Thursday, 29 August 2013 09:21


Written by  A.J. Neumann, DVM
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When I was in vet school way back when, the condition was known as ascending placentitis. It is estimated that 30% of all foal losses, from conception to birth, are due to placental infections in the pregnant mare. I believe this condition is becoming more prevalent as when foaling season comes around, I receive quite a few calls from breeders who are having a problem with the disease.

Every equine breeder should have a working knowledge of the anatomy of an open and a pregnant mare. He or she should understand the changes that occur in the reproductive organs when the mare becomes pregnant and the foal develops in the uterus.

With that knowledge aboard we know that a healthy placenta is vital for the growth and development of a viable foal. The foal develops normally in a sterile environment. To insure these tissues are kept free of infection, the cervix produces a thick, viscous, heavy mucus which seals the opening. This is known as the “cervical plug.”

In some mares, especially those in poor nutrition and those having a damaged cervix, bacteria and fungi will find their way past the cervical plug and into the uterus. There they can invade the placental tissues, the uterine wall and often the foal itself. This process becomes known as an “ascending placentitis.”

As the infection and inflammation damages the placental tissue, or the foal itself, the mare may prematurely abort the foal, or at the very least, the foal can be born early, dead or in a very weakened state.

In my experience, I have seen many more older mares with placentitis than younger ones. This stands to reason since the older mares have more of a chance to have a damaged cervix.

In some infected mares the inflammation and infection may stay in the general area of the cervix or it may move up into the placental tissues. Hence the condition is called “ascending placentitis.” In these cases the affected placental tissues will become thickened and eventually pull away from the wall of the uterus. Several things happen at this stage of the game, and all of them are detrimental to the development of a healthy live foal. As more of the placental tissues become involved, there is less oxygen and nutrients available to the developing fetus.

As this process progresses, the mare’s body starts to produce prostaglandins which eventually will cause the uterus to contract and expel the fetus and the afterbirth. Generally this abortion will occur somewhat early in the third trimester of pregnancy.

If the placental tissue has become thickened, the fetus is often expelled within it, the whole structure being an unbroken sack or bag. The placental tissues are red in color, where they had adhered to the uterine wall, thus the name “Red Bag Disease” or “Red Bag Abortion.”

I had a mare with this condition one time and she aborted her foal in the yard when no one was there. I found it was very difficult to identify the mare since none in my herd showed any signs of blood or fluids associated with the normal foaling process. The fetus was dead, of course, and entirely enclosed by the placenta. The mare had aborted the foal about four months before her foaling date. I had never noticed a discharge from the vulva or that she had “made a bag,” however it was a true “red bag” case.

It is not very difficult to diagnose “red bag disease” in a stricken mare. A good history furnished to you by a sharp herdsman or owner will very often put you on the right track. The following is the usual history given to you concerning the afflicted mare:

1. She is in her last trimester of pregnancy.

2. She is “making a bag,” and they can get some milk from the teats.

3. She has a light discharge from the vulva. It can be clear in color, slightly bloody or very bloody.

4. The discharge might not always be present, but some may be found on the tail hairs.

5. The mare is not visibly sick. She eats, drinks and looks well. If working, she will usually perform normally.

A mare with this history is generally either experiencing a twin pregnancy or undergoing an ascending placentitis.

I would, before the availability of ultrasound, do a rectal and vaginal exam of the mare. If the mare has a vaginal discharge, no matter how slight, the proper use of a vaginal speculum and light will reveal the discharge is coming from the cervix. Do not put your hand on the cervix or try to insert your finger into the lumen of it. You will just make matters worse in the long run.

After the vaginal exam is completed, a rectal examination of the mare should be undertaken. It may be possible to determine if the mare is carrying one or more foals as a result of this exam. It is also possible, in the case of twinning, to determine if one or more of the foals are underdeveloped or dead.

If the inflammation and infection has affected enough of the placental tissue, the fetus will begin to react to the lack of oxygen. It will be relatively still and then have a period where it kicks and moves violently in the uterus. These movements are easily felt when palpating the uterus of a mare with an advanced case of ascending placentitis.

The diagnosis of placentitis is relatively easy, especially if a good history is provided.

The latest methods used to diagnose placentitis are transrectal and transabdominal ultrasound procedures. In addition, there are several lab tests which can be employed in the diagnosis of placentitis. The fluids taken from the swollen udder can be tested as can blood serum. The mammary fluids are tested for certain electrolyte concentrations and the blood serum tests measure the concentration of progesterone and serum amigloid.

Now that we have the condition diagnosed, how do we treat it? If the placentitis goes untreated, we know what will happen to the foal. It may be aborted and is often found inside of the bag made from the infected, inflamed placenta.

The foal may be carried full term and, again, born inside of a sack of thickened placental tissue. The tissue will not rupture during the birthing process and the foal will be found dead within the bag.

Another possibility is that the foal is born, but it is too weak to stand and nurse. These foals become infected, in the uterus, and many will be weak and underdeveloped, as well as full of infection.

When ascending placentitis is diagnosed in a pregnant mare I try to save the foal if I can. Since that treatment consists of the use of antibiotics over a long term, I have tried to make the cost as affordable as possible.

The literature tells us that most cases of placentitis have an involvement of Strep Equi. Therefore the mare is given aqueous penicillin twice daily, at the highest dose recommended for her weight, for ten days.

I also put the mare on two grams of Aureomycin crumbles orally, per day, at the same time she is on the penicillin. These crumbles can be obtained from most animal feed stores. The crumbles are alfalfa-based pellets so almost all horses will eat them well when they are mixed in the grain ration. I keep the mares on the Aureomycin for 35 days.

If the mare has not foaled at the end of 35 days I take her off the crumbles for ten days and then give them to her for another 35 days. I keep her on the crumbles at this rate until she foals.

At foaling time, someone must be present to make sure that the placental membranes rupture so the foal can breathe. Remember, the placenta has thickened due to the infection and inflammation involving the tissues.

If the foal is born weak, unable to stand or unable to nurse, it must be treated with antibiotics and IV fluids immediately. Do not delay the treatment. I put them on a seven-day treatment of aqueous penicillin given twice daily in the muscle of the rump. I also give them a three-day treatment of Gentamicin which is administered IV twice daily.

There are some new drugs on the market that are being used for the treatment of placentitis in the mare. One which holds great promise is ceftiofur crystalline free acid. This drug can be given intra-muscularly, at four-day intervals to the mare.

The treatment I use may be old and I do not know how it all works, but down through the years it has seemed to do a good job for me. Besides–it’s cheap to use. Some people would call it shotgun therapy and they could be correct. I have always tried my best to save the mare and foal.

My practice has largely revolved around the value of the animal being treated, so often the cost of treatment is a major consideration.
Now you have the answer to the title question–that’s the story on “Red Bag Disease.”

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