Prednisolone Use In Dogs & Cats

Is there any other drug that can be all of these?

  • Overused,
  • Underused,
  • Harmful,
  • Essential

Love it or hate it, prednisolone is the most misunderstood drug in veterinary medicine. Its uses and side effects are too varied and complex to understand easily. Here I’ll help you to get informed.

Prednisolone is a steroid hormone. Even just that fact is confusing enough.

What Are Steroids?

The term ‘steroid’ is often used as shorthand for anabolic steroids, but the reality is very different. There are many different steroid molecules in the body. Some of the most famous are:

  • The sex steroids oestrogen, progesterone and testosterone
  • The corticosteroids aldosterone, cortisone and cortisol
  • Cholesterol
Steroids all have the same four ring structure

The one we’re interested in here is cortisol. Artificially synthesised as hydrocortisone it was the first medication of its class. These days we rarely use it, thanks to newer, more potent relatives. They include dexamethasone, prednisone and of course prednisolone.

Before moving on, it’s worth mentioning that prednisone and prednisolone are almost the same. If your pet has been prescribed prednisone, everything I say from here is just as true.

Effects Of Prednisolone

All the effects of prednisolone, both good and bad, can be put in two categories:

  1. Immunosuppressive
  2. Metabolic

If we like the effect, we call it a use. If we don’t like it then we call it a side effect! Although this is a very artificial divide, I’ll stick with it to describe everything that prednisolone does, both good and bad.

Uses & Doses Of Prednisolone

Prednisolone comes in 5mg and 20mg tablets for veterinary use. It is most commonly employed for its anti inflammatory effect. This is very useful for itchy skin diseases like atopic dermatitis, flea allergy, insect bite and hot spots. The dose here typically starts at 0.5 to 1 mg/kg per day.

What prednisolone also does here that’s just as important is stop self trauma. These dogs often get rapidly worse due to the damage caused by licking and scratching. Prednisolone helps them forget the itch so that the skin can heal.

Prednisolone at similar doses is also one of the few drugs which can reduce swelling. That’s essential for many diseases of the brain and spinal canal to reduce the pressure caused by swelling in a closed space.

At doses of 1 to 2 mg/kg once to twice daily, the immunosuppressive effect becomes great enough to treat autoimmune diseases. Without prednisolone we would have much more trouble controlling conditions like these:

Prednisolone at similar doses can also be used as an anti cancer drug, mainly for lymphoma. Lastly, at very low doses prednisolone can be used in Addison’s disease as a replacement hormone, though at Walkerville Vet we prefer cortisone.

Prednisone Side Effects in Dogs

In order of how often we see them, the adverse effects of prednisolone are:

  • Increased thirst
  • Increased appetite
  • Weight gain
  • Panting and heat intolerance
  • Excessive urination or incontinence
  • Abdominal enlargement
  • Loss of muscle mass
  • Lethargy and reduced fitness
  • Urinary or skin infections
  • Glucose intolerance and diabetes
  • Thin, fragile skin and hair loss
  • Poor wound healing
  • Demodex mite outbreaks
  • Gastrointestinal ulcers leading to vomiting or diarrhoea
  • Behaviour change, especially aggression
  • Infertility
  • Worsening of existing heart disease symptoms
  • Dependance and adrenal crisis if stopped suddenly

An adrenal crisis is a self- induced form of Addison’s disease caused by feedback suppression of the adrenal gland. After 14 days or more of daily treatment, dogs and cats should be weaned off corticosteroids gradually by changing to every second day dosing for at least two weeks.

In cats, we generally see milder side effects, but diabetes appears more common.

With all of these problems, you’d wonder why anyone would use prednisolone. Of course, with careful management, and only using it for selected cases, we usually only see the top few, and only mildly. Sometimes the disease is so severe that we willingly accept some of these effects as the price to pay for control.

Does Prednisolone Shorten Life?

There is no evidence of reduced lifespans in dogs or cats taking prednisolone. There is also no theoretical reason why this would occur. In our clinic we observe that animals on prednisolone live well into old age as long as side effects are kept under control, especially weight gain.

Some other side effects reported by others that I don’t see are liver damage or pancreatitis.

How To Make Prednisolone Safer

Here are the important ways you can reduce prednisolone side effects in your pet.

  1. Use the lowest effective dose
  2. Use it every second day if possible
  3. Use the shortest course possible
  4. Stop when side effects are unacceptable at the lowest dose
  5. Use dose-sparing strategies

Dose sparing strategies are anything that allows you to get away with a lower dose. Examples in itchy dogs might be:

In other diseases, it might be choosing a second drug alongside prednisolone.

Prednisolone will always be an integral part of veterinary medicine. If you’re concerned about it, that’s normal. I hope I’ve given you enough to make an informed decision with your vet.

I’ve also covered the specific case of using prednisolone in allergic skin diseases at Can I Give My Itchy Dog Prednisolone? You’ll see comparisons with the other common skin medications.

By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. These blogs are from a series regularly posted on email and Twitter. Subscribe via email here to never miss a story!
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