Successful treatment of hypodipsic/adipsic hypernatremia in a cat with lobar holoprosencephaly using oral desmopressin.

Case summary: A 2-year-old female spayed domestic shorthair cat was presented with a history of collapse, possible hypodipsia/adipsia, severe dehydration and hypernatremia. MRI of the brain revealed a failure of separation of the cerebral hemispheres as characterized by an absence of the rostral part of the corpus callosum, fornix and septum pellucidum and the presence of a single fused lateral ventricle. A diagnosis of hypodipsic/adipsic hypernatremia with lobar holoprosencephaly was made. Dietary management of the cat's condition was attempted by increasing oral water intake, but the cat's hypernatremia and azotemia persisted. Plasma arginine vasopressin (AVP) analysis revealed a low concentration of circulating AVP (2.3 pg/ml), prompting therapy with oral desmopressin in addition to the dietary management. This combined therapy decreased water consumption of the cat from 200 ml/day (85 ml/kg/day) to 100 ml/day (30 ml/kg/day), normalized plasma sodium concentration and resolved the azotemia. Relevance and novel information: To our knowledge, this is the second case report of an MRI diagnosis of lobar holoprosencephaly with hypodipsic/adipsic hypernatremia in a cat and the first case report of the successful management of this condition using oral desmopressin. This case report emphasizes that holoprosencephaly should be suspected in cats presented with hypodipsic/adipsic hypernatremia and highlights the utility of MRI in establishing the diagnosis. Measurements of plasma osmolality and AVP concentration corroborate the pathophysiology and support the use of oral desmopressin in addition to dietary management to resolve the hypernatremia.

Pathology in Practice.

In collaboration with the American College of Veterinary Pathologists.

Ultrasonographic features of colonic B-cell lymphoma with mesenteric lymphomatosis in a cat.

A 10-year-old male neutered Domestic Shorthair cat was referred for chronic inappetence, weight loss, and hematochezia and an abdominal mass. Abdominal ultrasonography revealed a heterogeneously hypoechoic transmural colonic mass, which extended beyond the serosa and into the adjacent mesentery. Cytology and clonality assays of fine needle aspirates of the mass and mesenteric nodules yielded a diagnosis of B-cell lymphoma. Colonic lymphoma with mesenteric involvement can have a similar appearance to carcinomatosis, therefore a definitive diagnosis requires sampling and further testing of the mesenteric lesions.