TOXICOLOGY Flashcards
Describe the lethal dose (LD50)
The dose that would kill 50% of the test population
Define the effective dose (ED50)
The dose that would benefit 50% of the test population
Define the therapeutic index (TI)
The ratio between the LD50 and the ED50 (LD50/ED50)
What are the five main routes of intoxication?
- Ingestion
- Cutaneous
- Inhalation
- Injection
- Ocular
What does VPIS stand for?
Veterinary poison information service
What is the overall role of the VPIS?
To provide advice on poisons and treatments
What are the eight components found in a ToxBox?
Activated charcoal
Apomorphine
European viper serum
Fresh frozen plasma
Methocarbamol
Acetylcysteine
Vitamin K1
Intralipid 20%
How would you treat a poisoned animal?
- Stabilise heart rate, breathing and temperature
- Gather info from owner
- Prevent continued absorption of the poison
- Give antidote if available
- Give symptomatic and supportive care
List five methods of preventing continued poison absorption
Wash
Gastric evacuation
Gastric lavage
Absorbant
Elimination
List three drugs used to induce gastric evacuation (vomiting)
3% Hydrogen peroxide
Xylazine (cats)
Apomorphine (dogs)
When might you not want to induce gastric evacuation (vomiting) in an animal?
- Seizures due to risk of aspiration
- Depression/coma
- Loss of gag reflex
- Hypoxia
- Species unable to vomit
- Ingestion of corrosive/acidic substances as this will cause damage to the oesophagus on the way back up
- Recent abdominal surgery/hernia
Within how many hours after poison ingestion would it still be effective to induce gastric evacuation?
Within two hours of ingestion
Describe briefly a gastric lavage procedure
- Put the animal under a light anaesthesia
- Place a cuffed endotracheal tube (to prevent water/normal saline entering the lungs)
- Infuse tepid water/normal saline into the stomach via the endotracheal tube
- Use gravity flow to aspirate
- Repeat until the stomach is clear
What does activated charcoal do in the case of ingested poisons?
Absorbs the poison itself to prevent further tissue absorption
What do chelating agents do?
Bind non-specifically to metal ions
What is the function of cathartics?
To speed up gut movement via pulling water into the gut - diluting the poison as well as increasing gut movement
What is the toxic component of chocolate?
Theobromine
What are the clinical signs of chocolate poisoning?
Vomiting
Excitability
Ataxia
Tachycardia
What are the treatment methods for chocolate poisoning?
Decontamination
Symptomatic treatment
What are four of the toxins that have specific antidotes?
Anticoagulant rodenticides
Ethylene glycol
Psychoactive drugs
Paracetamol
What are the clinical signs of anticoagulant rodenticide poisoning?
Depression
Anorexia
Vascular collapse
Internal/external haemorrhage
How would you diagnose anticoagulant rodenticide poisoning?
Prolonged clotting time
Urinalysis: haematuria
Post mortem: haemorrhage
What can be used to treat anticoagulant rodenticide poisoning?
Vitamin K1
What are the early clinical signs (1-2 hrs) of ethylene glycol poisoning?
Weakness
Vomiting
Un-coordination
What are the delayed clinical signs (24-96 hrs) of ethylene glycol poisoning?
Polydipsia
Anuria
Haematuria
Death
What can be used to treat ethylene glycol poisoning?
Ethanol (20% ethanol via IV)
What are the clinical signs of psychoactive drug poisoning?
Rapid CNS signs dependent on psychoactive agent
What is the treatment for psychoactive drug poisoning?
Decontamination
Symptomatic treatment
Specific antidote (if aware of which specific drug was ingested)
What is the enzyme missing from some animals making them susceptible to paracetamol poisoning?
Glucoronyl transferase
How does the glucoronyl transferase enzyme prevent paracetamol toxicity?
Glucoronyl transferase metabolises the toxic intermediate of paracetamol metabolism - N-acetyl-p-benzoquinone - which oxidises haemoglobin into methaemoglobin
What are the clinical signs of paracetamol poisoning?
Facial/pulmonary oedema
Cyanosis
Haemolysis
Jaundice
What treatment is used for paracetamol poisoning?
Acetlycysteine
Vitamin C
Methylene blue
