The Power of Steroids

These drugs can make a huge difference in your cats quality of life, but they are not without drawbacks

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Steroids can be lifesaving drugs, but they can also have deleterious side effects. So, what do you do when the veterinarian suggests using a steroid? Well, first, you need to understand that these compounds occur naturally in your cat and are essential for health.

The adrenal gland is the primary producer of steroids, but other organs can produce certain steroids as well. Production in the adrenal glands occurs in response to the secretion of ACTH (adrenocorticotropic hormone) by the anterior pituitary gland. Steroids can also be manufactured synthetically and used to treat a variety of health conditions.

The term “corticosteroid” comes from the fact that most steroids are produced by the cortex of the adrenal glands. The three basic types are glucocortiods, mineralocorticoids, and the “sex” steroids or hormones that fit the steroid chemical picture.

Types of Steroids

Glucocorticoids are important in modulating inflammatory responses. They can suppress the immune system, which is why they are helpful when added to a cat’s treatment for immune-related diseases. Steroids that can help with an immune problem, however, can also lower your cat’s resistance to pathogens.

Glucocorticoids also influence your cat’s ability to manufacture and conserve glucose, which is used as an energy source by the tissues of the body. Most synthetic steroids used to treat cats are much more potent than the natural versions in effect and/or longevity of action.

Mineralocorticoids help to maintain electrolyte homeostasis. Regulating electrolytes, such as sodium and potassium, is important for the function and survival of virtually all cells in the body. Aldosterone is the primary mineralocorticoid in the cat and acts on the kidneys to conserve sodium and excrete potassium. Sodium balance is important for normal hydration and for the function of skeletal and heart muscle and the nervous system.

The primary sex steroids or hormones in cats are estrogen, progesterone, and testosterone. These compounds are important for the secondary sex characteristics in cats and for reproductive health and fertility. Depending on the breed, these characteristics may include body size, coat quality and color, and head size. These hormones can also influence behaviors such as urine marking and territoriality.

The most commonly used synthetic steroids for cats are glucocorticoids used for allergies, immune illnesses, and as anti-inflammatory agents. Steroids are one of the drugs your veterinarian may reach for if your cat presents with anaphylactic shock. More commonly, you will encounter glucocorticoids for a cat with allergic reactions.


Prednisone and prednisolone are the two most frequently prescribed corticosteroids. They are usually dispensed as pills. Initially, these medications are dosed daily (possibly even multiple times a day), but the goal is to gradually reduce the dose to the absolute minimum required to keep your cat comfortable.

These steroids may be used as part of a chemotherapy protocol, to aid a cat with severe arthritis, to help a cat with allergies get relief, or topically to treat small areas of skin reactions. They also can help in life-threatening immune conditions such as autoimmune hemolytic anemia (AIHA). These medications should only be used as needed while other therapies, potentially aimed at the cause of the health problem, are instituted. For example, prednisone can control itching due to a flea allergy and make the cat comfortable, but the flea infestation needs to be dealt with.

Side Effects

Side effects of steroid use include increased drinking (and urinating) along with an increase in appetite. You might notice your cat being more lethargic than usual. These short-term side effects will usually return to normal once the medication is stopped. Steroid treatments should not be stopped abruptly unless told otherwise by your veterinarian. Your cat usually will need to be “weaned” off these medications, which means gradually tapering the dose down from the originally prescribed amount until the time the therapy is stopped.

Long-term usage can lead to more troubling problems. Loss of muscle and skin thickness along with hair loss is common. There is a risk of developing diabetes mellitus. In addition, your cat’s immune system may be weakened, so he may be more susceptible to infections, including urinary tract and fungal infections. Long-term usage may also interfere with your cat’s natural production of these compounds.

Anabolic steroids such as testosterone (made in the testes) can help with adding muscle mass to a debilitated cat and are sometimes used to treat cases of anemia.

For some cats, steroids may make the difference between life and death or may be essential for a cat to enjoy a good quality of life. These medications do come with some side effects, however, and should only be used under veterinary guidance.