Rhinitis and Tracheitis
Inflammation of the nasal mucosa is common in young
animals. Many agents that affect the ciliated nasal epithelium
can also affect the tracheal ciliated epithelium.
Table 21.5 lists some common causes of rhinitis and
sneezing in pigs. The cause is often infectious (pseudorabies
disease virus, influenza virus, cytomegalovirus,
B. bronchiseptica, toxigenic strains of P. multocida, M.
hyorhinis), but air pollution such as elevated ammonia
and dust in the air can initiate mucosal inflammation.
Pasteurella multocida can colonize even a slightly
damaged mucosa and induce progressive atrophic rhinitis
with permanent distortion and shrinkage of turbinates (see Figure 21.4). The structural changes in
atrophic rhinitis are the result of altered turbinate bone
metabolism. While presumed to
have an effect on growth rate, the economic impact
associated with atrophic rhinitis is uncertain.
A cilia-associated respiratory (CAR) bacillus has been
identified in the trachea of pigs with other respiratory
diseases, but its role as a pathogen remains unclear.