Metoclopramide is a versatile medication that serves dual roles as a prokinetic (stimulating gastrointestinal motility) and an antiemetic (reducing nausea and vomiting). It has been a mainstay of veterinary GI medicine for decades and is commonly used in rabbits, dogs, and cats. In rabbits, metoclopramide is one of the key medications used to treat gastrointestinal stasis, often in combination with cisapride and supportive care. In dogs and cats, it is frequently prescribed for nausea, vomiting, and delayed gastric emptying. This is a prescription medication that requires veterinary supervision.
What Is Metoclopramide Used For?
- GI stasis in rabbits: stimulates upper GI motility as part of multimodal stasis treatment
- Nausea and vomiting: in dogs and cats from various causes including parvovirus, pancreatitis, chemotherapy, and motion sickness
- Gastroparesis: delayed gastric emptying
- Gastroesophageal reflux: reduces reflux by increasing lower esophageal sphincter tone and promoting gastric emptying
- Ileus: post-operative or drug-induced intestinal hypomotility
- Megaesophagus (dogs): occasionally used to improve esophageal clearance
How Does Metoclopramide Work?
Metoclopramide has multiple mechanisms of action:
- Dopamine D2 receptor antagonism: blocks dopamine receptors in the chemoreceptor trigger zone (CRTZ) of the brain, producing an antiemetic effect
- Peripheral prokinetic activity: enhances acetylcholine release at the myenteric plexus of the upper GI tract, increasing gastric emptying and small intestinal transit
- 5-HT3 receptor antagonism: contributes to antiemetic effects at higher doses
- 5-HT4 receptor agonism: mild prokinetic effect
A key distinction from cisapride is that metoclopramide primarily affects the upper GI tract (stomach and proximal small intestine) and has limited effect on the colon and cecum. For rabbits with GI stasis, cisapride (which affects the entire GI tract) is often preferred or used in combination with metoclopramide.
Dosage
Dosing must be determined by your veterinarian.
| Species | Typical Dose | Route | Frequency |
|---|---|---|---|
| Rabbits | 0.5 to 1 mg/kg | Oral, SC, IM | Every 6 to 12 hours |
| Dogs | 0.2 to 0.5 mg/kg | Oral, SC, IM, IV | Every 6 to 8 hours |
| Cats | 0.2 to 0.5 mg/kg | Oral, SC, IM, IV | Every 6 to 8 hours |
For oral administration, metoclopramide should be given on an empty stomach (30 minutes before meals) for best effect. For parenteral administration in hospitalized patients, it may be given as a continuous rate infusion (CRI) in dogs and cats for more consistent effects.
Constant rate infusion (CRI) dosing for hospitalized dogs/cats: 1 to 2 mg/kg/day IV as a continuous infusion provides more stable blood levels and better antiemetic/prokinetic control.
Side Effects
Common side effects:
- Mild sedation
- Restlessness or agitation (especially in cats)
- Mild abdominal cramping
- Changes in appetite
Serious side effects:
- Extrapyramidal signs: involuntary muscle movements, tremors, or abnormal postures due to dopamine blockade in the CNS; more common at high doses or in sensitive individuals
- Behavioral changes: agitation, hyperactivity, or disorientation (particularly in cats)
- Tachycardia or bradycardia: cardiovascular effects at high doses
- Diarrhea: from excessive prokinetic activity
Cats appear to be more sensitive to the neurological side effects of metoclopramide than dogs. Report any unusual behavior, trembling, or neurological signs to your veterinarian promptly.
Contraindications
- Gastrointestinal obstruction: metoclopramide must not be used if a mechanical GI obstruction is suspected; stimulating motility against an obstruction can cause perforation
- GI perforation or hemorrhage
- Seizure disorders: metoclopramide can lower the seizure threshold
- Pheochromocytoma: may precipitate hypertensive crisis
Drug Interactions
- Anticholinergic drugs (atropine, glycopyrrolate): oppose prokinetic effects
- Opioids: may reduce prokinetic effect of metoclopramide
- Other CNS depressants: additive sedation
- Phenothiazines: increased risk of extrapyramidal effects
- Cyclosporine: metoclopramide may increase cyclosporine absorption
Species-Specific Considerations
Rabbits:
- Part of the multimodal GI stasis treatment protocol (along with cisapride, fluids, pain management, and syringe feeding)
- Primarily stimulates upper GI motility, so cisapride may be preferred for complete GI tract activation
- May be administered orally or by subcutaneous injection; injection is useful when the rabbit will not accept oral medication
- Rabbits tolerate metoclopramide well at standard doses
Dogs:
- Commonly used for parvovirus, pancreatitis, and post-operative nausea
- Effective for motion sickness
- CRI dosing preferred in hospitalized patients with ongoing vomiting
- Watch for extrapyramidal signs at higher doses
Cats:
- More prone to behavioral side effects than dogs
- Useful for chronic kidney disease-related nausea (though maropitant/Cerenia is often preferred)
- Start at lower end of dose range
Comparison with Other Antiemetics
- Maropitant (Cerenia): a newer NK1 receptor antagonist with superior antiemetic effect and fewer side effects; now first-line for vomiting in dogs and cats
- Ondansetron: 5-HT3 antagonist useful for chemotherapy-induced nausea and severe vomiting
- Cisapride: superior prokinetic for lower GI tract (cecum, colon); preferred for rabbit GI stasis and feline megacolon
- Metoclopramide: retains a role for upper GI motility issues and as a lower-cost alternative
Storage
Store metoclopramide at room temperature, protected from light. Oral solutions and injectable formulations should be stored according to label directions. Check expiration dates regularly.
Always consult your veterinarian before starting, stopping, or changing any medication. GI obstruction must be ruled out before starting prokinetic therapy. This information is for educational purposes and does not replace professional veterinary advice.