nausea

Japanese Pieris

Vomiting

Ergot 

Fungal parasite of grasses

Chronic: lameness, dry gangrene (feet, tail, ears), constriction of arterioles

Acute: nervous signs - hyperexcitability, convulsions

Buegreen Algae

Nausea, abdominal pain, diarrhea, tremors, cyanosis, convulsions, death

Death Cup

Sudden abdominal pain and vomiting, liver failure, death in 4-8 days

Fly Mushroom

GI upset, hallucinations

(Rarely fatal)

Prunus (Cherry)

Cyanide - Inhibits cytochrome oxidase so blood is bright red, cellular anoxia

Apple (Malus)

Cyanogenic seeds

Fermentation - Drunken cows

Sorghum (Sudan grass, Johnson grass)

Cyanogenic - Urinary incontinence, alopecia/urine scald on hind legs, cystitis, ataxia, myelomalacia, fetal arthrogyrposis

Nitrates - Dark brown blood

Arrowgrass

Cyanide - Bright red blood, excitation, tremors, dyspnea, death

Flax

Cyanide - Bright red blood, excitation, tremors, dyspnea, death

Marijuana

Cattle and Horses - Excitement, tremors, sweating, salivation, death

Dogs - Depression, ataxia, emesis, hypothermia

Yellow Star Thistle

Nigropallidal encephalomalacia - Chewing disease, starvation

Russian Knapweed

Nigropallidal encephalomalacia - Chewing disease, starvation

Day-Blooming Jessamine

Chronic debilitation in cattle and horses - Hypercalcemia, dystrophic calcification, lameness, plaques in aorta and endocardium

Chinaberry

Coffeeweed

Myodegeneration, recumbent, dark red urine, pale skeletal muscle, cardiomyopathy

Cotton

Cardiac insufficiency in monogastrics

Red Maple

Acute death with methemoglobinemia, cyanosis, depression

Prolonged: Intravascular hemolysis, Heinz bodies, hemoglobinuria, death 1-6 days

Panicum

Icterus

Black Walnut

Limb edema and laminitis when shavings are used as bedding 

Gastroenteritis and convulsions if dogs chew on moldy husks

False Dandelion

Stringhalt - Horses develop high stepping gait with hyperflexion

Usually resolves when taken off pasture

Hoary Alyssum

Fever, limb edema and possible laminitis in horses

English Ivy

Possible contact dermatitis

(not big cause of poisoning)

Stinging Nettle

Itching, burning skin rash

Weakness, vomiting, bronchial constriction, slow irregular heart beat in hunting dogs that run through a lot of it

Perilla Mint

Bovine pulmonary emphysema, proliferative pneumonia

Sweet Potato

Mold toxin causes pulmonary emphysema in cattle

Buckthorn

GI upset - Nausea, vomiting, colic, diarrhea, red gut mucosa

Easter Lily

Kidney damage in cats (destroys everything but basement membrane)

Easter Lily

Kidney damage in cats (destroys everything but basement membrane)

Day Lily

Kidney failure in cats

Sago Palm

Fatal liver failure in dogs

Sago Palm

Fatal liver failure in dogs

Macadamia

Vomiting, weakness, ataxia 

Vitis (Grapes and Raisins)

Vomiting and renal failure in dogs 

Hops

Malignant hyperthermia in dogs (esp greyhounds)

Kentucky Coffee Tree

Salivation, diarrhea, colic, weakness

Avocado

Cardiac failure in birds

Mastitis and cardiac failure in goats

Persimmon

Tannins in unripe fruits

Form phytobizar in horse GI tract that can't be passed

Hydrangea

Vomiting, diarrhea

Burdock

Corneal ulcers from bristles/burs (horses)

Giant Hogweed

Contact photodermatitis with large persistent blisters