Prednisone and prednisolone are closely related corticosteroids. The key difference is activation: prednisone has to be converted by the liver into prednisolone, while prednisolone is already active. Dogs convert prednisone efficiently, so veterinarians often treat the two as interchangeable. Cats and pets with liver disease don't, so prednisolone is usually preferred.
If your veterinarian prescribed one and you've seen the other name online, it's easy to wonder whether there's a mix-up. There usually isn't. Below, we compare prednisone vs. prednisolone and explain which one fits cats, dogs, and pets with liver issues. We'll also cover the forms available.
The difference between prednisone and prednisolone is how they become active. Prednisone is a prodrug, meaning the liver has to convert it into prednisolone before it can work. Prednisolone skips that step.
A prodrug is a medication that is inactive when given and has to be converted by the body, usually the liver, into its active form.
Once converted, the two are considered bioequivalent, according to VCA Animal Hospitals' 2025 drug guide for prednisolone and prednisone. Both mimic cortisol, the body's natural steroid, and both are used to manage inflammation and calm an overactive immune response.
Prednisone vs. Prednisolone at a Glance |
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|---|---|---|
|
Prednisone |
Prednisolone |
|
|
Activation |
Converted by the liver into prednisolone |
Already active |
|
Best fit for cats |
Not preferred; cats convert it poorly |
Preferred choice |
|
Best fit for dogs |
Commonly used |
Commonly used; often interchangeable |
|
Pets with liver issues |
Usually avoided |
Usually preferred |
|
Commercial forms |
Tablets, oral liquid |
Tablets, oral liquid |
|
Compounded options at Mixlab |
Chew treats, capsules, oral suspensions |
Capsules, chew treats, oral suspensions |
Cats can take prednisone, but most veterinarians prescribe prednisolone instead because cats convert prednisone poorly. That means less of the dose turns into the active drug.
VCA's drug guide goes further and advises against using prednisone in cats at all. If your cat was prescribed prednisone, don't switch on your own. Ask your veterinarian whether prednisolone is a better fit.
For more on dosing and side effects in cats, see our prednisolone for cats guide →
For most dogs, yes. Dogs convert prednisone into prednisolone efficiently, so veterinarians often treat prednisone vs. prednisolone for dogs as interchangeable at equivalent doses.
Which one your dog gets usually comes down to practical details: the dose your veterinarian wants, the form that's easiest to give, and whether your dog has liver concerns.
Some dogs do better with a flavored chew than a bitter tablet, and that's where compounding can help. Learn more in our prednisolone for dogs guide →
Our Take: Bitter tablets are one of the most common reasons pet parents struggle with steroid courses. If your pet spits out their pills, ask your veterinarian about a compounded chew, capsule, or liquid in the same strength.
Prednisolone is usually the better fit for cats and dogs with liver disease. Because it's already active, it doesn't depend on a liver that may not convert prednisone efficiently.
VCA's drug guide notes that prednisone shouldn't be used in pets with liver dysfunction and that prednisolone is the alternative. It also notes effects may last longer in pets with liver or kidney disease, so your veterinarian may adjust the dose or monitoring schedule.
Prednisone and prednisolone are prescribed for a wide range of inflammatory and immune-related conditions in dogs and cats. Common uses include:
Many of these uses are off-label, which is common in veterinary medicine. Your veterinarian chooses the drug, dose, and length of treatment based on your pet's condition.
Prednisone and prednisolone share the same side effects because they're the same active drug once prednisone is converted. The most common side effects are increased thirst, urination, and appetite.
Higher doses or long-term use can also cause:
Contact your veterinarian if you notice any of these. Never stop either medication suddenly. Both suppress the body's own cortisol production, so they need to be tapered gradually under veterinary guidance.
Alternatives to prednisone for dogs depend on what's being treated, and your veterinarian is the one to decide if a substitute makes sense. Common options include:
Note: NSAIDs and steroids generally shouldn't be given together, so never combine them without your veterinarian's direction.
Mixlab compounds prednisone and prednisolone in pet-friendly forms based on your veterinarian's prescription. Your veterinarian sends the prescription, and we prepare and ship it.
Compounding medications lets veterinarians choose a specific strength or a form your pet will actually take, like a flavored chew, capsule, or oral suspension.
Veterinarians, order compounded prednisone or prednisolone →
Pet parents, ask your veterinarian to send your pet's prescription to Mixlab →
No. Once prednisone is converted in the liver, the two are considered equally potent at equivalent doses. The difference is that prednisolone doesn't need that conversion step, which matters most for cats and pets with liver disease.
Cats convert prednisone into its active form poorly. A study found only about 21% of oral prednisone reached a cat's bloodstream as active prednisolone. Giving prednisolone directly avoids that problem, which is why it's the usual choice for cats. Mixlab compounds prednisolone for cats in capsules and chews.
Only if your veterinarian approves the switch. Dogs convert prednisone efficiently, so veterinarians often consider the two interchangeable, but the dose and form still need to come from your veterinarian. If a switch makes dosing easier, Mixlab can compound the new prescription in a form your dog will take.
No. Both medications reduce your pet's natural cortisol production, so stopping suddenly can cause serious problems, including adrenal insufficiency. Your veterinarian will give you a tapering schedule that lowers the dose gradually. Follow it exactly, even if your pet seems fine.
Yes. Both are prescription medications, so a veterinarian has to examine your pet and prescribe them. Your veterinarian can send that prescription to Mixlab, and we'll prepare the medication in the strength and form they choose.
Increased thirst, urination, and appetite are the most common side effects of prednisone in dogs, according to VCA's drug guide. Panting is also common. Let your veterinarian know if these seem severe or if your dog shows vomiting, diarrhea, or unusual behavior.
Sources:
Forsythe, Lauren R., and Rania Gollakner. Prednisolone/Prednisone. VCA Animal Hospitals, updated 2025.