Climate
Climate may have a direct or indirect influence on the onset of mastitis. Older authors7,43 insist a great deal on the fact that exposure to intense cold, draughts, excessive humidity or heat predisposes cattle to mastitis.
Just as they foster our colds, rapid changes in temperature can encourage mastitis. Research on how temperature influences the incidence of mastitis indicates that temperature extremes interact with other factors to cause mastitis but rarely will temperature alone cause the disease21. Temperature extremes may also affect somatic cell counts. Therefore the incidence of mastitis increases with extreme temperatures. In Florida, a higher rate of clinical mastitis was observed three years in seven during very hot periods28.
A particular type of mastitis often called summer mastitis, is caused by biting insects that contaminate the udder with the bacteria Corynebacterium pyogenes and other anaerobic bacteria. The frequency of this type of mastitis varies according to the regions, with humid valleys being most susceptible.
Climate may also have an indirect influence. For example, muddy conditions outdoors caused by abundant rainfall will increase the number of microorganisms and thus increase risks of infection.