L5. Bromethalin

Question 1

Bromethalin

Answer 1

Rodenticide

Formulated into baits

Block mitochondrial energy production (CNS)

Mahor toxic effect is cerebral edema

Cats are more sensitive

Question 2

Bromethalin

Clinical Picture

Answer 2

• At a higher dose
  
  • above LD50
  • SIgns develop 4-24 hours after ingestion
  • Muscle tremors, hyperthermia, hyperesthesia, excitability, seizures
• At lower Doses
  
  • below LD50
  • Signs develop within 2-7 days
  • Progressive CNS depression with ataxia, paresis, hing limb paralysis, coma

Question 3

Bromethalin

Toxicity

Answer 3

Question 4

Bromethalin

MOA

Answer 4

Metabolized to desmethylbromethalin

Parent and metabolite uncouple oxidative phosphorlyation especially in the CNS

REduced ATP impairs sodium pump, and leads to fluid accumulation in myelin sheaths and CNS

Edema of myelin tracts leads to paralysis

Question 5

Lesions

Answer 5

No gross lesions

Question 6

Clinical SIgns

Answer 6

• Lower doses
  
  • tremors
  • ataxia
  • Vomiting
  • Anisocoria
  • Progressive depresison
  • HInd linl paralysis
  • Lateral recumbancy
  • Coma
• Higher doses
  
  • onset in 4-36 hrs
  • Muslce tremors, convulsions, hyper exticability, running fits, hyperesthesia, focal or generalized motor seizures percipitated by light/noise

Question 7

Bromethalin:

Diagnosis

Answer 7

History of exposure

Characteristic microscopic lesions in brian and spinal cord

Possible hyperglycemia

EEG: spike and wave acitivty, voltage depression. abdnormal Hi voltage slow wave typical of cerebral edema

Chemical detection of bromethalin in tissues, (Brain, fat, liver, kidney)

Question 8

Bromethalin:

Treatment

Answer 8

Emetics early – before seizures

Repeat acitvated charcoal, saline, cathartic,

Dexamethasone prolongs survival time but does not reverse syndrome

Mannitol / furosemide for cerebral edema

Diazepam, methocarbamol or phenobarbital as needed for seizures

Supportive care: upt o 3 weeks for recovery

Prognosis: Very guarded in moderate to severe cases

Question 9

Bromethalin

Environmental and Food Safety

Answer 9

All animals species are targets

Low probability for relay toxicosis

Food Safety impact is not known

Fat soluble so can pass through milk

Question 10

Strychnine:

Sources

Answer 10

Extract of stychnos-nux vomica

Indole alkaloid

Rodenticide

Red ro Green Dye

Question 11

Strychnine:

Mechanisms

Answer 11

Rapidly absorbed

Antagonizes glycine

Inhibitory effects of relflex acrs are lost

Excreted via urine

Question 12

Strychnine:

Toxicity

Answer 12

Dogs most sensitive

Cats also affected

Question 13

Strychnine:

Clinical Picture

Answer 13

Acute onset - 15 min to 2 hours

Nervousness, resltless, tremors early after exposure

Rarely vomit

Sensitive to external stimuli - especially loud noises, touch, light

“Saw horse” stance

Explosive onset of tetanic seizures - whole body regidity

Death from anoxia

Question 14

Strychnine:

Diagonsis

Answer 14

Does not reliably produce lesions

Finding bait in stomach is common

Dye from baits is a great clue

Detection of strychnine in stomach

Urine too, liver last resort

Question 15

Strychnine:

Differentials

Answer 15

Tetanus, metaldehyde, penitrem A, Roquefortine, Avitrol, Theobromide, Nicotine, Caffeine, Amphetamine, Cocoain, OP’s, Carbamates, Pyrethrins, Mushrooms, Blue-green algea, chlorinated hydroxarbons, Water deprivation

DDX: for seizuers is tough

Strychnine intoxications are exceptionally sensitive to external stimuli

You can start a voilent seizure with a loup clap

Question 16

Strychnine:

Treatment

Answer 16

Control Seizures

Supportive care

Decontamination

Fluids