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Omeprazole in Dogs and Cats: Is It Safe for Vets to Use?

Updated: May 11, 2023

The medical world is awash with chemical compounds and medications for use with broad systemic effects, narrow niche benefits, and everything in between. There’s just one problem: most of that is only ever looked at or tested on humans, and we only know the effects they have on people.

When it comes time to treat our furry friends, the options are a lot more limited.

Unless that is, we’re willing to go off-label. Off-label usage is powerful but potentially risky because that same lack of testing means it’s often difficult to predict how weak or strong an effect will be (if there will be any side effects) and how long a medication can safely be used.

That’s why we’ve put together this guide. Omeprazole is a common medication for people, and vets often prescribe it for pets, but is it safe? We’re here to answer your questions as best we can.

What is Omeprazole?

First, let’s start off with the basics. What even is Omeprazole?

Omeprazole is the generic name for a medication that functions as a proton pump inhibitor.

It’s also commonly known under brand names like Prilosec, Losec, and Gastrogard.

Proton Pump Inhibitors, or PPIs, are a kind of medication that affects a specific function of the digestive system, the one that produces stomach acid. The medication functions by inhibiting the function of the proton pumps, which reduce stomach acid build-up.

They’re highly potent and the best available drugs for dealing with a variety of gastrointestinal ailments stemming from stomach acid production, and they are more effective than reactive treatments like antacids. PPIs are so vital that they’re listed on the World Health Organization’s list of essential medications.

All of this is, of course, for humans. The use of these medications in dogs, cats, and other animals is not validated but is relatively common due to similarities in biology and observed beneficial effects.

What is Omeprazole Used to Treat?

In humans, Omeprazole is used to treat a variety of stomach and intestinal ailments.

These include:

  • Dyspepsia

  • Peptic ulcers

  • H. pylori eradication

  • GERD (gastroesophageal reflux disease)

  • Barrett’s Esophagus

  • Stress gastritis

Generally, anything that is either caused by excessive stomach acid production or exacerbated by that stomach acid can be treated with Omeprazole. These treatments are generally meant to be short-term, but some ailments require longer-term or even indefinite treatments.

For dogs and cats, Omeprazole is used to treat ulcers in the stomach and upper small intestine, gastric erosions caused by other medications, acute gastritis, H. Pylori, and other stomach issues caused by stomach acid.

Does Omeprazole Work for Dogs and Cats?

Yes. It’s generally prescribed to treat erosions or ulcers or to help prevent them from forming when other drugs (like NSAIDs), which can cause ulcers, are also prescribed.

These medications are available in various forms, such as oral tablets, capsules, and even as an injectable solution. Veterinarians prescribe these medications based on the specific needs and condition of the animal.

While relatively little testing has been done on animals to observe the full extent of the effects of Omeprazole, many vets have prescribed the medication and have seen first-hand that it’s both practical and generally safe. There may be some risk of side effects, which we’ll discuss in a moment, but it’s generally not going to be a risky medication to give to a beloved pet when handled safely.

Omeprazole is commonly used for many animals because the effects – inhibiting the movement of hydrogen atoms that are used to create the hydrochloric stomach acids – work on a wide range of different biology. That said, it’s most common in humans, followed by dogs and cats, with ferrets also benefitting from it for gastric diseases. Other animals often have different kinds of treatments available or don’t respond as well to Omeprazole.

The time it takes for Omeprazole to work can vary depending on the individual animal and the severity of its condition. Generally, it starts to work within one to two hours after administration, and the effects can last up to 24 hours. However, observing significant improvement in the animal's condition may take several days, as the stomach lining needs time to heal.

When Should Omeprazole Be Prescribed for Dogs and Cats?

Omeprazole is generally used in pets to prevent ulcers from forming or to help allow ulcers to heal.

It does this by inhibiting the production of stomach acid, which aggravates ulcers.

Prescribing Omeprazole is a matter of your best judgment as a vet, of course.

Generally, the two most common scenarios are:

  • When the pet is brought in to be evaluated and is diagnosed with an ulcer or erosion, usually accompanied by gastrointestinal distress, loss of appetite, and other standard symptoms. They may also cause blood in the stool or vomit. Once the ulcer is diagnosed, Omeprazole can be part of a treatment strategy to inhibit stomach acid while the ulcer heals.

  • When the pet is being prescribed another medication that is highly likely to cause ulcers or erosions. Several medications, including NSAIDs, are said to be ulcerogenic – that is, they can cause ulcers – and that damage can be counteracted by Omeprazole.

  • When the pet is going to have surgery or otherwise needs to be intubated. The tube can aggravate the throat and stomach, and acid can wash back up the esophagus, causing damage. Omeprazole can help reduce that acid to leave less residual damage when the tube is removed.

As a vet, it is generally your job to evaluate the circumstances, consider the risks and side effects of treatment, and make recommendations to help avoid or circumvent side effects and manage symptoms. However, we know that you’re not necessarily comprehensively trained to know every detail of every medication or ailment off the top of your head.

You’re front-line diagnosis and treatment. That’s why we offer contact services to help advise you on tricky cases or areas where you may have questions. From internal medicine to critical care, if you have patients with complex situations and you’re not confident whether or not Omeprazole is a good idea, you can give us a call, and we’ll be happy to help.

Is Omeprazole Safe for Dogs and Cats?

Generally, yes. Some animals experience side effects, typically digestive upset involving vomiting, diarrhea, upset stomach, gas, and loss of appetite. These usually resolve themselves quickly, but in some small number of pets, they can persist, at which point, you should discontinue the use of Omeprazole and look for other options.

Omeprazole is metabolized quickly and lasts around 24 hours, so it’s a once-a-day dosage medication.

Some animals with kidney or liver disease may take longer to metabolize the medication, however, so those may need longer times between doses, or smaller quantities, to avoid overburdening their systems.

Some minuscule percentage of pets can also be allergic to Omeprazole specifically or to PPIs in general. Whenever you prescribe such medication, be sure to give instructions to your patients to watch for the signs of allergic reactions and to discontinue the medicine if they occur.

In some rare cases, dogs and cats taking Omeprazole may experience nervous system changes or get a urinary tract infection. These are exceedingly rare (and, in the case of the latter, easily treatable.)

Omeprazole can interact with other medications. Before prescribing it for a patient, look to see if they’re already taking:

  • Antibiotics, like ampicillin

  • Benzodiazepines

  • Clopidogrel

  • Cyanocobalamin

  • Cyclosporine

  • Digoxin

  • Diuretics

  • Ketoconazole

  • Levothyroxine

  • Phenobarbital

  • Rifampin

  • Warfarin

Additionally, ask your patients if they’re giving their dogs any supplements, including vitamins, herbal remedies, or other medications. Cross-reference these as necessary to look for additional interactions and determine if Omeprazole is suitable for the patient or if they should be told to discontinue certain other medications or supplements while administering Omeprazole.

Overdose Notes: Overdosing on Omeprazole is rarely dangerous. As a PPI, taking too much of the medication increases its effects; excess medication has no further real effect. Supermassive doses may cause a problem but are generally rare.

The most likely result of an overdose is a rebound when the medication wears off, and the patient’s body works overtime to produce acid in response to the prior lack. That said, if a pet takes too much Omeprazole and experiences adverse side effects, your clients may call you, so it’s important to know what to do or who to refer them to.

Typically, this will be an emergency vet, where they can be given additional medications, monitoring, and care they need.

Is Omeprazole Legal to Prescribe for Dogs and Cats?

Yes. While the use of Omeprazole in cats and dogs is off-label, it’s perfectly legal to prescribe it. Off-label usage means the medication has not been extensively tested and approved for use in animals, not that it’s in any way dangerous or illegal.

It’s only if a medication is tested, found problematic, and prohibited that prescribing it can be a matter of the law.

How is Omeprazole Administered to Dogs and Cats?

Omeprazole comes in three general forms.

  • A pill or capsule, similar to how it’s found in human medications.

  • An oral suspension or liquid, typically with a dosage of 2mg per ml.

  • A paste meant for animal consumption, with a single syringe containing 2.28 grams.

There’s little difference between each method of administration beyond how easy or difficult it is for pet owners to administer the medication to their animals. Some animals much prefer a paste over a pill.

Others, of course, are averse to anything that smells like medication, and an oral suspension may be the best option.

Pills are the easiest to store and manage, but many animals are resistant to accepting pills. Discuss the specific patient with your clients, and ask them how well their animal accepts pills before determining which version of the medication to prescribe.

What’s the Right Dosage for Omeprazole for Dogs and Cats?

Since Omeprazole is not licensed to be given to pets, the dosage has been developed over time by experience from vets. Current recommendations are for a dose somewhere between 0.25 and 0.50 mg per pound of an animal. Thus, a cat at a healthy 10 pounds would get somewhere between 2.5 and 5 mg per dose.

A dog weighing 50 lbs. would get 5x that amount, and so on. Alternatively, and practically, we give large dogs 20 mg of the over-the-counter, commercially available omeprazole, by mouth twice daily and small dogs 10 mg by mouth twice daily. Ultimately, it’s up to your discretion, the symptoms, and the severity of the ailment to determine whether you should aim for the lower end of that range or the higher end.

Since Omeprazole lasts about 24 hours in most people and pets, the dosage is once per day. A general course is usually four weeks of Omeprazole, but the specifics of the situation can modify this. For example, if Omeprazole is meant to prevent damage to the esophagus during intubation, it may only be administered during the patient’s treatment. Conversely, some animals with chronic conditions may be on an indefinite omeprazole prescription.

Make sure to caution your patients to follow through with a full prescription, even if their pet seems to be feeling better. Discontinuing PPIs can lead to temporary rebound acid production. Usually, this won’t be more than a day’s discomfort, but if an animal is still healing from a stomach ulcer, this rebound acid can aggravate it again and set back its healing.

If a patient misses a dose, they should continue to skip it and simply pick up the dosing the next time their regularly-scheduled dose would be administered. Do not double up or adjust the timing of the doses, to maintain consistency and prevent overlap.

Expert Advice At Your Fingertips

As a vet, keeping in mind the details of medications like Omeprazole isn’t easy. Sure, everything we’ve written here may be reasonable and straightforward, but when you have hundreds or thousands of different medicines and treatments to keep in mind, it can very quickly become overwhelming.

That’s why we offer the services we do. We’re the experts you can keep on standby.

When you have a patient with a condition that may benefit from Omeprazole, and you aren’t sure if it’s going to interact with another medication they’re on or if it’ll even be effective, you want to talk to an expert who knows what the most likely outcomes will be. We’re that expert. All you need to do is reach out and set up a contact with us.

When you have the need for an expert opinion on anything from oncology to dermatology to emergency medicine to internal medicine, all you need to do is ask us! You can email us to request a consult at, or give us a call at (253) 341-5835​ for personalized client recommendations.

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