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)
