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Introduction: Conn’s syndrome (primary hyperaldosteronism) is one of the most common causes of human hypertension due to hormonal disorders. However, it is thought to be one of the rarest endocrine disorders in cats with only a small number of feline cases reported to date. In this syndrome, hyperaldosteronism results from unilateral or bilateral nodular hyperplasia, adenomas, adenocarcinomas or diffuse, bilateral adrenocortical hyperplasia of the zona glomerulosa.
Materials and Methods: A 14-year-old European shorthair cat with clinical hyperaldosteronaemia and hypokalaemia was humanely destroyed because of central nervous system abnormalities, neuromuscular dysfunction and suspected renal failure.
Results: Necropsy examination revealed concentric hypertrophy of the left ventricle, interstitial nephritis with marked glomerulosclerosis and multifocal intravascular thrombi within the vessels of the brainstem and the cerebellum. Additionally, severe myocardial and renal interstitial fibrosis was found and similar fibrotic changes were present in the tunica media of various blood vessels. The adrenal glands had multifocal, bilateral nodular hyperplasia with intralesional, proliferating cells that were immunohistochemically positive for aldosterone.
Conclusions: The present case indicates that Conn’s syndrome may cause severe clinical and pathological changes in cats, which primarily result from severe hypertension as well as regulative hypokalaemia. Cats with hyperaldosteronism commonly die due to renal and/or cardiac failure, thrombosis or musculoskeletal dysfunction so that histopathological examination with particular regard to the adrenal glands may support the aetiological diagnosis of Conn’s syndrome.