Dairy cows: reducing the risk of contagious mastitis 

To control contagious mastitis, you’ll need to reduce the risk of infection spreading from cow to cow. Two things contribute to this:  

1. Ensuring there are fewer infected cows – either by treatment or possibly by culling.  

2. Preventing the spread of infection – by avoiding bacteria transferring directly from cow to cow.  

Below and on linked pages, we look at some of the practical steps you can take to lower the infection risk on your farm.  

One way to reduce the risk of new cases is to cure as many infected cows as possible. Using the traditional Five Point Plan, you can do this by:  

• Using antibiotic dry cow treatment (DCT) for infected cows at the end of lactation  
• Early and effective treatment in lactation, and recording clinical mastitis cases  
• Culling chronic mastitis cases  
• Post-milking teat dipping  
• Milking-machine maintenance  

To prevent the spread of infection from cow to cow, you will need to consider aspects of herd management, including biosecurity, segregation and grouping, post-milking teat disinfection, milking routines and machine maintenance, teat-cup-liner maintenance and somatic cell count (SCC).  

To measure the effectiveness of your efforts to reduce the risk of contagious mastitis, it’s helpful to set some key performance indicators. We recommend the following targets:  

• Cure rate in dry period (cell count high in and low out): over 85%  
• Cows with first case of mastitis after day 30 in milk: less than 17%  
• Percentage of animals with an SCC ≥200,000: less than 20%  

All high-risk cows must be clearly marked, as this makes it easier to manage the risks of antibiotic bulk milk tank failures and the risk of spreading infection to other cows.  

 Clearly mark animals, including:  

• Cows with clinical mastitis  
• Cows treated with antibiotics  
• Cows with high somatic cell counts: SCC >200,000 cows cells/ml for two of the last three months  

When marking affected cows:  

• Use tail tape, leg bands, sprays, and so on  
• Take care to avoid high-risk cow milk contaminating your hands or other cows through splashes or aerosols  

Make sure your cow identification is clearly visible to the herdsperson, and keep milk from cows treated with antibiotics out of the tank.