Glucocorticoid Therapy

What are Glucocorticoids?

Glucocorticoids are a group of drugs commonly used in treatment of allergic skin diseases. They may also be known as corticosteroids, steroids, by their trade names (Prednil, Pred-X, Macrolone, Delta Cortef, Depomedrone) or by their active ingredient (prednisolone, hydrocortisone, dexamethasone). They may be administered as tablets, injections or creams and are often used for temporary relief of pruritus(itchiness) and inflammation. In most cases treatment is rapidly effective but the beneficial effects are sometimes combined with a wide range of side effects.

The risk of side effects from glucocorticoids correlate with the dose and duration of therapy i.e. the higher the dose and the longer the therapy the more likely side effects are to occur.

To reduce the likelihood of side effects long-acting injectable corticosteroids are usually avoided. A short acting glucocorticoid tablet such as prednisolone is used instead. This allows the dose to be fine tuned to the lowest effective level and therefore reduces the risk of side effects. The dose is generally tapered to the lowest effective alternative day regime. Once the problem starts to recur please contact your attending vet to determine how to proceed. The maintenance dose may vary with season and other therapy.

If modest doses are used for periods up to three months the risk of significant side effects is minimal whereas if prednisolone is used for longer periods much smaller doses are recommended. If we feel that the maintenance dose of prednisolone needed is too high we may introduce ancillary therapies such as antihistamines and essential fatty acids to allow the dose to be lowered. If the dose needed increases (particularly if it has been stable for some time) you should discuss the situation before increasing the dose, as this is often the result of secondary infections.

Side Effects of Glucocorticoids

• Increased thirst: Most pets show an increased thirst and urination rapidly when glucocorticoids are administered. Pets should therefore be given unlimited access to water and allowed to urinate more frequently. In some cases pets become incontinent.
• Increased appetite: This may result in begging and weight gain if pets are allowed to eat extra food.
• Depression: Glucocorticoids can also cause depression. Pets will often be less energetic and sleep more.
• Mental Changes: In rare cases pets may become aggressive and disorientated.
• Gastrointestinal disease: There may be increased gastric acid and pepsin secretion and decreased gastric mucosal cell proliferation predisposing to gastric ulceration. Therefore other drugs that predispose to gut irritation should be avoided while administering prednisolone.
• Diabetes mellitus: Glucocorticoids inhibit the action of insulin predisposing pets to diabetes mellitus.
• Liver Damage: Increased glycogen storage in the liver results in swelling and liver damage.
• Suppressed immunity: Glucocorticoids suppress many parts of the immune system, resulting in increased episodes and duration of secondary bacterial infections of the skin and bladder.
• Catabolism of muscular and fibrous tissue: This results in muscular weakness, skin fragility, vascular weakness and joint weakness. Dogs on long term glucocorticoid therapy are at increased risk of joint injuries.
• Bone weakness: Increased absorption of calcium from the bone, decreased absorption of calcium from the gut and increased gut and urinary calcium loss may result in bone weakness.
• Calcinosis cutis: This abnormal deposition of calcium in the skin results from excess glucocorticoids.
• Poor hair coat/alopecia: Glucocorticoids inhibit hair growth resulting in hair loss and/or poor hair coat.
• Suppression of secretions from the skin glands.
• Suppression of thyroid hormone, growth hormone, sex hormones and reduction of natural corticosteroid synthesis. This means that blood tests for hormones will be affected by glucocorticoid therapy.

There is now an alternative to using steroids for allergic skin disese, it is a drug called Apoquel, please contact us if you would like more information about this new product