Mastitis in sows : clinical, bacteriological and cytological examinations in assessing udder health during early lactation and at weaning

Mastitis during the early lactation in sows is predominantly caused by Escherichia coli, and implicated in the agalactia post partum (APP). Chronic granulomatous mastitis (CGM) has a polybacterial etiology often diagnosed at time of weaning. E. coli mastitis in APP sows and the CGM in lactating sows lead to impaired udder health. The first study was designed to obtain more information about the potential influence of 2 late gestation feeding regimes (restricted vs standard) on health status of sows with reference to APP. The second study focused on teat injuries and palpable changes of the mammary glands and their potential impact on udder health at time of weaning. The third study comprised CGM sows that were examined before and after slaughter. In all three studies, results from thorough clinical examinations of the sows and their udders were confirmed by bacteriological and cytological analyses of milk amplified with analyses of pH during the early lactation period and histopathological examinations of mammary tissue specimens after weaning.The incidence of APP was significantly lower (14.4%) in the restricted-fed compared with the standard-fed sows (26.6%). APP sows showed a significant increase in rectal temperature one day before parturition and an increase in number of stillborn piglets (0.4) compared with clinically healthy sows, indicating an establishment of the disease before partus.Bacteriological examination of colostrum from APP sows and from clinically healthy sows, yielded growth of E. coli from one or several glands in 80% and 30% of the lactations, respectively. The growth of E. coli declined rapidly and was eliminated between days 3 and 8. Healthy sows with E. coli were designated as being subclinically infected. In colostrum, a substantial elevation of the total cell content (TCC) and its percentage of polymorphonuclear leucocytes (PMNLs) was demonstrated in 49 (64%) out of 77 APP lactations and 15 (16%) out of 96 clinically healthy lactations. Udder symptoms of clinical mastitis were poorly correlated to E. coli mastitis (TCOlOxlO6).Teat and udder skin injuries were numerically more frequent within the milk-producing glands of the udder. The prevalence of teat injuries subsided and 76% of the teat injuries were clinically normal at re-examination 7 days post weaning. The prevalence of palpable changes increased from first to second and subsequent lactations (15%, 30% and 60%).CGM was confirmed by histopathological examination in 10 out of 11 sows. A polybacterial flora predominated and comprised of S. aureus, A. pyogenes, F. necrophorum, P. anaerobicus, P. granulosum and Prevotella spp. As an appendant result, a ‘new’ bacteria belonging to the genus Actinomyces (Actinomyces - EF group 78, CCUG 37626) was isolated from tissue collected from an additional sow with CGM.