Quiz

Question 1

Neurotoxicants

Organophosphate pesticides

Answer 1

• MOA Irreversible inhibition of AChE => cholinergic overstimulation
• ​CS Muscarinic:
  
  • SLUDGE-M
  • Nicotinic muscle fasciculations face
    
    • Horses => colic, dehydration
    • Cattle => rumen stasis; NOT MIOSIS + sheep => depression
    • Dogs/Cats => CNS progressing to convulsions
  • Chlorpyrifos => more severe nicotic signs in cats (muscarinic tolerance) ​
• DX: Atropine test ​
• TX:
  
  • GI decon
  • Atropine Oximes => reactivates AChE
  • Diazepam, barbiturates ​
• OPIDN (OP-induced delayed nurotoxicity) motor neuron degeneration no tx

Question 2

Neurotoxicants

Ivermectin

Answer 2

• Soil fungus: stretomyces avermitilis
• Dewormer/antihelminth in cattle
• MOA: GABA-A receptor agonist; inc GABA release
• CS
  
  • Ataxia, disorientation, lethargy, mydriasis, coma, bradycardia
• DX
  
  • HX of admin
  • measured in GI, liver, fat, feces
• TX:
  
  • GI dcon (act charcoal)
  • epinephrine
  • seizure: short acting barbiturates (NOT BENZOS)
  • supportive care

Question 3

Neurotoxicants

Rodenticides (3)

Answer 3

• Bromethalin: parent and metabolite uncouple oxidative phosphorylation in CNS
• Nicotine: stimulate then block nicotinic ACh receptor
• Metaldehyde:
  
  • fuel for small heaters, molluscicide
  • metabolism converts to acetaldehyde => CNS excitation

Question 4

Neurotoxicants

Mycotoxin: Slaframine

Answer 4

• Black patch fungus on red clover
• MOA
  
  • ACh mimic; primarily muscarinic cholinergic agonism, esp exocrine glands
• CS
  
  • slobbers, bloat, diarrhea, frequent urination, feed refusal
• DX
  
  • consumption of clover with black fungus
• DDX
  
  • OPs, Botulism
• TX
  
  • Remove source, maintain hydration and electrolytes,
  • Atropine,
  • rarely fatal
  • Clinical signs resolve 48 hours after last exposure

Question 5

Neurotoxicants

Mycotoxin: Fumonisin

Answer 5

• Metabolite of fusarium from corns with stars
• MOA
  
  • Inhibits sphingosine-N-Acetyltransferase => inc sphinganine => cytotoxic
  • CS
    
    • PPE
      
      • inc RR, dec HR, pulmonary edema, resp distress, open mouthed breathing, death *
      • pigs usually recover if feed is removed
    • ELEM
      
      • target brain and liver
      • hyperexciteability, anorexia, ataxia, circling, drowsiness, blindness
      • nearly 100% fatal

Question 6

Neurotoxicants

Tremorgenic mycotoxins

Answer 6

• Penicillin, Aspergillus, Claviceps
• From food, stored grains/nuts, forage, garbage, compost
• MOA
  
  • Release of neurotransmitters from synaptosomes in CNS
• CS
  
  • diminished activity, immobility, hyperexciteability, m. tremor, ataxia, tetanic seizure

Question 7

Neurotoxicants

Ammoniated feed toxicosis

Answer 7

• Non protein nitrogen sources (urea, ammonium salts) imidazoles
• MOA: ?
• CS bovine bonkers, excitability, rapid blinking, alternate between excited and normal
• DX
  
  • HX of exposure, CS, food/rumen analysis
• DDX
  
  • OP pesticides, cyanide, grain overload, meningitis, encephalitis
• TX
  
  • Feed removal
  • 5-10 gallons cold water plus 1 gallon vinegar

Question 8

Neurotoxicants

Strychnine

Answer 8

• Seeds of strychnos-nux vomica, alkaloids to control pocket gophers
• Often used as a malicious poison
• MOA
  
  • competitive antagonist at post-synaptic spinal cord and medulla for glycine receptors => muscle disinhibition
• CS
  
  • rapid onset, little to no vomiting
  • anxiety to restlessness to stiff neck and gait to violent seizures from external stimuli
  • Death from respiratory failure and asphyxiation/exhaustion
  • saw horse stance
• DX
  
  • CS, sizure, sawhorse
• DDX
  
  • other seizure causing things
• TX
  
  • aggressive
  • Control seizures: Phenobarb or methocarbamol
  • prevent asphyxiation
  • emesis, gastric lavage
  • ion-trapping if not acidotic: ammonium chloride
  • Bicarb for acidosis

Question 9

Neurotoxicants

Salt toxicity

Answer 9

• Usually from dehydration
• MOA
  
  • diffusion of Na into CSF
  • when serum Na lowers, water diffuses into CSF
• CS
  
  • CNS, salivation, inc thirst, abdominal pain, diarrhea
• DX
  
  • serum Na levels
• TX
  
  • lower plasma Na by 0.5-1mEq/L/hr
  • loop diuretics

Question 10

Neurotoxicants

Pharmaceuticals: Xanax (Alprazolam)

Answer 10

• Benzo
• MOA
  
  • works on limbic, thalamic, hypothalamic CNS
• CS
  
  • ataxia, depression, tachycardia, diarrhea, ptylism
• TX
  
  • Flumazenil
  • GI decon, support

Question 11

Neurotoxicants

Pharmaceuticals: Ambien (Zolpidem)

Answer 11

• Bezo-like
• MOA
  
  • binds to benzo omega-1 receptor
• CS
  
  • ataxia, vomiting, lethargy
• TX
  
  • supportive, symptomatic

Question 12

CV and Hem tox

Rodenticides

Answer 12

• MOA
  
  • inhibits vitamin K1 epoxide reductase
  • prevents the formation of vit K dependent clotting factors (2, 7, 9, 10)
• CS
  
  • hemorrhage, coagulopathies, depression, anorexia, anemia
• DX
  
  • History of exposure, coagulopathy, response to vit K, clotting tests
• TX
  
  • emetic, absorbant, cathartics, vit K, transfusion
• 1st gen: warfarin, short half life, low potency
• 2nd gen: brodifacom, long half life, high potency

Question 13

CV and Hem tox

Nitrate toxicosis

Answer 13

• Fertilizers, many plants, contaminated water
• Pigs > cattle > sheep > horses
• MOA
  
  • nitrate to nitrite => vasodilation and oxidized ferrous => methemoglobin CS
  • cyanosis, brown MM, ataxia, seizures, coma, death
• DX
  
  • nitrate levels feed/water
• TX
  
  • methylene blue
  • cats and horses = ascorbic acid
  • cattle = feed corn

Question 14

CV and Hem tox

Cardiac glycosides

Answer 14

• Ornamental plants
• MOA
  
  • Inhibits Na/ATPase pump through competition with K for binding sites
• CS
  
  • 1hr to weeks after ingestion
  • trembling, staggering dyspnea
  • Inc Ca and intracellular Na
  • racing HR, arrhythmias, weak pulse
  • hyperkalemia
• DX
  
  • hx of access, CS, analysis of vomitus
• TX
  
  • GI decon
  • DIGOXIN
  • arrhythmias: propranalol
  • hyperkalemia: diuretics

Question 15

CV and Hem tox

Cyanide tox

Answer 15

• Wild cherry, white clover, fresh sorghum, fertilizers, pesticides, rodenticids
• DRY: NON-TOXIC
• Hydrogen cyanide: VOLATILE
• MOA
  
  • inhibition of cytrochrome C oxidase
  • blocks mitochondrial function and cell respiration
• CS
  
  • cherry red, non-clotting blood
  • sudden death, dyspnea
• DX
  
  • HX, cherry red, non-clotting blood, frozen stomach contents
• TX
  
  • Sodium nitrite => induces methemoglobinemia
  • Sodium Thiosulfate

Question 16

CV and Hem tox

Methylxanthines

Answer 16

• coffee, caffeine, chocolate
• MOA
  
  • competitive antagonist of adenosine receptors
  • CNS stimulation
  • vasoconstriction, tachycardia
  • prevents Ca reuptake => inc skeletal and cardiac m. contractility
  • Inhibits phosphodiesterase => inc cAMP and GMP
• CS
  
  • vomiting, diarrhea, diuresis, hyperactivity, seizures, coma, arrhythmias
• DX
  
  • Theobromine, chem analysis serum, organs
• TX
  
  • GI decon
  • arrhythmias: lidocaine (except cats)
  • seizure: bezos and barbiturates
  • maintain respiration
  • fluid diurese

Question 17

Musculoskeletal Toxicity

Phenoxyacetic acid herbicides

Answer 17

• MOA: unknown
• CS
  
  • GI, weakness/ataxia, myotonia w/serious toxicosis, renal tubular necrosis, rumen atony, hepatic necrosis
  • DX
    
    • Oral/GI ulcers
  • TX
    
    • GI decon
    • ion trapping

Question 18

Musculoskeletal Toxicity

Ergot alkaloids

Answer 18

• Produced in small grains by claviceps purpurea and endophylic fungus in tall fescue
• MOA
  
  • Alkaloids are dopamine serotonin agonists and alpha adrenergic antagonists
• CS
  
  • Cows: summer slump, fescue foot, reduced feed intake, weight gain, heat intolerance, retain winter coat, poor reproduction
  • Horses: abortions, weak foals, prolonged gestation
  • Pigs: infertility, early parturition, decreased milk production
• TX
  
  • remove source and prevent secondary infection
  • Metoclopromide and domperidone
    
    • normalizes gestation in mares

Question 19

Musculoskeletal Toxicity

Ionophores

Answer 19

• Monensin in beef/dairy to prevent bloat and coccidiosis
• MOA
  
  • Increased intracellular Na and Ca => mitochondrial swelling and cell death in muscles
  • CL 12-17 hours after OD
• horses: anorexia, colic, sweating on flanks, weak
• cattle: above plus diarrhea and respiratory difficulty
• poultry: less susceptible, down with legs and wings stretched out
• dogs: posterior paresis, lasalocid => paralysis
• cats: salinomycin => neuropathy
• DX
  
  • increased muscle enzymes, myoblobinuria, inc AST, inc CK, inc LDH
  • dec K, dec Ca
• DDX
  
  • other colic sources: vit E and Se deficiency, white snakeroot, blister beetle, gossypol, botulism
• TX
  
  • feed change, supportive therapy
  • recovered animals may die later from exertion

Question 20

Musculoskeletal Toxicity

Tetanus

Answer 20

• Clostridium tetani
• MOA
  
  • toxins block release of GABA and glycine => muscle overstimulation
• CS
  
  • LOCKJAW
  • stiff, twitching, collapse, death
• TX
  
  • Antitoxin if early in exposure
  • vaccination
  • supportive therapy
  • poor prognosis

Question 21

Respiratory toxins that cause ventalatory muscle paralysis

Answer 21

1. Botulism
2. Tetanus
3. Snake Venom
4. OP insectisides
5. Strychnine

Question 22

Respiratory toxins that cause respiratory center depression

Answer 22

1. Barbiturates
2. Opiaites/opioids
3. hypnotics4. sedatives
4. ethylene glycol
5. tricyclic antidepressants
6. crude oil