Veterinarians now recommend leaving a retained placenta alone to avoid harming uterus
HEALTH PRECAUTIONS FOR HUMANS
Dr. Jim Logan, Wyoming State Veterinarian says several diseases can cause retained placenta, including Brucellosis. “Sometimes there’s no rhyme nor reason that we can figure out regarding a retained placenta; it just happens. The key thing to be aware of, however, is that it could be an infectious cause; keep in mind that you need to protect yourself when handling that cow or placenta.” If the cow was aborting because of Brucellosis, for instance, this disease can be spread to other animals and to humans who come into contact with the birth fluids or aborted fetus or membranes.
“Use protective gloves when handling a dystocia or any kind of birth problem, or a placenta,” says Logan. When the fetus is aborted or the placenta shed, these tissues should always be properly disposed of rather than left lying there, in case it was an infectious situation.
“Be aware of the possibility of zoonotic diseases that could potentially be spread from an aborted fetus (such as Brucellosis or leptospirosis) or even from a live calf. Any placenta—whether it’s retained or one you happen to find—it’s a good idea to properly dispose of it because the placenta can be a source of infection,” says Logan.
The placenta is also a good diagnostic tool. “If there was an abortion or a young calf died and there is a retained placenta, salvaging that tissue so a sample could be sent in to the lab can be helpful. This might enable the lab to find bacterial or viral causes of abortion or illness in the newborn calf. It’s wise to collect those membranes and keep it as clean as you can, in case your veterinarian recommends sending a sample for diagnosis,” he says.
Most cows “clean” soon after calving, shedding placental membranes within 2 to 12 hours. If it takes longer than 12 hours, it is called a retained placenta or retained fetal membranes, according to Dr. Russ Daly (Extension Veterinarian, South Dakota State University). “When I was in practice we didn’t consider doing any kind of intervention until the placenta had been retained up to 72 hours, but our understanding of how best to treat these issues has changed,” he says.
Dr. Bill Lias of Interstate Vet Clinic, Brandon, South Dakota, says that veterinarians used to recommend removing the placenta if a cow didn’t clean within a day or so, but research has shown that it’s better to just leave them alone. “Back when I graduated from veterinary school, standard practice was to try to remove those placentas, but in recent years we’ve discovered that is not the way to go for the health of the cow and her future fertility; it’s best to just leave those cows alone,” says Lias.
Daly says that standard practice in the past was for a veterinarian to go in and manually unhook the attachments and remove the placenta. “We thought we had to get rid of it so the cow wouldn’t get an infection. We’ve learned that this intervention can damage the uterus more than just leaving it alone,” says Daly.
“When you manually remove the placenta, studies in dairy cows showed that this can delay a functional heat cycle for up to 20 days longer, compared with the cows that were just left alone to shed the placenta normally. Trying to remove those membranes can do more harm than good,” he explains. A mild local infection will generally clear up on its own and won’t affect the cow’s ability to rebreed on time.
“I still get calls occasionally from people wanting me to come clean a cow, and I have to tell them we don’t do that anymore. There is always risk for damage when we try to remove those membranes. There are attachment sites where the placenta interfaces with the uterine lining–caruncles in the uterus attach to the cotyledons of the placenta. A cow has a set number of caruncles and if any of those are torn off they do not regenerate. A certain number of these are required to support a pregnancy, so it’s not a good idea to manually try to remove the placenta and risk damage to those caruncles,” he says.
“We also run the risk of introducing more contaminants into the uterus when we go in and try to remove the placenta. The standard of care today, and recommendation to producers, is to leave those cows alone, and the majority of them do fine,” says Lias.
Often no treatment is required; the membranes come away on their own in a few days (sometimes up to a week or 10 days) and the cow will be fine, but occasionally a retained placenta can lead to serious infection. “Keep the cow in a clean, dry environment until she sheds those membranes. Some times of year, that’s a challenge,” Lias says.
Often the cow is better off out in a pasture, moving around, rather than confined in a dirty corral. “The main complicating factor is introduction of infection when those membranes are hanging out and she’s lying in manure or mud,” says Lias. The placenta can act as a wick to bring pathogens right into the uterus. Any cow that retains her placenta should be closely monitored to make sure she does not develop an infection. The uterus can generally handle a local infection and clean itself out, but if the infection goes systemic the cow will definitely need help.
“Our best advice is to leave the cow alone, in a clean place, and watch her. Most cows will be fine, but if she starts acting sick, consult a veterinarian. If the cow remains normal, with good appetite, she doesn’t need treatment, even if it takes her a week or longer to clean. If they don’t get sick, those cows do fine and rebreed on schedule. Cows are very hardy animals!” says Lias.
If the cow goes off feed, she may have a fever, and will likely need treatment. A veterinarian should be contacted. He or she would likely suggest systemic antibiotics and possibly anti-inflammatory medication, said Lias. Severe cases could call for a veterinarian flushing the uterus with antiseptic. The uterus can generally handle a local infection and clean itself out, but if the infection goes systemic the cow will definitely need help.
“This kind of treatment would only be needed in a few cases. If people worry about the rotten material hanging out, they could trim that part off and leave the rest to come out on its own,” says Daly. People used to think it would be helpful to tie a stick or something to the dangling membranes to add weight to help gradually pull the rest on out, but what’s still in the uterus at that point is still attached; the connections must disintegrate so all of that material can come loose. Those connections will come apart when they are ready.
In the past, many cows with retained placenta were also treated with oxytocin or drugs like Lutalyse and prostaglandin after calving. “Most of the data today has shown that these treatments are really not very helpful,” says Lias. “The bovine uterus is no longer receptive to oxytocin about 24 hours after calving, and it has not shown to have much benefit in terms of helping a cow clean,” he says.
“Oxytocin is a drug that makes the uterus contract,” says Daly. “It’s not a long-acting drug; it only lasts a short time in the animal’s system. We’ve found that it doesn’t really do much in terms of hastening the shedding of fetal membranes. Squeezing the uterus doesn’t help that connection deteriorate,” he says.
“There is a tight junction between the placenta and the uterus and oxytocin doesn’t affect that connection; it simply stimulates more uterine contractions.” If the placenta is already coming loose, contractions can help pass those membranes, but if the connections haven’t let go yet (which is usually the case in a retained placenta), it will take time for them to disintegrate and come apart, and the oxytocin does no good.
CAUSES – Several things may cause a retained placenta, including individual animal conditions and herd-based conditions. Daly said regardless of the cause, all retained placentas should be treated – or not treated – the same. Infectious causes could include diseases that lead to abortion. Abortions of any cause can result in retained placenta. Any time a cow calves prematurely—an aborted fetus, twins, or a premature calf—the placenta generally does not come away normally and must take time for the attachments to disintegrate and come loose later.
Lias says there are a number of reasons a cow might calve early—an abortion, an infection, a toxic insult, a premature calf, twins, etc. “We almost always see retained placenta in those situations. Nutritional deficiencies can also be a cause. With dairy cows, especially, the cows that are low on calcium or have milk fever have a much higher incidence. Retained placenta has also been linked to vitamin A deficiency, vitamin E and selenium deficiency, and sometimes copper. There may be more nutritional causes than we know,” says Lias.
“If producers start to see more than a few incidences of retained placenta, without the common and logical causes they should have their nutritional program evaluated. If you are having normal births but a higher than normal incidence of retained placenta, consult with a nutritionist and see if vitamin and mineral levels in the feed are where they need to be.” Take feed samples and perhaps also some blood samples from the cows to check their mineral status.
Other causes for an occasional retained placenta would be cows that are very thin or very fat. Having your cows in proper body condition, with good nutrition and good health are the best prevention.
“An abortion or early calf is probably the highest risk for retained placenta,” says Daly. “Twins often come a bit early, and even when they don’t come early, twins are another reason a cow might retain the placenta. A difficult birth may also be a cause. These are usually individual animal cases rather than a herd problem. If producers are seeing a lot of retained placentas without a reason like an abortion or a difficult calving, this would be a clue that something is wrong in the herd. If its normal calving and you see cows hanging onto the placenta for no apparent reason, the most common herd factor in those situations is deficiency in vitamin E and selenium,” Daly says.