Feline hyperaldosteronism

Ghita Benchekroun

doi:10.22233/9781910443866.32

British Small Animal Veterinary Association , 309 (2023); https://doi.org/10.22233/9781910443866.32

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Feline hyperaldosteronism

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Author: Ghita Benchekroun
From: BSAVA Manual of Canine and Feline Endocrinology
Item: Chapter 32, pp 309 - 317
DOI: 10.22233/9781910443866.32
Copyright: © 2023 British Small Animal Veterinary Association
Publication Date: August 2023

Abstract

Primary hyperaldosteronism is an uncommon but emerging endocrine disorder in cats. This chapter discusses the clinical manifestations, aetiology, pathophysiology, diagnosis and treatment options for feline hyperaldosteronism. It highlights the challenges in diagnosis due to nonspecific clinical features and the lack of a reliable confirmatory test. Treatment options include potassium supplementation, mineralocorticoid antagonists and surgical adrenalectomy. The prognosis for cats receiving surgical treatment is generally excellent.

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Figures

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32.2

Cervical ventroflexion caused by hypokalaemic polymyopathy in a cat with primary hyperaldosteronism. Cervical ventroflexion is a specific sign of hypokalaemia in cats and its recognition during clinical examination can direct the diagnostic approach. © 2023 British Small Animal Veterinary Association

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32.2 Cervical ventroflexion caused by hypokalaemic polymyopathy in a cat with primary hyperaldosteronism. Cervical ventroflexion is a specific sign of hypokalaemia in cats and its recognition during clinical examination can direct the diagnostic approach.

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32.3

A 14-year-old Domestic Shorthaired cat presented for blindness and bilateral mydriasis. (a) The red colour of the eye through the pupil is consistent with vitreal haemorrhage. Mydriasis was unresponsive to light and blindness was associated with bilateral retinal detachment and retinal haemorrhage. (b) Fundus examination of the right eye showed a large vitreous and subretinal haemorrhage with retinal detachment. (c) Fundus examination of the left eye revealed retinal oedema, partial perivascular retinal detachment and small retinal haemorrhage. Blindness is one of the major clinical complaints of primary hyperaldosteronism. If there is retinal haemorrhage and/or retinal detachment, blood pressure should be measured. In cases of systemic hypertension, differential diagnoses include primary hyperaldosteronism, which should be investigated by potassium measurement and adrenal ultrasonography. (Courtesy of Dr Chahory, Ophthalmology Unit, ChuvA) © 2023 British Small Animal Veterinary Association

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32.3 A 14-year-old Domestic Shorthaired cat presented for blindness and bilateral mydriasis. (a) The red colour of the eye through the pupil is consistent with vitreal haemorrhage. Mydriasis was unresponsive to light and blindness was associated with bilateral retinal detachment and retinal haemorrhage. (b) Fundus examination of the right eye showed a large vitreous and subretinal haemorrhage with retinal detachment. (c) Fundus examination of the left eye revealed retinal oedema, partial perivascular retinal detachment and small retinal haemorrhage. Blindness is one of the major clinical complaints of primary hyperaldosteronism. If there is retinal haemorrhage and/or retinal detachment, blood pressure should be measured. In cases of systemic hypertension, differential diagnoses include primary hyperaldosteronism, which should be investigated by potassium measurement and adrenal ultrasonography. (Courtesy of Dr Chahory, Ophthalmology Unit, ChuvA)

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32.4

Fundus examination in a Domestic Shorthaired cat showing a large peripapillary retinal detachment (the hazy area indicated by the asterisk). (Courtesy of Dr Chahory, Ophthalmology Unit, ChuvA) © 2023 British Small Animal Veterinary Association

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32.4 Fundus examination in a Domestic Shorthaired cat showing a large peripapillary retinal detachment (the hazy area indicated by the asterisk). (Courtesy of Dr Chahory, Ophthalmology Unit, ChuvA)

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32.8

Adrenal tumours are the most commonly recognized cause of primary hyperaldosteronism in cats, but bilateral adrenal hyperplasia can also be responsible. Ultrasonography of the adrenal glands helps to determine the aetiology. (a) In this case, (ai) an adrenal mass was identified in the right adrenal gland (RA), whereas (aii) the left adrenal gland (LA) was of normal size. (b) In this case, both the (bi) right and (bii) left adrenal glands were moderately increased in size. In both cases, primary hyperaldosteronism was confirmed. (Courtesy of the Imaging Unit, ChuvA) © 2023 British Small Animal Veterinary Association

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32.8 Adrenal tumours are the most commonly recognized cause of primary hyperaldosteronism in cats, but bilateral adrenal hyperplasia can also be responsible. Ultrasonography of the adrenal glands helps to determine the aetiology. (a) In this case, (ai) an adrenal mass was identified in the right adrenal gland (RA), whereas (aii) the left adrenal gland (LA) was of normal size. (b) In this case, both the (bi) right and (bii) left adrenal glands were moderately increased in size. In both cases, primary hyperaldosteronism was confirmed. (Courtesy of the Imaging Unit, ChuvA)

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32.9

Macroscopic appearance of the adrenal mass detected by ultrasonography in Figure 32.8ai . Neither the macroscopic appearance of an adrenal tumour nor the histological examination findings are specific for primary hyperaldosteronism. © 2023 British Small Animal Veterinary Association

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32.9 Macroscopic appearance of the adrenal mass detected by ultrasonography in Figure 32.8ai . Neither the macroscopic appearance of an adrenal tumour nor the histological examination findings are specific for primary hyperaldosteronism.

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32.10

Micrographs of sections from the adrenal mass shown in Figure 32.9 . Histopathology can confirm an adrenocortical tumour in cats with primary hyperaldosteronism but can rarely distinguish between the involvement of different zones of the cortex or discriminate malignant from benign tumours (carcinoma versus adenoma). (a) Low-power image. The adrenal gland has been partially incised (*). At the periphery, a rim of residual and compressed adrenal parenchyma (arrowed) is separated from the tumour by a thin pseudocapsule. There is a focus of capsular effraction (arrowhead). (Haematoxylin-eosin-saffron stain). (b) Medium-power image. At the periphery, a rim of residual and compressed adrenal parenchyma (*) is separated from the tumour by a thin pseudocapsule. Neoplastic cells are organized in convoluted trabeculae supported by a delicate fibrovascular stroma. Neoplastic cells tend to be elongated with a central nucleus, resembling cells of the zona glomerulosa. There is a focus of effraction of the tumour capsule (arrowed), suggestive of malignant behaviour. (Haematoxylin-eosin-saffron stain). (Courtesy of Dr Reyes-Gomez, Histology Unit, Biopôle) © 2023 British Small Animal Veterinary Association

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32.10 Micrographs of sections from the adrenal mass shown in Figure 32.9 . Histopathology can confirm an adrenocortical tumour in cats with primary hyperaldosteronism but can rarely distinguish between the involvement of different zones of the cortex or discriminate malignant from benign tumours (carcinoma versus adenoma). (a) Low-power image. The adrenal gland has been partially incised (*). At the periphery, a rim of residual and compressed adrenal parenchyma (arrowed) is separated from the tumour by a thin pseudocapsule. There is a focus of capsular effraction (arrowhead). (Haematoxylin-eosin-saffron stain). (b) Medium-power image. At the periphery, a rim of residual and compressed adrenal parenchyma (*) is separated from the tumour by a thin pseudocapsule. Neoplastic cells are organized in convoluted trabeculae supported by a delicate fibrovascular stroma. Neoplastic cells tend to be elongated with a central nucleus, resembling cells of the zona glomerulosa. There is a focus of effraction of the tumour capsule (arrowed), suggestive of malignant behaviour. (Haematoxylin-eosin-saffron stain). (Courtesy of Dr Reyes-Gomez, Histology Unit, Biopôle)