Inflammation of the udder (Mastitis)

Mastitis is a complex disease and different management factors play a part. However, mastitis is basically caused by pathogenic bacteria penetrating the teat channel. The disease partly destroys the milk producing tissue and by that reduces the cow’s milk production for ever. Often, mastitis infected cows must be culled.


Decreases in milk yield in case of mastitis are as follows:

  • Sub-clinical mastitis: 5 – 10 % decrease in milk yield
  • The cow loses one teat: 15 – 20 % decrease in milk yield
  • The cow becomes dry: 100 % decrease in milk yield

Previously, it was often infection from cow to cow that caused mastitis, but now it is instead environment bacteria which are the cause of most of the cases, often acute mastitis. First and foremost, environmental mastitis must be prevented by a clean and dry pen and a good housing climate. The costs of a mastitis case vary between DKK 1,450 – 4,850 depending on decrease in milk yield and increased culling. Approximately half of the Danish dairy cows are treated for mastitis.

Streptococcus uberis is the most frequent cause of mastitis in dry cows. The bacterium is normal on the teat skin as well as other parts of the body and is often found in the bedding material. Cure with antibiotics is often poor so prevention is very important.