Diagnosis of Mastitis in Cows

Early identification of all cases of clinical mastitis is a key weapon in preventing further outbreaks of mastitis and is a key part of the overall mastitis control programme, ensuring maximum herd health, milk quality and dairy farm profitability.

The organisms that cause mastitis in dairy cows are divided into 2 main groups; contagious and environmental mastitis. There is some degree of interplay between these two types, for example strep uberis is primarily an environmental organism that can become ‘cow adapted’ and change into a contagious organism.

Each type of mastitis may present in an entirely different way. For example as infection with Staphylococcus aureus progresses through a herd the incidence of clinical mastitis may be quite low but the herd cell count continues to rise.
Streptococcus uberis may present with a high level of clinical cases and fluctuating bactoscans and herd somatic cell counts. Once ‘cow adapted’ strains of Strep uberis develop the herd cell count will increase rapidly due to the contagious transfer of infection.

Each farm has its own mastitis profile and the first task when investigating a problem is to establish the main organisms involved.

This can be assessed in two ways:

  1. Take a bulk milk sample under strict conditions and submit it for specialist examination.
  2. Take samples from each case of mastitis and store them in the freezer. These can then be analysed at a later date for the causative organisms.