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CHRONIC STEROID USE
Most people are familiar with the term "cortisone" and may even know that it is a steroid but, despite the fact that steroids are commonly prescribed to both people and animals, much more knowledge than that is not really mainstream. Let's take a few moments to straighten out the vocabulary of steroids hormones so as to understand what is actually contained in that bottle of pills so frequently dispensed.
Corticosteroids: Steroids produced by the outer area (the cortex) of the adrenal glands. Corticosteroids can be either glucocorticoids (involved with sugar metabolism) or mineralocorticoids (involved in electrolyte balance). We will limit our discussion to the glucocorticoids, as the mineralocorticoids are only used therapeutically in one situation (to treat a deficiency in mineralocorticoids known as "Addison's disease.")
Examples of Glucocorticoids:
Cortisol: This is the natural hormone produced by one's adrenal glands to regulate sugar, fat, and salt metabolism in times of stress.
Hydrocortisone: Just another name for Cortisol.
Cortisone: A synthetic but inactive version of cortisol.
Prednisone: In order for cortisone to become an active hormone, it must be processed by the liver. The first step in the activation of cortisone is its conversion into prednisone. Prednisone can be produced in the laboratory and is readily available as a medication.
Prednisolone: In order for prednisone to become an active hormone, it must be processed by the liver into prednisolone. Again, prednisolone can be produced in the laboratory and is readily available as a medication.
Methylpredisolone (Medrol®): Adding a methyl group to the predisolone molecule reduces the salt retention effects (thereby reducing the increased thirst side effect. This is frequently desirable for pets as increased thirst translates to increased urination which in turn translates to urinating in the house. Obviously, this would be a side effect to reduce.)
Dexamethasone (Azium®): More mehthylation creates an even stronger steroid with even less salt retention side effects. Dexamethasone can also be manufactured in the laboratory and is readily available as a medication.
Further modifications of the cortisol molecule can create steroids that last for a prolonged period (methylprednisolone acetate), or that are more water soluble (prednisolone sodium succinate). These further modifications are generally for the injectable products while those listed above are oral.
THERE HAS NEVER BEEN A CLASS OF DRUG
INDEED, THIS GROUP IS RIVALLED ONLY
That said, side effects from the glucocorticoid group are numerous and can be classified into those seen with short term use and those seen in long term use.
SHORT TERM SIDE EFFECTS
The pet on glucocorticoids is likely to experience the following:
Further, pre-diabetic animals may be “tipped over” into a diabetic state with steroid use. Often in these cases, the diabetes resolves once the steroid wears off.
A similar situation exists for patients with borderline for heart failure (a situation for which cats are notorious). The extra salt retention from steroid use can prove to be just too much for a heart that can barely manage its normal fluid volume. The salt retention causes fluid retention and a borderline heart may not be able to manage.
If inconvenient side effects become problematic, adjusting to a lower dose of medication frequently solves the problem. The goal with glucocorticoids is always to find the lowest dose of medication that is still effective. For more serious side effects, a medication of a different class may be needed.
LONG TERM SIDE EFFECTS
There are many conditions which require long term suppression of the immune system. Glucocorticoid doses generally include an “anti-inflammatory” dose which is lower and an “immune suppressive” dose which is higher, though with long enough term use, lower doses will become immune suppressive. When steroid use stretches out for more than four months, a new set of side effects (in addition to those listed above) becomes of concern:
All of the above listed effects can be seen and be considered symptoms of this syndrome.
When long term therapy is needed, monitoring tests become especially important; requesting refill after refill without regard for the potency of these medication is not appropriate. Periodic urine cultures, check ups and even blood testing is part of responsible on-going corticosteroid use. For details on what tests are best for your pet, please consult your veterinarian.
When a long term dose of steroids is deemed to be excessive, it is time to seek another medication so as to spare the amount of steroids needed if not replace the steroid altogether. There has recently been a proliferation of medication for itch relief without the use of steroids. For more information on these click here. For alternative immunomodulating drugs, consult your veterinarian.
Page last updated: 7/23/2019