Polypoid nasal neoformations in sheep: Pathological investigations

This paper reports four cases of nasal polyps in adult sheep from Piedmont and Sicily farms.The clinical course and post-mortem findings are described. Macroscopically numerousnasal polyps obstructing the nasal cavities, with the erosion of nasal concha, were observed.Histologically the neoformations, consisting of a different number of fusiform fibrocyticcells arranged in a variable amount of amorphous mesenchymal matrix, were located in thesubmucosa and covered by a simple disorganized columnar epithelium. Non-suppurativeinfiltration was also observed. Microbiological investigations revealed positivity for Pseu-domonas aeruginosa only in one case; no bacteria were isolated in polyps collected fromthe other three sheep. Chronic and massive infestation by Oestrus ovis was present in threecases. The etiology and pathogenesis of these proliferations remain to be clarified, evenif the authors postulate that one biological agent (bacterium or parasite) may have beenresponsible for the reaction of the nasal mesenchyma