Distribution of atrophy in the nasal ventral conchae of piglets infected experimentally with Bordetella bronchiseptica.

The distribution and extent of atrophy caused by Bordetella bronchiseptica in the nasal ventral conchae were investigated by intranasally infecting piglets at day 4 of life. Experimental and control piglets were killed at one, two, three, four, five and six weeks of age. Serial transverse 80 microns thick nondecalcified sections were cut throughout the entire length of the nasal ventral conchae, and microradiographed. It was observed that the distribution and extent of atrophy was not uniform along the ventral conchae. The articular and transverse laminae as well as the connecting zone were not atrophied, except at their rostral extremity. The entire dorsal scroll was atrophied. This atrophy was moderate, except at the rostral and caudal extremities of the dorsal scroll, where its size was less than half that of the controls. The ventral scroll was less atrophied than the dorsal scroll, although a marked atrophy was present at its rostral extremity. From these observations, it is suggested that two transverse sections should be made through the nose of pigs in order to establish a diagnosis of atrophic rhinitis at slaughter: one section at the level of the first-second premolar tooth and one more rostral section, at the level of the canine tooth.