Decontamination
All emergency cases should initially be evaluated in the same manner with a major body systems assessment (cardiovascular, respiratory, neurological) and provided with empirical support of these systems if any is abnormal. Decontamination procedures should be initiated at the earliest possible opportunity. Key points regarding decontamination are noted below.
- If the animal cannot undergo immediate dermal decontamination, place an Elizabethan collar to prevent grooming and oral ingestion.
- Isolate the patient from any other pets/children to prevent grooming or contamination.
- Consider carefully clipping hair, especially in long haired animals.
- Warm water and mild detergents (e.g. baby shampoo) are sufficient for most dermal contaminants.
- Contamination with oily substances may require stronger degreasing detergents such as Swarfega®. Such detergents need to be washed off thoroughly in turn.
- Take care not to induce hypothermia, especially in small patients.
- Do not use solvents such as alcohol or white spirit as this may spread the contaminant further and may irritate the skin.
- Never neutralize acids with alkalis/bases or vice versa.
- Ensure veterinary staff members are adequately protected by the use of plastic aprons, gloves and goggles if necessary.
Gastrointestinal decontamination should be considered in all acute cases of toxin ingestion and generally includes gastric evacuation and administration of an adsorbent. Gastric evacuation is performed either by induction of emesis or gastric lavage. In some situations gastric evacuation is not required or recommended.
Contraindications to gastric evacuation include:
- If the ingested substance was caustic, corrosive, petroleum- based or volatile
- If the substance was ingested greater than 2 to 3 hours prior to presentation (seek advice, after this time as some substances may still be retrieved after this period).
In patients with suspected oral toxin ingestion, the induction of emesis is recommended at the earliest possible opportunity. Contraindications to the induction of emesis include:
- If the ingested substance is caustic, acidic, volatile, petroleum or detergent based
- If the patient has severe CNS depression
- If the patient has respiratory distress
- If the poison ingested is known to cause seizures.
Remember that some emetics have a short delay before action.
Emetics cannot be used in horses, rodents, rabbits or ruminants.
There are several options for the induction of emesis:
- Apomorphine – this is the licensed product available in the UK for induction of emesis in dogs. The licensed dose is 0.1 mg/kg (s.c.). Apomorphine can however be effective when given by other routes including intramuscular, intravenous or conjunctival. The doses recommended for these routes are 0.04–0.25 mg/kg. It is a centrally acting emetic that is extremely effective in dogs but is not recommended in cats as it is variably effective.
- Xylazine (0.6 mg/kg i.m. or 1 mg/kg s.c.), dexmedetomidine (3–5 μg/kg i.m.) or medetomidine (5–20 μg/kg i.m.) – can be used in cats, although the sedative effects may be unwelcome. They are more effective if the cat’s stomach is full.
- Sodium carbonate (washing soda) crystals – an effective emetic in dogs and cats. The dose is empirical but usually a large crystal in a medium- to large- breed dog and a small crystal in a small dog or cat is sufficient. Although it may be administered by the owner, caution is recommended as it is mildly caustic. It is also vital that it is not confused with caustic soda (sodium hydroxide)!
- Ropinirole (Clevor 30 mg/ml eye drops) is also licensed for induction of emesis in dogs. The dose is 2–15 µl/kg (equivalent to 1-8 drops).
- Other options such as Syrup of Ipecac, household remedies (table salt, mustard) and hydrogen peroxide are not recommended and can be dangerous.
- Gastric lavage should be performed if it is not safe to induce emesis. It is not as effective as emesis so if emesis can be safely induced this is preferred.
- Patient should be lightly anaesthetized and the trachea intubated with a cuffed endotracheal tube.
- A large bore stomach tube should be used to instil 10 ml/kg warm tap water.
- The patient’s stomach should be gently agitated by manual palpation.
- The fluid should be allowed to drain by lowering the stomach tube and the patient’s head.
- The procedure should be repeated (commonly 10 to 20 times) until the fluid returns relatively clear.
- This procedure will be ineffective if the material ingested is too large to pass up the tube.
The most commonly used adsorbent is activated charcoal. This must be administered as a powder or slurry as its effectiveness is related to its surface area.
- Activated charcoal (AC) should be administered post emesis/gastric lavage; it acts as an adsorbent for many toxins and further reduces GI absorption.
- Slurries are more effective than tablets or capsules.
- Recommended dose is 1–4 g/kg and may be repeated every 4 to 6 hours for the first 24 to 48 hours or until charcoal is seen in the faeces.
- Repeat dose administration of AC is particularly important when the agent is enterohepatically recirculated, e.g. salicylates, barbiturates, theobromine and methylxanthines.
- AC slows GI transit time, thus co-administration of a cathartic (e.g. sorbitol or magnesium sulphate) can be considered although is not recommended in dehydrated patients or patients where there is a suspicion of ileus.
- AC use may be contraindicated if orally administered/treatments or antidotes are to be given.
Ocular exposure is uncommon but leads to severe clinical signs, especially if there is extensive corneal damage. Alkaline damage is particularly severe and can result in deep corneal ulceration.
Ocular exposure should be managed promptly.
- As a first aid measure, owners can be advised to flush the eye with water prior to presentation at a veterinary practice, the potential severity of toxic exposure should be emphasized and the owner encouraged to attend as soon as possible.
- Contaminated eyes should be flushed with copious volumes of 0.9% saline or water for a minimum of 10 to 15 minutes.
- Sedation or anaesthesia may be required to facilitate decontamination.
- Repeated flushing may be required.
- After flushing the eye the corneal surface should be stained with fluorescein and examined carefully for ulceration.
- In the case of alkaline exposures or severe corneal damage a veterinary ophthalmologist should be contacted.
- In the case of alkaline exposure the ocular surface pH can be monitored using a urine dipstick. If the pH remains greater than 7.5 repeat flushing is recommended.
- Neutralizing agents MUST NOT be used as they may worsen damage.
- Mild corneal damage should be managed with ocular lubrication, topical antibiotics and parenteral analgesics as required.