Post-Foaling Problems In Mares
Birth of a foal in the spring is a wondrous event for many reasons. Foremost, the foal is usually the embodiment of hopes and dreams, whether it is born as one of many at a large commercial stable or if it is the only arrival for the year at a private farm. Second, it is a wondrous event from a medical point of view because it represents fruition of a process that began with the mare's being bred to a stallion and continued for 11 long months with numerous potential obstacles that could have terminated the pregnancy along the way.
Unfortunately, the birth of the foal is not the end of the problem era. There can be many more difficulties waiting in the wings. The first concern at birth is the foal itself. Is it strong and healthy? Will it stand and nurse and thus obtain the all-important colostrum? How about its limbs? Are they free from deformity? Is it breathing well? Is it suffering from septicemia? Is there a strong heartbeat? The list goes on.
Next on the concern list immediately after foaling is the mare. Did she come through the short, but almost violent birthing process unscathed? Or are we facing some post-foaling problems that could compromise her health, her ability to conceive again, or even threaten her life? Again, the list goes on.
The problems that can afflict a mare in the wake of foaling are many and varied. Some are relatively benign, such as an inability to produce enough milk for the foal. Although benign when compared to medical emergencies, this problem can have serious consequences, economic and otherwise. Other post-foaling problems border on the catastrophic, as might be the case with a ruptured uterus or internal hemorrhaging.
In between are a host of other potential problems with the most common one being a retained placenta. On the surface this might seem like a relatively benign problem, especially to individuals involved with raising cattle. A cow might retain a placenta for a day or more with only negligible damage to the reproductive system.
Not so with the horse.
If the placenta isn't expelled or removed within a matter of hours, the mare's reproductive capability can be compromised, laminitis and/or metritis might develop, and her very life might be at risk.
One of the reasons the problem is so serious with mares, says Glen Gamble, DVM, of Riverton, Wyo., is basic physiology. For starters, he points out, the placenta of a mare is attached to almost all parts of the uterine wall.
Basically, there are only five spots in the uterus where placental membranes are not attached. They are the area in contact with the internal, or uterine, opening of the cervix (cervical star); small areas at the tip of each uterine horn in contact with the uterine tube opening; and areas representing the primitive yolk sac attachment and endometrial cup remnants.
What this means as a practical matter, says Gamble, is that there is a multitude of opportunities for portions of the placental membrane to remain attached to the uterus and cause infection and scarring.
By contrast, the placental membranes of a cow are attached at several locations--cotyledons. Thus, if one of these areas fails to detach, the problem isn't as severe as it is with the equine. If there is scarring at one cotyledon site, the others can make up for it in an ensuing pregnancy and the fetus will get appropriate nourishment.
With the horse, even a small amount of uterine scarring can be detrimental. In spots where scarring occurs, the placental membranes might not be able to attach during the next pregnancy. An inability of the placenta to attach to all parts of the uterine wall can be a death sentence for the fetus.
This means, says Gamble, that special care should be taken to remove the retained placenta with no violation of the uterine wall that can result in scarring. Equally important is the matter of staving off bacterial invasions.
Before we get into the various approaches to removing a retained placenta, it would be well to discuss what is normal and what is abnormal as to the time frame between birth of a foal and the expelling of the placenta or afterbirth.
A consensus of practitioners and researchers indicates that the normal length of time between birth and expulsion of the placenta is between 30 minutes and three hours. This does not mean that immediate harm will befall at three hours and one minute. The general consensus, again, is that eight to 12 hours can elapse before serious harm is done. However, after three hours have elapsed and the placenta has not been expelled, the condition moves into the category of retained placenta.
Generally, when there is a retained placenta, it will be obvious. A portion of the afterbirth will be hanging from the vulva. Because it is so important that undue force not be applied to the uterine walls, it might be advisable to tie the dangling membrane into a knot or attach it to the mare's tail to keep it from dragging on the ground. This will prevent her from stepping on it and perhaps causing internal damage.
There are, however, cases where the entire placenta is retained and none is showing at the vulva level.
In addition, there are cases where it might appear that the entire placenta has been expelled when, in fact, a portion has been retained. It is for this reason that the expelled placenta should be carefully examined immediately after being expelled. If the amateur horse breeder isn't sure what the appearance of a complete placenta should be, it would wise at this juncture to have it examined by a veterinarian.
For the average horse owner, the logical approach if a placenta is retained for three hours or more should be to call a veterinarian. This is one time when a "wait and see" attitude is not appropriate. The consequences potentially are so serious that delay in seeking professional help should not be considered.
Gamble's initial approach in dealing with a retained placenta is to administer oxytocin and Banamine. The oxytocin brings on uterine contractions that, hopefully, will cause the retained placenta to be expelled.
The Banamine, he says, works in three specific ways. First, it is an analgesic that can help stave off pain from colic. Second, it is an anti-inflammatory. Third, it does battle against endotoxins that can cause metritis and laminitis.
If the contractions brought on by the administration of oxytocin don't get the job done, Gamble says, he will attempt to infuse the retained placenta with a saline solution. The pressure brought on by the liquid within the uterus often works to free the membrane where it is attached, he said. In some cases, he also will seek to infuse the solution between the inner uterine wall and the external portion of the placental membrane. Again, this will bring gentle pressure to bear in the areas where the membrane remains attached.
Almost never will he insert his hand into the area between the inner uterine wall and the placenta, Gamble says. The risk of carrying harmful bacteria into the area is simply too great.
Proliferating bacteria are responsible for the release of endotoxins that can bring on a bout of laminitis. Bacteria multiply quickly in the traumatized areas, Gamble says. "We are dealing here with gram-negative bacteria. They have a short life span and when they die, the bacterial walls break down, with the contents spilling out. These are the harmful endotoxins that are carried through the bloodstream and can cause laminitis."
The key, throughout the treatment process, Gamble says, is never to apply heavy force in attempting to remove the retained placenta. Application of force can cause the membrane to tear free, but it also can allow a portion to remain attached to the uterine wall. This will be a source of infection and scarring. A second danger involves possible uterine hemorrhaging.
If any force at all is applied, he said, it should be in the form of gentle, steady traction on the portion of the placenta that is present at the vulva.
The number of mares that retain placentas in the wake of foaling is believed to be between 2-10%, says Terry L. Blanchard, DVM, MS, Diplomate ACT, one of a number of reproduction researchers at Texas A&M University. Blanchard has written extensively on equine reproductive matters and frequently has been a presenter on the subject at such gatherings as American Association of Equine Practitioners and the Society for Theriogenology. He also has authored portions of the veterinary textbook, The Horse, Disease & Clinical Management. Much of what follows concerning post-foaling problems in mares comes from his presentations and reports, along with other varied sources and some personal experiences.
The probability of retained placenta, Blanchard says, increases in the wake of dystocia--problem birthing. It also can be the result, he says, of a disturbance of normal uterine contractions. Retention also is likely, he said, if severe placentitis (inflammation of the placenta) has occurred.
Interestingly, he adds, if there is only partial retention, such as in one of the uterine horns, it is more likely that the retention will have occurred in the non-gravid horn--the one where the fetus was not attached via the umbilical cord.
The reason this occurs, he believes, is that the chorioallantoic membrane attached there is thinner, resulting in easier tearing.
An interruption of the uterine contractions that normally would expel the placenta, Blanchard feels, might be the result of an endocrine dysfunction. In other words, the mare's body is not releasing enough oxytocin or the myometrium is not responding appropriately to what would normally be the correct amount of oxytocin.
For Blanchard, the administration of oxytocin also is the first line of attack when battling a retained placenta. Recommended dosages, he says, range from 20 to 120 units and can be given subcutaneously, intramuscularly, or intravenously. Dosages can be repeated every few hours if the placenta is not passed. Under normal circumstances, he says, there will be signs of abdominal discomfort within minutes after oxytocin is administered. The discomfort normally is followed by increased straining.
Blanchard suggests this approach: "For ease of administration, I prefer to administer 20 units of oxytocin intramuscularly, as small doses administered by this route have been found to stimulate more orderly, sustained uterine contractions without producing uterine spasms."
If that doesn't do the job, he also turns to infusing the retained placenta with warm saline. Stretch receptors are activated when the chorioallantois and uterus are distended, he says, followed by the mare's body releasing more oxytocin. The use of warm saline in this manner, Blanchard reports, also can cause separation of the chorionic villi from the endometrial crypts.
Blanchard also recommends, in cases where there is concern that the patient might develop septic or toxic metritis and laminitis, the administration of systemic and intrauterine antimicrobials.
For the average horse owner who suspects a retained placenta the advice is this: Don't tarry and don't try to solve the problem yourself; immediately call a veterinarian.
If retained placenta is the most common post-foaling problem, perhaps the most rare is uterine prolapse, something the cowman and sheep raiser must deal with more frequently.
I have been involved with breeding horses for many years and on only one occasion have I had to contend with a prolapsed uterus. There was no dystocia involved. In fact, the birth had been rapid and the placenta quickly expelled. I went to bed late that night feeling that all was well. The foal was nursing, the placenta had been intact, and the mare was quietly eating.
The next morning I was shocked to see that the mare had prolapsed. I immediately called for a veterinarian who, first of all, cleaned the exposed portion, then gently returned it to its rightful place. I can't remember the specific treatment regimen, but I do know that the problem was solved with that one treatment.
The mare was an average broodmare and had been broke to ride. Convinced that she would never conceive again and carry a foal to term, I placed her in an auction, with the disclaimer that she might not be a breeder, but was being sold as a riding horse. Because of the disclaimer, she didn't bring much money as this was a breeding stock sale and not a performance horse sale.
A couple of years later, I was amazed to see an advertisement of a foal for sale that listed this mare as its dam. I had sold her in the fall and her buyers had waited until the following spring to breed her. She apparently conceived immediately, presented them with a foal, and had bred back after a normal delivery with no hint of prolapse.
That particular story has a good ending for the people who purchased the mare. That isn't always the case when a rare prolapse does occur.
A mare is more apt to prolapse immediately after giving birth, Blanchard reports, but it can occur three to four days later. The reasons for its occurrence can be varied. There might have been strong vaginal trauma, or there might have been very poor uterine tone. Whatever the cause, immediate treatment by a veterinarian is a must.
The first line of attack normally is to control straining of the mare. If memory serves, I don't believe my mare was still straining when I first discovered her. However, straining often continues even after the prolapse has occurred.
Blanchard recommends that steps be taken immediately to stop the straining either by the administration of sedatives, epidural anesthesia, or general anesthesia. If the straining is not controlled, the problem can quickly worsen with the possible rupture of internal uterine vessels and shock. It should go without saying that exposing that portion of the uterus also predisposes to the development of tetanus.
Once the straining has stopped, it is time for cleaning the exposed portion of the uterus. Blanchard recommends the use of disinfectant soap. The uterus, he said, should be gently cleaned, with any pieces of attached placenta being removed. Bleeding vessels should be clamped and ligated, he says, and uterine tears should be sutured.
Next comes replacement of the uterus. Several techniques have been advocated for getting this job done. One of them, as explained by Blanchard, involves placing the uterus inside two or three plastic garbage bags. This approach is advocated as a way to reduce risk of puncturing or lacerating the uterus during the replacement process.
The garbage bags are removed as the uterus is pushed inside the vagina.
Gently filling the uterus with warm water can be helpful in ensuring complete replacement of the uterine horns, Blanchard points out. Excess fluid then is siphoned off. Small doses of oxytocin, he says, might stimulate uterine contractions that will be beneficial in getting the uterus back to normal.
Also advocated at this point is the administration of both systemic and intrauterine antibiotics.
The same advice to the average horseman pertains here as for the retained placenta--don't tarry; get professional help immediately.
Other post-foaling prob- lems that can afflict the mare, as outlined by Blanchard, include the following:
Dystocia often is involved when there is a rupture of the uterine wall. In some cases, the rupture occurs when the fetus is being maneuvered into position. It also can happen if treatment following foaling is overly vigorous, such as with a uterine lavage. Obviously, immediate treatment is a must. The best treatment for salvaging the mare's life and, hopefully, her breeding future, according to Blanchard, is laparotomy (surgical incision through the flank) and surgical repair of the ruptured area. In some cases, where the tear is very small, a more conservative approach might be taken, such as the administration of broad-spectrum antibiotics along with intravenous replacement of fluids and electrolytes as part of the protocol. An inherent danger with such an approach is the development of peritonitis.
Invagination of Uterine Horn
An invaginated (invaginate means to unfold one portion of a structure within another portion) uterine horn, reports Blanchard, is suspected when a mare has mild colic that does not respond to analgesics. Intrauterine examination, he states, will generally reveal the dome-shaped inverted tip of the horn projecting into the uterine cavity. The condition sometimes occurs when the placenta remains attached to the uterine horn. Treatment, according to Blanchard, involves replacement of the uterine horn to its normal position.
The rupture of uterine blood-carrying vessels and arteries can occur during parturition or shortly thereafter. According to Blanchard, it is rare that an artery will rupture prior to parturition. My only personal involvement with this condition involved an older Saddlebred mare. The folks who had owned her late sire wanted to keep the bloodline going and asked if she could be leased. We had no breeding plans for her, so she was sent from Kentucky to Minnesota and bred. She conceived and delivered a crackerjack foal. However, we were told, the mare became instantly ill after giving birth and within a short time was dead. A necropsy revealed that a major uterine artery had ruptured and she had bled to death. Not every rupture of a uterine blood-carrying vessel leads to death. Blanchard's recommended treatment when such a rupture occurs is to administer pain-killing and sedative agents immediately. He also recommends that the mare be placed in a quiet, dark stall to minimize stress and excitement and lower blood pressure.
There might be hemorrhages in the wake of the foaling process that are far less severe than a ruptured uterine artery. There can be bleeding, for example, if there are lacerations along the birth canal. Normally, such bleeding, if not profuse, doesn't require a whole lot of treatment. Profuse hemorrhage originating from blood vessels in the vagina, Blanchard says, often can be stopped by clamping and ligating (to tie or bind with suturing material). More serious bleeding can result if undue force is used in removing a retained placenta. The result can be uterine hemorrhage.
Still another post-foaling problem that can occur is a tear in the cervix. It has been found that such tears are more apt to occur in older mares.
At the 42nd AAEP Convention in Denver, Colo., in 1997, Corey Miller, DVM, Texas A&M University, gave a report on the surgical repair of cervical lacerations in 53 Thoroughbred mares. A prime problem with cervical tears, he reported, involved getting the mare pregnant after the tear is repaired.
As part of his research, Miller studied the medical records of all mares referred to the Rood and Riddle Equine Hospital, Lexington, Ky., for repair of cervical lacerations between March of 1986 and January of 1995.
The age, breed, reproductive history, and description of the laceration at the time of surgery were obtained from the records. Only those mares which had been bred for at least one complete breeding season following surgical repair of a cervical laceration were included in his study. While much of Miller's report dealt with the surgery procedure and techniques involved, his findings relative to success in solving the problem and getting the mare pregnant again are of more interest to the average horseman.
Following are his conclusions:
"The results of this study suggest that older (mean age, 12.8 years) multiparous (mean number of foals produced before surgery, 6.2) mares may be predisposed to cervical lacerations. Eighty-six percent of the mares in this study population (were) presented for cervical laceration repair after an apparently normal parturition. This supports previous anecdotal information that suggests that cervical lacerations are just as likely to occur during an unremarkable parturition as during a dystocia.
"Surgical repair is an effective treatment of cervical lacerations, resulting in a postsurgical pregnancy rate of 75% for the mares in this study population. The client should be made aware of the potential recurrence of the cervical laceration at subsequent foalings or breedings.
"The potential benefits of the surgery appear to far exceed the few complications associated with the procedure."
Proving his point that there might be a recurrence of the condition was the revelation that a number of mares in the study group underwent the surgical procedure more than once. Seven of the mares had two surgical repairs, three mares had three surgical repairs, and four mares had four surgical repairs. Fourteen of the mares were presented multiple times for surgical repair after a subsequent parturition or breeding.
Only 11 of the total number of 78 surgical repairs were preceded by dystocia.
In The Wake Of Foaling
To this point, we have been discussing post-foaling problems that involve a medical emergency or, at least, near-emergency. However, these aren't the only problems that might occur in the wake of foaling.
There is, for example, foal rejection. Granted, it doesn't occur with frequency, but when it does, it is a problem filled with frustration, consternation, and potential ill effects, especially for the foal.
I don't think anyone is capable of looking into the mare's mind and determining why she might reject her foal. The reasons, like the degree of rejection, vary.
It might, for example, involve a young, first-foal mare which simply is too dazed by the whole process to recognize that bumbling object that is flopping around in the straw. Often, the problem can be solved with a bit of patience and help from an attendant or attendants. If one person restrains the mare gently with a lead shank fastened to her halter and another presents the foal for her to sniff and lick, her motherly instincts generally will come to the fore.
This also might be the mare which, even though she is not aggressive toward the foal, will not allow it to nurse. To her, nursing is equated with pain as the foal seeks to get its mouth on a nipple that is attached to a sore and swollen udder. The young mare only knows that when the foal touches the udder, it hurts. Again, this is a time for skillful handling. Normally, if the mare can be painlessly restrained while the foal nurses, the problem will be short-lived. Once she discovers that the nursing relieves pressure and pain, she will find it to be a pleasurable experience and will welcome the contact.
Normally, the first nursing involving a mare that is rejecting her foal can be accomplished with little restraint. In exaggerated cases, however, more elaborate steps might have to be taken. It might be necessary, for example, to employ the use of a bar that holds the mare against a solid wall. The bar should be at the height of the shoulder joint. It will keep the mare standing in one spot while the foal can be positioned to nurse.
The important thing at this point is for the foal to ingest the all-important colostrum and not be injured by snapping teeth or flying hooves in the process.
In some mares, rejection can be brought on by well-meaning attendants who interrupt the normal bonding procedure immediately after birth. When the mare gets to her feet after giving birth, the true bonding begins. It is at this point that she will lick the wet foal and breathe in its scent. It is a time, if possible, to let her be alone with the youngster. How much bonding time is required will vary from mare to mare.
With an older mare, it might not be necessary at all. With a younger one, it might require a prolonged period. The important thing is that attendants be cognizant of the fact that this is a crucial time in the bonding process. Even if one imprints the foal, the mare always should be within sight and smell of the newborn.
Scent is important in the bonding process for all animals. In dealing with our cattle and sheep, for example, we have found that we can graft an orphan offspring to a female other than its mother once that youngster begins digesting milk from the surrogate cow or ewe. This might involve milking the surrogate animal and feeding the milk via bottle if nursing isn't permitted. Once the surrogate mother smells the feces from milk that originated in her body, she seems quite willing to accept the newcomer as her own.
The role played by fecal scent in horses might or might not play quite as important a role.
Preventing injury during the process of getting a mare to accept a rejected foal is of paramount importance. If the mare is nervous and upset with her offspring, she might trample it as she charges around the stall in an effort to avoid contact. This is another reason for restraining her, either with halter and lead shank or behind a bar.
This type of rejection, as already mentioned, is usually short-lived. The same isn't true for the mare which is savagely aggressive toward her newborn.
Again, I don't think anyone knows exactly why this occurs. Researchers tell us it seems to happen more frequently with Arabians than other breeds. I don't know about that, but I do know that it is frightening and discouraging when it does occur.
My only experience involved a mare (not an Arabian) that was brought to our stable in Minnesota to foal. The owners said they did not have an appropriate facility and wanted someone with experience to be on hand when the mare gave birth.
No problem, said I.
The mare had an uncomplicated delivery, but that's where it ended. I stayed out of the stall as she got to her feet. The foaling stall was spacious--10 X 20 feet. Instead of nuzzling the foal, she walked to the opposite end from where it lay. I waited for a time, then waited some more as the foal struggled to its feet. Still, the mare did not approach it. When the foal wobbled toward her, she pinned her ears and walked to the other end of the stall, leaving a confused youngster in her wake. Eventually, I entered the stall and haltered her. I led her quietly to the foal. She pinned her ears and wouldn't so much as give him a sniff. Instead, she bared her teeth and snapped at him.
I tied her to the stall wall where she couldn't attack the foal and eased the little guy toward her side. Once he nurses, I reasoned, all will be well. Not so. As the foal wobbled toward her, she pinned her ears again and when he bumped into her side, she lashed out at him with a back foot.
That began a two-day effort to convince the mare to bond with her newborn. It ended in failure. We managed to get some colostrum out of the mare by hand milking, no easy task, but nothing we, nor the attending veterinarian, did could convince the mare that she should accept this foal as her own.
Ultimately, we gave up and the owners began the task of raising an orphan foal. My advice was that they not breed the mare again.
Why did she reject the foal in such a violent manner? I have no idea. The foaling occurred under ideal conditions. There was no dystocia, and nothing happened to disturb the relationship between mother and newborn immediately after birth.
Maybe if she were bred a second time, the same thing wouldn't occur. It wasn't something for inexperienced folks to try, however, and, to the best of my knowledge, the mare went back to being what she had been before, a riding horse.
Another problem that can occur in conjunction with bonding problems, and even without them, is the mare's refusal or inability to "let down" her milk. In other words, the foal might be nursing, but isn't receiving any milk.
Here again, oxytocin might be the drug of choice. Milk ejection often can be stimulated with 10 to 20 units of oxytocin administered intravenously, according to Michelle LeBlanc, DVM, Diplomate ACT, of the University of Florida.
The milk holding problem generally involves young, nervous mares.
A more severe problem involves the mare which is plenty willing to let down her milk, but just simply doesn't have any to provide. This condition is called agalactia. Involved in this serious problem might be mares which are suffering from fescue toxicosis or mares that just simply don't have the capability to produce milk. The goal in these relatively rare cases would be at least to get some colostrum from the mare into the foal, then deal with the matter of having an orphan foal to raise.
Milking capability varies from mare to mare. Some mares have copious quantities, while others only have a limited supply to offer the offspring. If you are lucky, there will be at least a sufficient quantity during the first several days, after which time supplemental milk replacer or creep feeding can be instituted.
Failure Of Passive Transfer
Another post-foaling problem of the mare that more directly impacts the foal involves a condition known as failure of passive transfer (FPT). We have mentioned several times the importance of the foal's ingesting colostrum immediately after birth. The reason is that the foal is born with little protection against infectious disease. That protection, at this stage of life, only can come from its mother in the form of immunoglobulins that are transferred from dam to offspring through the youngster's absorbing colostrum. (See Back to Basics article on Colostrum.)
One of the reasons that failure of passive transfer occurs could be that the mare's milk is low in immunoglobulins. Fortunately, there is a way to test foals for immunoglobulin deficiency, and there is a treatment for the condition. A diagnosis of FPT can be made between 18 and 24 hours of age by measuring serum immunoglobulin concentrations in the foal. (See article on Foal IgG in the February 1999 issue.) If there is a serious lack, one of the treatments might involve intravenous administration of equine plasma.
While failure of passive transfer can have no deleterious effects on the mare, it can be a death sentence for the foal in serious cases unless quickly dealt with.
If the mare owner has battled through any of the above post-foaling problems that have afflicted the mare, one obstacle remains to be surmounted before the whole program is a success. The obstacle involves getting the mare in foal again. This might not turn out to be a post-foaling problem. Much depends on which, if any, of the foregoing difficulties occurred and the seriousness of the incident.
That's the time for common sense, coupled with professional advice, to prevail.
Should the mare be bred on her foal heat?
The answer would likely be no, if she had suffered dystocia, if cervical tears had to be repaired, or if lacerations to the birth canal had to be dealt with. The same answer would apply if there had been a uterine rupture or hemorrhaging.
When there have been post-foaling problems and we rush to get the mare pregnant before those problems have been solved and the mare is in good breeding health once again, we are begging for a recurrence of those same problems. We also might heap on several more problems during and immediately after the next
So, getting the mare and foal safely through the post-partum experience is an exercise in planning and preparation, coupled with the ability to recognize problems early and act on them accordingly. Discuss these potential threats with your veterinarian before foaling time, and make sure your practitioner comes within 24 hours of delivery to check the mare and foal for complications that you might not have noticed.
About the Author
Les Sellnow is a free-lance writer based near Riverton, Wyo. He specializes in articles on equine research, and operates a ranch where he raises horses and livestock. He has authored several fiction and non-fiction books, including Understanding Equine Lameness and Understanding The Young Horse, published by Eclipse Press and available at www.exclusivelyequine.com or by calling 800/582-5604.
POLL: Colic Surgery