Prednisone for dogs: usage and side effects

Whether they're for your health or your pets' health, doctor's visits can feel overwhelming. So if you take your dog to the vet and come away with a prescription for prednisone and a lot of information that leaves you a little unnerved and confused, you're not alone. Even if your dog's vet is good at explaining health concerns and reasons for a new prescription, it can be hard to take it all in during moments of high stress. So if your vet prescribed your pup prednisone, here's what you need to know.

What is prednisone used for in dogs?‍

You may be generally familiar with the term “prednisone,” even if you and your pets have never used the medication before. In addition to being a drug for pets, it’s also a steroid used by humans. It’s a very strong medication typically used to treat autoimmune diseases and strong allergic reactions. So when a vet (or a doctor) prescribes prednisone, it’s often for a very good reason.

“There are only a few reasons dogs should be given corticosteroids, like prednisone,” Dr. Melissa Best, DVM, a US-trained-and-licensed veterinarian and the owner of Tranquila Vet in Costa Rica, says. “The top three are acute allergic reactions, a disease called hypoadrenocorticism (or Addison’s disease), and a condition called Immune-Mediated Hemolytic Anemia (IMHA), where the body’s immune system attacks and destroys its red blood cells.”

Of course, Addison’s disease and IMHA are more rare conditions, so generally speaking, if prednisone is prescribed, it’s in response to an acute allergic reaction.

Short vs. long-term use of prednisone in dogs‍

When prednisone is prescribed, it’s almost always for a short period of time to address your dog’s histamine response to an allergic reaction. “Steroids are very powerful and act quickly to relieve symptoms, but because of this fact, they also carry a high risk of side effects,” Dr. Best explains. “Occasionally, we will use a short course of steroids to relieve chronic allergy symptoms as it’s important to ‘break the itch-scratch cycle.’ However, this does nothing to address the underlying allergy and can cause serious, even life-threatening, side effects if used long-term.”

And this is exactly why you should understand the reasons for your vet’s prednisone prescription for your dog. If your pet receives a short course, likely it’s in response to an acute reaction that needs to be controlled. This is good news, but you need to know what the plan of action is to control the underlying reason for the allergic reaction in the first place.

If your vet prescribes a long-term course of steroids, you really need to understand the reasons. “The only time steroids would be used long-term is when the body can’t make its own steroids (such as in Addison’s disease), or when chronic suppression of the immune system is needed, such as in IMHA,” explains Dr. Best. “In these instances, we taper the dose to the least amount necessary to control symptoms over time while hopefully minimizing side effects.”

Side effects of prednisone in dogs‍

And, just as Dr. Best explains, prednisone is a strong drug that can cause significant side effects. If your vet prescribed prednisone to your dog, you need to be aware that your dog’s habits and behaviors may change short-term.

“Common side effects include markedly increased drinking and urination, increased hunger, restlessness, and very rarely, increased aggression. These all typically resolve when the medication is discontinued,” Dr. Best says.

While most side effects are short-term and resolve after you stop giving your dog prednisone, there are some significant downsides to a course of these corticosteroids.

“One of the most dangerous possible side effects is actually causing hypoadrenocorticism (Addison’s disease) in a patient. The body needs steroids to survive, and it usually does a great job at producing them in a very controlled way,” Dr. Best says. “When we give additional doses of steroids, we disturb the normal control pattern, and the body begins to produce less and less.”

The problem? If steroids are used too long, or are taken away suddenly, your dog may not be able to start producing his or her own steroids again. According to Dr. Best, this can be a life-threatening situation.

But that’s not the only potential long-term problem caused by significant or prolonged prednisone use. “We can also see changes to glucose metabolism leading to diabetes. In some patients, long-term steroid use can also lead to cardiovascular problems and higher risk of ulcers in the digestive system,” Dr. Best says. “It is critically important that all steroid administration is slowly reduced and never stopped suddenly for this reason. Even when serious side effects occur, we typically need to keep giving the prednisone in slowly-decreasing amounts to avoid causing an even more serious situation.”

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