Gastrointestinal decontamination by induction of emesis is a common first-line treatment in the management of poisoning in companion animals. It should be considered in acute cases where a potentially toxic dose of a substance has been ingested.
In most cases emptying the stomach is usually only worthwhile if ingestion was recent (i.e. within 1-2 hours) as the ingested material will have been absorbed or passed beyond the stomach. However, this is not always the case and some substances can remain in the stomach for longer, so it may be necessary to seek advice in these cases. The physical form of the substance ingested (large tablets or a solution, for example) will also influence the time that ingested material remains available in the stomach. The chemical nature is also a factor; some substances are digested slowly but others (e.g. alcohol) are absorbed directly from the stomach. Induction of emesis may be ineffective in some cases because the substance ingested has an anti-emetic action (e.g. cannabis, antihistamines).
It is important to note efficacy declines the longer the time between ingestion and emesis and that emesis is not always suitable depending on the substance ingestion and the clinical condition of the animal (see below).
Emesis is contraindicated in the following circumstances:
If the animal:
- has already vomited,
- is very drowsy or unconscious,
- is exhibiting seizure activity,
- has reduced cough reflex.
If the substance ingested:
- is likely to cause rapid onset of drowsiness or seizures,
- contains paraffin, petroleum products or other oily or volatile organic substances which could be aspirated into the lungs,
- contains detergent compounds, which could be aspirated into the lungs,
- is a strong acid or alkali, which could cause further damage to the oesophagus if regurgitated.
Apomorphine is the emetic of choice in dogs and in the UK is available as Apometic® from Forum Animal Health.
The following substances have been used as emetics in the past but they are obsolete and potentially dangerous:
- Salt (sodium chloride) should never be used. It can cause serious or fatal hypernatraemia in animals when used as an emetic.
- Mustard is unreliable and not recommended.
- Copper sulphate is a potent emetic but is not recommended because of risk of toxicity.
- Syrup of ipecac (ipecacuanha) was widely used in the past but is now not routinely recommended. It is relatively ineffective, slow to act, has a bitter taste and is no longer widely available.
The VPIS cannot comment on the use of emetics after ingestion of a foreign body.