Treating Ulcers in Dogs with Cimetidine

Dogs with stomach ulcers are often treated with cimetidine, a medication that reduces stomach acid production. While the most common cause for stomach ulcers in dogs is medications, other causes such as stress, mast cell cancers and injuries can be contributing factors as well.


Cimetidine, also known as Tagamet, is part of a class of drugs called histamine H2 receptor antagonists. This class of drugs helps to reduce the amount of acids that your dog’s stomach produces. Cimetidine not only inhibits acids triggered by ingestion of food, it also prevents stomach acids that may be produced throughout the day, and night-time production as well.

Administering Cimetidine

Because the majority of canine ulcers are caused by medications the dog is on for other problems, it is recommended that cimetidine is given within an hour following the medication causing the ulcer problems. Because cimetidine is a fast acting medication, it will reduce the amount of acid produced in the stomach by 50% in the first hour, and by up to 75% in the following 2 hours.

If your dog is no longer taking the medication that caused the ulcers, or if the ulcers are caused by something other than medication, cimetidine can be given at even intervals during the day to maintain lower stomach acid levels. Cimetidine can be given 2 to 4 times each day, depending upon the dosage and veterinary recommendations. Healing can take from 4 to 12 weeks, depending on the severity of the ulcers.

Cimetidine Dosage

Standard dosing for cimetidine is is 3 to 5 mg per pound, every 6 to 8 hours. Because the dosage can vary, especially if your dog has other conditions such as kidney disease or is on other medications, it's important to consult your veterinarian in order to administer the appropriate amount of cimetidine.

Precautions and Side Effects

Cimetidine, while relatively safe, should be used with caution if your dog is older, has liver or kidney disease or has blood abnormalities. It can also inhibit your dog from absorbing or metabolizing of other oral medications he is taking, so it's important to consult your veterinarian before starting treatment.

Side effects with cimetidine are rare. If side effects do occur, it is typically a mild case of diarrhea. If side effects such as rapid heart beat, panting, difficult breathing or hives occur, contact your veterinarian immediately.

While the use of cimetidine for the treatment of ulcers is typically prescribed your veterinarian, cimetidine can be used for other conditions relating to gastric discomfort. Cimetidine is also used to treat inflammation of the stomach (gastritis), inflammation of the esophagus and esophageal or gastric reflux. The reduction of stomach acids reduces the inflammation and the pressure caused by the increased stomach acids. Whether treating ulcers or treating any of the other gastric problems, consult your veterinarian to ensure there isn’t another, more critical condition causing problems with your dog. This is especially important if your dog is on other oral medications in order to prevent possible drug interactions. Taking care in the use of cimetidine can help bring your dog’s stomach health back into balance.