Steroids for Pets: the Essential Guide! (uses, side effects, warnings + monitoring)

Is your pet on steroids? Seriously, prednisone is a super common drug that has been used to treat almost every imaginable disease at one point or another. This powerful steroid can make a huge difference in a dog or cat with many different types of illness, but steroids also come with the potential for some pretty serious or disruptive side-effects.

This is what you need to know!


What is Prednisone?

I'll start off by saying that prednisone and prednisolone are steroids, or glucocorticoids. That's the class of drug that they are. Historically steroids have been used to treat almost every disease imaginable. Now, not all of these have been appropriate uses of steroids. We certainly know that now.

Chances are though that you've come across a dog or a cat being treated with steroids. Maybe your dog or cat has just been prescribed them, or perhaps you're actually taking them yourself as well.

They really are that common.

While steroids can be used in both dogs and cats, there is one point of difference here. Prednisone, which is often the drugs that’s being dispensed, is actually converted to it’s active form of prednisolone in the liver. This is a process that cats may not be able to do very efficiently. As a result, there's certainly an argument that we should be giving our cats prednisolone instead of prednisone.

While I feel that this step isn’t often needed, it should certainly be considered if you’re finding that treatment with prednisone isn't working in a cat with an appropriate disease. You may need to consider switching over. And why not just use prednisolone? It’s typically much more expensive!

What Diseases do Steroids Treat?

Steroids have 4 major areas of use:

  1. Anti-inflammatory

  2. Immunosuppresive

  3. Antineoplastic

  4. Natural steroid replacement


Steroids are used for their effects in four main, broad categories. The first of these is that they have an anti-inflammatory effect. And so they are used to treat and to reduce inflammation, which can be caused by a number of different diseases.


Secondly, they're used for their immunosuppressive effect. They actually damp down and reduce the body's immune system.

You can imagine then that we use this prednisone effect to control different diseases falling into the allergic diseases and autoimmune disease category. Allergic diseases are when the body's immune system pretty much goes into overdrive, having an exaggerated, inappropriate response to a foreign material or stimulus. Examples of this would be various forms of allergic skin disease (such as atopy or food allergies), and also extreme reactions to insect stings.

Autoimmune diseases are when the immune system goes haywire and starts to destroy its own body. This can include conditions like immune mediated hemolytic anemia (IMHA). In this disease the red blood cells are actually attacked by the body's own immune system. They are destroyed and as a result a dog or cat can come become incredibly anaemic. Untreated, this condition is fatal.

Dogs and cats also get something called immune mediated thrombocytopenia (IMTP). This is very similar, but instead of red blood cells, it's the body's platelets that are destroyed. Platelets are responsible, in part, for the blood clotting, and without those platelets an animal can effectively bleed to death.

So the second use of steroids is for their immunosuppressive effect.


Next up we have an anti-neoplastic effect. We can think of prednisone and steroids in general as a very crude, weak form of chemotherapy when used by themselves. In some cancers, such as lymphoma, if we use just prednisone there is the potential to get a pretty reasonable response that lasts for two to three months. Unfortunately this effect quickly tails off, and the cancer then becomes resistant to other chemotherapeutic agents as well as the steroid.

So by itself, steroids are not a fantastic form of chemotherapy. They are though very important when we use them as part of a treatment plan in addition to a number of other, different chemotherapeutic agents. Prednisone make a really big difference and plays a vital role in the treatment of some cancers, when used at the same time as other chemotherapy drugs.

Steroid replacement

And then the final use of prednisone is when it is used as a replacement when there's a problem with the body's adrenal gland.

The adrenals are where the body normally produces the stress hormone cortisol. If there's a problem here, and the production of cortisol is reduced, a patient will suffer from a disease called Addison's or hypoadrenocorticism.

We'll then use steroids as a replacement. Addisons is not a very common disease, only pretty rarely being something that we will find in dogs.

Prednisone Dose

The dose of steroids that are being given plays an important role in the effect that they have. If we're using steroids at a low dose, typically that would only have an anti inflammatory effect. But as we increase that dose, then we get more of an immunosuppressive effect.

This means we'll use low doses of steroids for the treatment of simple inflammation, but if we're looking for an immunosuppressive effect, certainly when we're starting treatment, we're going to use much higher doses to kick things off.

What can then happen is that we'll then taper the prednisone dose down, which I'll come onto later.

Steroid Side Effects in Dogs and Cats

You'll appreciate from all of these different ways that we can use steroids and the general conditions that we're using them to treat, steroids can affect a whole different range of diseases within different parts of the body. Pretty much every system in the body has a disease that you can use steroids to treat. This could be the skin, blood, liver, lungs, nervous system...the list goes on.

And because steroids act on every single body system, there are numerous side effects that you need to be aware of.

Major steroid side effects:

  • Increased appetite

  • Increased thirst

  • Increased urination

  • Weight gain

  • Lethargy

  • Panting

  • Muscle loss

  • Vomiting + diarrhoea

  • Hair loss,

  • Thinning of the skin

  • Kidney disease

  • Blood clot (thromboembolism)

  • Cruciate ligament rupture

Appetite, Thirst + Peeing

The first, and perhaps the most common are an increase in appetite, an increase in thirst and an increase in urination. These are more likely to be seen when a dog or cat starts treatment, and when high doses are being administered (as is often the case at the start of a treatment course).

The body is producing a lot more urine and your dog or your cat will need to pee all the time which can cause problems. Because of this increased urine production, they need to drink a lot to stay well hydrated.

One of the big difficult side effects of steroids to cope with and to manage is that your dog might have multiple accidents overnight. Reducing their water intake isn't going to solve this side effects, because they are actually producing more urine. Reducing their water intake could instead potentially result in them becoming dangerously dehydrated. Now this severity of increased urination isn't a problem all the time, but it's certainly something to be aware of.

These steroid side effects do also tend to resolve themselves as treatment continues, especially if we're able to reduce their dose over time. This though is really going to depend on what disease is being treated, and what dose needs to be given as a result. If really high doses need to be maintained then these side effects may also be maintained.

Long-term effects

Other common side effects of prednisone can develop with long term use, including weight gain, lethargy and panting. You might also see vomiting and diarrhea due to intestinal ulceration. If long term, high doses are maintained then your pet could develop thinning of the skin or thinning of the hair coat. This hair loss generally affects the flanks, the sides of the abdomen and the chest.

And then finally, steroid side effects can result in kidney damage, an increased risk of blood clot formation, increased risk of cruciate ligament rupture, and worsening of diabetes. These risks are very, very low thankfully.

Also, muscle wasting can develop, and a pet can develop a condition known as iatrogenic hyperadrenocorticism (or Cushing's disease). Cushings disease is naturally occuring with symptoms very similar to the steroid side effects I’ve just described. With long term, high dose steroid use, we can in effect give our pets this disease (which is what iatrogenic means).

That’s a long list of potential side-effects!

If you want to learn more about reducing these, then check out my post all about reducing drug side effects in dogs and cats.

When should steroids not be used (or used with caution)

After hearing about all these side effects, you can imagine that there are then numerous different situations and conditions where using prednisone should only be considered with care. So that's not to say they should definitely not be used, but we should only use them carefully and after full consideration of the risks and possible alternatives.

Are they the most appropriate medication, or are they the only option available to your pet?

Fungal disease

Really, glucocorticoids should not be used in systemic fungal infections. Depending on where you are in the world depends on whether these are really a concern or not. Generally these infections are more of a concern in tropical climates.

No diagnosis

We do need to be careful in many cases when a specific diagnosis has not been reached. This is because steroids have such a broad effect that using them can mask and hide important signs of a disease and so affect the job of making a proper diagnosis more challenging. Steroids can also alter diagnostic tests, making their interpretation either difficult or impossible.

Pre-existing diseases

We need to be careful giving steroids with animals that already have Cushing's disease (or hyperadrenocorticism). Care is also needed in dogs and cats that have heart failure or diabetes, if they've got an infection, pre-existing kidney disease, and also if they've got intestinal disease.

That said, steroids are very appropriately for dogs or cats with various intestinal diseases, such as inflammatory bowel disease. This is an autoimmune disease where the body's immune system is effectively attacking the lining of the intestine.

Long-acting injection risk

We also need to be especially careful with the use of long acting injectable preparations, especially in cats. This is because a single injection has the (very small) potential to result in diabetes. This really is very rare, but it's something to consider if your cat needs steroids and you are able to medicate them with a tablet.

Diabetes risk aside, by and large, cats are actually much more resistant to the side effects of steroids compared to dogs. We often don't see a lot of the potential side effects in cats. This is even despite the fact that cats need to be given higher doses of steroids to have a similar effect to dogs. So, if you've got a dog and a cat that are both receiving steroids, you might find that on a body weight basis your cat’s dose could well be twice as high.

Never Stop Steroids Suddenly

As you’ll already have gathered, in most cases of steroid treatment, dogs and cats will start off on a high dose and then be weaned down onto a lower dose before finally stopping treatment. Even if long term treatment is needed, it is often the case that a much lower dose can end up being used, yet still have the desired effect.

The reason you should never stop steroids suddenly is that doing so can result in collapse and death. This is because something known as an Addisonian crisis can be triggered. What effectively happens is that the body gets used to receiving this extra steroid, and so the adrenal glands stop producing cortisol, the bodies stress hormone, in as much of a quantity as is needed. The prednisone we give effectively takes over. If we remove the prednisone too quickly, the body is not able to respond quickly enough and body steroid levels plummet.

Unless you’re only giving really short term prednisone treatment that’s lasting only a few days, never just stop giving your dog or cat their medication. Instead, slowly tapering the drug off, following the label instructions from your veterinarian.

If you’re having problems. If your pet won’t take their medication suddenly. If you’re really struggling because of severe side-effects (like your dog having multiple accidents every night) then talk to your vet to find out the best plan going forward.

Monitoring Prednisone Treatment

Finally, we need to talk about monitoring a dog or cat on steroid treatment. Monitoring really depends on the disease that's being treated.

Typically this means watching out for the development of the side effects that have already been discussed. At the same time, you should be keeping an eye on the signs of the disease being treated so you can tell just how effective the treatment plan is being.

It may be that regular blood tests are taken or other tests run to monitor any effects on the health of the liver, kidneys, immune system, or other systems felt necessary by your pet’s vet.


Steroids get a lot of bad press. In actual fact, they are an incredibly useful drug. They are vital for the successful treatment of many different diseases.

Don't be put off just because of the potential side effects. In many cases there are no good alternatives that are really any better in regards to the potential for side effects.

Having said that, they should be used appropriately and with due consideration. There are some newer drugs that are better or safer options to use. Clear examples of this are the recent development of two drugs used to treat atopy or allergic skin disease. Apoquel and Cytopoint are much more targeted in how they act on the body. They don't affect every single body system in the same way prednisone does. As a result, when it comes to the long term treatment of allergic skin disease, these are undoubtedly the better choice of drug.

Now that's not to say that prednisone has suddenly stopped working. And it may be that, because of finances, Apoquel and Cytopoint are not an option for your pet, in which case steroids will still do a great job because we don't want your pet to be itching all the time. It's miserable. We just need to be more aware of the potential for side-effects and consider steroids as only one piece in an overall treatment plan.

The aim of treatment with steroids (for any condition) is to use as much as is needed, but as little as possible, and for as short a time as possible.

I'd be really interested to hear your experience of giving your dog or cat steroids in the comments down below. What disease were you giving it to treat? Did they experience any side effects and how much of a problem did this cause?

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