A case-control study of atypical guttural pouch empyema in Arabian foals.

Cytological examination of tracheal and guttural pouch aspirates revealed a neutrophilic exudate with lipid-laden phagocytes, suggestive of engulfed milk. Bacteriology revealed a high prevalence of Streptococcus equi ssp. zooepidemicus admixed with other opportunistic pathogens. Streptococcus equi ssp. equi was not isolated in any case.