Sialoadenitis in Horses: A Retrospective Study of 18 Cases (1998 to 2010)

Sialoadenitis of the parotid or mandibular salivary glands associated with dental disease or subsequent to sialolithiasis can develop in older horses. Ultrasonographic examination allows for identification of the affected gland and localization of a site for drainage if warranted.

1. Introduction

Sialoadenitis is an uncommon condition of horses, with few reported cases in the literature. The purpose of this study is to review cases presenting with sialoadenitis and describe diagnostic results, treatment, and outcome.

2. Materials and Methods

Records were reviewed for horses presenting to the UC Davis William R. Pritchard Veterinary Medical Teaching Hospital between 1998 and 2010 for salivary gland swelling. Cases were included if a diagnosis of sialoadenitis was made on the basis of oral examination and/or ultrasound and/or microbial culture. Data collected included age, breed, diagnostic results, treatment, and outcome.

3. Results

Eighteen horses were diagnosed with sialoadenitis affecting the parotid gland¹²  and the mandibular salivary gland.⁶  Age of affected horses ranged from 4 to 30 years (mean, 17.7 years). Fourteen of 15 (93.3%) horses had dental or other abnormalities on intraoral examination. Five of 18 cases had evidence of sialolithiasis. Culture of the infected salivary gland was performed in 9 horses, and all yielded growth of Fusobacterium sp., along with other aerobic and anaerobic bacteria. Infection resolved in 15 of 18 cases (83.3%), and 2 of 18 (11.1%) were euthanized.

4. Discussion

Dental disease and sialolith formation play important roles in the development of sialoadenitis in horses. Anaerobic infection should be assumed in all cases and treated as such until culture and sensitivity results are available. Prognosis is favorable (83.3%) with appropriate diagnosis and treatment.