Case Report Veterinary Clinical Department, University of Bologna, Bologna, Italy Pituitary Macroadenoma in a Cat with Diabetes Mellitus, Hypercortisolism and Neurological Signs F. Fracassi 1,5 , L. Mandrioli 2 , A. Diana 1 , M. Hilbe 3 , G. Grinwis 4 and G. Gandini 1 Addresses of authors: 1 Veterinary Clinical Department and 2 Department of Veterinary Public Health and Animal Pathology, University of Bologna, Via Tolara di Sopra 50, 40064 Ozzano dellÕEmilia (Bologna), Italy; 3 Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zu¨rich, Winterthurerstrasse 260, 8075 Zu¨rich, Switzerland; 4 Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands; 5 Corresponding author: Tel.: + 39 051 2097590; fax: + 39 051 2097593; E-mail: federico.fracassi@unibo.it With 3 figures and 1 table Received for publication November 1, 2006 Summary A 13-year-old neutered male European short-hair cat was presented because of blindness and behavioural abnormalities. On physical examination, abnormal behaviour, compulsive walking, circling, continuous vocalization and blindness were the main neurological signs. In addition, abdominal alopecia, thin and inelastic skin, weight loss despite polyphagia, polyuria and polydipsia were present. Laboratory investigation revealed diabetes mellitus and pituitary-dependent hypercortisolism. Diagnostic imaging showed bilaterally enlarged adrenals and a large pituitary mass. Histopathological and immunohisto- chemical examination confirmed the clinical diagnosis of an ACTH-producing pituitary macroadenoma. Introduction In cats, hypercortisolism due to a pituitary corticotroph adenoma that hypersecretes adrenocorticotrophic hormone (ACTH) is a rare disease. Since the first report in 1975 (Fox and Beatty, 1975), no more than 100 cases have been described in veterinary literature. In cats, pituitary-dependent hypercor- tisolism (PDH) is usually associated with diabetes mellitus. The most frequently observed clinical signs of PDH in this species are polyuria, polydipsia and polyphagia (Nelson et al., 1988; Duesberg et al., 1995; Goossens et al., 1995; Watson and Herrtage, 1998; Meij et al., 2001; Feldman and Nelson, 2004; Neiger et al., 2004). About 50% of the pituitary tumours in cats are micro- scopic in size; the remaining tumours are usually large enough to be visualized with computed tomography (CT) or magnetic resonance imaging (MRI) (Feldman and Nelson, 2004). In dogs, approximately 10–20% of cases with PDH are associated with a pituitary macroadenoma and neurological signs (Feldman and Nelson, 2004). Altered mentation (dis- orientation and depression), ataxia, tetraparesis, pacing, pathologic nystagmus, circling, head pressing, behaviour changes, blindness, seizures and coma have been reported in dogs with PDH due to a pituitary macroadenoma (Feldman and Nelson, 2004). To the authorsÕ knowledge, except for lethargy and abnormal gait, the concomitant presence of specific central nervous system (CNS) neurolog- ical signs in cats with a pituitary macroadenoma and secondary hypercortisolism have only been rarely reported (Mayer et al., 2006). Here, we report on the physical, endocrine, diagnostic imaging and (histo)pathological findings in a cat with hyperc- ortisolism and CNS signs due to an ACTH-secreting pituitary macroadenoma. Materials and methods Endocrine tests The ACTH stimulation test was performed by collecting blood samples at 0 and 60 min after the IV administration of 0.125 mg tetracosactide esacetate (Synacthen Ò ; Novartis, Origgio, Italy). The dexamethasone suppression test was performed by injecting dexamethasone (Dexadreson Ò ; Inter- vet, Peschiera Borromeo, Italy) at 0.1 mg/kg IV and collecting blood at baseline and after 4 and 8 h. Hormone determination The plasma growth hormone (GH) concentration was meas- ured by a homologous radioimmunoassay (RIA), as described previously (Eigenmann and Eigenmann, 1981). The intra-assay and inter-assay coefficients of variation were 3.8% and 7.2% respectively. The sensitivity of the assay was 0.3 lg/l. The present work was carried out at the Veterinary Clinical Department of the University of Bologna (Italy). Neuropatho- logical examination was performed at the pathology section of the Department of Veterinary Public Health and Animal Pathology of the University of Bologna (Italy). Immunohisto- chemistry was performed at the Institute of Veterinary Pathol- ogy of the University of Zu¨rich (CH) and Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht Univer- sity, Utrecht, The Netherlands. Determination of plasma con- centrations of GH and a-MSH was performed at the Department of Clinical Sciences of Companion Animals, Faculty of Veter- inary Medicine, Utrecht University, Utrecht, The Netherlands. www.blackwell-synergy.com J. Vet. Med. A 54, 359–363 (2007) Ó 2007 The Authors Journal compilation Ó 2007 Blackwell Verlag ISSN 0931–184X