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Clinical endometritis or “whites” is defined as the presence of pus in the vagina from 21 days after calving. The greatest impact and cost of endometritis is due to its detrimental effect on fertility, which persists way beyond the duration of the disease itself. In addition to creating a uterine environment which is unfavourable for embryo development, endometritis also disrupts follicle growth, leading to reduced egg quality. This is particularly important for eggs which are ovulated between 60-120 days in milk.


The impact of endometritis on fertility:

  • Calving to first service interval was extended by 11 days
  • Conception was delayed by 32 days
  • Cattle were 1.7 times more likely to be culled for reproductive failure

From a study of over 10,000 dairy cattle


80-90% of cows have bacterial contamination of the uterus post-calving.

So why do some cows develop endometritis and others don’t?

Risk factors associated with endometritis:

  • Trauma of the reproductive tract:
    • Retained fetal membranes
    • Twins
    • Large calves
    • Dystocia
    • Caesarean section
    • Stillbirth
  • Reduced immune function around calving:
    • Metabolic disease
    • Negative energy balance
    • Ketosis
  • Poor hygiene

A healthy immune system is needed to clear bacterial contamination of the uterus. Anything which causes uterine damage, even on a microscopic level, will compromise the cows ability to clear uterine infections. A lack of energy or metabolic stress will further hinder the cows immune response.

The weight of the uterus changes from 9kg at calving to 1kg by 30 days in milk. This process of involution requires a healthy immune system, energy and essential nutrients. Cows experiencing metabolic stress post-calving will have a compromised immune response are more likely to develop endometritis.

Up to 80% of cows with endometritis show no vulval discharge. Checking cows for “whites” after 21 days post calving will help to identify affected cows so that they can be treated promptly. A target for the incidence of clinical endometritis is <5%.