Mastitis
Mastitis is the most expensive disease in the dairy industry today.

Mastitis-causing organisms
About 95 percent of all infections are caused by Streptococcus agalactiae, Staphylococcus aureus, Streptococcus dysgalactiae, Streptococcus uberis and and Escherichia coli. The remaining five percent are caused by other organisms.

Contagious organisms
Contagious organisms are spread by hands, milking units, etc. They include Strep. agalactiae, Staph. aureus and Strep. dysgalactiae. Strep. agalactiae lives in the udder and cannot exist outside it. It is susceptible to penicillin and once eliminated, usually does not return to the herd unless infected cows are purchased. Staph. aureus lives in the udder and on the skin surfaces of an infected cow. It can be controlled effectively with good management and is moderately susceptible to antibiotics when the infection first involves the gland.

Older infections usually do not respond to treatment. Severe cases may cause death. Strep. dysgalactiae lives almost anywhere, from the udder and rumen to feces and the barn. It can be controlled with proper sanitation and is moderately susceptible to antibiotics.

Environmental organisms
Environmental organisms live in the cows’ environment and are always present. E. coli bacteria are environmental pollution organisms which live in feces, polluted water and bedding material. Excellent environmental and premilking teat hygiene is needed for their control. They are not susceptible to antibiotics. Strep. uberis live almost everywhere, from the rumen and feces to the udder. They can be controlled by proper sanitation and milking clean, dry udders.

Prevention
It has long been known that the rate of new infections increases with the number of bacteria at the teat end. Previous associations have been made between clean housing, clean cows and lower bulk tank somatic cell counts. An index of environmental sanitation based on the amount of manure present on the cow and in her environment was a predictor for the occurrence of coliform mastitis in one study. A recent tail-docking study completed at the University of Wisconsin-Madison demonstrated a significant increase in the prevalence of environmental mastitis pathogens as poor udder hygiene scores increased. A good milking routine is essential for good udder health.  EL