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This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

There are numerous occasions when the use of an anti-emetic drug is indicated in veterinary practice. However, these drugs have different modes of action and understanding these is important so that the most appropriate drug can be selected for use under specific clinical circumstances.

Antiemetic drugs have different modes of action on the complex sequence of events involved in the vomiting reflex - from visceral receptors to the chemoreceptor trigger zone (CRTZ) in the brain.

Basically there are 2 pathways leading to vomiting :

  • A bloodborne (humoral) route - uraemia, glycosides, apomorphine, other toxins.
  • A neural route - vagosympathetic, chemoreceptor trigger zone, vestibular or cerebrocortical stimulation

The following table classifies the most frequently used anti-emetics and their uses. Some drugs have more than one mode of action.

5-HT3 serotonergic antagonists.  Metoclopramide, Ondansetron Prevent vomiting due to chemotherapy and radiation
5-HT4 serotonergic antagonists Cisapride Promotes gastric emptying by activation of receptors
a2 adrenergic antagonists Chlorpromazine, Prochlorperazine, Yohimbine Prevent vomiting due to activation of the CRTZ or emetic centre
D2 dopaminergic antagonists Butyrophenones, Domperidone, Metaclopramide, Phenothiazines Trimethobenzamine,    Counteract mild emesis due to chemotherapy, uraemia, septicaemia and gastrointestinal disorders including pancreatitis.
H2 histaminergic antagonists Diphenhydramine Dimenhydrinate Motion sickness
M1 cholinergic antagonists Chlorpromazine,  Scopolamine Motion sickness
Motilin agonists Erythromycin (low dose) Facilitates gastric emptying during fasting
Opiate antagonists Butorphanol Prevent vomiting due to some types of chemotherapy (eg cisplatinum)



Updated January 2016