No vaginal discharge is evident. Sometimes examination with a speculum will reveal a purulent discharge, but not always. Cultures of the uterus may or may not verify a microbial infection. For example, many times the repeat breeder is negative on culture. Subclinical endometritis can be positively diagnosed by microscopic examination of a uterine biopsy.
Controversy exists over the effects of metritis and endometritis on fertility in cattle.
Responses of individual animals to intrauterine treatment are quite variable. Some respond well to medication and conceive while others do not. Most cases of metritis and endometritis are initiated during the period from calving to the time the uterus returns to normal size. The process by which the uterus returns to its normal non-pregnant size is called involution. Involution in the cow varies from 26 to 56 days after calving, with an average time of 42-47 days.