Canine iatrogenic persistent hypoadrenocorticism after short-term treatment of hyperadrenocorticism with trilostane - a case report

An 8-year-old, spayed female, mixed breed dog diagnosed with hyperadrenocorticism and treated with trilostane for 13 days was presented to the clinic due to vomiting, shaking, and weakness. The ACTH stimulation test and electrolyte analysis confirmed hypoadrenocorticism. Treatment with prednisolone and fludrocortisone gave good results, however long lasting exogenous glucocorticoid administration led to a decrease in total and free thyroxine concentrations and caused clinical signs of hypothyroidism, such as lethargy and reduced appetite. The authors suspected euthyroid sick syndrome. After sixteen months therapy with prednisolone and fludrocortisone ACTH stimulation tests still revealed low plasma cortisol concentrations in this dog, which suggested persistent hypoadrenocorticism. To the authors' knowledge there have only been a few cases in which canine iatrogenic persistent hypoadrenocorticism or hypocortisolism was described after short term treatment with trilostane. However, in the previous cases the longest duration of hypocortisolism was 12 months.