Canine hypercortisolism

Ian K. Ramsey; Michael E. Herrtage

doi:10.22233/9781910443866.29

British Small Animal Veterinary Association , 271 (2023); https://doi.org/10.22233/9781910443866.29

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Canine hypercortisolism

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Authors: Ian K. Ramsey and Michael E. Herrtage
From: BSAVA Manual of Canine and Feline Endocrinology
Item: Chapter 29, pp 271 - 294
DOI: 10.22233/9781910443866.29
Copyright: © 2023 British Small Animal Veterinary Association
Publication Date: August 2023

This chapter gives a comprehensive overview of the diagnosis, treatment, and management of hypercortisolism (the cause of Cushing’s syndrome). Topics include the physiology of the adrenal gland, causes of hypercortisolism, tests including ACTH response tests and diagnostic imaging, and treatment options including trilostane and mitotane. The chapter provides guidance on differentiating between ACTH-dependent and -independent hypercortisolism and the differences in their treatment.

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Figures

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29.1

(a) The pituitary–adrenal axis in adrenocorticotropic hormone (ACTH)-dependent hypercortisolism. There is a failure of the normal negative feedback effect of cortisol on ACTH (dashed red line). (b) The pituitary–adrenal axis in ACTH-independent hypercortisolism. The excess cortisol produced by the abnormal adrenal gland suppresses ACTH secretion (dashed green lines). The contralateral adrenal gland shrinks in size due to reduced stimulation by ACTH.

= stimulation;

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29.1 (a) The pituitary–adrenal axis in adrenocorticotropic hormone (ACTH)-dependent hypercortisolism. There is a failure of the normal negative feedback effect of cortisol on ACTH (dashed red line). (b) The pituitary–adrenal axis in ACTH-independent hypercortisolism. The excess cortisol produced by the abnormal adrenal gland suppresses ACTH secretion (dashed green lines). The contralateral adrenal gland shrinks in size due to reduced stimulation by ACTH.

= stimulation;

= inhibition. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.

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29.2

Pituitary macroadenoma found on post-mortem examination of a 13-year-old Golden Retriever that had been successfully treated with mitotane for hypercortisolism for 5 years. There were no neurological signs associated with this tumour. © 2023 British Small Animal Veterinary Association

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29.2 Pituitary macroadenoma found on post-mortem examination of a 13-year-old Golden Retriever that had been successfully treated with mitotane for hypercortisolism for 5 years. There were no neurological signs associated with this tumour.

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29.3

The cut surface of both adrenal glands from a case of adrenocortical carcinoma of the right adrenal gland, seen to the left of the image (see Figure 29.4 ). Note the severe cortical atrophy (pale rim) in the contralateral adrenal gland. © 2023 British Small Animal Veterinary Association

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29.3 The cut surface of both adrenal glands from a case of adrenocortical carcinoma of the right adrenal gland, seen to the left of the image (see Figure 29.4 ). Note the severe cortical atrophy (pale rim) in the contralateral adrenal gland.

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29.4

Intraoperative photograph of the same case as Figure 29.3 . The carcinoma is invading the phrenicoabdominal vein. The caudal vena cava can be seen at the top of the image. © 2023 British Small Animal Veterinary Association

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29.4 Intraoperative photograph of the same case as Figure 29.3 . The carcinoma is invading the phrenicoabdominal vein. The caudal vena cava can be seen at the top of the image.

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29.6

A 6-year-old entire Poodle bitch with adrenocorticotropic hormone-dependent hypercortisolism. Note the abdominal distension, muscle wasting, alopecia and thin skin. © 2023 British Small Animal Veterinary Association

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29.6 A 6-year-old entire Poodle bitch with adrenocorticotropic hormone-dependent hypercortisolism. Note the abdominal distension, muscle wasting, alopecia and thin skin.

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29.7

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29.7 The skin on the ventral abdomen can be tented to assess elasticity.

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29.8

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29.8 In hypercortisolism, the abdominal veins are visible through the thin skin.

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29.9

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29.9 Comedones around a nipple. The skin is thin and abdominal veins are visible.

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29.10

Extensive bruising on the neck of a Pomeranian with hypercortisolism. This resulted from a single needle insertion with minimal restraint and pressure being applied for a minute or so afterwards. © 2023 British Small Animal Veterinary Association

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29.10 Extensive bruising on the neck of a Pomeranian with hypercortisolism. This resulted from a single needle insertion with minimal restraint and pressure being applied for a minute or so afterwards.

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29.11

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29.11 Partial breakdown of an abdominal incision in a Boxer with hypercortisolism.

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29.12

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29.12 Skin in the inguinal area of a Poodle. Focal areas of calcinosis cutis can be seen eroding through the epidermis. Comedones are also present.

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29.15

Abdominal radiograph of a Cairn Terrier with adrenocorticotropic hormone-dependent hypercortisolism. The radiographic signs include hepatomegaly, abdominal distension, calcinosis cutis, dystrophic calcification in the soft tissues along the spine, an enlarged bladder and osteopenia. © 2023 British Small Animal Veterinary Association

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29.15 Abdominal radiograph of a Cairn Terrier with adrenocorticotropic hormone-dependent hypercortisolism. The radiographic signs include hepatomegaly, abdominal distension, calcinosis cutis, dystrophic calcification in the soft tissues along the spine, an enlarged bladder and osteopenia.

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29.16

Abdominal radiograph of a Yorkshire Terrier with an adrenal tumour. A calcified mass can be seen in the dorsocranial area of the abdomen (black arrow). In addition, cystic (white arrow) and urethral (arrowheads) calculi are present. Despite this extensive urolithiasis, the dog was able to urinate normally, possibly due to the anti-inflammatory effects of the excessive glucocorticoids. © 2023 British Small Animal Veterinary Association

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29.16 Abdominal radiograph of a Yorkshire Terrier with an adrenal tumour. A calcified mass can be seen in the dorsocranial area of the abdomen (black arrow). In addition, cystic (white arrow) and urethral (arrowheads) calculi are present. Despite this extensive urolithiasis, the dog was able to urinate normally, possibly due to the anti-inflammatory effects of the excessive glucocorticoids.

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29.17

Ultrasonography of the canine adrenal gland. (a) The left adrenal gland of a 9-year-old Jack Russell Terrier with adrenocorticotropic hormone (ACTH)-dependent hypercortisolism. The gland measures 40 mm in length and 16 mm in width. (b) A 7-year-old male crossbreed with ACTH-independent hypercortisolism. (bi) The left adrenal tumour can be seen and (bii) extends into the phrenicoabdominal vein and caudal vena cava (CVC). (biii) Despite the size of the neoplastic thrombus in the caudal vena cava, some blood flow around the thrombus can be seen using colour flow mapping. (c) The cranial abdomen of a 10-year-old Labrador Retriever bitch with an adrenocortical carcinoma that has invaded the caudal vena cava (CVC). © 2023 British Small Animal Veterinary Association

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29.17 Ultrasonography of the canine adrenal gland. (a) The left adrenal gland of a 9-year-old Jack Russell Terrier with adrenocorticotropic hormone (ACTH)-dependent hypercortisolism. The gland measures 40 mm in length and 16 mm in width. (b) A 7-year-old male crossbreed with ACTH-independent hypercortisolism. (bi) The left adrenal tumour can be seen and (bii) extends into the phrenicoabdominal vein and caudal vena cava (CVC). (biii) Despite the size of the neoplastic thrombus in the caudal vena cava, some blood flow around the thrombus can be seen using colour flow mapping. (c) The cranial abdomen of a 10-year-old Labrador Retriever bitch with an adrenocortical carcinoma that has invaded the caudal vena cava (CVC).

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29.18

Computed tomographic dorsal plane reconstruction using maximum intensity projection that shows a left adrenal mass displacing the renal vein caudally. A small thrombus can be seen extending into the lumen of the caudal vena cava. © 2023 British Small Animal Veterinary Association

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29.18 Computed tomographic dorsal plane reconstruction using maximum intensity projection that shows a left adrenal mass displacing the renal vein caudally. A small thrombus can be seen extending into the lumen of the caudal vena cava.

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29.19

(a) Sagittal and (b) transverse T2-weighted magnetic resonance images of a pituitary macroadenoma in a 10-year-old entire crossbreed bitch with adrenocorticotropic hormone-dependent hypercortisolism and central diabetes insipidus. © 2023 British Small Animal Veterinary Association

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29.19 (a) Sagittal and (b) transverse T2-weighted magnetic resonance images of a pituitary macroadenoma in a 10-year-old entire crossbreed bitch with adrenocorticotropic hormone-dependent hypercortisolism and central diabetes insipidus.

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29.20

Summary flowchart of the key stages in diagnosing canine hypercortisolism. ACTH = adrenocorticotropic hormone; ALP = alkaline phosphatase; ALT = alanine aminotransferase; LDDS = low-dose dexamethasone suppression; RBC = red blood cell. © 2023 British Small Animal Veterinary Association

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29.20 Summary flowchart of the key stages in diagnosing canine hypercortisolism. ACTH = adrenocorticotropic hormone; ALP = alkaline phosphatase; ALT = alanine aminotransferase; LDDS = low-dose dexamethasone suppression; RBC = red blood cell.

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29.23

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29.23 Interpretation of measurements of plasma cortisol concentrations before and after administration of synthetic adrenocorticotropic hormone (ACTH).

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29.24

Interpretation of measurements of plasma cortisol concentrations before and after the administration of a low dose of dexamethasone. The dashed line represents the lower limit of cortisol (27 nmol/l). (Data from Bennaim et al., 2018 and Zeugswetter et al., 2021 ). © 2023 British Small Animal Veterinary Association

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29.24 Interpretation of measurements of plasma cortisol concentrations before and after the administration of a low dose of dexamethasone. The dashed line represents the lower limit of cortisol (27 nmol/l). (Data from Bennaim et al., 2018 and Zeugswetter et al., 2021 ).

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29.26

A 10-year-old crossbreed dog with adrenocorticotropic hormone-dependent hypercortisolism. (a) Before treatment; (b) after commencing treatment with mitotane; (c) 6 months later. © 2023 British Small Animal Veterinary Association

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29.26 A 10-year-old crossbreed dog with adrenocorticotropic hormone-dependent hypercortisolism. (a) Before treatment; (b) after commencing treatment with mitotane; (c) 6 months later.