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Steroids
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There are two types of steroid. These are corticosteroids and anabolic steroids. Corticosteroids are anti-inflammatory agents and
Corticosteroids
Corticosteroids are hormones which occur naturally in both dogs and cats. They are produced by the adrenal gland which lies in front of the kidney in times of stress and has effects on most of the body's systems. They produce three different types of steroids: mineralocorticoids, sex steroids, and the glucocorticoids. Glucocorticoids regulate protein, carbohydrate, and fat metabolism where-as Mineralocorticoids regulate electrolyte balances.
Corticosteroids |
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Mineralocorticoids |
Mineralocorticoids get their name from the fact that they have the responsibility of maintaining the levels of the minerals sodium and potassium in the body, and because they are produced by the cortex of the adrenal glands. Through their effect on sodium and potassium, as well as other actions, they conserve or maintain the body's concentration of water at a near constant level. Mineralocorticoids exert most of their effect on the kidneys, causing parts of these organs to selectively excrete excess potassium in the urine and at the same time conserve or retain sodium. These actions maintain the concentrations of these electrolytes within a very narrow range that is compatible with life. The use of the mineralocorticoids or their synthetically produced imitations in veterinary medicine is much less common than the other two forms of steroids. |
Glucocorticoids |
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previously mentioned cortisol belongs to the glucocorticoid group. The
members of this group get their name because they affect glucose
metabolism and are produced by the cortex section of the adrenal
glands. The glucocorticoids are the predominant steroids used in
veterinary medicine. These naturally occurring steroids cause proteins
(e.g., muscles) and lipids (e.g., body fats) to be chemically broken
down and converted into glucose. This is why the glucocorticoids are
also referred to as the "catabolic" steroids. Catabolism means to break
down large molecules into smaller ones. Additionally, the
glucocorticoids also cause carbohydrates stored in the form
of glycogen to be converted back to glucose and deposited into the
circulating blood. There it is available to all the body's tissues. To
break down the proteins or fats of the body may seem harmful to the
animal, but remember that glucose is the main energy source for all of
the body's activities. The vast majority of the glucose that the body
utilizes comes directly from the diet or stored glycogen, but in
emergency situations it can be derived from its own protein and lipids.
It is generally thought that the glucocorticoids only cause this to
occur to a significant degree during periods of exceptional need.
Glucocorticoids also suppress inflammatory processes within the body. A bruise, bee sting, bacterial infection, or arthritis are just a few examples of inflammation within a pet's body. Inflammation is specifically defined as an area of the body characterized by redness, swelling, heat, and pain, often with impaired function. The warmth and redness seen in these affected tissues comes from an increase in the number and size of blood vessels within the area. The swelling (edema) is caused by free fluid within the tissues and also the engorged blood vessels. All of these changes are brought on by physical trauma and/or irritants within the tissues. The pain is caused by the swelling, by harmful substances putting pressure on, or by stimulating the local nerve fibers. The loss of function can be caused by pain or the simple inability of the body to move or act correctly. |
Sex Hormones |
The other steroid type produced by these glands is the sex steroids. Examples of these are the female hormones estrogen and progesterone and the male androgens such as testosterone. These same substances are also produced in much greater quantities by the ovaries in the female and the testicles in the male. The androgens are the group that are sometimes referred to as anabolic steroids. Although they have accepted uses in medicine today, they often get considerable publicity when they are abused by athletes to increase their strength and abilities unethically. They are totally different in activity and usage from the glucocorticoids or mineralocorticoids. |
Generic formulations are very common and can be applied topically, as part of treatment for skin conditions, or injected into specific areas, such as a tendon or joint. They can also be given orally to treat respiratory conditions.
Injectable:
Injectable forms of steroids include betamethasone, dexamethasone,
flumethasone, methylprednisolone, and triamcinolone. These agents are
usually given intramuscularly
and have between one week and six months duration depending on the
product, the dose, and the individual animal.
Oral supplementation allows a more accurate and tailored dose, but injectables may be preferred in several situations. Injectables are preferred in animals that are very difficult to give pills to, and in animals that need immediate relief. Once the injection is given, it is impossible to reverse its effects and side effects. With oral administration, if unwanted side effects appear, the product can be discontinued and the side effects will diminish.
Oral: Most of the injectable forms of steroids also come in a tablet form. As mentioned earlier, it is much easier to customize an individual dosage with the tablet form. The affected animal usually begins with daily therapy for a period of three to five days, and then the dose is reduced to every other day dosing. If the animal needs to be treated for more than a couple of weeks, then the dose is halved weekly until a minimum therapeutic level can be established. The goal with all steroids is to use the minimum dose necessary to alleviate the symptoms. By taking this approach, the side effects are eliminated or reduced.
Long term usage of steroids (usually over a period of months), may induce internal changes to the patients body, resulting in an over-production of the patient's cortisol (patient's own body steroid) production. This condition, known as Cushing's disease, can necessitate the need for specific treatment. Otherwise, simply slowly reducing the dose of steroid, will result in an automatic decrease in the patients cortisol levels. Some other high dose, long-term side effects include increased incidence of infections, poor hair coat and skin, immunosuppression, diabetes mellitus (The use of cortisones makes it harder to control insulin dosages in diabetic pets and they may even help to induce diabetes in susceptible pets), adrenal suppression, and liver problems. The potential problems can be severe, however, it must be stressed that these side effects are dose dependent. In the long term, weight gain may occur,and ulcers have been reported after long term corticosteroid use and in some cases there may be an increased incidence of pancreatitis in dogs.
