|Kehrli jr, Marcus|
Submitted to: Abstracts World Buiatrics Congress
Publication Type: Proceedings
Publication Acceptance Date: 12/5/2005
Publication Date: 8/11/2005
Citation: Burvenich, C., Kehrli, Jr., M.E., Paape, M.J., Bannerman, D.D. 2005. Role of neutrophils in the pathogenesis of bovine coliform mastitis. In: Proceedings of the 29th National Buiatrics Congress, August 11-13, 2005, Puebla, Pue, Mexico. p. S1. Interpretive Summary:
Technical Abstract: Around parturition dairy cows are at increased risk for intramammary coliform infections. A high proportion of these infections may develop disease characterized by inflammatory signs and sepsis during the first 60-70 days of lactation. The clinical picture is reputed as toxic mastitis. There is a remarkable variability in the clinical expression and complications of coliform mastitis around parturition, ranging from clinical severe to moderate and mild. The increased incidence of intramammary infections with coliforms around parturition can be explained by decreased innate immunity and dysregulation of the inflammatory reaction (immunocompromised condition) that is related to parturition and rapid induction of lactation. Neutrophils are one of the most important components of the efferent innate arm. Since the beginning of the 90ies, research on bovine mammary innate defense mechanisms, especially neutrophil functions, increased significantly. Most efforts have been focused on diapedesis, phagocytosis and killing by these phagocytes. Viability and programmed cell death (apoptosis) in neutrophils, was also studied. How neutrophil functions and viability/apoptosis modulate the clinical outcome of coliform mastitis have also been the subject of intensive research. The metabolic demands of increasing milk secretion (protein and energy) seem to impact the ability of the periparturient cow to manage its metabolism and its ability to recover from its immunocompromised condition. Cows with low glucose, ketosis, fatty liver and elevated NEFA’s have poorer immune, especially neutrophil function. The study of the afferent (sensing) arm that recognizes of a diverse array of pathogens, is a new area of interest of the last years. The mechanism of endotoxin sensing may have immense practical importance. The easiest prophylaxis today to prevent toxic mastitis is to provide periparturient cows not only with optimal hygiene conditions but also with appropriate diets during the transition period and as few additional stress events as possible around calving. Vaccine strategies have had limited success in reducing clinical symptoms associated with Gram-negative mastitis. Anti-microbial treatment of Gram-negative intramammary infections and therapeutic treatment to counteract the excessive inflammatory response elicited by LPS and Gram-negative pathogens remain often sub-optimal.