Veterinary Medicine - November 2008 - (Page PD13)

can tolerate higher doses and glucocorticoids with a longer duration. Thus, longer-acting injectable glucocorticoids such as methylprednisolone acetate are a particularly attractive alternative. Many veterinary dermatologists carefully utilize this drug successfully and safely for occasional therapy. Intermediate-term therapy. Often, less than one week of therapy (by either a single injection or daily oral medication) is necessary to break the pruritic cycle. Administer short-acting oral preparations every 48 hours or less often to mitigate suppression of the adrenal axis. Administer intermediateacting preparations every 72 hours or less. The safe annual steroid dose is a guideline to be considered in these patients. You should further investigate and treat the underlying cause of the inﬂammation and pruritus. According to the American College of Veterinary Dermatology Task Force on Canine Atopic Dermatitis, allergen-speciﬁc immunotherapy is the only mode of therapy shown to result in partial or complete remission of canine atopic dermatitis without the further need of additional antiinﬂammatory drugs. Glucocorticoids are an integral part of our pruritic patients’ comfortable existence. They have many advantages over other forms of therapy and can be safely used for therapeutic purposes. However, they are not without potential side effects. When prescribing glucocorticoids, as with so much of what we do, monitoring and client education are essential aspects of patient care. Guidelines for calculating glucocorticoid use1 By Candace Sousa, DVM, DABVP, DACVD As with any other class of drugs, glucocorticoids have clear value when used to treat a disorder for which they have proven therapeutic beneﬁt and when administered at the appropriate dose, frequency, and duration of administration. The beneﬁts of any therapy must always be weighed against the potential side eﬀects. The primary dosing guidelines for glucocorticoid use is to always use an appropriate induction dose to gain eﬀective control of the clinical signs for the shortest amount of time and then taper to the lowest eﬀective dose possible to maintain control of the condition. Furthermore, the use of alternate day therapy has been recommended to minimize adrenocortical suppression and the other side eﬀects of the prolonged administration of glucocorticoids. For alternate-day therapy to be successful, the administration of glucocorticoids with a duration of action of 12 to 36 hours (prednisone, prednisolone, or methylprednisolone) is necessary. When considering dose and duration, the following information may be used as a guide for the practitioner to consider when evaluating an animal needing an additional treatment course or long-term glucocorticoid therapy. These recommendations are based upon clinical experience and personal opinion. There is no evidence-based formula for what is safe, and individual variation in side eﬀects also needs to be considered. Every animal and every disease condition diﬀers. The following calculations allow a practitioner to look at the total dose of exogenous (prescribed) steroid administration through the lens of what a normal patient sees naturally through the endogenous production of cortisol. This combined with using the dosing guidelines listed above may be a helpful tool for veterinarians to determine the lowest eﬀective, safe dose possible. This “safe annual steroid dose” is a starting point and does not replace the need for monitoring with examinations and laboratory testing as indicated for animals on long-term therapy. Calculating the “safe annual steroid dose” A normal dog manufactures 0.2 to 1 mg/kg/day of cortisol which is necessary to survive. This is illustrated by using a 40 kg dog as an example: 40 kg X 0.4 mg X 365 days = 5840 mg of cortisol produced / year2 Diﬀerent glucocorticoids have diﬀerent potencies. For example, prednisone (or prednisolone) is considered to be about 4 times as potent as hydrocortisone (cortisol), and methylprednisolone is about 5 times as potent. If you divide 5840 by 4 you get an equivalent amount of prednisone. Thus, this 40-kg dog would “see” in a normal physiologic state 5840 mg of cortisol / year, which is equivalent to approximately 1460 mg of prednisone (or prednisolone) / year. Assuming that an animal is receiving every other day therapy for longterm glucocorticoid administration and that the practitioner is dosing for the lowest eﬀective dose, the following calculation maybe used as a guideline to help determine a “safe annual steroid dose.” BW (kg) X 30 = mg prednisone (prednisolone) / year3 or BW (lb) X 15 = mg prednisone (prednisolone) / year Considering the 40-kg dog: 40 X 30 = 1200 mg of prednisone to be the “safe annual steroid dose.” This value is less than the range of what is considered physiologic for that dog (5840 mg cortisol / year or 1460 mg prednisone / year). References/notes on pg 15. SPONSORED BY PFIZER ANIMAL HEALTH 13

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Veterinary Medicine - November 2008 Contents Leading Off Editors' Guest Just Ask the Expert Letters Practice Makes Perfect Clinical Exposures Practice Matters Idea Exchange Author Guidelines A Challenging Case: Esophageal Leiomyoma in a Dog Osteoarthritis in Cats: What We Now Know About Recognition and Treatment Product Preview CE Form/Advertiser Index Marketplace/Classifieds Mind Over Miller

Veterinary Medicine - November 2008

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