Do not rush to remove a retained placenta in a cow

I have had a number of calls by farmers in the last two weeks reporting that their cows have calved down but the placenta is retained. Those from near Nairobi, my practice base, requested me to go remove the placenta. Those from far, on the other hand, asked me to advise when the placenta should be removed.

Many of the farmers said they feared to have the placenta removed because past experiences had left them with infected cattle or animals that took very long to recover. In fact one of the farmers said her cow became very thin progressively after placenta removal and never conceived again.

Another farmer said her cow stayed discharging fluids from the vulva and only conceived after almost a whole year since the last calving. The farmers actually questioned whether the placenta should be removed physically. They wondered whether there was any medicine that could be injected into the cow to help push out the waste. They also wondered what would happen if the placenta was left to drop naturally.

All the farmers had valid points. Second, I have a policy of not arguing with farmers especially when they present issues they have personally observed. I normally will take their issues as my challenge and seek to educate them on what causes their observations or experience, how it occurs, its effect on the animal and any impact on humans, especially for cases that may affect humans in an adverse way.

The retained placenta issue was affecting the farmers by making them anxious hence denying them peace of mind. If handled improperly, the issue could cost the farmer money, productivity of the animals or even loss of the affected cows.

Before answering the farmers’ questions, let me first explain issues around retained placentas in cattle. Once a cow calves down, it should normally drop the placenta within the next 12 hours. Beyond that time, the placenta is said to be retained. 

A retained placenta may have some portions hanging over the vulva opening or the whole placenta may be anywhere within the birth canal. In most cases, the placenta will still be attached to the walls of the uterus and therefore cannot drop off even if the cow pushes.

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It is very rare for the placenta to detach from the uterine wall and float in the uterus. It will usually be pushed out by the contractions of the birth canal especially the uterus.

When a cow completes calving, the body will normally cut blood supply to the placenta and the process of detachment of the organ from the uterine wall begins. In cattle, this temporary but functional organ belongs to the foetus and not the mother. It is also generally referred to as foetal membranes. It is the shared organ between the foetus and the mother that functions to exchange blood, nutrients, immunity and breathing gases between the mother and the unborn baby.

In short, it is the calf’s lifeline efficiently delivering survival, growth and development resources from the mother for the nine months of pregnancy. 

The placenta is attached to the uterus by button-like organs called cotyledons that snugly latch onto corresponding organs on the internal surface of the uterus called caruncles. There are approximately 100 caruncles in the uterus of a cow. They have a button-like surface and a neck that attaches to the uterus tissue.

The necks of the caruncles is very important when a doctor intervenes to remove a retained placenta because they provide a firm hold between the index and middle finger while the thumb is used to peel off the cotyledon to effect detachment. The doctor does all the work from the memory and feeling of the location of each caruncle.

When the uterus is not pregnant, the caruncles regress to the size of pimples on the internal surface of the uterus but at maximum size during pregnancy, some may be the size of a passion fruit. This is part of the wonder that the uterus is.

When not pregnant, the uterus of a cow fits in the palm of the doctor but at birth, it carries a calf weighing 45kg and over 20 litres of fluid making a combined weight of over 60kg when the weight of the placenta is included. It is therefore important for farmers to know when they feed a pregnant cow, they create about 60kg of completely new tissues.

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In normal circumstances, the placenta will detach from the uterus and be pushed out by contractions of the reproductive tract within 12 hours after calving. Farmers should closely watch newly calved cows until the placenta is confirmed discharged. 

If the placenta does not drop off within 12 hours of calving, the farmer should inform their animal health service provider that the cow has a retained afterbirth. However, the service provider should not rush to remove the placenta.

Scientifically, it is known that a retained placenta in a cow should be removed between 48 and 72 hours from calving to allow for the organ to fully disengage from the uterus caruncles. Removal before that time may cause excessive bleeding, infection of the uterus or leave some undetached placenta pieces in the uterus.

Infection of the uterus causes the prolonged discharge of fluids from the vulva, poor health and delayed return to heat. If remnants of the placenta are left but no infection occurs, the animal takes long to get rid of the tissues and hence delays return to good health and conception. Infection or remnants of the placenta is the main cause of progressive weight loss in cows that have calved down and the placenta was removed before 48 to 72 hours from calving.

If the placenta is left for too long, beyond 72 hours, the decaying tissues of the placenta may produce toxins that make the cow sickly. Infection may also set in due to the decaying tissues and the cervix remaining open for too long. The cervix does not close when the placenta is still retained.

The drug oxytocin may be given to cattle with retained placenta to assist contraction of the uterus. This helps in detaching the placenta if blood supply has been cut off. However, the drug has a limited action period of about 10 minutes. It is therefore not of much use in cases where the placenta is still firmly attached.

The placenta can, nonetheless, be removed earlier than 48 hours if it makes the cow sickly. This would indicate either infection or some parts decomposing and producing toxins. As long as the cow looks normal, the placenta should be removed within 48 to 72 hours from the time of calving.

To the farmers’ delight, all the cows reported to me dropped the placentas uneventfully within 30 hours from the time of calving down. 

jmugachia@yahoo.com