TOXICOLOGY - Clinical Approach to Poisoning Flashcards
How do you manage a poisoning case?
- Stabilise the clinical signs
- Take a detailed history
- Prevent continual absorption of the toxin (decontamination)
- Give an antidote if available
- Removal of the toxin
Which six paramaters should be included when establishing a database for investigating poison cases?
PCV/TS
Urea/creatinine (to investigate renal function)
ALT (to investigate hepatic function)
Glucose
Electrolytes
Urinalysis
Which five decontamination techniques can you use to prevent further absorption of a toxin into the gastrointestinal tract?
Induce emesis
Gastric lavage
Absorbants
Enemas
Surgical removal
List six contraindications to inducing emesis
Patients with neurological dysfunction
Corrosive ingestion
Patients predisposed to aspiration
If toxin was ingested over 4 hours ago (emesis won’t be helpful at this point)
If patients have already vomited the toxin
Ingestion of button batteries
Why is inducing emesis contraindicated in patients with neurological dysfunction?
Patients with neurological dysfunction are at an increased risk of aspirating the vomit
What can you use as a decontamination technique instead of emesis in patients with neurological dysfunction?
Gastric lavage
Why is inducing emesis contraindicated in patients that have ingested button batteries?
If you induce emesis and the batteries get stuck in the oesophagus, they can establish an electrical current and cause oesophageal necrosis
Give two examples of toxins that prevent emesis
Cannibus
Codeine
Which emetic drug is most commonly used in dogs?
Apomorphine
What classification of drug is apomorphine?
Opioid
What is the mechanism of action of apomorphine?
Apomorphine acts on the dopamine receptors in the chemoreceptor trigger zone to trigger emesis
How should apomorphine be administered?
Subcutaneously
How can the sedative effects of apomorphine be reversed?
You can reverse the sedative effect of apomorphine with naloxone
Which emetic drug is most commonly used in cats?
Dexmedetomidine
What classification of drug is dexmedetomidine?
α2-adrenoreceptor agonist
What method is recommended to improve the effectiveness of dexmedetomidine?
Administer the dexmedetomidine followed by slowly spinning the cat on a chair
How can the sedative effects of dexmedetomidine be reversed?
The effects of dexmedetomidine can be reversed with atipamezole
How do you carry out a gastric lavage?
- Place your patient under general anaesthetic (making sure to intubate with a cuffed endotracheal tube to reduce the risk of aspiration)
- Advance a stomach tube and infuse with 5 - 10ml/kg of warm water
- Repeat until the water runs out clear
List three contraindications to carrying out a gastric lavage
Corrosive ingestion
Patient is a high anaesthetic risk
If toxin was ingested over 4 hours ago (gastric lavage won’t be helpful at this point)
Which three methods can you use to administer activated charcoal?
In small volumes of food
Syringe
Stomach tube
How often should you administer activated charcoal if your patient has ingested a toxin that undergoes enterohepatic recycling?
Administer activated charcoal every 4 hours for 24 - 48 hours
Give three examples of toxins which undergo enterohepatic recycling and thus require repeated doses of activated charcoal?
Paracetamol
Theobromine
Ibuprofen
Why should you leave two hours between giving activated charcoal and oral medication?
The activated charcoal with absorb the oral medication
What should you warn the owners of after administering activted charcoal?
Warn the owners activated charcoal will stain the faeces black
You can get formulations of activated charcoal with cathartics. What is the function of cathartics?
Cathartics speed up gut movement by pulling water into the gut - diluting the toxin as well as increasing gut motility
Which two common toxins are not absorbed by activated charcoal?
Xylitol
Ethylene glycol
Which two decontamination techniques can you use to prevent further topical absorption of a toxin?
Washing
Ocular irrigation
What can you use to prevent the animal from grooming themselves when you’re carrying out topical decontamination?
Buster collar
Shaving the fur
Why is it important to never wash an animal in an active seizure?
Animals in an active seizure are at risk of aspirating the water
How long should you carry out ocular irrigation to decontaminate the eye?
Irrigate the eye for at least 15 minutes with water or saline
What can you use to check the eye for corneal ulcers?
Fluoroscein
Which two methods can be used to help remove a toxin from the body?
Intravenous fluids
Intravenous lipid emulsion
How can intravenous fluids be used to help remove toxins from the body?
Intravenous fluids can be administered to increase renal elimination of toxins (e.g. theobromine)
How can intravenous fluids also be used as supportive care in poisoning cases?
Intravenous fluids can be used to support the kidneys, rehydrate patients exhibiting vomiting and diarrhoea and stabilise blood pressure in hypotensive patients
How can intravenous lipid emulsions be used to help remove toxins from the body?
Intravenous lipid emulsions can be used to eliminate lipophilic toxins and toxins with a short half life
Give three examples of toxins that can be removed from the body with intravenous lipid emulsions
Permethrin
Cannibis
Ibuprofen
What is important to note when using intravenous lipid emulsions?
Intravenous lipid emulsions are off-liscence drugs and thus should only be used for severe toxicosis when recognised treatments have been unsuccessful
What are three of the possible adverse effects of intravenous lipid emulsions?
Pancreatitis
Fluid overload as they act as colloid solutions
Coagulopathies
Why are cats so susceptibe to paracetomal toxicity?
Cats lack the enzyme glucoronyl transferase which makes them particularly susceptible to paracetamol toxicity as this enzyme usually metabolises the toxic by-product of paracetomal metabolism - N-acetyl-p-benzoquinone which causes hepatocellular necrosis, oxidative damage to red blood cells resulting in methaemaglobinaemia and heinz body anaemia
Which organ metabolises paracetamol?
Liver metabolises paracetamol
What are the seven clinical signs of paracetamol toxicity in the first 24 hours of ingestion?
Anaemia
Cyanosis or muddy brown mucous membranes
Tachycardia
Tachypneoa
Lethargy
Facial and paw oedema
Vomiting
What are the four clinical signs of paracetamol toxicity 24 hours after ingestion?
Signs of liver failure
Icterus
Seizures
Haematuria/haemoglobinuria
What is a rare clinical sign of paracetamol toxicity?
Kerratoconjunctivitis sicca
At what dose of paracetamol ingestion should you begin treatment for paracetamol toxicity in cats?
If the cat has ingested more than 10mg/kg of paracetamol you should begin treatment for paracetamol toxicity in cats
At what dose of paracetamol ingestion should you begin treatment for paracetamol toxicity in dogs?
If the dog has ingested more than 50 - 100mg/kg of paracetamol you should begin treatment for paracetamol toxicity in dogs
Which decontamination techniques can you use for paracetamol toxcicity?
Emesis
Activated charcoal (remember to repeat doses due to enterohepatic recycling)
Within how many hours after paracetamol ingestion would it still be effective to induce emesis?
Within 2 hours following paracetamol ingestion
What supportive care should you provide patients with paracetamol toxicity?
Goal directed fluid therapy
Oxygen supplementation
Whole blood or packed pRBC transfusion
What can you use to reverse methaemaglobinaemia due to paracetamol toxicity?
Ascorbic acid
What can be used as a liver protectant in animals with paracetomal toxicity?
S-adenosylmethionine (S-AME)
What is the antidote for paracetamol toxicity?
N-acetylcysteine
What is the toxic component found in slug bait?
Metaldehyde
(T/F) Metaldehyde poisoning has a slow onset
FALSE. Metaldehyde poisoning has a rapid onset of between 30 minutes and 3 hours
What are the four main clinical signs of metaldehyde poisoning?
Tremors
Seizures
Hyperthermia
Hyperaesthesia
What is hyperaesthesia?
Hyperaesthesia is excessive physical sensation
How can metaldehyde poisoning progress and cause death?
Metaldehyde poisoning can progress to severe seizures, respiratory arrest and disseminated intravascular coagulation (DIC) - which can all result in death
Which decontamination techniques can you use for metaldehyde poisoning?
Emesis if they have not started with tremors or seizures
Activated charcoal
Gastric lavage
What supportive care should you provide patients with metaldehyde poisoning?
Intravenous fluid therapy
Antiepileptic drugs to control the seizures
Muscle relaxant to help alleviate tremors and muscle rigidity
Which muscle relaxant drug can you give to patients with metaldehyde poisoning?
Methocarbamol
How can you administer methocarbamol if you are unable to administer them orally (i.e. if they are in active seizures) in patients with metaldehyde poisoning?
You can crush methocarbamol tablets and give them via an enema