Most of us know term or and have used cortisone. This is a type of steroid that anti-inflammatory properties. It is not the same as an anabolic steroid, which builds muscle. In fact, this type of steroid is catabolic and breaks down muscle and other soft tissue structures, however, it has a number of medical applications for both animals and humans.
Steroids produced by the outer area (the cortex) of the adrenal glands including the naturally glucocorticoid cortisol. This is the natural hormone produced by the adrenal glands to regulate sugar, fat, and salt metabolism in times of stress.
Another name for cortisol. And there are topical products sold under this name.
In order for cortisone to become an active hormone, it must be processed by the liver. The first step in activating cortisone is its conversion into prednisone. Prednisone can be produced in the laboratory and is commonly dispensed as a human and veterinary.
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. It is often given to cats in lieu of prednisone as felines have a harder time than dogs with the conversion to prednisolone.
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.)
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 that has more application in disease treatment than the glucocorticoid class. But they come with many side effects – both short-term and long-term
Short-Term Side Effects
A pet taking glucocorticoids is likely to experience the following:
- Increased hunger
- Increased thirst (and possibly urinary incontinence if there is inadequate access to an area for appropriate urination)
- Panting (dogs)
- Hard plaques of diseased skin called calcinosis cutis; this is calcium deposited in the skin.
- General loss of energy
- Recrudescence of latent infection (hidden infection being unmasked).
Furthermore, 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 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
Latent urinary tract infections in up to 30 % of patients. Monitoring for these is necessary with periodic urine cultures. The patient will not have the usual symptoms of urinary infection as the steroid will suppress the inflammation associated with the infection. Culture may be the only way to detect the infection. There are many conditions that require long-term suppression of the immune system. Glucocorticoid doses generally include an anti-inflammatory dose that is lower and an immune suppressive dose that is higher; when used long enough, lower doses will suppress the immune system. 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:
- Development of thin skin, blackheads, and poor ability to heal wounds or grow hair
- Development of obesity and muscle weakness
- Hard plaques of diseased skin called calcinosis cutis. These plaques represent deposited calcium in the skin.
- Predisposition to infection of any kind, weakening of immune defenses
- Development of iatrogenic (medically induced) Cushing’s synsdrome
- Loss of a protein called anti-thrombin III, which can increase the risk of forming ethombolic emboli
All of the above listed effects can be seen and can be considered symptoms of this syndrome.
When long-term therapy is needed, monitoring tests become important; requesting refill after refill without regard for the potency of these medications pets your pet at considerable medical risk. Periodic urine cultures, checkups and even blood testing is part of responsible on-going corticosteroid use. For details on what tests are best for your pet, consult your veterinarian.
When a long-term dose of steroids is deemed to be excessive, it’s time to seek another medication so as to spare the amount of steroids needed if not replace it altogether. There has recently been a proliferation of medications to alleviate itching that are outside of the steroid class and don’t have the same side effects. For other drugs that can be used to replace steroids, talk with your veterinarian.