Outbreaks of clinical mastitis are sometimes seen in summer following a few hot, humid days. A major reason for such outbreaks relates to the things cows do to keep cool.

Cows are highly susceptible to mastitis if their teats come in contact with high numbers of bacteria, particularly when their natural ability to resist infection is compromised.

On hot days, cows tend to congregate - and therefore dung - around watering troughs and in shaded areas. When this happens soon after milking, while the teat ends are still partly open, there is a good chance that some bacteria from the environment will enter the teat end.

Well-intentioned strategies to keep cows cool and comfortable can also result in dirty udders. For example, spraying the milking herd on entry to or exit from the dairy increases the amount of mud and faeces that is flicked around as the cows walk. Or using parking bays to hold cows that have left the shed provides a perfect venue for them to sit in the bacteria-containing mud!

Environmental bacteria can cause severe infections. To establish whether you may have a problem in the making, record the number of clinical cases you have each month – an easy way is to write them on the whiteboard where they are clearly visible. Move quickly to investigate the cause if you have more than 2 clinical cases per 100 cows. For a 200-cow seasonal calving herd, the trigger point for action would be a recording of more than 4 clinical cases in December.

The only way of knowing what sort of mastitis you are dealing with is by submitting milk samples from the clinical cases for culture. Bacteria that are often responsible for environmental mastitis are Strep uberis, E. coli, coliforms and Pseudomonas.

In heatwaves it may also pay to spend a little extra time checking the foremilk for signs of clinical mastitis such as wateriness or clots in the milk that persists for more than 3 squirts.

This may help you stop an outbreak before it heats up. Prevention is always better than cure for cases of environmental mastitis!

Image and caption

Caption: Stop an outbreak before it heats up. 

Countdown Downunder Farm Guideline or Technote
Farm Guideline Introduction, 4.2, 4.3, 13.1

Keywords
Environmental, clinical cases, cow behaviour, milk culture

Word length
322