Omeprazole (Prilosec) for dogs

Omeprazole is an acid reducer used in dogs to treat or prevent ulcers. For people, omeprazole is a common fixture on store shelves as an over-the-counter heartburn drug, probably best recognized by the brand name Prilosec OTC. For veterinarians, it’s usually the first choice to reduce stomach acid in dogs with stomach or duodenal ulcers or who are taking ulcer-causing drugs. Although vets consider it the most effective drug at reducing stomach acid, they only consider it safe for up to four weeks.

RELATED: Save up to 80% on omeprazole

What is omeprazole used for in dogs?

Omeprazole works by lowering stomach acid production. Veterinarians use it to help dogs with stomach or small intestine ulcers. It can also prevent ulcers or stomach inflammation (gastritis) in dogs taking ulcer-causing drugs like nonsteroidal anti-inflammatory drugs (NSAIDs). They also give it to dogs as part of “triple therapy” to eradicate Helicobacter infections associated with gastritis.

The veterinary use of omeprazole in dogs is off-label, meaning the U.S. Food and Drug Administration (FDA) does not approve it for this use. However, it is well-studied, and veterinarians have decades of experience using it as a canine medication. 

Omeprazole belongs to a class of drugs called proton pump inhibitors, or PPIs. This sounds like science fiction, but it’s very simple. Acid levels in the stomach are due to hydrogen protons. The more hydrogen protons, the more acidic the stomach becomes. Omeprazole blocks the stomach lining from dumping hydrogen protons into the stomach. 

Omeprazole for ulcers

Omeprazole is usually a veterinarian’s first choice for treating dogs with stomach or duodenal ulcers. It rapidly and dramatically reduces stomach acid, relieves symptoms, and gives the ulcer time to heal. Veterinarians may also use it when a dog is taking medications that cause stomach lining irritation, erosion, or ulcers. In those cases, veterinarians may use famotidine, a different stomach acid reducer. It’s less effective at reducing stomach acid but has fewer side effects than omeprazole and minimal drug interactions.

Dogs may develop gastrointestinal ulcers for reasons similar to those of humans, such as experiencing stress, engaging in strenuous exercise, taking medications that can lead to ulcers, or having medical conditions like kidney disease that cause ulcers. Treating dog ulcers is a normal part of veterinary medicine. 

Symptoms aren’t specific, but the dog will clearly show signs of sickness: 

• Vomiting
• Loss of appetite
• Abdominal pain
• Weight loss

The dog may sometimes also have black and tarry stools or have blood in the vomit. If the dog is weak or showing signs of shock or extreme pain, take the dog to a veterinarian immediately.

Veterinarians can only definitively diagnose GI ulcers through an endoscopic examination. Once an ulcer has been diagnosed, veterinarians will typically start the dog on omeprazole. 

Omeprazole for Helicobacter eradication

Helicobacter is a common bacterial infection of the stomach. Helicobacter pylori usually infects humans. The infection eventually leads to inflammation, erosion, and ulcers. Dogs are never infected with H. pylori, but most are infected with other Helicobacter species. We don’t know if these infections cause the same problems in dogs as humans.

Because we don’t know if Helicobacter infections cause problems in dogs, veterinarians may test dogs who show signs of gastritis for a Helicobacter infection. They will use a blood test, a breath test, or a biopsy to confirm a Helicobacter infection.

If a dog diagnosed with gastritis tests positive for Helicobacter, which is common in most cases, the veterinarian might opt for “triple therapy” to eliminate the infection. This therapy combines omeprazole with antibiotics, such as amoxicillin and metronidazole. 

Is omeprazole safe for dogs?

Omeprazole is considered safe for dogs as a short-term treatment. 

However, drugs are never 100% safe. Omeprazole should never be used in dogs that have had an allergic reaction to it. Veterinarians will also use the drug with caution in dogs with kidney or liver disease because of the risk of side effects.

The most significant safety issue is stomach acid suppression. Stomach acid serves many useful functions, so long-term use may cause vitamin B12 deficiency. Reduced stomach acid also produces an environment conducive to infections. Due to this factor, omeprazole is considered a safe dog medication when administered daily for four weeks. 

Side effects of omeprazole in dogs

The most common side effects of omeprazole in dogs are:

• Loss of appetite
• Nausea
• Vomiting
• Flatulence
• Diarrhea

Side effects are generally mild. If a dog experiences GI distress, try giving the omeprazole dose with food to see if that fixes the problem.

Omeprazole can sometimes increase liver enzymes in the blood. When this does happen it is generally mild and shouldn’t cause symptoms.

More serious side effects include:

• Blood abnormalities
• Urinary tract infections
• Protein in the urine
• Central nervous system abnormalities

Interactions of omeprazole with other pet meds

Omeprazole has several drug interactions that may cause problems. It’s one of the veterinary drugs most likely to be involved in drug interactions. For this reason, tell the veterinarian about all the drugs and supplements the dog is taking. 

Veterinarians’ biggest worry is that omeprazole slows down the breakdown of many other types of drugs. When those drugs are combined with omeprazole, they’re more likely to cause side effects. The adverse effects of omeprazole are comparatively mild, but these other drugs might be more dangerous. These include benzodiazepines such as diazepam, the blood thinner warfarin, some types of seizure medication, the immune-suppressing drug cyclosporine, and the heart rhythm drug digoxin.

Another problem is that omeprazole can make some drugs less effective. That’s because those drugs require stomach acid to be broken down enough that they can be absorbed into the body. These drugs include:

• Certain types of antifungal medications, such as ketoconazole
• Some types of antibiotics 
• Iron salt supplements

Omeprazole dosage for dogs

The standard omeprazole dosage for dogs is 0.5–1 mg/kg, administered once per day.

Plumb’s Veterinary Drug Manual lists several omeprazole dosages for different conditions:

• To treat or prevent ulcers: 0.5–1 mg/kg given orally once per day
• For stomach cancer (gastrinomas) or esophagitis: 0.7–1.5 mg/kg given orally once per day
• For severe gastrinomas or esophagitis: 1-2 mg/kg given orally every 12 hours
• For Helicobacter eradication: 0.7 mg/kg given orally once per day with amoxicillin, metronidazole, and Pepto-Bismol twice daily for 2 weeks

The omeprazole used in dogs is the same tablets and capsules used in humans. The veterinarian or a compounding pharmacy can also supply an oral suspension for easier dosing. It also comes as an oral paste (Ulcergard or Gastrogard) formulated for horses. Doses are not equivalent to omeprazole tablets or capsules, so veterinarians usually don’t prescribe omeprazole paste to dogs.

Can dogs overdose on omeprazole?

Do not give your dog larger doses than prescribed. In humans, an overdose can cause problems but isn’t considered a major crisis unless the overdose is extreme. If a dog ingests too much omeprazole, contact a pet poison helpline or the veterinarian for advice.

Can I give my dog omeprazole every day?

Omeprazole must be given to dogs daily for several weeks to be effective. It may take a few days of daily dosing for symptoms to improve.

It’s safe to give dogs omeprazole daily for up to four weeks, following the advice of a veterinary professional. Sometimes, a vet may have a dog take omeprazole for up to eight weeks. 

How to give your dog omeprazole

Omeprazole is given to a dog every day for several weeks:

• Follow all the veterinarian’s instructions.
• Omeprazole is administered every day.
• The dog should be given omeprazole for the prescribed duration, even if all the symptoms improve.
• To work best, omeprazole should be given to the dog on an empty stomach. 
• The best time to give a dose is in the morning, about 30 minutes before the dog eats their first meal.
• If the dose causes nausea, vomiting, or appetite loss, try giving the dose with food.
• If you don’t know how to give a dog a tablet, ask a veterinary technician at the vet’s office to demonstrate.
• If the dog is too resistant to taking a tablet, the tablet can be crushed and mixed with fruit juice. Do not mix omeprazole with food or water.
• If you give an oral suspension, shake the bottle before measuring a dose. Always measure the dose with an oral syringe. A veterinarian can provide one for free.
• Do not miss a dose. If a dose of omeprazole is missed, give it when remembered. However, if it’s almost time for the next dose, skip the missed dose and give the dog the next dose on schedule. Never give the dog a double dose to compensate for a missed dose. 
• Store this medicine at room temperature in a light-resistant container.

Omeprazole alternatives for dogs

If a dog cannot take omeprazole, there are alternatives. There are other proton pump inhibitors, but they aren’t as well studied in dogs as omeprazole.

Chances are, the vet will try a different type of gastric acid reducer called H2 blockers. These drugs block receptors in the stomach lining that stimulate stomach acid secretion. The most common H2 blockers used in dogs are Pepcid (famotidine), or Zantac. It’s effective, has minimal side effects, and has very few drug interactions. Other choices include cimetidine and nizatidine, but they’re usually second choices. 

Antacids are another safe option, but only for mild conditions like heartburn. Veterinarians do not consider them effective at treating acid reflux or ulcers. Talk to the veterinarian first if you want to give your dog an antacid. Antacid doses should be spaced at least two hours before or after an omeprazole dose. 

Other alternatives include sucralfate and misoprostol. These drugs protect the stomach lining from acid, so they can be used to treat or prevent ulcers. These medications are usually used combined with omeprazole and not in place of it. 

Summary

Omeprazole for dogs is a safe and effective way to treat and prevent ulcers. To work, it must be given every day to the dog for several weeks. It’s best if the dog takes each day’s dose on an empty stomach about 30 minutes before the first meal.