What are steroids?
The adrenal glands produce two forms of corticosteroids:
- Glucocorticoids such as cortisol control carbohydrate, fat and protein metabolism and reduce inflammation through several different mechanisms
- Mineralocorticoids such as aldosterone control electrolyte and total body water levels, primarily by causing sodium retention in the kidneys.
Why are corticosteroids prescribed?
Because of their anti-inflammatory properties, corticosteroids are a valuable class of medications. They are commonly used to treat mild inflammatory conditions, or to suppress the inflammation associated with an allergic response. When administered in high doses, they act as immunosuppressant drugs.
Most forms of corticosteroids that are prescribed are synthetic.
These synthetic forms of cortisteroids are many times more potent than the naturally occurring forms and typically last much longer. Because of their increased potency and duration of activity, if synthetic corticosteroids are used, the patient must be monitored to minimise the risk of side effects.
For decades, this class of drugs has benefited humans and animals. They are a vital part of the treatment protocol for many life-threatening diseases. Their benefits far outweigh any risks in the majority of cases. When used properly, very few side effects occur.
What side effects can corticosteroids cause?
Corticosteroids may have both short term and long term side effects that cause different problems in your pet. It is easier to discuss these side effects as either short-term or long-term side effects.
What are some of the short-term side effects?
Short-term side effects are those that we expect a pet to experience when initially placed on corticosteroids. These side effects depend both on the type of steroid prescribed and on the dosage administered, and include:
- Increased thirst and urination
- Increased hunger
- Panting (especially dogs)
- General loss of energy
- Development or worsening of infections (especially bacterial skin infections)
- Vomiting or nausea (less common)
- Some pre-diabetic dogs or cats may become diabetic with corticosteroid usage
In many of these cases, the diabetes resolves once the steroid is discontinued. If any of these side effects occur, they can often be eliminated by lowering the dosage or frequency of administration. In some cases, your veterinarian may prescribe another type of corticosteroid in an attempt to reduce the side effects. The objective is to determine the lowest dose of medication that controls the condition with the least number of side effects.
What are some of the more common long-term side effects?
Some diseases and medical conditions require long-term treatment with corticosteroids, at either an anti-inflammatory dose or an immunosuppressive dose. When corticosteroids will be used for more than three to four months, particularly at immunosuppressive doses, additional side effects become a concern. The most commonly seen long-term side effects include:
- Urinary Tract Infections (UTI) in up to 30% of patients. Monitoring for the development of UTI is achieved by performing periodic urine cultures. A patient receiving steroids will not experience the usual symptoms of urinary tract infection because the steroid will suppress the inflammation and discomfort commonly associated with a UTI. In many cases, a urine culture may be the only way to detect the infection
- Development of thin skin, blackheads, and a poor or thin hair coat
- Poor wound healing ability
- Development of obesity due to increased hunger
- Muscle weakness secondary to protein catabolism (breakdown)
- Development of hard plaques or spots on the skin called calcinosis cutis. These plaques are the result of calcium deposition in the skin
- Increased susceptibility to opportunistic or secondary bacterial infections
- Increased susceptibility to fungal infections (especially of the nasal cavity)
- Development of adult onset demodectic mange
- Predisposition to diabetes mellitus
I've been told that corticosteroids can cause Cushing's disease. Why is this?
An excessive level of corticosteroids may cause Cushing's disease. When a pet is on long-term, high doses of glucocorticoids, there is an increased risk that it will develop a condition called iatrogenic (medication induced) Cushing's disease. The clinical signs of Cushing's disease include:
- increased thirst and urination
- an increase in UTI's
- skin and ear infections
- a "pot-bellied" appearance
- thinning skin and hair loss
In the treatment of some diseases, the risk of iatrogenic Cushing's disease is unavoidable. To minimize this risk, corticosteroid doses are tapered down over time, or several different drugs may be used in combination.
How do I reduce the risk of any of these side effects in my dog?
Fortunately, most dogs can safely use corticosteroids if a few simple guidelines are followed, such as; avoid using glucocorticoids on a daily basis except when specifically instructed by your veterinarian. Only life-threatening immune-mediated diseases require long-term daily steroid use. Most corticosteroid protocols require daily use only during the initial treatment phase. If your dog is receiving corticosteroids to reduce itching or for musculoskeletal pain, you should strive to administer them every other day. If you feel your pet requires daily corticosteroid use, inform us, we may recommend an additional or alternative treatment combination.
If your dog requires more than three to four months of corticosteroid usage, the condition should be re-evaluated or other treatment options should be pursued.
Dogs on long-term corticosteroids should be monitored with quarterly examinations and with urine and blood tests every six months. Corticosteroids can be life-saving medications and improve the quality of life for many dogs. By working closely with us, you can safely administer these drugs and provide your dog with the high quality of care he needs and deserves.