Retrospective evaluation of the effect of trilostane on insulin requirement and fructosamine concentration in eight diabetic dogs with hyperadrenocorticism.

To describe the effect of trilostane on insulin requirements and serum fructosamine in dogs with diabetes mellitus (DM) and hyperadrenocorticism (HAC). Observational retrospective study of eight dogs. Median fructosamine concentration at presentation was 401 μmol/L (range 244 to 554 μmol/L). Median insulin dose at presentation was 1·1 IU/kg/dose (0·4 to 2·1 IU/kg/dose) administered twice daily in five animals and once in three. Four dogs had their insulin dose prospectively reduced at the start of trilostane therapy. The HAC was controlled within 28 days in seven dogs. The remaining case was controlled by 17 weeks. Two dogs died within 40 days of starting trilostane. The median fructosamine concentration was 438 μmol/L (range 325 to 600 μmol/L) after stabilisation of the HAC. One case had a consistent reduction in serum fructosamine concentration over the first four months. The median insulin dose after stabilisation of HAC was 1·5 IU/kg dose (range 0·25 to 3·0 IU/kg/dose). Insulin requirements were reduced in two cases after treatment with trilostane. Four dogs required increased insulin doses. Insulin requirements and fructosamine concentrations do not consistently reduce during trilostane treatment for HAC. Prospective studies are required to provide recommendations regarding reductions in insulin doses with trilostane treatment.