Bronchopneumonia with interstitial pneumonia in feedlot cattle: Epidemiologic characteristics of affected animals

Abstract

Bronchopneumonia with interstitial pneumonia (BIP) of feedlot cattle is characterized by gross and histologic lesions of cranioventral bronchopneumonia (BP) and caudodorsal interstitial pneumonia. This study described the characteristics and frequency of BIP in western Canadian feedlot cattle and identified epidemiologic differences between BIP and either BP or acute interstitial pneumonia (AIP). The study of 9909 deaths on 4 western Canadian feedlots included 1105 BIP, 1729 BP, and 878 AIP cases. A population of 55 cases with gross, histopathology, and microbiology data was used to validate the primary data set. BIP was the second most common reason for death (or euthanasia) from respiratory disease (1105/9909 cases), and the observed frequency was twice what was expected from random concurrence of BP and AIP. Based on logistic regression models, epidemiologic characteristics of BIP were comparable to those of BP, although BIP cases were more chronic with more instances of clinical illness prior to death. BIP was epidemiologically distinct from AIP. Specifically, BIP more frequently affected steers than heifers, deaths occurred earlier in the feeding period at lower body weights and lower daily weight gains, and BIP cases had longer durations from the first clinical illness to death and more separate instances of clinical illness prior to death. Furthermore, death from BIP mainly occurred in winter and fall, while death from AIP was most frequent in summer. These findings define BIP as a unique condition of feedlot cattle and suggest that chronic BP may promote the development of fatal interstitial lung disease in at-risk cattle.

Bronchopneumonia with interstitial pneumonia in beef feedlot cattle: Characterization and laboratory investigation

“…The findings indicate that in BIP cases, cranioventral BP precedes caudodorsal alveolar and bronchiolar damage, blood cytokine storm does not appear to play a role, and BIP cases appear to have dysfunction of lung surfactant that is independent of protein exudation into lung fluids. The morphological and microbiologic features of BIP resembled those of the component lesions; however, the findings of a separate study 11 indicate that BIP is a distinct condition rather than chance concurrence of BP and AIP (namely, a higher concurrence of lesions than expected by chance, and differences between BIP and AIP in the sex predominance, seasonality, timing relative to entry to the feedlot, and prior clinical illnesses 11 ). Compared with histopathology, gross diagnosis of BIP by a single experienced feedlot veterinarian reviewing postmortem photographs had a high sensitivity (83%) and moderate specificity (73%).…”

“…Thus, using histopathology as the gold standard, gross diagnosis of BIP had a sensitivity of 83% and a specificity of 73%. As BIP was estimated to represent 11.2% of all deaths on western Canadian feedlots, 11 gross diagnosis of BIP had a positive predictive value of 28%, a negative predictive value of 97%, and an accuracy of 74%.…”

“…In a separate study, we found that BIP cases (compared with BP cases) had a longer interval from first illness to death and more instances of clinically recognizable illness. 11 Thus, these differences in histologic lesions probably reflect a more chronic bronchopneumonia in BIP than in BP cases, or lung that is more typically infected with lower virulence or secondary bacterial pathogens. The similarity of cranioventral lung lesions in BIP and BP also highlights the diagnostic value in histologically examining ≥2 sections of caudodorsal lung to detect the alveolar and bronchiolar damage.…”

Image Classification and Automated Machine Learning to Classify Lung Pathologies in Deceased Feedlot Cattle

“…Visual signs of respiratory distress have moderate accuracy due to variability in subjective evaluation and biological variation in disease presentation [ 9 ]. Recently, bronchopneumonia with an interstitial pattern (BIP) diagnosis was described as an emerging lung disease in feedlot cattle [ 10 ]. The report of BIP cases raised the questions of respiratory diseases possibly being inaccurately diagnosed and only classified as AIP and BRD.…”

Determining Frequency of Common Pulmonary Gross and Histopathological Findings in Feedyard Fatalities

“…Multiple pathogenic processes have been considered for inciting AIP; however, little is known about risk factors for this disease [ 20 , 21 ]. Bronchopneumonia with an interstitial pneumonia (BIP) is a combination of pulmonary lesions consistent with both BP and AIP [ 22 , 23 ]. While a diagnosis of BIP is recorded by some veterinarians, other diagnosticians will attribute cause of death to either BP or AIP.…”