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Drugs Used for Emesis Induction in Dogs

Jack Lee, DVM, University of Tennessee

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

Pharmacology & Medications

|July 2022|Peer Reviewed

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German shepherd dog puppy

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 dogs. To read about drugs used for emesis induction in cats, click here.


Ropinirole

Ropinirole is an FDA-approved selective D2 agonist that acts on the CRTZ to induce emesis in dogs.

Formulation

  • Ophthalmic solution (30 mg/mL) in single-use droppers

Dosage

  • 3.75 mg/m2 ophthalmic (see Table for number of drops)10 

Key Points

  • 95% efficacy in healthy dogs in one study11
  • A second dose can be administered if vomiting does not occur within 20 minutes.10
  • Should not be given to patients with pre-existing ocular irritation, ulceration, or injury10 
  • Most commonly reported adverse effects include tachycardia, lethargy, and hypotension. Mildly to moderately injected gums, elevated third eyelid(s), and conjunctival discharge were transiently noted.11,12 
  • Can be specifically antagonized by metoclopramide in cases of protracted emesis11 
  • Not expected to work in cats due to the low number of dopamine receptors in the CRTZ13
  • Not labeled for use in cats

table

ROPINIROLE OPHTHALMIC SOLUTION MANUFACTURER RECOMMENDATIONS10

Weight Number of drops
4-11.1 lb (1.8-5 kg) 1
11.2-22.1 lb (5.1-10 kg) 2
22.2-44.1 lb (10.1-20 kg) 3
44.2-77.2 lb (20.1-35 kg) 4
77.3-132.3 lb (35.1-60 kg) 6
132.4-220.5 lb (60.1-100 kg) 8

 

*Table adapted from package insert.52

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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