Metoclopramide is a dopamine antagonist with antiemetic and upper gastrointestinal prokinetic effects. It is used mainly in dogs and cats for selected vomiting and gastric motility disorders, with specialist applications in equine ileus. Its pituitary effects can increase prolactin, providing a separate empirical role in selected lactation-support situations.
Metoclopramide blocks dopamine D2 receptors in central emetic pathways, reducing dopamine-mediated vomiting. Peripheral D2 antagonism and serotonin 5-HT4-related effects enhance cholinergic activity in the upper gastrointestinal tract and can improve coordinated motility and lower esophageal sphincter tone. Pituitary D2 blockade removes dopamine’s inhibitory effect on prolactin release, linking the drug to its lactation-support applications.
Loading 0.4 mg/kg, then 0.3 mg/kg/hour, potentially up to 1 mg/kg/hour in refractory cases. A separate recommendation gives a chemotherapy total of up to 2 mg/kg/24 hours, which is incompatible with those ongoing rates; these must not be applied as one universal protocol.
Lactation support
0.2 mg/kg
PO
Every 6 h
Up to 6 days; Domperidone is preferred for some lactation indications; assess the dam and cause of poor lactation.
Experimental perioperative reflux protocol
Reference only
IV
One study used 1 mg/kg loading plus 1 mg/kg/hour; other studies did not confirm benefit. This is not a routine reflux prescription.
Vomiting
0.1–0.4 mg/kg
PO, SC, IM
Every 6 h
Antiemetic or prokinetic alternative
0.2–1 mg/kg
PO, SC, IM
Every 6 h
Higher doses have greater neurologic risk; chemotherapy emesis often responds better to other antiemetics.
Antiemetic infusion
0.0416666667–0.0833333333 mg/kg/hour
IV
Continuous
Exact hourly equivalent of 1-2 mg/kg/day; a separate low-rate protocol is listed independently.
Antiemetic infusion
0.01–0.02 mg/kg/hour
IV
Continuous
Distinct lower-rate protocol, not numerically equivalent to 1-2 mg/kg/day.
Higher-rate antiemetic infusion
0.08–0.16 mg/kg/hour
IV
Continuous
Reported as approximately 2-4 mg/kg/day; keep separate from lower-rate protocols.
Pancreatitis-associated vomiting
0.1–0.5 mg/kg
IM
Every 8 h
Oesophagitis adjunct
0.2–0.4 mg/kg
PO
Every 8 h
Limited oesophageal motor benefit; cisapride may be more effective in cats.
Bladder-contractility adjunct
0.2–0.5 mg/kg
PO
Every 8 h
Lactation support
0.1–0.2 mg/kg
SC
Every 12 h
Assess cause of agalactia; separate from oxytocin-driven milk let-down.
Cats
Use / stage
Dose
Route
Schedule
Instructions
Vomiting
0.5 mg/kg
IV, IM, PO
Every 8 h
Antiemetic infusion
Reference only
IV
Loading 0.4 mg/kg, then 0.3 mg/kg/hour, potentially up to 1 mg/kg/hour in refractory cases. A separate recommendation gives a chemotherapy total of up to 2 mg/kg/24 hours, which is incompatible with those ongoing rates; these must not be applied as one universal protocol.
Lactation support
0.2 mg/kg
PO
Every 6 h
Up to 6 days; Domperidone is preferred for some lactation indications; assess the dam and cause of poor lactation.
Antiemetic infusion
0.0416666667–0.0833333333 mg/kg/hour
IV
Continuous
Exact hourly equivalent of 1-2 mg/kg/day; a separate low-rate protocol is listed independently.
Antiemetic infusion
0.01–0.02 mg/kg/hour
IV
Continuous
Distinct lower-rate protocol, not numerically equivalent to 1-2 mg/kg/day.
Oesophagitis adjunct
0.2–0.4 mg/kg
PO
Every 8 h
Limited oesophageal motor benefit; cisapride may be more effective in cats.
Bladder-contractility adjunct
0.2–0.5 mg/kg
PO
Every 8 h
Lactation support
0.1–0.2 mg/kg
SC
Every 12 h
Assess cause of agalactia; separate from oxytocin-driven milk let-down.
Antiemetic or prokinetic alternative
0.2–0.4 mg/kg
PO, SC
Every 6–8 h
Horses
Use / stage
Dose
Route
Schedule
Instructions
Postoperative ileus
0.125–0.25 mg/kg/hour
IV
Continuous
Observe closely for potentially dangerous excitement and abdominal discomfort.
Postoperative ileus
0.04 mg/kg/hour
IV
Continuous
Separate lower-rate prokinetic protocol; monitor behaviour.
Monitor behaviour closely during IV use, especially in horses.
Not a reliable ruminant prokinetic: higher doses can cause neurologic reactions without improving motility.
Protect injection from light; avoid freezing and incompatible admixtures. Published guidance reports less than 24-hour stability if unprotected from light.
Postoperative canine oral/SC 0.2-0.5 mg/kg may be scheduled at least 30 minutes before meals and at bedtime, rather than forced into an arbitrary uniform interval. The alternative 0.01-0.02 mg/kg/hour infusion totals only 0.24-0.48 mg/kg/day; it must not be described as equivalent to the 1-2 mg/kg/day regimen.
