What Are Steroids?
Steroids are substances that circulate in the blood stream and affect almost every part of the body. Many steroids are made by the adrenal glands. The outer part of the adrenal glands (the adrenal cortex) releases and regulates three groups of steroids:
- Mineralocorticoids (aldosterone and desoxycorticosterone). Mineralocorticoids regulate circulating sodium, chloride and potassium levels, blood volume and blood pressure.
- Glucocorticoids (cortisol [hydrocortisone], cortisone and corticosterone). Glucocorticoids regulate blood glucose levels, aid in metabolism and influence growth, development and inflammatory reactions. They also affect bone, cartilage, calcium metabolism, pregnancy and heart, kidney and central nervous system function.
- Sex hormones (androgens and estrogen-like compounds). The importance of adrenal sex hormones is unclear. They probably have masculinizing or feminizing effects similar to testosterone, estrogens and progesterone.
Mineralocorticoids and glucocorticoids together are referred to as “corticosteroids”. Many people refer to corticosteroids simply as “steroids.”
The inside of the adrenal glands (the adrenal medulla) releases and regulates epinephrine (adrenaline) and norepinephrine (noradrenaline), which are critical to the response to stress and regulation of blood sugar. These steroids increase heart rate, cardiac output, blood pressure and metabolism and slow the movement of food through the digestive tract.
Why Are Steroids Used?
Anti-Inflammatory and Immunosuppressive Steroids
Most steroids suppress inflammation by reducing heat, redness, swelling, tenderness and pain. They also suppress the immune system, which can be good or bad, depending on the situation. Steroids typically are used for a short period of time when an animal hasn’t responded well to treatment with non-steroidal anti-inflammatory drugs (NSAIDs). Long-term steroid use is reserved for dogs whose immune system isn’t working properly. Steroids are used to treat:
- Eye disease
- Gastrointestinal disease
- Heat stroke
- Immune-mediated disease
- Kidney disease
- Lung disease
- Neurologic/central nervous system disorders
- Termination of pregnancy
- Skin disease
- Systemic lupus erythematosus
Anabolic steroids increase the production of red blood cells, which increases the amount of circulating oxygen and promotes tissue growth. Testosterone, made by the testes, is a naturally-occurring anabolic steroid. Synthetic anabolic steroids are similar to testosterone, but they don’t have as many masculinizing effects. Anabolic steroids are used to treat chronic, non-regenerative anemia in pets. They also are used to increase muscle mass, improve body weight and condition in older dogs and restore weight and body condition in animals after surgery or debilitating disease.
Side Effects of Steroids
Steroids can be dangerous if used improperly. Because they suppress pain and other signs of inflammation, steroids can interfere with owners’ and veterinarians’ ability to recognize and monitor a dog’s illness or injury and response to treatment. Steroids make it look like a dog is getting better, when it may not be. They also impair a dog’s ability to fight disease. Some of the adverse effects of steroids include:
- Adrenal damage
- Cartilage damage
- Delayed wound healing
- Gastrointestinal complications (vomiting, diarrhea, nausea, bleeding, ulceration, erosion, perforation; can be catastrophic)
- High blood pressure
- Iatrogenic Addison’s disease
- Iatrogenic Cushing’s disease
- Increased eating and drinking; excess urination and weight gain
- Interference with diabetes mellitus treatment
- Liver damage
- Reduced resistance to infection
- Reduced effectiveness of antibiotics
Synthetic anabolic steroids can cause sodium and water retention, liver and kidney damage and development of secondary male sex characteristics (masculinization), especially in females.
Steroids shouldn’t be given together with NSAIDs. Concurrent use of antibiotics and steroids is controversial. Most steroids are given orally, although topical and injectable preparations are available. Because long-term steroid use can be harmful, veterinarians prescribe the lowest effective dose at the longest effective intervals. Dogs should be weaned off steroids gradually.