Poisonous Plants, part 1 Flashcards
What are the cyanide/cyanogen containing plants?
Chokecherry (Prunus sp), Vetch, Hydrangea, Johnson grass (Sorghum)
What is the toxic principle with cyanide ?
- hydrogen cyanide is absorbed from the GI tract and inhibits mitochondrial cytochrome oxidase.
- oxyhemoglobin cannot release oxygen for electron transport in the cytochrome system leading to cellular hypoxia
What are the CS with cyanide/cyanogen toxicity?
- often acute death
- key finding is bright red blood and/or MM. hydrogen cyanide gas in the rumen may have a faint bitter almond smell
- also excitement, muscle tremors, dyspnea, salivation, urination/defecation
Tx of cyanide toxicity
- sodium nitrite: creates methemoglobin which has greater affinity for cyanide than cytochrome oxidase, stripping cyanide from the enzyme
- sodium thiosulfate: reacts with cyanide to form thiocyanate, which can be excreted by urine
What are the nitrate accumulating plants?
Pigweed (Amaranthus), Nightshades (Solanum), Oat hay, Sorghum, Rye, Alfalfa
What species is most affected by nitrate accumulating plants?
-cattle due to re-education to nitrite by microbes in the rumen
What is the toxic principle of nitrate accumulation?
-nitrite causes methemoglobinemia, leading to dark brown/chocolate colored blood, which has diminished oxygen carrying capacity
What are the CS associated with nitrate accumulation?
-muddy MM, dyspnea, tremors/convulsions, ataxia, tachycardia
What is the tx for nitrate accumulation?
-1% methylene blue (reduces methemoglobin)
Which plants are cardiotoxic?
- Oleander (cardiac glycosides)
- Foxglove (cardiac glycosides)
- Lily of the valley (many cardiac glycosides)
- Yew (taxing alkaloids)
- Azalea/rhododendron (andromedotoxins)
What are the clinical signs associated with cardiotoxic plants?
- salivation, nausea, vomiting, hematochezia
- weakness, bradycardia, hypotension
- AV block
- Collapse and acute death are possible
What is the treatment for cardiotoxic plants?
- emesis in SA
- charcoal
- SC
- atropine for severe bradycardia
- isoproterenol, procainamide, or quinidine for AV block
Which plant causes primary photosensitization?
St. John’s wort (Hypericum perforated)
Which plants cause secondary photosensitization (liver failure)?
- Rape (Brassica sp.)
- Blue green algae (Microcystis sp.)
- Groundsel (Senecio sp)
- Crotalaria sp
- Amsinckia intermedia
What is primary photosensitization?
When ingested or absorbed agent is metabolized to become photodynamic (becomes a high energy molecule when exposed to UV light, causing membrane and free radical damage)
What is secondary photosensitization?
When impaired hepatic function reduces excretion of plant pigments (such as phylloerythin, a chlorophyll breakdown product).
What are the CS with photosensitization
- erythema, edema, peeling
- pruritus
- hyperesthesia
- may progress to exudation, ulceration
What kind of toxin is Lupine?
A neurotoxic plant
What species does Lupine affect?
-most commonly affects sheep but is teratogenic in cattle
What CS does lupine ingestion cause?
-salivation, incoordination, head pressing, aimless angering, excitement, muscle tremors, seizures, dyspnea
What teratogenic affects does lupine have in cattle?
- valves exposed in utero, day 40-70 of gestation …causes “crooked calf syndrome”
- torticollis, scoliosis, carpal flexure
Treatment of lupine toxicity?
None
What kind of toxin is poison hemlock?
A neurotoxin, pyridine-type alkaloid
What are the clinical signs associated with poison hemlock?
- very rapid CS
- salivation, V/D, muscle tremors, weakness, convulsions, death from respiratory failure
What is the tax for poison hemlock?
None
What kind of toxin is Larkspur?
A neurotoxin, contains polycyclic diterpene alkaloids
-neuromuscular blocker, cholinergic and nicotinic antagonist
Which species is most susceptible to larkspur?
Cattle
What are the CS associated with Larkspur?
-bloat, excitability, muscle tremors, stiffness, paresis, seizures, arrhythmias, death from respiratory paralysis
What is the tx for larkspur?
Physostigmine may reverse the neuromuscular blockade
- relieve bloat if present
- decontaminate and supportive care
What kind of toxin is Nightshade?
Neurotoxin
- accumulating nitrates
- GI irritant (glycoalkaloid)
- neurotoxin (aglycone)
What are the CS associated with nightshade?
- anorexia, nausea, abdominal pain, v/d
- apathy, paresis/paralysis, prostration, unconsciousness
