A Case report: Phenobarbital - responsive sialadenosis in a dog

Abstract

A 5-year old, 1.2 kilogram, spayed female, mixed breed dog presented with vomiting, gulping, retching, excessive
salivation and weight loss for 6 months. The dog had both mandibular salivary gland enlargement but was cytologically
normal. Hematology blood chemistry and urinalysis were unremarkable except for neutrophilic leukocytosis and
hypokalemia. Contrast study radiography found gas in the gastrointestinal (GI) tract and contrast medium left in the
esophagus while abdominal ultrasonography was unremarkable. Oropharyngeal and upper GI endoscopy confirmed
cervical esophageal dilatation. The dog did not respond to symptomatic treatment. Sialadenosis was diagnosed based
on the clinical signs and the ruling out of other diseases with a similar presentation. Medical treatment with
phenobarbital was initiated at a dosage of 1.5 mg/kg orally twice daily for 3 months. The clinical signs diminished in
a few days and were completely absent within 2 weeks. The mandibular salivary glands were smaller and softened
after 2 weeks of treatment. After 3 months, phenobarbital dosage was tapered (reduced) every month and withdrawn
at 6 months. Seven months after treatment, the mandibular salivary gland could not be palpated and the dog gained
weight and had no clinical signs. This is the first case of phenobarbital - responsive sialadenosis reported in Thailand.