Page 280 - WSAVA2018
P. 280

 25-28 September, 2018 | Singapore
neuroendocrine tumours of pancreatic or gastrointestinal origin and C cell carcinomas of the thyroid gland.
Often associated with extreme elevations in cortisol
and pronounced clinical signs, administration of corticotropin releasing hormone (CRH) generally does not increase ACTH concentrations. The tumours may
be very small and advanced imaging techniques may be necessary for their location. There has been a recent report of probable ectopic ACTH production
in a dog6. Aberrant expression of functional hormone receptors in the adrenal gland may also give rise to hyperadrenocorticism. A recent case report described
a dog with clinical signs of hyperadrenocorticism and potential food induced hyperadrenocorticism7. Based on these two case reports it has now been suggested that hyperadrenocorticism be viewed as being ACTH dependent (PDH and ectopic ACTH production) and ACTH independent (adrenal tumours and food induced).
Hyperfunction of the adrenal gland may also
involve mineralocorticoids or catecholamines. Hyperaldosteronism associated with adrenal neoplasia (Conn’s syndrome) in humans is usually associated with hypokalaemia, hypertension and metabolic alkalosis. Conn’s syndrome is more commonly recognised in cats but has occasionally been diagnosed in dogs. It may be related to excess aldosterone production or
its precursors and diagnosis requires depiction of their elevation together with reduced renin activity.
Phaeochromocytomas are increasingly recognised in dogs. The majority are unilateral and they are commonly malignant. Clinical signs relate to catecholamine excess but as catecholamine secretion is variable, these
signs may be sporadic, unpredictable, intermittent or paroxysmal. Signs typically involve the cardiovascular and neuromuscular systems. Whilst hypertension
is considered the cardinal sign, it is only present in approximately 50 % of cases. There may be many non-specific signs such as polyuria/polydipsia or signs related to tumour growth. Diagnosis is best made
using measurement of urinary free normetanephrine concentration or urinary normetanephrine:creatinine ratio8. Many case reports have suggested that dogs with phaeochromocytoma potentially have disorders akin
to multiple endocrine neoplasia syndromes in humans. However, few have included all the typical manifestations noted in humans and the concurrent involvement of tumours in several endocrine glands simultaneously
may be purely coincidental in dogs.Increasingly
adrenal masses are found during either abdominal ultrasonography or CT where other non-endocrine diseases are being investigated. Overall the prevalence is between 4 and 9 % and they are typically found in older animals9,10. Tumours > 2 cm in size are more likely to be malignant. When found diagnostic investigation should centre on determining whether functional or not.
1. Ristic JME, Ramsey IK, Heath FM, et al. The use of 17-hydroxyprogesterone in the diagnosis of canine hyperadrenocorticism. J Vet Internal Med 2002; 16; 433-439.
2. Behrend EN & Kennis R. Atypical Cushing’s syndrome in dogs: arguments for and against. Vet Clin North Am Small Anim Pract 2010; 40; 285-296.
3. Greco DS, Peterson ME, Davidson AP, et al. Concurrent pituitary and adrenal tumors in dogs with hyperadrenocorticism: 17 cases (1978-1995). J Am Vet Med Assoc; 1999; 214; 1349-1353
4. Norman EJ, Thompson H, Mooney CT Dynamic adrenal function testing in eight dogs with hyperadrenocorticism associated with adrenal neoplasia. Vet Rec; 1999; 144; 551-554.
5. Syme HM, Scott-Moncrieff JC, Treadwell NG, et al. Hyperadrenocorticism associated with excessive sex hormone production by an adrenocortical tumor in two dogs. J Am Vet Med Assoc; 2001; 219, 1725-1728.
6. Galac S, Kooistra HS, Voorhout G, et al. Hyperadrenocorticism in a dog due to ectopic secretion of adrenocorticotropic hormone. Dom Anim Endocrin; 2005; 28, 338-348.
7. Galac S, Kars VJ, Mol JA, et al. ACTH-independent hyperadrenocorticism due to food-dependent hypercortisolaemia in a dog: a case report. Dom An Endocrin; 2008; 177; 141-143.
8. Salesov E, Boretti FS, Sieber-Ruckstuhl NS, et al. Urinary and plasma catecholamines and metanephrines in dogs with pheochromocytoma, hypercortisolism, nonadrenal disease and in healthy dogs. J Vet Intern Med; 2015; 29; 597-602.
9. Cook AK, Spaulding KA, Edwards JF Clinical findings in dogs with incidental adrenal gland lesions determined by ultrasonography: 151 cases (2007-2010). J Am Vet Med Assoc; 2014; 244; 1181-1185.
10. Braum JI, Boston SE, Case JB Prevalence of adrenal gland masses as incidental findings during abdominal computed tomography on dogs: 270 cases
(2013-2014) J Am Vet Med Assoc; 2016; 249; 1165-1169.

   278   279   280   281   282