Central diabetes insipidus in a cat with central nervous system B cell lymphoma.

A 6-year-old male neutered cat presented with blindness, lethargy, polydipsia, hyposthenuria and severe hypernatraemia. Central diabetes insipidus was demonstrated by means of a low measured anti-diuretic hormone (ADH) concentration in the face of hypernatraemia, and clinical response to supplementation with desmopressin. Magnetic resonance imaging of the brain showed a discrete mass in the region of the hypothalamus. The cat was euthanased and post-mortem histological examination demonstrated B cell lymphoma involving the brain, optic nerves, urinary bladder wall and diaphragm. To the authors' knowledge, this case report is the first to describe central diabetes insipidus caused by central nervous system lymphoma in the cat.

Another case of canine amoebic meningoencephalitis--the challenges of reaching a rapid diagnosis.

A case of granulomatous amoebic meningoencephalitis in a previously healthy, mature, apparently immunocompetent dog, with a history of exposure to stagnant water, is reported. The case presented with ataxia and a tendency to fall to the left side. A computed tomography (CT) showed a ring-enhancing lesion within the cerebellum; an examination of cerebrospinal fluid (CSF) revealed nonspecific mixed-cell pleocytosis. Despite antibiotic and anti-inflammatory therapy, clinical signs progressed rapidly to decerebellate rigidity over 4 days, and the dog was euthanased. Significant post-mortem findings were restricted to the brain, with a localised lytic lesion in the deep cerebellar white matter. Histopathological examination of the brain showed focally extensive cavitation of the white matter and communication of the lesion with the fourth ventricle. The affected area contained structures consistent with amoebae and was infiltrated by neutrophils mixed with lower numbers of macrophages, plasma cells and lymphocytes. The amoebae were identified as Balamuthia mandrillaris, based on specific immunofluorescence detection. Amoebic meningoencephalitis should be considered in dogs with evidence of focal cavitary lesions in the brain, particularly in cases with a history of swimming in stagnant water.

Distensible superficial venous orbital malformations involving the lower eyelid in two horses.

CASE DESCRIPTION: 2 horses were examined because of vascular masses involving the lower eyelid. CLINICAL FINDINGS: Both horses had a unilateral, fluctuant mass involving the lower eyelid. For horse 1, the mass had been present since birth and had slowly increased in size over time. The mass also changed in size in response to various environmental stimuli, alterations in the position of the horse's head, and digital obstruction of superficial vessels adjacent to the mass. Horse 2 was brought to the hospital for euthanasia, and no historical or antemor-tem data were available. A combination of contrast angiography, Doppler ultrasonography, surgical exploration, and blood gas analysis (horse 1) and postmortem and histologic examination (horse 2) were used to determine that the masses consisted of non-neoplastic distended venous channels with anastomoses to the inferior lateral palpebral and angularis oculi veins (both horses) as well as the facial vein (horse 2). Histologic examination (horse 2) revealed large, endothelial cell-lined, blood-filled spaces within the deep dermis consistent with a distensible superficial venous orbital malformation. TREATMENT AND OUTCOME: Horse 1 underwent surgical exploration and ligation of the vascular malformation. Six months after surgery, the mass was markedly reduced in size, and size of the mass was static regardless of head position or environmental stimuli. CLINICAL RELEVANCE: Thorough preoperative planning with Doppler ultrasonography, contrast angiography, and blood gas analysis is recommended when attempting surgical correction of these malformations in horses. Surgical ligation can result in a successful cosmetic and functional outcome.