It is sometimes claimed that milk contains pus, but this is simply not true.
In May 2008, the Advertising Standards Authority stated that "to refer to the white blood cells naturally present in milk as 'pus' was misleading". All milk - including human breast milk - naturally contains somatic (white) cells, which are critical in fighting infection and ensuring good health.
The dairy industry monitors somatic cells to ensure that levels remain at a consistent level, well below the permitted EU limit. In the UK, the average somatic cell count is around half of what is allowed within the EU.