Bovine Respiratory Disease Complex: Prevalence of the Different Bacteria Involved in Pneumonia in the Iberian Peninsula

Abstract

Bovine Respiratory Disease is the most frequent cause of disease and the main cause of death in cattle, which results in financial losses. The aim of this article is to present the prevalence of the different bacteria involved in Bovine Respiratory Disease in animals with respiratory symptoms in the Iberian Peninsula. Information was collected from a private laboratory, selecting the data from the analyses of the bovine respiratory disease panel performed between January 2017 and January 2020, which included the major respiratory pathogens. Samples originated from all across Spain (mostly from the North and Northeast) and Portugal. The type of sample was classified into four groups: organs, bronchoalveolar lavage, nasal and tracheal swabs. A farm was considered positive if at least one of the tests performed was positive to either real time qPCR or culture. Four hundred and fourty-eight reports were created representing 370 cattle farms with animals that showed respiratory symptoms. The observed prevalence of Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, and Mycoplasma bovis in the period examined was 32.8% (95% CI: 28.5%-37.2%), 55.6% (95% CI: 51.0%-60.2%), 24.1% (95% CI: 20.2%-28.1%), and 53.6% (95% CI: 49.0%-58.2%), respectively. Regarding the age of the animals in the reports examined, 7.4% (33) were samples from adult animals (beef or dairy cattle), 51.3% (230) were from fattening calves (feedlots), and 23.2% (104) were from veal calves. The age group or production system was not identifiable in 18.1% (81) of the remaining reports. As for the types of samples, the majority (58.5%) were organs from animals suffering from Bovine Respiratory Disease (lungs), followed by bronchoalveolar lavage (29.7%), nasal swabs (6.5%), and tracheal swabs (1.6%). In 3.8% of cases, the farms sent various types of sample together. In 88.3% of cases where a virus was detected, bacteria were also found. On the other hand, in 45.3% of all the reports, the only agents detected were bacteria. Bacteria were involved in at least 77.2% of outbreaks. These results confirm the need for preventing bacterial pneumonia to reduce the use of antibiotics and improve the financial returns and animal welfare.