A Deep Nasopharyngeal Swab Versus Nonendoscopic Bronchoalveolar Lavage for Isolation of Bacterial Pathogens from Preweaned Calves With Respiratory Disease.

BACKGROUND: Nonendoscopic bronchoalveolar lavage (BAL) is a practical alternative for a deep nasopharyngeal swab (DNS) to sample the airways of a large number of calves in a short period of time. The extent of commensal overgrowth and agreement of BAL with DNS culture results in preweaned calves are unknown. OBJECTIVES: To compare commensal overgrowth and bacterial culture results between DNS and BAL samples. ANIMALS: A total of 183 preweaned calves (144 with bovine respiratory disease and 39 healthy animals). METHODS: Cross-sectional study. Deep nasopharyngeal swab and BAL samples were taken from each calf and cultured to detect Pasteurellaceae and Mycoplasma bovis. Agreement and associations between culture results of DNS and BAL samples were determined by kappa statistics and logistic regression. RESULTS: Bronchoalveolar lavage samples were less often polymicrobial, more frequently negative and yielded more pure cultures compared to DNS, leading to a clinically interpretable culture result in 79.2% of the cases compared to only in 31.2% of the DNS samples. Isolation rates were lower in healthy animals, but not different between DNS and BAL samples. Only Histophilus somni was more likely to be isolated from BAL samples. In clinical cases, a polymicrobial DNS culture result did not increase the probability of a polymicrobial BAL result by ≥30%, nor did it influence the probability of a negative culture. A significant herd effect was noted for all observed relationships. CONCLUSIONS AND CLINICAL RELEVANCE: Nonendoscopic BAL samples are far less overgrown by bacteria compared to DNS samples under the conditions of this study, facilitating clinical interpretation and resulting in a higher return on investment in bacteriologic culturing.

A new predilection site of Mycoplasma bovis: Postsurgical seromas in beef cattle.

Mycoplasma bovis is a highly contagious bacterium, which predominantly causes chronic pneumonia, otitis and arthritis in calves and mastitis in adult cattle. In humans, Mycoplasma species have been associated with post-surgical infections. The present study aimed to identify the bacteria associated with three outbreaks of infected seromas after caesarian section in Belgian Blue beef cattle. A total of 10 cases occurred in three herds which were in close proximity of each other and shared the same veterinary practice. M. bovis could be cultured from seroma fluid in five of the six referred animals, mostly in pure culture and was isolated from multiple chronic sites of infection (arthritis and mastitis) as well. DNA fingerprinting of the isolates targeting two insertion sequence elements suggested spread of M. bovis from chronic sites of infection (udder and joints) to the postsurgical seromas. Identical genetic profiles were demonstrated in two animals from two separate farms, suggesting spread between farms. Mortality rate in the referred animals positive for M. bovis in a seroma was 80% (4/5), despite intensive treatment. A massive increase in antimicrobial use was observed in every affected farm. These observations demonstrate involvement of mycoplasmas in outbreaks of postsurgical seromas in cattle.

Intestinal clostridial counts have no diagnostic value in the diagnosis of enterotoxaemia in veal calves.

Enterotoxaemia is an important cause of sudden death in veal calves. This study aimed to evaluate intestinal Clostridium perfringens counts as a diagnostic tool for enterotoxaemia. Field necropsies were conducted on 48 sudden death cases in Belgian Blue veal farms. In 31/48 suddenly deceased calves, the diagnosis of enterotoxaemia was made based on haemorrhagic lesions in the small intestines, while in seven of these cases, no clear-cut diagnosis could be made based on macroscopic appearance of the gut. In the 10 remaining calves, a definitive cause of death other than enterotoxaemia could be identified. Samples of the intestinal content were taken for quantification of C perfringens. After matching cases and controls for diet, and the interval between death and sampling, no significant differences could be detected between the mean C perfringens counts of the small intestines in enterotoxaemia cases and counts in the matching segments in the control group. These results indicate that intestinal C perfringens counts cannot be advised as a discriminative postmortem diagnostic tool for enterotoxaemia in veal calves, not even when sampled within three hours after death.