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Drugs Used for Emesis Induction in Cats

Jack Lee, DVM, University of Tennessee

Adesola Odunayo, DVM, MS, DACVECC, University of Tennessee

Pharmacology & Medications

|July 2022|Peer Reviewed

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Editor's note: The dexmedetomidine section of this article has been updated to provide clarification regarding oral detomidine transmucosal gel. Updated December 13, 2022.

Emesis is the action or process of vomiting and is commonly indicated for upper GI decontamination in dogs and cats that have ingested toxic agents or for removal of gastric foreign material.1 Important contraindications include ingestion of caustic or corrosive agents (eg, bleach, chemicals), high risk for aspiration pneumonia (eg, altered mentation, laryngeal paralysis, absent gag reflex), previous protracted vomiting after toxin ingestion, respiratory distress, ingestion of a nontoxic or very low toxicity substance or dose, severe acid−base abnormalities that could become worse after GI fluid loss, and excessive sedation.2

Physiology

Vomiting is coordinated by the emetic center in the medulla oblongata of the brain stem, leading to an efflux of gastric and proximal duodenal content.3 The emetic center receives afferents from both the CNS and the periphery, particularly the GI tract and vestibular apparatus, but can also include viscera (eg, urinary and reproductive tracts).

The chemoreceptor trigger zone (CRTZ) is located in the medulla oblongata and contains dopamine 2 (D2), neurokinin-1 (NK-1), 5-hydroxytryptamine, acetylcholine, and histamine receptors that respond to substances circulating in the blood. Unlike dogs, cats have a significant number of alpha-2–adrenergic receptors in the CRTZ, making alpha-2–adrenergic agonists more likely to cause emesis.4 The forebrain can also provide input to the CRTZ in response to noxious stimuli (eg, pain, repulsive smells or sights).3

Peripheral input from the GI tract acts via NK-1 and serotonin receptors and transmits signals into the emetic center through vagal and other afferents.5 The vestibular system can also induce vomiting through histamine and acetylcholine receptors. Knowledge of these receptors is helpful when considering drugs that induce emesis in dogs and cats.

Complications

Complications associated with emesis induction can include aspiration pneumonia, ineffective recovery of ingested substances, sedation, and gastroesophageal intussusception (rare).6

Administration of an antiemetic (maropitant, 1 mg/kg IV or SC; metoclopramide, 0.4-0.6 mg/kg SC or 2 mg/kg/day IV CRI; ondansetron, 0.5-1 mg/kg IV) should be considered after successful emesis induction to prevent protracted nausea and/or retching.7-9

Emetic drugs can act via peripheral or central mechanisms.

Keep scrolling for details on drugs used for emesis induction in cats. To read about drugs used for emesis induction in dogs, click here.


Dexmedetomidine

Dexmedetomidine is an alpha-2–adrenergic agonist that acts on the CRTZ to induce emesis in cats.16 This drug is generally considered the emetic agent of choice in cats due to high concentration of alpha-2–adrenergic receptors in the CNS; in dogs, however, alpha-2–adrenergic agonists are unlikely to induce emesis. Use of dexmedetomidine as an emetic is extra-label.

Formulation

  • Injectable (100 or 500 µg/mL)

Dosage

  • 7-10 µg/kg IM (up to 18 µg/kg has been reported)35
  • 3.5 µg/kg IV35

Key Points

  • Efficacy is reported as 58% to 81%.4,16
  • Evidence in cats supports superior efficacy compared with xylazine.4
  • Sedative adverse effects can be reversed with atipamezole.35
  • Other common adverse effects include peripheral vasoconstriction, hypertension, arrhythmias, and reflex bradycardia.35 
  • Caution should be used in cats with cardiac disease or hemodynamic instability. 
  • Administration of butorphanol may reduce the emetic effect.36
  • One study evaluating application of oral detomidine transmucosal gel in cats demonstrated that 100% of healthy cats vomited after administration,37 making this route of administration a possible alternative to injectable dexmedetomidine for emesis induction. 
    • Avoiding needles may reduce anxiety related to visiting the clinic and promote stress-free handling in cats.

References

For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

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