Normally a cow will pass the placenta (afterbirth) in a matter of hours (four to eight) after calving. It can take a full day for some cows to pass the placenta but if it takes longer than this the condition is classified as a retained placenta.

Cause

The condition is more prevalent in dairy cows than suckler cows and is most likely to occur after abortion, stillbirths, twin births, premature birth, dystocia (obstructed labour), poor calving hygiene, milk fever, ketosis and fatty liver syndrome, negative energy balance in late pregnancy, or some other debilitating disease during pregnancy. Vitamin E/selenium deficiency is a common mineral deficiency that can lead to a retained placenta. Like most diseases, the incidence of retained placenta can be higher where hygiene is poor.

Symptoms

Diagnosis is usually straightforward. Discoloured and more often than not foul smelling membranes will be hanging from the cow’s vulva. Sometimes the retained membranes will remain inside the uterus and not be readily visible. In this situation, a foul smell combined with discharge from the vulva will be an indication of the problem. Sometimes, severe symptoms of fever and illness will be apparent. If the case is uncomplicated and treated properly there should be no real negative effects on the cow in the short term. However, affected cows with retained afterbirth are at an increased risk of developing metritis and endometritis (see page 24). This can lead to considerable difficulty in getting the cow back in calf.

Treatment

If a cow is showing signs of fever or there is a reduction in milk yield a vet should be called for assistance. If the cow shows no signs of ill health, treatment can be left until four to five days after calving. Treatment is not straight forward. Many treatments used on farms have not proven to be effective. Removal of the placenta is not recommended and can be harmful to the fertility of the cow. Intra-uterine antibiotics are also ineffective and may be detrimental. Prostaglandins and oxytocin were all found to be ineffective for treating the disease. All cows should be closely monitored (taking rectal temperatures) for the first 10 to 14 days after giving birth as they are at higher risk of developing infection and fever and, if so, should be treated with systemic antimicrobials.

Prevention and control

To prevent the occurrence of retained placenta you have to look at the factors causing the condition. If you can get a handle on the factors such as abortions, stillbirths, calving difficulties, milk fever and mineral deficiencies you should be able to reduce the incidence of retained placenta. It is good management practice to provide good-quality minerals to cows in the six weeks prior to calving. These are most commonly provided in boluses and powder on silage. Body condition score can also play a role in the retention of placentas, with overfat cows most at risk. Overall, good cow management and a well thought out animal health plan are essential tools to prevent the causative factors mentioned above. Every herd is likely to have a cow retaining the afterbirth from time to time. However, if the problem is particularly bad, with more than 5% of cows affected or a lot of cows affected in quick succession during a calving season you should talk to your vet about the best plan of action.