ABSTRACT
A 12-year-old spayed female Yorkshire terrier dog was presented with two-weeks history of lethargy, mental dullness and polydipsia. Neurologic examination revealed proprioceptive defect of all limbs and loss of swallowing gag reflex. The dog revealed persistent dehydration, hypernatremia, hyperosmolarity and hyposthenuria. On magnetic resornance imaging (MRI), the mass were heterogeneous signality on T1 weighted images, hyperintense signality on T2 weighted image with contrast enhancement on hypothalamohypophyseal lesion. Based on these findings, the dog was suspected as having pituitary gland tumor. Through water deprivation test and response to desmopressin acetate (1-deamino-8-D-arginine, DDAVP), this case was diagnosed by central diabetes insipidus (CDI). This paper reports the clinical sign, MRI, response to the exogenous antidiuretic hormone of CDI due to suspected pituitary tumor in a dog and DDAVP administration was evaluated effective therapy to correct hypernatremia induced by CDI.