Steroids can offer relief for skin conditions, but use cautiously
Treatment application The usefulness of glucocorticoids in helping to manage allergic skin disease, specifically atopy, is unquestioned, while their ability to control other allergic skin diseases (food allergy, flea allergy and contact allergy) is more controversial. However, owing to their undesirable side effects, the use and, in some cases, misuse may result in additional problems. In addition, there are many alternatives that exist for dealing with an allergic patient. Many of these can be safe and relatively inexpensive, so steroids may be best reserved for those patients that are nonresponsive to an exhaustive search for other control methods.
This is a common problem seen at the author's practice that at least a portion of dogs that are presented as chronic allergic dogs for intradermal skin testing, are in fact, noncontrolled bacterial or Malassezia pyodermas that have not been resolved effectively. The inability to resolve the pyoderma often results from the lack of administration of appropriate antibiotics for an appropriate length of time or due to the immunesuppressive effects of steroids leaving the body unable to resolve the pyoderma by its own immune response or both.One of the most important pieces of advice that dermatologists can give to the general practitioner regarding glucocorticoid usage is to adhere to a well regimented and step wise workup of all pruritic dogs to eliminate these other pruritic diseases. This will allow the practitioner to be much more successful in managing pruritic patients in particular and dermatological patients in general. Pruritus in the absence of bacterial or Malassezia pyoderma, parasitic infestation (Sarcoptes, cheyletiella or fleas), lack of response to appropriate food trials as well as lack of response to various antihistamines, fatty acids and topical therapies may be an indication for glucocorticoids, however using glucocorticoids for the clinical signs of pruritus without addressing these other issues will often lead to chronic frustration for veterinarian and owner alike.
After a diagnosis of atopy has been made, either by intradermal skin test or by exclusion of other pruritic diseases, and a decision has been made to use glucocorticoids, the practitioner must select the appropriate steroid and route of administration. Various routes of administration include topical, oral, subcutaneous, intramuscular, intravenous or intralesional depending on individual disease and drug used. There are numerous synthetic glucocorticoids available for use in the United States and in general, these are more potent in regard to their glucocorticoid activity than naturally produced cortisol. Synthetic glucocorticoids also have a higher affinity for the steroid receptor, slower degradation and a longer duration of action.
Duration of action for injectable glucocorticoids is influenced by the form of the glucocorticoid in the preparation. Since synthetic glucocorticoids are synthesized as esters, the less soluble the ester, the slower the rate of absorption. For example, highly soluble esters include products such as Solu-Delta Cortef (Pharmacia/Upjohn) and Azium SP® (Schering-Plough). Moderately insoluble esters include products such as Depo-Medrol® (Pharmacia/Upjohn) while poorly soluble esters include Vetalog (Solvay).