Abstract
Spontaneous hypercortisolism or Cushing's syndrome is a common endocrinopathy in dogs. Pituitary-dependent and adrenal-dependent hypercortisolism each require specific treatment and diagnostic imaging is very helpful in choosing the treatment that is appropriate. The aims and expectations of the treatment need to be established beforehand and discussed with the owner to avoid unexpected disappointments. The clinical signs of pituitary-dependent hypercortisolism caused by a pituitary microadenoma can be managed with the adrenocorticostatic drug trilostane, but the drug will not affect the pituitary tumor. Hypophysectomy is therefore preferred in those dogs that have an enlarged pituitary but are in good clinical condition and have a long life-expectancy. Inoperable pituitary tumors can be treated by radiotherapy. The best treatment in dogs with cortisol-secreting adrenocortical tumors is adrenalectomy. If surgery is not possible, because of vascular invasion or metastatic spread, mitotane is recommended. Treatment with trilostane can be considered but is only palliative: it does not affect the adrenocortical tumor.