PNS II - ANS II

Question 1

Provide the locations of nicotinic receptors. What type of receptors are they? How do they function?

Answer 1

• nicotinic N
  
  • ligand gated
  • autonomic ganglia, adrenal medulla
• nicotinic M
  
  • ligand gated
  • neuromuscular junctions
• function - channel protein, ACh binds and allows cations to rush in

Question 2

What is the effect of nicotine on the parasympathetic ganglia?

Answer 2

• stimulates then blocks them

Question 3

Describe how to treat nicotine toxicosis in a dog.

Answer 3

• decontamination
  
  • emesis if orally exposed in past hour
  • gastric lavage within 2-4 hours, give activated charcoal and cathartic, whole bowel irrigation
  • dermal exposure - wash with mild hand dishwashing detergent
• control seizures - benzodiazepines (diazepam, lorazepam), barbiturates
• treat hyperthermia - external cooling with tepid running water and fanning
• positive pressure ventilation and supplemental oxygen
• treat symptoms - isotonic crystalloid fluids for cardovascular effects
• atropine for severe bradycardia
• acidification of urine with ammonium chloride to hasten excretion

Question 4

What is used to acidify urine? Why is urine acidification useful in treating nicotine toxicosis?

Answer 4

• ammonium chloride - hastens excretion

Question 5

Name three toxic compounds found in tobacco. What are their toxic effects?

Answer 5

• pyridine alkaloids (nicotine)
• teratogens (anabasine, anatabine)
• polycyclic aromatic hydrocarbons (PAHs) on combustion - carcinogenic, mutagenic, teratogenic

Question 6

What is the most appropriate method for decontamination following ingestion of tobacco plants and why?

Answer 6

• emesis, enterogastric lavage, activated charcoal
• charcoal is most common as most cases are livestock
  
  • in livestock decontamination is limited to charcoal

Question 7

What is the purpose of administering atropine to treat tobacco plant toxicosis?

Answer 7

• to treat parasympathetic effects

Question 8

Name three toxins found in poison hemlock. What is the general name of these toxins and how do they act?

Answer 8

• piperidine alkaloids
  
  • stimulates then blocks nicotinic receptors at autonomic ganglia, neuromuscular junction, adrenal medulla
• effect depends on toxin
  
  • y-coniceine is stimulatory, teratogenesis, early stages of plant, most toxic
  • coniine has mixed effects, teratogenesis, late stages of plant (seeds)
  • N-methyl coniine is inhibitory

Question 9

Which of the toxins in poison hemlock is most toxic?

Answer 9

• y-coniceine

Question 10

What is the characteristic smell of urine and breath of animals with poison hemlock toxicosis?

Answer 10

• musty and mousy, smells like rotting cardboard

Question 11

Name the toxins found in lupine. What are the mechanisms of action of these toxins? What is lupinosis?

Answer 11

• quinolizidine alkaloids - nicotinic
• piperidine alkaloids - nicotinic
• anagyrine - teratogenic
• lupinosis - acute liver atrophy due to eating lupines

Question 12

Which domestic animal species is most commonly affected by lupine poisoning and why?

Answer 12

• sheep - they will eat anything

Question 13

Name two US states in which lupine toxicity is prevalent.

Answer 13

• montana
• idaho
• utah

Question 14

Name the lupine toxin associated with teratogenesis. What is the appearance of animals affected by the teratogenic syndrome induced by lupine toxins? Explain this teratogeny.

Answer 14

• anagyrine
• animals have crooked front limbs, neck, and spine
• may have a cleft palate
• happens in utero - dam eats toxic lupines and it affects embryo/fetus

Question 15

Describe how to treat poison hemlock or lupine toxicosis.

Answer 15

• nonspecific - charcoal, gastric lavage, assisted respiration
• avoid overexcitement and stress

Question 16

Name a toxin present in lobelia and its mechanism of action.

Answer 16

• nicotinic alkaloids - lobeline, lobelidine

Question 17

Name the toxin found in golden chain and its mechanism of action.

Answer 17

• nicotinic quinolizidine alkaloid - cytisine

Question 18

Provide the mechanism(s) of toxicity of levamisole (imidazothiazole) .

Answer 18

• acts as a nicotine like ganglionic stimulant
• has both nicotinic and muscarinic effects
• first there is stimulation than blockade of ganglionic and skeletal muscle transmission

Question 19

Describe how to treat levamisole toxicosis.

Answer 19

• no antidote
• just supportive and symptomatic care
• atropine ca be used to help control some cholinergic signs

Question 20

Why is decontamination not possible or advisable for poisoning by bronchodilators?

Answer 20

• rapid absorption and onset of clinical signs - don’t have time
• emesis only possible within 15-30 minutes of ingestion

Question 21

Describe how to treat poisoning due to bronchodilators.

Answer 21

• supportive therapy for clinical signs
  
  • IV fluids for hypotension
  • diazepam for hyperactivity
  • IV propranolol for tachycardia

Question 22

Name a drug used to treat tachycardia.

Answer 22

• propranolol

Question 23

What are the clinical signs of β-adrenergic syndrome (decongestant toxins)?

Answer 23

• weakness
• tachycardia
• vasodilation (hypotension)
• bronchodilation
• hypokalemia
• hyperactivity
• tachypnea
• depression
• muscle tremors
• death

Question 24

Describe how to treat poisoning due to decongestants.

Answer 24

• decontamination
  
  • emesis in early toxicosis
  • activated charcoal, cathartic
  • gastric lavage
• control seizures, hyperactivity, tremors
  
  • phenothiazine (acepromazine, chlorpromazine) or barbiturate
• give IV fluids, treat hyperthermia
• treat tachycardia with IV propranolol
• acidify urine with ammonium chloride to enhance drug elimination

Question 25

Identify two drugs that can be used and one that should not be used to control seizures following poisoning by decongestants.

Answer 25

• yes use - acepromazine, chlorpromazine
• no use - diazepam (can make dogs more agitated)

Question 26

Provide the mechanism(s) of toxicity of amitraz (found in mange, mite, tick, and lice treatments and pesticides). Why is amitraz contraindicated in horses?

Answer 26

• binds to a2 adrenergic receptors in CNS causing sedation (agonism)
  
  • a2 receptor is presynaptic
  • stimulation - decreased neurotransmitter (NE) release
• binds to a1 and a2 receptors in PNS causing agonism
• inhibits monoamine oxidase (MOA) causing behavioral and neurotoxic effects
  
  • MAO catabolizes catecholamine neurotransmitters intraneuronal
• amitraz is contraindicated in horses because it causes ileus

Question 27

What is the antidote for amitraz toxicosis? What is its mechanism of action?

Answer 27

• a adrenergic antagonists - atipamezole, yohimbine
• reverse bradycardia, hyperglycemia, and CNS depression

Question 28

Provide four clinical signs of adrenergic syndrome and two toxic agents that can cause them.

Answer 28

• a adrenergic syndrome
  
  • hypertension, tachycardia, pale mucous membranes, mydriasis, decreased GI motility, hyperactivity
• B adrenergic syndrome
  
  • weakness (hypotension), bronchodilation, hypokalemia, hyperactivity, tachypnea, depression, muscle tremors, death
• mixed a and B adrenergic syndrome
  
  • hypertension, tachycardia, mydriasis, dry mucous membranes
• toxins causing adrenergic syndromes - decongestants
  
  • pseudoephedrine
  • phenylephrine
  • phenylpropanolamine
  • ephedrine

Question 29

Provide four clinical signs of sympatholytic syndrome and two toxic agents that can cause them.

Answer 29

• sympatholytic - adrenergic drugs that inhibit the SNS by affecting the release of NE or EPI
  
  • anti adrenergic syndrome
• vomiting, hyperventilation, convulsion, hypotension, bradycardia or tachycardia, heart block, arrhythmias, lethargy, decreased or absent bowel sounds
• a adrenergic antagonists
  
  • non specific - phentolamine, phenoxybenzamine
  • a1 specific - prazosin, doxazosin, tamsulosin
  • a2 specific - yohimbine, idazoxan
• B adrenergic antagonists
  
  • non specific - propranolol, timolol, nadolol, pindolol
  • B1 specific - metoprolol, acebutolol, atenolol, esmolol
  • B2 specific - butoxamine