Pathogenesis and pathology of bovine pneumonia

Abstract

Pneumonia is a major cause of death and economic losses to the cattle industry. Recognizing the patterns of pneumonic lesions and understanding the pathogenesis of the various types of pneumonia are important for correct diagnosis and interpretation of the lesions. Bacterial pneumonias consist of bronchopneumonia, fibrinous pneumonia, and pleuropneumonia as well as caseonecrotic, aspiration, and tuberculous pneumonias. Two major patterns of interstitial pneumonia are recognized in cattle, and verminous pneumonia is associated with Dictyocaulus viviparus infection.

Fig. 1

Bronchopneumonia (suppurative bronchopneumonia, lobular bronchopneumonia).

Fig. 2

Cranioventral, acute, suppurative bronchopneumonia (lobular pneumonia).

Fig. 3

Acute suppurative bronchopneumonia demonstrating bronchiolar and peribronchiolar pattern of inflammation with pus-filled airways.

Fig. 4

Fibrinous pneumonia and fibrinous pleuropneumonia (lobar bronchopneumonia).

Fig. 5

Fibrinous pneumonia (lobar pneumonia) demonstrating marbled appearance due to pale areas of coagulation necrosis and dark areas of acute pneumonia. Interlobular septa are distended with fibrin-rich exudate.

Fig. 6

Fibrinous pleuropneumonia (lobar pneumonia) with extensive fibrinous exudate.

Fig. 7

Caseonecrotic (Mycoplasma) pneumonia.

Fig. 8

Caseonecrotic bronchopneumonia typical of M bovis infection. Small (arrow) to large (asterisk) areas of coalescing foci of necrosis are present. (Courtesy of Dr Jeff Caswell, University of Guelph, Guelph, Ontario, Canada.)

Fig. 9

Acute interstitial pneumonia.

Fig. 10

Secondary interstitial (so-called feedlot interstitial pneumonia).

Fig. 11

AIP in a feedlot calf. Overinflated cranioventral lobules interspersed with darker pneumonic lobules (checkerboard). Caudal dorsal lung contains diffuse gray areas of pneumonia. (Courtesy of Dr Amelia Woolums, University of Georgia, Athens, GA.)

Fig. 12

AIP with lobules clearly separated by interlobular edema. Subtle differences are seen in various lobules. (Courtesy of Dr John King, Cornell University, Ithaca, NY.)

Fig. 13

Severe anemia.

Fig. 14

Aspiration pneumonia.

Fig. 15

Aspiration pneumonia with severe, multiple, necrotic cavitations.

Fig. 16

Embolic pneumonia.

Fig. 17

Aspirated (inhaled) blood distributed as feathery, lacy-appearing dark areas throughout lobules.

Fig. 18

Verminous (parasitic) bronchitis and pneumonia (Dictyocaulus viviparus).

Fig. 19

Tuberculous pneumonia with enlarged regional lymph nodes (arrows).