Diarrhea in Dogs From Prednisone: Causes, Symptoms, and Treatment

Your veterinarian might prescribe the corticosteroid prednisone for a variety of canine ailments. While they might warn you that your dog will drink more water and urinate more frequently while on the drug, that's not prednisone's only side effect. The medication can also cause diarrhea, among other complications, though these side effects are more common in dogs receiving prednisone in high doses or long term.

Prednisone is a synthetic corticosteroid, or glucocorticoid. Corticosteroids are a class of steroid hormones produced in the adrenal cortex. Prednisone is used to treat several conditions in multiple species, though it is most often prescribed for its anti-inflammatory properties.

Prednisolone is a distinct but very similar medication. Because it is converted to prednisone in the liver, prednisolone is considered bioequivalent, and the drugs are frequently used interchangeably, especially in dogs.

Prednisone and prednisolone are available in tablet and liquid forms, which should be taken with food. If your dog is on a once-daily dose, give them their medication in the morning. Veterinarians can also administer prednisone or prednisolone as injections.

Veterinarians typically prescribe prednisone for acute or short-term conditions. "Most times, prednisone is prescribed is for short-term situations due to more of the side effects being seen with higher doses and longer-term use," explains Dr. Jordan Kautz, a veterinarian at Crestview Veterinary Clinic in Austin, Texas. "If long term administration is needed, then commonly, additional medications are added in conjunction with prednisone to allow a potentially lower dose and therefore less side effects."

Your veterinarian may prescribe prednisone if your dog is diagnosed with allergies (for itch relief), joint pain, hypercalcemia (to reduce blood calcium levels), cancer, shock, or disorders of the central nervous system. Your dog may also receive prednisone if their immune system is out of whack due to an autoimmune disease, such as Addison's disease, or a gastrointestinal issue, such as ulcerative colitis. Large doses of the medication can act as an immunosuppressive.

The most common side effects of prednisone are increased drinking, urination, and appetite. Other side effects, including vomiting and diarrhea, are more likely to occur in higher doses and with long-term use of prednisone. Additional side effects include mild behavior changes, lethargy, panting, delayed wound healing, skin thinning, and hair loss. Weight gain is also common due to increased appetite.

Mild side effects, such as increased urination and drinking, are unlikely to produce any serious complications, but vomiting and diarrhea can lead to dehydration if not properly monitored and addressed. If your pet is experiencing any severe or prolonged side effects from prednisone, talk to your veterinarian about changing their dosage or using complementary medications. Do not discontinue use without your veterinarian's supervision.

With long-term prednisone meds usage, dogs can also develop gastrointestinal ulceration, signs of which include a lack of appetite, black or bloody stools, bloody vomit, a high fever, weakness, pot belly, and weight gain. Other potential complications of prednisone include diabetes mellitus or Cushing's disease. The latter is a life-threatening condition that occurs when the adrenal glands produce excess cortisol, putting your dog's body at risk of kidney damage and other issues. Young dogs taking prednisone may suffer from impaired growth.

If your dog develops diarrhea while on prednisone, call your veterinarian. Try to obtain a fecal sample if necessary. Your veterinarian may reduce the dosage or switch your dog to another medication. Make sure it is the prednisone that's causing loose stools. If you've changed your dog's food or if they got into the garbage or otherwise ate something inappropriate, the prednisone may not be the cause of the diarrhea. But you'll want to investigate before you give them the next dose.

You might also investigate if it is possible that drug interactions between the prednisone and other meds the dog might be taking are causing problems. There are several drugs that may cause drug interactions with prednisone including pain relievers, seizure drugs, immunosuppressing drugs, and drugs for bacterial infections. If your dog is receiving vaccinations while on prednisone, talk to your veterinarian about whether or not prednisone might make the vaccines less effective.

Pet owners might encounter prednisone and prednisolone being used to treat a range of conditions in human and veterinary medicine. In canines, the drugs are most frequently used to alleviate allergies, joint pain due to arthritis, and other inflammatory conditions. Serious side effects are unlikely, but complications like diarrhea and vomiting can occur, especially with long-term use or high doses of prednisone. If your dog is taking this corticosteroid and experiences loose or bloody stools, vomiting, or other concerning symptoms or behavior changes, alert your DVM.