Omeprazole is dosed by body weight, so the right amount depends on how much your horse weighs. Enter the weight below to estimate the daily dose at the standard label rates — the 4 mg/kg treatment rate for active ulcers and the 1 mg/kg prevention rate.
Omeprazole dosage estimator
Enter your horse’s weight for an estimate of the daily omeprazole dose at the standard label rates. This is an educational guide, not a prescription — confirm the dose and course length with your veterinarian.
Estimates use the FDA-approved label rates for omeprazole in horses. The approved pastes (GastroGard, UlcerGard) are pre-calibrated by body weight, so in practice you set the syringe plunger to your horse’s weight rather than measuring milligrams. A common protocol steps down to a 2 mg/kg maintenance dose after treatment. Always confirm dosing and duration with your veterinarian, and don’t dose unapproved or compounded products without veterinary direction.
How omeprazole dosing works
The dose scales with weight. For active ulcers, the FDA-approved treatment rate is about 4 mg/kg once daily (the GastroGard rate) for roughly 28 days. For prevention, the rate is about 1 mg/kg once daily (the UlcerGard rate), and many horses step down to a 2 mg/kg maintenance dose after a treatment course. Because the approved pastes are pre-calibrated, in practice you simply set the syringe plunger to your horse’s weight. For the full plan, see how treatment works and our complete guide to equine ulcers.
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Frequently asked questions
How much omeprazole does a horse need for ulcers?
The standard treatment rate is about 4 mg/kg of omeprazole once daily. For a 1,000 lb horse (about 454 kg) that works out to roughly 1,800 mg per day. Use the treatment dose under veterinary direction.
What is the omeprazole prevention dose for horses?
The prevention (maintenance) rate is about 1 mg/kg once daily - the UlcerGard rate - which is roughly 450 mg per day for a 1,000 lb horse.
How much GastroGard does a 1,000 lb horse need?
GastroGard is calibrated by body weight, so you set the syringe plunger to your horse's weight rather than measuring milligrams. At the treatment rate that is about 1,800 mg of omeprazole per day for a 1,000 lb horse, and one tube treats roughly 1,250 lb.
Is omeprazole for horses dosed by body weight?
Yes. The FDA-approved pastes are marked by body weight, so the dose scales with how much your horse weighs - heavier horses need more.
What is the maintenance dose of omeprazole for horses?
After a treatment course, many horses step down to about 2 mg/kg per day for a period, then to a prevention dose. Confirm the right step-down plan with your veterinarian.
References & sources
- Sykes BW, et al. ECEIM Consensus Statement: Equine Gastric Ulcer Syndrome in Adult Horses. J Vet Intern Med. 2015;29(5):1288–1299.
- Merck Veterinary Manual — Gastric Ulcers in Horses (clinical)
Dosing figures follow FDA-approved label rates for omeprazole; cost ranges are general market estimates. Always confirm diagnosis, dosing, and treatment with your veterinarian.