Nineteen microorganisms have been identified as causative agents of mastitis in cattle. Yeast and fungus have also been found frequently infecting the udder, but usually go unnoticed because they produce a mild or subclinical mastitis. The relationship between the amount of mammary tissue affected by microorganisms and the form of mastitis is shown in figure 2. The incidence of mastitis is greater in closely confined flocks. Bedding material in barns should be clean, especially before and after lambing.
Microorganisms thrive in dark, wet, warm bedding.
When the ewes lay down to rest, the bacteria in dirty bedding can easily enter the teat when the udder is full of milk. Microorganisms can enter the teat canal. Dirty bedding and crowding will make this possible. Lambs from infected ewes will often nurse other ewes, spreading the microorganisms to others in the flock. Isolating ewes suspected of chronic or acute mastitis will help reduce the incidence of mastitis in a flock.