Gaschromatographic Analysis of Summer Mastitis Secretions for the Presumptive Diagnosis of Infections by Obligate Anaerobic Bacteria

Abstract

Udder secretions sampled during the summer in 1984 and 1985 from mastitis quarters of 51 non-lactating heifers and dry cows were examined bacteriologically for the presence of (facultative) aerobic and obligate anaerobic bacteria (OAB) and by gas liquid chromatography (GLC) in order to detect volatile fatty acids (VFA), metabolic endproducts of OAB. Forty-nine samples yielded positive cultures and in 20 cases these were mixtures of (facultative) aerobes and OAB. Only 2 specimens appeared to be sterile and from one specimen only OAB were cultured. In most specimens (19/21) which yielded OAB after culturing, VFA (C₃–C₆) could be detected by GLC. A specific pretreatment method had to be developed for GLC-analysis of udder secretions to avoid interfering peaks on the chromatogram and to prevent poisoning of the GLC-column. Two false negatives and one false positive were noted. Detection of VFA by GLC-analysis in summer mastitis secretions appeared to be a useful technique for evaluating the importance and association of OAB with summer mastitis. Because samples can be easily collected and stored at —20°C this is especially advantageous in situations where adequate facilities for isolation of OAB are not readily available, as in most veterinary clinical situations.