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34 Cards in this Set
- Front
- Back
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What are the Big 3 classes of toxicosis causing insecticides?
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1. Organophosphates
2. Carbamates 3. Pyrethrins / Pyrethroids |
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Organophosphates and Carbamates
How are they used? |
Either:
Topical or Systemic |
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Organophosphates and Carbamates
Sources? |
Contaminated Feedstuffs
Improper use on crops/animals Malicious use -> poisoning |
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Organophosphates and Carbamates
ADME |
Absorption - Rapidly absorbed by any ROA
Distribution - rapid Metabolism - P450s (Sulfone has more Toxic metabolites - "oxons") Excretion - rapid |
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Organophosphates and Carbamates
Mechanism |
Competitive INHIBITION of carboxyl ester hydrolases (AchE)
causing continuous stimulus by Ach |
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Organophosphates and Carbamates
Difference in mechanisms -- what's the deal with Organophosphates? |
OP's will Phosphorylate the AchE - an IRREVERSIBLE binding which causes "Aging" of the enzyme
Tx: 2-PAM given before aging (2-PAM, primarily at N-R's) |
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Organophosphates and Carbamates
Difference in mechanisms -- what's the deal with Carbamates? |
Carbamylate the AchE - this is REVERSIBLE and may alst minutes-hours (avg 30-40 mins)
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Organophosphates and Carbamates
Clinical Signs are related to what systems? |
Muscarinic, Nicotinic, CNS
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Muscarinic Signs
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Muscarinic = Dumbels
Diarrhea Urination Miosis Bronchospasm (and resp secretion) Emesis Lacrimation Salivation |
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Nicotinic Signs
CNS Signs |
Twicthing, Shakiness, Tremoring, Seizures
Behavior Changes, Comatose |
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Cause of Death in OP/Carbamate toxicosis?
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Hypoxia due to Respiratory Depression and Paralysis
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Name two specific OPs.
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Coumaphos *slow than usual OP, seizure leads to death
Chlorpyrifos *moreso in Large Animals (rumen stasis) and Cats -- depression, anorexia, tremors, cervical ventroflexion |
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Dx? (OPs and Carbamates)
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Meausre AchE inhibition (if >80% inhibited, it is likely the cause of signs)
Whole Blood in Mammals Plasma in Birds OR Brain or Retina *also Atropine Response (will reverse most dumbels signs) |
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Tx? (OPs and Carbamates)
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Emesis (often spontaneous)
AC Dermal - BATHE 1st: Atropine (Muscarinic Signs) 2nd: 2-PAM aka Pralidoxime (Nicotinic Signs) Supportive Care |
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Pyrethrins (from flower) and Pyrethroids (synthetic)
Two Types? |
Type I - Permethrin -- gah cats!
Type II - Fenvalerate - contains CN group |
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Pyrethrins and Pyrethroids
ADME |
RAPID everything
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Pyrethrins and Pyrethroids
Toxicity |
Variable among species - but Piperonyl Butoxide enhances P450 metabolism with prolonged toxicity
About 100x (300x w/piperonyl) more toxic to Insects than mammals |
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Pyrethrins and Pyrethroids
Mechanism |
Enhance voltage-gated Na channels --> continuous stimulation of cells (and enhanced NT release)
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Pyrethrins and Pyrethroids
Signs |
minutes - hours (typically start w/in minutes)
Hyperexcitable: Tremor, seizure, salivation, emesis, dyspnea, death |
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Dx? (Pyrethrins and Pyrethroids)
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Can be detected in blood, brain, or liver to confirm EXPOSURE (not necessarily toxicosis)
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Tx? (Pyrethrins and Pyrethroids)
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Decon / Bathe
Control Seizures, Tremors Methocarbamol IV (tremors) 20% IV lipid (bind vascular drug) Supportive Care |
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Metadehyde... where do you find it?
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Used in Slug/Snail baits
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Metadehyde... what does it do?
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Rapidly absorbed - Metabolized to Acetaldehyde - crosses BBB -> toxicity -- decreases Serotinin, NE, and GABA in brain, increases MAO.... complete CNS disregulation
(LD bw 100-500mg/kg) |
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Metadehyde... clinical signs?
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Anxiety, Mydriasis, tremors
Ataxia (rums) Colic (horses) polypnea, tachycardia, opisthotonus, acidosis, hyperthermia |
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What are the big differences between Metaldehyde Tox and:
A. Strychnine Tox? B. OP Tox? |
A. **NOT really hyperesthetic like with Strychnine
B. **No Vomit or Diarrhea like OPs |
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Metaldehyde Tx?
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Decon, control seizures/tremors, ventilation, fluids, acid/base (caution with NaHCO3)
Supportive Care Prognosis good if caught early |
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Amitraz...where is it?
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in Flea Collars for dogs
used for some parasite control in cattle and swine (dog eats collar... spray/dip used carelessly) |
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Amitraz - caution
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NEVER use on Horses or Cats
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Amitraz - mechanism?
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not completely known, but think it is an Alpha-agonist and weak MAOI
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Amitraz - signs?
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ataxia, depression, disorientation, vocalization
bradycardia emesis, diarrhea, anorexia |
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Amitraz - Dx?
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can detect in tissues (again, exposure only, not level)
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Amitraz - Tx?
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the usuals - decon/bathe, maybe IV-lipid
...perhaps Alpha-Antagonist (yohimbine or atipamizole) |
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Citrus Oil Extracts
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Not well understood - but may cause CNS depression and hypothermia
Salivation, Skin Irritation, Tremors, possibly Acute Necrotizing Dermatitis and Septicemia |
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Macrolides are bad for?
(-ecitns) |
Collies (sheepdogs, Australian shepherds) and collie-like dogs
Lack of p-glycoprotein at BBB --> GABAergic problems. *IV-lipid shows some promise |
