Pathological effects of Bordetella bronchiseptica

The inflammatory response to Bordetella bronchiseptica infection is initiated by damage to the respiratory epithelium causing the release of inflammatory cytokines.

The release of toxins following colonisation is responsible for local and systemic inflammatory damage for the first 3-5 days after infection. The first clinical signs of Bordetella infections may be noticed after this time. After onset of the local immune response the bacteria are gradually eliminated (Bemis et al 1977). In cats most illness appears self-limiting with spontaneous resolution occurring after about 10-14 days. However, severe bronchopneumonia associated with Bordetella bronchiseptica (Bb) may occur, particularly in kittens.

Bb is adapted to establish long-term asymptomatic infection. The bacterium is able to modulate the immune response associated with infection (Yuk et al 2000). Infections are typically chronic, often asymptomatic, and notoriously difficult to clear even with antibiotic therapy. There is increasing evidence of resistance to certain antibiotics including tetracyclines and ampicillin.

Thoracic radiograph of a cat with bacterial bronchopneumonia (lateral view).

Thoracic radiograph of a cat with bacterial bronchopneumonia (click to enlarge)