21 – Poisonous Mushrooms

Question 1

What is mushroom poisoning relatively common in?

Answer 1

• Humans
• Dogs: indiscriminate eating habits
  o Mushrooms fragment easily in the GIT

Question 2

Death cap mushroom

Answer 2

• Wet, warm weather
• Related to ‘destroying angel’
• MOST toxic mushroom in the WORLD
• **majority of poisonings in animals is DOGS

Question 3

*Death cap mushroom: target

Answer 3

• LIVER
• KIDNEY
• GIT
• *one mushroom can be LETHAL (LD50 in dogs: 0.5mg/kg BW)
  o Poor to grave diagnosis (high mortality rate!)

Question 4

*What are the 4 classical stages of death cap mushroom toxicity?

Answer 4

1. Latency period: 6-12hrs post ingestion
   a. No clinical signs, detection of alpha-amantins in urine
2. GI phase: 6-24hrs post ingestion
   a. Vomiting, bloody diarrhea, abdominal pain, anorexia, dull/lethargic
3. Honeymoon phase: 24-48hrs post ingestion (lasts 12-24 hrs)
   a. False recovery, close monitoring of bloodwork is essential: elevated liver enzymes
4. Terminal phase/”hepatorenal” phase: 36-72hrs post-ingestion
   a. Fulminant liver failure, hepatic encephalopathy, increase liver enzymes, azotemia, metabolic acidosis, death due to acute liver failure

Question 5

Death cap mushroom: histo

Answer 5

• Centrilobular to massive hepatocellular necrosis with collapse of hepatic cords
• Hemorrhages

Question 6

Death cap mushroom: management

Answer 6

• NO antidote
• Early decontamination: often missed due to long latency
• Aggressive supportive care with hepatoprotectants
  o OCTREOTIDE: inhibits gall bladder contraction and contracts Sphincter of Oddi

Question 7

Fly agaricus and panther cap

Answer 7

• Worldwide
• Characteristic ‘warts’
• Fishy odour=attractive to dogs

Question 8

*Fly agaricus and panther cap: target

Answer 8

• CNS
• *one mushroom can be lethal
• Ibotenic acid=excitatory (NDMA glutamate receptor agonist)
• Muscimol=inhibitory (GABA agonist)
• Onset: could be within 30mins of ingestion

Question 9

Fly agaricus and panther cap: clinical features

Answer 9

• Alternating phases of CNS depression and CNS stimulation
• GI: vomiting, diarrhea, abdominal pain, hypersalivation
• CNS: disorientation, lethargy, miosis, hyperesthesia
• Severe: respiratory failure, bradycardia, seizures, coma

Question 10

Fly agaricus and panther cap: management

Answer 10

• No antidote
• Early decontamination
• Sedation: acepromazine (if not hypotensive)
• Tremors: methocarbamol
• Seizures: GABA-agonist drugs with caution (diazepam)
  o **Could potentially lead to excessive CNS depression (increased risk of severe sedation, respiratory depression or even coma)
• Symptomatic and supportive care

Question 11

Fly agaricus and panther cap: diagnosis and prognosis

Answer 11

• History, rapid onset of neuro signs, mushroom ID
• VDL: detection of muscimol and ibotenic acid in stomach contents, urine
  o PCR mushroom ID
• Prognosis: variable on response to symptomatic and support care
  o Dogs have died

Question 12

Magic mushrooms

Answer 12

• Hallucinogens and heat sensitive
• Limited toxicity info in animals
• Death is unlikely
• Serotonin receptor agonists

Question 13

Magic mushrooms: clinical features

Answer 13

• CNS: mydriasis, ataxia, disorientation, vocalization, nystagmus
• Aggression
• Hyperthermia, tachycardia
• Not associated with coma
• Rarely fatal

Question 14

Magic mushrooms: management

Answer 14

• Decontamination
• No antidote
• Mild cases: self-limiting
• Symptomatic and supportive care
  o Low stimulation environment
  o Agitation: sedation
  o Thermoregulation
  o Seizure management

Question 15

What are some points about other mushrooms with clinical significance?

Answer 15

• GI irritants
• **ACUTE GASTROENTERITIS
• Management: decontamination, supportive care (IVFT, gastroprotectants)
• Prognosis: good with treatment (recovery within hours to days)
• Ex. Agaricus spp., Chlorophyllum spp.