Corticosteroids
March, 1998
Lorticosteroids, the term used to refer to cortisone ande its
derivatives, are some of the most commonly used drugs in human
and veterinary medicine. They are synthetic versions of a
chemical that is required by the body, and produced in our
adrenal glands.
The word “steroid” is not spedific and its use can be
misleading. Another class of drug, called anabolic steroids,
possesses different qualities and are used in different
situations than the corticosteroids. Anabolic steroids are those
that are used and abused by athletes to help build muscle and
improve athletic performance. They also have some uses in
veterinary medicine, such as in treating problems associated with
kidney failure and in building muscle in weak or debilitated
older dogs.
Corticosteroids have a large number of possible uses and just as
many possible side effects. The body’s immune system
produces inflammation as a proper response to a number of
insults. This “normal” response can sometimes cause
signs that we wish to alleviate. Therefore these drugs are used
to treat spinal inflammation from disc disease, brain swelling
seen after head trauma, or joint pain and stiffness arising from
arthritis or sprains.
These drugs are also commonly used to treat diseases whose
underlying cause is an over-reaction by the immune system, such
as allergies or autoimmune diseases. The common allergic reaction
in dogs is dermatitis, but asthma or upper respiratory disease
(hay fever) can occur. Examples of tru autoimmune disease include
hemolytic anemia, Pemphigus and Lupus. These require long term or
lifetime treatment.
Cortisone is frequently used to treat cardiovascular shock. After
a major physical trauma, if an animal is panting, non-responsive
and has pale gums (even without blood loss) he is likely to be in
shock. It includes a major alteration in blood flow that involves
shunting of blood away from the periphery and toward some
internal organs. However, this protective mechanism can be
life-threatening and can rapidly reversed with corticosteroids
and intravenois fluid adminstration.
Corticosteroids can be used to treat a few types of cancer, such
as lymphoma or mast cell tumors, by actually slowing down the
production of tumor cells. With other types of cancer, they can
still eliminate some inflammation and pain and delay the need for
euthanasia.
Addison’s disease is a condition that involves inadequate
production of all the hormones of the adrenal glands’ outer
layers. These hormones, including corticosteroids, need to be
supplemented for life. They can also be given to decrease high
levels of calcium in the bloodstream, while the cause is being
investigated, or to elevate the blood sugar level when an
insulin-secreting tumor threatens to drop it below normal.
With all these legitimate uses for cortisone, the veterinarian
must still be careful to avoid overuse because the possible side
effects are also many and varied. The most common side effects
seen in dogs are the least serious. Many dogs drink and urinate
excessively. Some also have a voracious appetite, probably due to
the stimulation of an appetite center in the brain. Another
common side effect involves an increase in the level of certain
liver enzymes. This is not associated with any outward signs, but
it can interfere with the interpretation of routine blood
analysis.
Whenever a dog’s course of treatment with corticosteroids
includes oral medications to be given at home for a while, it is
important to slowly decrease the dose over time before
discontinuing the drug completely. This is because administration
of any form of cortisone causes the body to decrease its own
production. The adrenal glands take time to get back to the
normal level of production when the drug is no longer given.
Sudden withdrawal of the drug can cause signs of cortisone
deficiency - usually weakness, lethargy, and poor appetite.
Corticosteroids have the potential to affect many body systems
and different dogs will respond differently to this medication.
Because of their effect on the body’s immune system,
corticosteroids can produce a susceptibility to infection and
poor wound healing. From the effects on the nervous system, one
may see restlessness and panting. Corticosteroids use has been
implicated as leading to pancreatitis (inflammation of the
pancreas) in some dogs, which causes vomiting and abdominal pain.
Repeated injection of dexamethasone can apparently lead to
intestinal ulceration and, in extreme cases, perforation. In
breeding animals, possible side effects include infertility
problems and abortions. Fortunately, most of these more serious
adverse effects are seen relatively infrequently.
The effectiveness of corticosteroids in a large number of
veterinary patients makes them an indispensible tool. However,
the potential for overuse is great. We frequently encounter
owners of allergyplagued dogs who use corticosteroid
administration as a “crutch” when other courses of
management are recommended, such as intensive flea treatment in a
household where one dog is allergic to fleas. It is up to
veterinarians and dog owners to use these and any drugs with care
to help improve the overall quality of life in our animals. it