[Therapy of primary hypoadrenocorticism in dogs with low dose desoxycorticosterone pivalate].

Objective: Since 2016 the only approved drug for the treatment of primary hypoadrenocorticism (Addisons disease) in dogs in Germany is desoxycorticosterone pivalate (DOCP), namely Zycortal. The initial dose recommended by the manufacturer is 2.2 mg/kg. Our own experience and select publications raise the suspicion that a distinctly lower initial dose would be sufficient. Mainly cost reduction motivates for dose reduction and with it comes a higher owner motivation and compliance. It was the objective of our retrospective study to show that an initial dose of 1.5 mg/kg DOCP is sufficient for controlling canine hypoadrenocorticism.

Material And Methods: Dogs with primary hypoadrenocorticism were included if the initial starting dose was 1.5 mg/kg DOCP subcutaneously. The first, second and the last known dose of DOCP were documented. Electrolyte concentrations at the time of diagnosis as well as 10-14 days after the first injection, on the day of the second injection as well as at the last known injection were recorded. A dog was considered medically well-regulated when clinically healthy, sodium and potassium concentrations within the reference ranges, and when the responsible veterinarian did not recommended a dose alteration.

Results: All 13 included dogs were clinically healthy after the first or second injection. One dog received 1.6 mg/kg DOCP as last documented dose, all other dogs received ≤ 1.5 mg/kg (median: 1.3, range: 0.4-1.6) DOCP. Eleven dogs were injected once monthly, 2 dogs received injections every 60 days. The dogs were followed at least 7 months (median: 20 months, range: 7-26 months).

Conclusion And Clinical Relevance: We were able to show that a starting dose of 1.5 mg/kg DOCP (Zycortal) is sufficient for controlling primary hypoadrenocorticism in dogs. Adjustments of the dose are needed in some dogs. Regular measurement of electrolyte concentrations 10 days after treatment initiation and at the monthly DOCP injection is required for a correct disease management with DOCP.