Poisonous Plants Flashcards
What are 4 common cyanide/cyanogen containing plants?
- Chokecherry - Prunus spp
- Vetch
- Hydrangea
- Johnson grass - Sorghum
What is the mechanism of toxicity of cyanide?
- absorbed from the GI tract and inhibits mitochondrial cytochrome oxidase
- oxyhemoglobin cannot release oxygen for electron transport in the cytochrome system
- this leads to cellular hypoxia
When do clinical signs of cyanide toxicity occur? What is seen?
commonly within 10-15 mins of ingestion
- excitement, muscle tremors
- dyspnea
- salivation
- urination and defecation
- acute death is commonly the only sign
What are the 2 key finding associated with cyanide toxicosis?
- bright red blood (cherry-colored) and mucous membranes
- hydrogen cyanide gas in the rumen may have a bitter almond smell
What 2 treatments are used for cyanide toxicosis?
- sodium nitrate - creates methemoglobin, which has a greater affinity for cyanide than cytochrome oxidase, thus stripping cyanide from the enzyme
- sodium thiosulfate - reacts with cyanide to form thiocyanate, which can be excreted in the urine
What are 3 common nitrate-accumulating plants?
- Pigweed - Amaranthus
- Nightshade - Solanum
- Sorghym
(+ oat hay, rye, alfalfa)
What is the mechanism of toxicity of nitrate?
cause methemoglobinemia, leading to dark brown or chocolate-colored blood, which has diminished oxygen-carrying capacity
What clinical signs are indicative of nitrate toxicity?
- muddy mucous membranes
- dyspnea
- tremors, convulsions
- ataxia
- tachycardia
What treatment used for nitrate toxicity?
1% methylene blue - reduced methemoglobin
What are 5 common cardiotoxic plants?
- Oleander - Nerium oleander (oleandrin, neriine)
- Foxglove - Digitalis purpurea (increase contractility and decrease HR via vagal stimulation, prolonging diastole)
- Lily-of-the-valley - Convallaria majalis
- Yew - Taxus cupsidata (taxine alkaloids A and B, inhibit cardiac depolarization)
- Azalea (rhododendron) - andromedeotoxins bind membrane sodium channels, leading to excitation and movement of calcium intracellularly
What clinical signs are indicative of cardiotoxic plant toxicity?
- salivation, nausea, vomiting
- hematochezia
- weakness
- bradycardia, hypotension
- AV block
- collapse and acute death
What are 5 options for treating potential cardiotoxic plant ingestion?
- small animals - induce emesis if recent ingestion and minimal signs of weakness
- activated charcoal
- supportive care - IV fluids, supplemental oxygen
- severe bradycardia - Atropine
- AV block - isoproterenol, procainamide, quinidine
What plant most commonly causes primary photosensitization?
St. Johns Wort - Hypericum perforatum
What 5 plants most commonly cause secondary photosensitization?
- Rape - Brassica
- blue-green algae - Microcystis
- Groundsel - Senecio
- Crotolaria
- Amsinckia intermedia
What is photosensitization?
increased susceptibility to UV light damage
Where on the body are animals most commonly affected by photosensitization? In what areas of the world is this most common?
- white-skinned area of the dorsum and lateral body wall
- thin and non-pigmented areas, like the sclera, udders, and muzzle
regions and seasons of more intense sunlight
What are the 2 types of photosensitization?
PRIMARY - ingested or absorbed agent is or is metabolized to become photodynamic (high energy molecule is exposed to UV light and causes membrane and free radical damage) –> better prognosis, usually restricted to the skin
SECONDARY - impaired hepatic function reduces excretion of plant pigments (phylloerythrin, a chlorophyll breakdown product) –> liver and skin damage
What clinical signs are indicative of photosensitization?
- erythema, edema, peeling (sunburn)
- pruritus
- hyperesthesia
- exudation, ulceration
(most common on poorly pigmented skin!)
What animal is most commonly affected by ingesting lupine? What is the toxic principle?
sheep
lupinine - quinolizidine alkaloid that induced nicotinic effects on the CNS
What clinical signs are indicative of lupine toxicosis in sheep?
- salivation
- incoordination
- head-pressing, aimless wandering
- excitement
- muscle tremors, seizures
- dyspnea
How does lupine toxicosis compare in cows vs. sheep?
teratogen in cattle, but not sheep
- causes crooked calf syndrome to those exposed in utero days 40-70 of gestation = torticollis, scoliosis, carpal flexure
What is the toxic principle of poison hemlock?
coniine and pyridine-type alkaloids cause CNS effects
(Conium maculatum)
What clinical signs are indicative of poison hemlock toxicosis?
- salivation
- vomiting, diarrhea
- muscle tremors, weakness, convulsions
- death from respiratory failure
What animals are most susceptible to larkspur toxicosis? What is the toxic principle?
cattle
polycyclic diterpene alkaloids - neuromuscular blocker, cholinergic and nicotinic antagonist
(Delphinium)
What clinical signs are indicative of larkspur toxicosis in cattle?
- bloat
- excitability
- muscle tremors, stiffness, paresis, seizures
- arrhythmias
- death from respiratory paralysis
What are 3 parts to treating larkspur toxicosis in cattle?
- physostigmine - reverse neuromuscular blockade
- relieve bloat
- decontaminate and supportive care
Other than nitrates, what are 2 toxins found in nightshade (Solanum)?
- glycoalkaloid - GI irritant
- aglycone - neurotoxin
What clinical signs are indicative of nightshade (Solanum) toxicosis?
- anorexia, nausea
- abdominal pain
- vomiting, diarrhea
- apathy
- paresis/paralysis
- prostration
- unconsciousness
What are the 2 toxic principle of bracken fern (Pteridium aquilinum)?
- thiaminase - cleaves vitamin B1 –> polioencephalomalacia
- ptaquiloside - alkylates DNA, leading to carcinogenicity and bone marrow suppression in ruminants
What clinical signs are indicative of bracken fern toxicosis in large animals? What toxin causes specific signs in ruminants?
- incoordination
- standing with legs apart
- depression
- muscle tremors, ataxia
- blindness, retinal degeneration
ptaquiloside - BM suppression, hemorrhage, anemia, elevated pyruvic acid, tumors in bladder and other organs
What toxin in bracken fern (Pteridium aquilinum) causes specific signs in ruminants? What is commonly seen?
ptaquiloside
- BM suppression
- hemorrhage, anemia
- elevated pyruvic acid
- tumors in bladder and other organs
How is bracken fern toxicity treated?
- injectable thiamine
- no treatment for ptaquiloside
What species are most susceptible to black walnut (Juglans nigra) intoxication? What is a common source?
horses
sawdust or shavings from black walnut trees used in bedding
What clinical signs are most commonly seen in black walnut toxicity?
- acute onset of laminitis –> may progress to necrosis of dorsal laminae
- distal limb edema
- fever
What treatments are recommended for black walnut toxicosis?
- remove source and decontaminate GI tract with mineral oil or activated charcoal
- wash legs and feet
- treat for laminitis
What is the toxic principle found in castor beans (Ricinus communis)?
ricin - highly toxic glycoprotein
What clinical signs are associated with castor bean toxicosis?
- anorexia
- vomiting, diarrhea
- weakness
- muscle spasms
- uremia
- sweating, ataxia (horse)
- extensive organ edema and damage
What is the toxic principle found in cottonseed? What species are most commonly affected?
gossypol - cardiotoxic
young cattle, sheep, and pigs
What clinical signs are associated with cottonseed toxicity?
- anorexia
- red urine
- thin, pot-bellied appearance
- poor performance
- sudden death due to heart failure
What clinical signs are associated with dumbcane toxicosis?
- irritation of mucous membranes
- ptyalism
- edematous swelling of tongue and lips
- difficulty swallowing or breathing
(Dieffenbachia)
What clinical signs are associated with locoweed toxicosis?
- ataxia, hypermetria
- clicking of dewclaws (cracker heels)
- conscious proprioceptive deficits
- emaciation
- emphysema (sheep)
- abortions, teratogenesis (contracted tendons)
(Astralgus, Oxytropis)
What is the toxic principle seen in waterhemlock? What clinical signs are associated?
cicutoxin - highly toxic to cattle and horses
- acute violent tetanic seizures resembling strychnine poisoning
- rapid progression from salivation to muscle twitching, seizures, coma, and death
What does yellow star thistle cause?
nigropallidal encephalopmalacia (Chewing Disease) in horses
(Centaurea solstitiallis)
What is a classic sign associated with yellow star thistle toxicosis? What is also seen?
chewing and dropping food
- inability to eat or drink due to dystonia to muscles of lips and tongue
- continuous chewing motions with an empty mouth
- jamming food into mouth in desperation
- similar to early signs of rabies!
What is the toxic principle seen in perilla mint? What does it lead to?
perilla ketone –> pulmonary edema and pleural effusion
What clinical signs are associated with perilla mint toxicosis?
- respiratory distress (on exhalation) due to atypical interstitial edema and emphysema
- nasal discharge
What is the toxic principle found in Western false hellebore (Veratum californium)? What animals are most commonly affected?
cyclopamine –> teratogenic!
sheep, stillborn lambs
What does the effect of Western false hellebore (Veratum californium) depend on? What is seen?
stage of gestation
- day 14 = classic cyclopean deformity (monkey-faced lambs)
- day 17-18 = hind limb motor nerve paralysis
- day 12-30 = craniofacial deformities (cleft palate, harelip, brachygnathia)
- day 30-36 = shortened leg from metacarpal and metatarsal bone hypoplasia
What is the toxic principle in white snakeroot (Eupatorium ragosum)? What animals are most commonly affected?
trematone (ketone) –> passed to young in milk
horse and cattle
What clinical signs are associated with white snakeroot (Eupatorium ragosum) toxicity?
- weakness, depression
- myocardial necrosis and congestive heart failure –> ventral edema, jugular pulse, tachycardia (horses)
- ataxia, depression, muscle tremors, acetone breath (cattle)
What does red maple (Acer rubrum) toxicity lead to? What clinical signs are associated?
RBC lysis in horses
- depression
- icterus
- anemia
- hemoglobinemia, heomglobinuria
What does Ponderosa pine (Pinus ponderosa) toxicity cause?
abortions characterized by weak contractions, excessive discharge, a small calf, and retained fetal membranes
