Headshaking associated with a unique presentation of guttural pouches infection and otitis media in a Quarter Horse stallion: diagnosis, medical treatment and outcome.

A 3-year-old Quarter Horse stallion was referred for headshaking (HS) syndrome of one month duration. The horse underwent complete HS workup. Physical examination revealed up-and-down head movements associated with nose snorting during lunging and riding, in the absence of other abnormalities at rest or in motion. Lameness, neurologic and behavioural evaluations were unremarkable. Endoscopic examination of the upper respiratory tract showed bilateral guttural pouches (GPs) inflammation. The mucosal surface was altered by the presence of areas of microbullous appearance coalescing into some bullae of larger diameter. A bacterial culture obtained by flushing, brushing and biopsy of the GP mucosa was positive for Serratia marcescens. Computed tomographic evaluation was indicative of: moderate bilateral GP inflammation, bilateral otitis media, and nuchal ligament enthesopathy, with uncertain significance. The horse was treated with antimicrobials according to the sensitivity test, systemic NSAIDs and rest. At the one-month follow-up, HS condition was improved and the endoscopic examination showed a limited number of bullous lesions remaining. Bacterial culture re-obtained from the GPs lavages was positive for Streptococcus equi zooepidemicus. Based on the residual evidence of GP infection, the horse was re-treated with antimicrobials according to the sensitivity test, systemic NSAIDs and rest. At the two-month follow-up, HS condition was considered resolved based on clinical evaluation, the horse resumed gradually training with satisfactory results. Endoscopy and bacteriology showed resolution of GP infection. At one-year follow-up no relapses were reported.