Omeprazole

Omeprazole is a proton pump inhibitor used for sustained suppression of gastric acid secretion. Its veterinary applications include acid-related gastroduodenal injury, reflux esophagitis and gastric hypersecretory states. Equine formulations are widely used for gastric ulcer treatment and prevention. Oral product design influences delivery of this acid-labile drug to its absorption site.

Group

Proton pump inhibitor

Mechanism of Action

After absorption, omeprazole concentrates in the acidic secretory canaliculi of active gastric parietal cells and is converted to a reactive form. It binds and inhibits the H+/K+-ATPase responsible for the final step of acid secretion. Suppression persists until functional pumps are replaced, producing a longer effect than plasma drug persistence alone would predict.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Gastric acid suppression	20 mg/animal	PO	Every 24 h
Gastric acid suppression	1–2 mg/kg	PO	Every 24 h
Gastric acid suppression	1–2 mg/kg	PO	Every 12 h	Twice-daily dosing gives more consistent suppression.
Gastric acid suppression	0.5–1 mg/kg	PO	Every 24 h
Uremic gastropathy	0.5–1 mg/kg	PO	Every 24 h
Gastrinoma or esophagitis	0.7–1.5 mg/kg	PO	Every 24 h
Severe esophagitis or gastrinoma	2 mg/kg	PO	Every 12 h
Esophagitis	0.7 mg/kg	PO	Every 12 h
Uremic vomiting	0.7 mg/kg	PO	Every 12 h

Cats

Use / stage	Dose	Route	Schedule
Gastric acid suppression	1 mg/kg	PO	Every 24 h
Gastric acid suppression	1 mg/kg	PO	Every 12 h
Gastric acid suppression	0.5–1 mg/kg	PO	Every 24 h
Gastric acid suppression	0.7–1.5 mg/kg	PO	Every 12–24 h
Uremic gastropathy	0.7 mg/kg	PO	Every 24 h

Horses

Use / stage	Dose	Route	Schedule	Instructions
Gastric ulcer treatment	4 mg/kg	PO	Every 24 h	Up to 28 days
Gastric ulcer treatment	4 mg/kg	PO	Every 12 h	Alternative for ulcers responding poorly to once-daily treatment.
Gastric ulcer treatment	1–2 mg/kg	PO	Every 24 h	Lower-dose alternative reported as effective in some studies.
Gastric ulcer prevention	1–2 mg/kg	PO	Every 24 h
Parenteral acid suppression — Loading	1 mg/kg	IV	Once	Only if an appropriate injectable formulation is available.
Parenteral acid suppression — Maintenance	0.5 mg/kg	IV	Every 24 h	Up to 28 days; Reported treatment course 14-28 days.

Ferrets

Use / stage	Dose	Route	Schedule	Instructions
Gastroenteritis acid suppression	0.7 mg/kg	PO	Every 24 h

Pigs

Use / stage	Dose	Route	Schedule	Instructions
Gastric ulcer management	40 mg/animal	PO	Every 24 h	Up to 2 days; Reported short protocol included 48-hour fasting.

Indications

Treatment of acid-related gastroduodenal ulceration or erosive disease in dogs, cats and selected other veterinary species.
Reduction of gastric acid exposure during treatment of reflux esophagitis.
Treatment and prevention of equine gastric ulcers, particularly equine squamous gastric disease, with an appropriate equine product.
Suppression of pathological gastric acid secretion associated with gastrinoma or other hypersecretory states.
Selected prophylaxis of documented high-risk acid-related gastric injury, including supported exercise-associated gastric disease prevention in working dogs.

Contraindications

Check excipients: some powder formulations contain xylitol.

Interactions

Can reduce absorption of acid-dependent drugs such as ketoconazole and itraconazole.
Give sucralfate 60-90 minutes after omeprazole for equine combined treatment.

Adverse effects

Occasional diarrhea; long-term acid suppression may alter intestinal flora.

Toxicity

A major overdose is managed according to clinical signs with supportive treatment; an animal-specific antidote is not described.

Preparations

Preparation	Form	Strength	Route
Omeprazole capsule 20 mg	Capsule	20 mg / capsule	PO
Compounded omeprazole in bicarbonate 2 mg/mL 100 mg capsule contents in 50 mL 8.4% sodium bicarbonate; stability depends on the stated formulation and storage.	Oral Liquid	2 mg / mL	PO

Monitoring and Administration

Give horses 60-90 minutes before feeding. Glandular ulcers may respond less well than squamous ulcers; management and diet are part of treatment.

Prefer protected commercial dosage forms. Equine paste in oil at 10 or 40 mg/mL was stable for 6 months at 7 C protected from light. A 2 mg/mL preparation in 8.4% sodium bicarbonate was stable for 14 days at 24 C or 30 days at 5 C or -20 C.

Withhold for 7 days before serum gastrin testing; interpret clinical response before continuing prolonged treatment.

For equine glandular gastric disease, a reported combined plan uses omeprazole 4 mg/kg orally every 24 hours plus sucralfate 12 mg/kg orally every 12 hours; separate sucralfate by 60-90 minutes. Gastric healing may require 28-35 days, with dietary and environmental management.

Helicobacter combination example: omeprazole 0.7 mg/kg orally daily, amoxicillin 15 mg/kg twice daily, metronidazole 10 mg/kg twice daily and bismuth product twice daily for 14 days; bismuth tablet strength/size-based amount is not fully specified. Alternative macrolide combinations require an individualized complete plan. A sled-dog exercise study used approximately 0.85 mg/kg daily starting 48 hours before exercise, 30 minutes before feeding; the 20-mg example is not a universal fixed dose.

For foals, 4 mg/kg orally daily is a reported treatment amount and 1-2 mg/kg daily a prevention range; routine prophylaxis in every sick foal is not supported. A post-healing recurrence-prevention course at 2 mg/kg daily was continued for at least another 4 weeks, not a maximum 4-week course.