What are steroids?
Corticosteroids (commonly called steroids or cortisone) are a class of steroid hormones that are naturally produced in the adrenal glands. Corticosteroids are involved in a wide range of body activities, including stress response, immune system response and inflammation control, nutrient metabolism, and maintenance of blood electrolyte levels.
The adrenal glands produce two forms of corticosteroids:
Glucocorticoids, such as cortisol. They control the metabolism of carbohydrates, fats, and proteins and reduce inflammation through several different mechanisms.
Mineralocorticoids such as aldosterone. They control electrolyte levels and total body water, primarily causing sodium retention in the kidneys.
Why are corticosteroids prescribed?
Because of their anti-inflammatory properties, corticosteroids are a valuable class of drugs. They are commonly used to treat mild inflammatory conditions and/or to suppress inflammation associated with an allergic response. When given in high doses, they act as immunosuppressants, that is, they suppress or prevent an immune response.
"Because of their anti-inflammatory properties, corticosteroids are a valuable class of drugs.
Most prescribed corticosteroids are synthetic and include prednisone, prednisolone, dexamethasone, triamcinolone and methylprednisolone. These synthetic forms of corticosteroids are many times more effective than the natural forms found in the body and usually last much longer. It is because of their effectiveness and increased duration of activity that they must be carefully monitored or serious side effects from these drugs can occur.
For decades, this class of drugs has benefited humans and animals. They are an important part of the treatment of many life-threatening diseases. Their benefits far outweigh any risks in most cases. There are very few side effects when used correctly.
What side effects can corticosteroids cause?
Corticosteroids have both short-term and long-term side effects that cause various problems for your cat.
Short-term side effects.
Short-term side effects are the effects we expect a cat to have when we initially take corticosteroids. These side effects depend on both the type of steroid prescribed and the dose prescribed and include:
- Increased thirst and urination
- increased hunger
- general loss of energy
- development or worsening of infections (especially bacterial skin infections)
- Vomiting or nausea (less frequently)
- Some pre-diabetic cats may become diabetic with corticosteroid use. In many of these cases, the diabetes goes away after the steroids are discontinued.
If any of these side effects occur, they can often be managed by reducing the dosage or frequency of administration. In some cases, your veterinarian may prescribe a different type of corticosteroid in an attempt to reduce the side effects. The goal is to determine the lowest dose of medication that controls the condition with the fewest side effects.
Long-term side effects.
Some conditions and medical conditions require long-term treatment with corticosteroids at an anti-inflammatory or immunosuppressive dose. When corticosteroids are used for more than three to four months, especially at immunosuppressive doses, additional side effects occur. The most commonly observed long-term side effects include:
Urinary tract infections (UTIs), which occur in 30% of patients. The development of UTIs is monitored through periodic urine cultures. A patient receiving steroids may not experience the usual symptoms of a urinary tract infection because the steroid will suppress the inflammation and discomfort normally associated with a UTI. In many cases, urine culture may be the only way to detect infection.
Development of thin skin, blackheads, and poor or thin hair
Poor wound healing ability
development of obesity due to increased starvation
secondary muscle weakness to protein catabolism (breakdown)
Development of hard plaques or patches on the skin called skin calcinosis. These plaques are the result of calcium deposition in the skin.
Exposure to opportunistic or secondary bacterial infections
increased susceptibility to fungal infections (especially of the nasal cavity)
predisposition to diabetes mellitus
I have been told that corticosteroids can cause Cushing's disease. Why?
Excessive levels of corticosteroids can cause Cushing's disease. When a cat takes high doses of glucocorticoids for an extended period of time, there is an increased risk of developing iatrogenic (drug-induced) Cushing's disease. Clinical signs of Cushing's disease include increased thirst and urination, increased UTIs, skin/ear infections, a "pudgy" appearance, thinning skin and hair loss. The risk of iatrogenic Cushing's disease is unavoidable when treating certain conditions. To minimize this risk, corticosteroid doses are gradually reduced, or several different drugs may be used in combination.
How do I reduce the risk of these side effects in my cat?
Fortunately, most cats can safely take corticosteroids if you follow a few simple rules, such as:
Avoid daily use of glucocorticoids unless specifically directed to do so by your veterinarian. Only life-threatening immune-mediated diseases require long-term daily steroid use. Most steroid protocols require daily use only at the beginning of treatment. If your cat is receiving steroids to reduce itching or musculoskeletal pain, ideally you should administer them every other day. If you feel your cat needs daily steroid use, let your veterinarian know, who may recommend an additional or alternative treatment combination.
If your cat needs more than three to four months of steroid use, reevaluate the condition or find other treatment options.
Cats on long-term steroid therapy are usually checked with quarterly tests and urine cultures, and blood tests, every six months.
Corticosteroids can be life-saving medications and improve quality of life for many cats. Working closely with your veterinarian, you can administer these medications safely and provide your cat with the highest level of care. If you have any questions or concerns about your cat's medications, please contact your veterinarian.