Fact Sheet: Environmental Mastitis

The Disease

Environmental mastitis is as the name implies mastitis that is “caught” by the cow from the environment in which she lives. The organisms may be found in bedding, soil, walkways, on pasture or any surface the cow comes in contact with. Organic bedding such as wood shavings or straw is a most commonly incriminated source. At pasture in hot weather the cows congregate in cool areas and soon contaminate the ground with manure and other discharges. Thus making this area a source of mastitis causing bacteria. The causative agents include Streps, other than Strep agalactiae, Staphs, other than Staph. aureus. Coliformes, Pseudomonas, Proteus, Serratia, and Prototheca. These bacteria are problematic as few of them respond well to antibiotics. Because of this clinical cases should be cultured before treatment and good records kept and reviewed to recognize trends that change over time.

The Consequences

All incidences of mastitis result in loss to the producer. At best this loss is confined to medication costs, discarded milk and reduced production as the cow recovers. At the worst the production of the cow may be reduced or lost for a lactation with high medical costs, or the cow may suffer permanent damage to her milk producing system or even die. Clinical coliform cases may negatively impact reproduction in the herd adding to the costs of this disease.
Environmental mastitis is more common on farms with excellent control of contagious mastitis. The procedures that reduce the reservoir of contagious mastitis pathogens will not reduce the huge and ever- present supply of environmental organisms. Reducing teat-end exposure to environmental pathogens is the goal of an environmental mastitis control program.


The goal here is to keep the cow and her environment as clean and dry as possible.

  • Cow stalls of adequate size, comfortable, clean and dry .
  • Cow areas inside and out are clean and well drained and muddy areas are avoided.
  • Barns should be well ventilated and kept as cool as possible to retard growth and survivability of bacteria.
  • Teats should be well washed, sanitized and dried prior to application of the milker.
  • During milking insure good claw alignment and support and that inflations are in good condition to avoid liner slips.
  • Be alert to weather conditions (hot and humid) that may presage an outbreak of environmental mastitis.
  • Record keeping and culturing of all clinical cases can indicate the early stages of a mastitis outbreak.