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What is the toxic principle in red maple leaf toxicity?
- toxin has not been IDed, but it has oxidant properties and is most toxic when leaves are wilted/ dried
- gallic acid implicated in metHgb and hemolysis
- only toxic in horses and related species
What is the mechanism of toxicity of red maple leaves?
- oxidizing agents form hydrogen peroxide in excess of the cell's detoxifying mechanisms--> formation of heinz bodies--> hemolytic anemia
- intravascular hemolysis from erythrocyte damage and hemoglobin oxidation
- extravascular hemolysis from heinz body formation
What are signs of red maple leaf toxicity? (8)
- MMs icteric at first, then brown later
- brown urine
What is the treatment for red maple leaf toxicity?
- activated charcoal
- IV fluids
- blood transfusion
- ascorbic acid to reduce methemoglobin
What is the toxic principle in taxus yew?
- taxine alkaloids
- affects cattle and horses
What is the mechanism of toxicity of taxus yew?
taxine alkaloids produce direct effects on cardiac ion channels, resulting in conduction disturbances
What are signs of taxus yew intoxication? (5)
What is the treatment for taxus yew toxicity?
- activated charcoal
- (usually die)
What is the toxic principle in prunus (wild cherry/ sorghum/ sudan grass family)?
cyanogenic compounds, most common being glycosides amygdalin and prunasin
What is the mechanism of toxicity of prunus (wild cherry/ sorghum/ sudan grass family)?
HCN has high affinity for Fe+++ in cytochrome oxidase, thus preventing cellular respiration--> death
What are signs of prunus (wild cherry/ sorghum/ sudan grass family) toxicity? (8)
- dilated pupils
- bright red MMs
- coma or clonic seizures
- respiratory failure/ dyspnea
What is the treatment for prunus (wild cherry/ sorghum/ sudan grass family) toxicity?
- [2 step treatment]
- 1. sodium nitrite: converts Hgb to metHgb, which competes with cytochrome oxidase for CN--> forms cyanometHgb--> reactivates cytochrome oxidase, which is essential for cellular respiration
- 2. sodium thiosulfate: combines with CN molecule and cleaves it from cyanometHgb to form sodium thiocyanate--> excreted in urine
What is the toxic principle in jimson weed? (4)
- tropane alkaloids
What is the mechanism of toxicity of jimson weed?
inhibition of the parasympathetic nervous system
What are signs of jimson weed toxicity? (4)
- signs of PNS blockade
- dry MMs
- GI atony
What is the treatment for jimson weed toxicity?
- anticholinesterase- physostigmine, neostigmine (allow Ach to accumulate and be more successful in stimulating receptors)
What is the toxic principle of mushrooms?
- amanita phalloides (most toxic mushroom)- cyclopeptides (amatoxins, phallotoxins), causing liver failure
- amanita muscaris also contains parasympathomimetic agent, muscarine
What is the mechanism of toxicity of mushrooms?
- amanitins inhibit nuclear RNA polymerase-> decreased mRNA--> decreased protein synthesis--> cell death
- cells with high metabolic rate (hepatocytes, renal tubular cels, GI epithelium) are most vulnerable
What are the signs of mushroom toxicity?
- [4 phase clinical course]
- 1. asymptomatic latency (0-6 hours)
- 2. GI symptoms- nausea, vomiting, bloody diarrhea
- 3. lag period, where animal appears to have recovered
- 4. after 36-48 hours--> signs of liver failure, kidney damage, etc
What is the treatment for mushroom toxicity?
- supportive care
What is the toxic principle of dieffenbachiae (includes lilies)?
- calcium oxalate (raphides) crystals producephysical damage to skin and MMs, also cause hypocalcemia and kidney damage
- may also contain proteolytic enzymes--> histamine and kinin release (swelling of pharynx)
What is the mechanism of toxicity of dieffenbachiae (includes lilies)?
- Chewing leaves and stems causes sharp crystals (raphides) to be forcibly ejected from plant cells--> crystals readily penetrate soft tissues of GI--> physical damage to tissues
- Juice of plants--> hypocalcemia, renal tubular damage
What are signs of dieffenbachiae (includes lilies) toxicity? (5)
- pain in mouth immediately, head shaking, salivation, vocalization
- nausea, vomiting
- rarely, swelling of MMs and pharynx--> dyspnea
- muscle and cardiac signs of hypocalcemia if enough of juice/ plant water was ingested
- ultimately, renal failure in severe cases
What is the treatment for dieffenbachiae (includes lilies) toxicity? (4)
- rinse mouth with water or vinegar
- activated charcoal
- calcium (to precipitate soluble oxalates)
- if renal failure, address accordingly