Metritis diagnosis considerations
What is metritis?
Metritis is an inflammation of the uterus after calving, characterized by an enlarged uterus with an abnormal, foul-smelling vaginal discharge and usually accompanied by other systemic signs of disease such as fever, loss of appetite or drop in milk yield. Most metritis cases occur in the first 14 days in milk (DIM) with a peak around 5 to 7 DIM. Cows that had dystocia, twins, stillbirth or retained fetal membranes (RFM) are at a greater risk of metritis. The incidence of metritis varies significantly across herds ranging from 10 to 25 %. The average cost per metritis case is estimated at $304 to $354. Economic losses are associated with culling, decreased milk yield, poor reproductive performance, treatment costs and discarded milk.
How can metritis be diagnosed on dairies?
There is no gold standard to identify metritis, thus, a combination of signs is used to diagnose this postpartum disease. Two of the following signs should be present:
- Systemic signs of health disorders: poor appetite, low production, and dull attitude.
- Fever: rectal temperature above 103ºF.
- Abnormal vaginal discharge: watery, foul-smelling, and brownish.
Does fever always means metritis?
Elevated rectal temperature in postpartum cows is considered a sign of a health disorder, most likely associated with an infectious disease such as metritis. However, 45 to 70% of healthy postpartum cows can have at least one elevated temperature event during the first 10 DIM. Moreover, it should be taken into consideration that 22% of cows with signs of metritis can self-recover within the first 4 days after calving.
What is the cut-off point of fever?
In dairy cows, normal body temperature (BT) is 100.4º F to 102.5º F. Cows are considered to have fever when BT is ≥ 103 ºF. However, factors such as parity [primiparous cows have higher (0.4º F) BT] and season (higher BT in summer) should be taken into consideration when defining fever. In summer months, a BT of 104º F can be normal. Thus, it is recommended to check the BT of 4-5 healthy looking cows and add an additional 1.5 to 2º F to define the cut-off temperature for fever on hot days.
Based on our survey results from 45 dairies in the San Joaquin Valley, most herds have adopted ≥ 103º F as the cut-off for fever. However, 3 dairies used a lower cut-off point ( ≥ 102.5º F) for all cows, only for primiparous cows, or only during summer season.
Take home message
Metritis is diagnosed as a combination of signs. The observation of a single sign of a health disorder should not lead to treatment. Consider the season and lactation number of cows when defining fever. Ask your veterinarian for advice on postpartum health protocols and to train your fresh cow evaluators to properly identify metritis cases.
