A 10-year-old, neutered male domestic longhair (DLH) cat presented for evaluation of cloudiness in the anterior chamber of both eyes. He was diagnosed with anterior uveitis, chorioretinitis and systemic hypertension. An abdominal ultrasound (AUS), adrenal panel and urine metanephrine fractionation test were consistent with an oestradiol-secreting adrenal tumour. Additional testing was consistent with diabetes mellitus (DM) and hyperthyroidism. A right adrenalectomy was performed and the patient was subsequently determined to have hypoadrenocorticism, though mineralocorticoid deficiency never developed. DM and systemic hypertension resolved following adrenalectomy. The patient was reported to have a good quality of life with steroid supplementation. A hepatic mass, cytologically consistent with metastatic disease, was discovered on AUS 2 years following adrenalectomy. The patient subsequently developed congestive heart failure secondary to hypertrophic cardiomyopathy, and humane euthanasia was performed.