The purpose of this study was to determine the prevalence oi environme
ntal mastitis in dairy herds and identify the main environmental patho
gens, and to evaluate the influence of season, housing and management.
A total of 20 310 quarters of 5216 animals from 52 dairy herds in 32
counties was examined. Milk samples were aseptically collected for lab
oratory examination from mammary glands testing positive to any of the
field tests. From these, 736 environmental infections were identified
. The most frequently isolated environmental pathogens were algae of t
he genus Prototheca sp. (41.2%), Streptococcus uberis (21.1%), fungi (
19.5%), enterobacteriacea (8.3%) and Nocardia sp. (6.6%). The occurren
ce of mastitis was not influenced by the herd size, use of dry cow the
rapy, or post milking teat dipping. A tendency for increased occurrenc
e of environmental mastitis during the months of September to February
(hot and wet weather) was observed, suggesting a seasonal influence.