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Equine Protozoal Myeloencephalitis: An overview
Equine Protozoal Myeloencephalitis (EPM) is a commonly diagnosed neurologic disease of the horse that has captured the attention of equine veterinarians and horse-owners alike since it was first documented 30 years ago. It is a progressive and degenerative disease of the equine central nervous system, and is caused most commonly by the protozoan species, Sarcocystis neurona. (There have been few documented cases identifying Neospora hughesi as the causative agent, though the two species are clinically indistinguishable from one another.) Recent studies show that approximately 22-65% of horses in the United States are seropositive with antibodies from S. neurona, but only a small portion of these horses will go on to develop clinical disease.
The definitive host of Sarcocystis neurona is the opossum. This is the host in which sexual reproduction of the parasite occurs. Infected opossums shed sporocysts in their feces which are in turn transmitted to the intermediate host when ingested. Intermediate hosts include cats, armadillos, skunks, raccoons, and sea otters, and once infected, they develop sarcocysts in their skeletal muscle. Once this muscle is ingested by the opossum, the life cycle is completed. In the pathogenesis of EPM, horses are considered aberrant, or dead-end hosts, which halt the life cycle of the organism. Horses become infected through ingestion of contaminated feed or water and once infection is established, disease progression ensues.
While the pathogenesis of EPM infection is still widely a mystery, it is postulated that the ingested sporocysts are able to penetrate the intestinal wall and enter the cells that line the horse's arteries. The organism develops within the arterial walls until they rupture into the bloodstream where they can spread to other parts of the body. At this point it is possible for the horse to clear the infection on his own, leaving him seropositive, but without any clinical signs or evidence of disease. It is unknown how S. neurona enters the CNS in horses, though once the protozoa gain access they can establish infection in any area of the brain or spinal cord. Horses infected with S. neurona are unable to transmit the disease to other horses.
EPM can manifest itself through a variety of clinical signs, though the most classic are the three As: Ataxia, Asymmetry, and Atrophy. A common appearance of a horse with EPM is one with severe asymmetrical gluteal muscle atrophy. Since the organism can infect any area of the central nervous system, ataxia, or incoordination, is frequently observed in horses with EPM. Moreover, a variety of neurologic deficits can be seen, ranging from cranial nerve abnormalities in the form of a head tilt or facial paralysis to a dull or depressed mentation. Various gait abnormalities may also be seen and can occasionally be mistaken for lameness. The timeline for disease progression is variable, but if left untreated, in its most severe form, EPM can lead to seizures, coma, and even death.
Obtaining a diagnosis for EPM can be challenging, and it's important to know that a truly definitive diagnosis may not be attainable during a horse's lifetime. That being said, tests for EPM in live horses include the Western blot, indirect fluorescent antibody test (IFAT), and surface antigen-1 ELISA test (SAG-1 ELISA). Simple seropositivity for S. neurona antigen is not sufficient for a diagnosis, as that only relays if there are circulating antibodies within the vasculature. All exposed horses should be seropositive, but it takes the protozoan entering the central nervous system from the systemic circulation for the horse to actually have EPM.
To make a diagnosis of EPM, cerebral spinal fluid (CSF) and blood samples should ideally be submitted together for paired testing and analysis. The Western blot test looks for IgG antibodies against S. neurona within the CSF, though false positives are possible, especially if there is blood contamination of the sample. With a specificity of only 44-60%, it is likely that the immunoblot tests are best to rule out the presence of EPM, rather than provide a diagnosis for the disease. The IFAT test has shown comparable sensitivity, better specificity, and it is less affected by blood contamination. However, this test might give positive results for the protozoa S. fayeri, which might or might not cause disease in the horse. The newest test, the SAG-1 ELISA, looks for the presence of a particular surface protein of S. neurona, but not all strains express this particular protein. Therefore, false negative results are common.
The gold standard for diagnosing EPM in the horse is based on finding characteristic lesions on post-mortem exam within the CNS. However, due to the small number of organisms needed to cause the disease, the diagnosis can be missed even with a full neurologic necropsy. In general for the live animal, a clinical diagnosis is best established in horses with clinical signs of neurological disease consistent with EPM combined with positive CSF testing. Another option for diagnosis of EPM is looking for improvement in clinical signs in response to treatment. Since test results can take days to weeks to come back, horses are often started on treatment for the disease once they begin showing signs of neurologic disease while other possible causes continue to be ruled out.
Treatment for EPM is generally successful with studies indicating clinical improvement in 60-70% of cases. However, a portion of horses that are treated will have some residual neurologic signs that do not completely resolve with treatment. Relapse of disease once treatment is stopped is possible, though uncommon. There are four drugs that have been approved by the FDA for treatment of EPM: pyrimethamine, sulfadiazine, ponazuril and diclazuril. The most common oral medication used for the treatment of EPM is ponazuril (Marquis). It is administered once daily for 28 days or more depending on disease severity. While studies show ponazuril can effectively rid horses of S. neurona, it does not improve the CNS damage that occurs before treatment begins. Regardless of which medication is instituted, early detection and prompt treatment are essential for a positive outcome and a full recovery.
If you have any questions regarding this article or the health of your horse, please contact your veterinarian or the doctors at New EnglandEquineMedical & SurgicalCenter.
Tessa Lumley, DVM
New England Equine Medical & Surgical Center, 15 Members Way, Dover, NH03820
Volunteer Management Survey Kicks Off
It probably comes as no surprise that volunteers are the life blood of the horse industry. Recruiting and retaining volunteers can be challenging, and it can be one of the key obstacles to growth. It can also be difficult to figure out where to start to improve volunteer management.
Blue Ribbon Consulting, LDO, LLC is conducting a volunteer management survey to develop a white paper that will provide a snapshot on where the horse industry stands. The survey results can help nonprofits to determine next steps to strengthen their volunteer management practices. Those that operate an equine oriented nonprofit, or on the board of directors are invited to take a few moments to participate in this survey. Answers are confidential and will only be used in aggregate to produce a white paper that will be posted to the Blue Ribbon Consulting website. If you don't run an equine nonprofit but know someone that does, please send the link along to them.
Find the survey here: https://www.surveymonkey.com/r/FFV9S3Y . Please complete the survey by December 15, 2014. The white paper will be available in early 2015.
Since 1995, Blue Ribbon Consulting has provided evaluation, planning, research, marketing and problem-solving services to clients around the world to take their horse businesses successfully through their business transitions. Lisa Derby Oden, Blue Ribbon Consulting’s founder and principal, has also been a nonprofit founder, board member, and executive officer for state and national organizations. She has worked with nonprofits in strategic planning, program development, corporate development, fundraising, grant writing and grant administration. Lisa has delivered business development, marketing, and leadership seminars throughout the United States. In addition to her horse business books, she has also been a columnist and freelance writer for many equine trade publications. Lisa has received state and national awards for her work in the horse industry.
Contact: Lisa Derby Oden
Blue Ribbon Consulting, LDO, LLC
Synovial infections in adult horses
Elizabeth Taylor, DVM, MS
Septic arthritis and tenosynovitis are orthopedic conditions in horses that develop following penetrating trauma or less commonly following an injection. They can carry serious complications for the horse if left untreated. Potential complications of synovial infections include arthritis, irreversible cartilage damage, adhesions, and severe lameness sometimes requiring humane euthanasia. It is important that these conditions be recognized promptly in order to instill immediate and accurate diagnosis and treatment aimed at eliminating the infection, reducing pain and inflammation and ultimately returning the horse to function.
In adult horses, joint or tendon sheath infection usually results from contamination via wounds. Because the lower leg of horses is poorly covered with soft tissue, joints and tendon sheaths are located very superficially and are prone to contamination following many lacerations, including heel bulb lacerations, and lacerations to the front or back of the pastern or fetlock.
It is important to contact your veterinarian if your horse has a laceration of the lower leg in a location near a synovial structure. Typically, horses with a synovial infection are quite lame (grade 4/5), however if the affected joint or tendon sheath is open and draining, lameness can be less severe. Frequently there is marked effusion (swelling), heat and sensitivity to the touch.
Analysis of synovial fluid is key in diagnosing and treating an infection. A sample should be obtained for both cytology and culture. Culture of the fluid is the “gold standard” for the diagnosis of an infection, however this only occurs in approximately 50% of cases. Therefore, analysis of the fluid’s cell count and protein, as well as examination under a microscope can help with an immediate diagnosis.
Diagnostic imaging can also aid in the diagnosis of a synovial infection. Ultrasonography can be helpful in the acute phase, when effusion is most prominent and accurate aspiration of fluid can be obtained. Radiography is less helpful in the acute phase, as soft tissue swelling is the only evidence of infection, but it can be useful to identify osteomyelitis (infection of the bone) should the infection spread.
The mainstay of treatment is to remove bacteria, devitalized tissue and other debris and reduce pain and inflammation. The goal of treatment is to return the articular cartilage to a normal environment, thus preventing cartilage loss. Cartilage health is imperative in maintaining an athletically sound horse.
Physical removal of bacteria and inflammatory mediators is best accomplished early and with a high volume of fluid. This can be done via needle lavage, arthroscopy or open drainage. Arthroscopy is advantageous because it also allows evaluation of the articular cartilage and removal of debris.
Antimicrobial therapy is directed by culture results, however because results may take days and positive results are not always obtained, therapy should be broad spectrum. In addition to systemic administration of antimicrobials, local administration of antimicrobials results in high concentrations directly at the site, while avoiding untoward systemic effects.
Lastly, synovial infections are very painful and can lead to support limb laminitis if proper analgesia is not maintained. Non-steroidal anti-inflammatory drugs (NSAIDs), such as phenylbutazone or flunixin are used to decrease the pain and inflammation associated with synovial infections. Their use must be judicious as serious side effects (gastric ulcer formation, colitis and renal toxicity) can arise with long-term use.
It is important to monitor synovial infections very closely as they can become life threatening if the horse has continued pain and lameness. Early recognition, accurate diagnosis and aggressive therapy of synovial infections greatly increase the prognosis for a horse to return to full athletic function.
Seat Bones from the Horse's Side of the Saddle
By Nancy Wesolek-Sterrett
Dressage Department Head, Meredith Manor International Equestrian Centre
When a horse has trouble moving straight or difficulty bending in one direction or another, or the rider cannot circle without pulling on the inside rein, the first thing I think of is not, “What’s wrong with this horse?” I consider that the crookedness may be feedback and immediately check the rider’s position. Is she sitting up straight?
Sitting straight means that the rider is centered over the horse’s center of gravity with equal weight on both seat bones. As well as, the rider’s shoulders directly over the seat bones. This is important because unless a rider can sit this way, she will not be able to subtly modify those seat bone pressures correctly to communicate direction, bend, speed and other information to her horse. When the rider’s seat bones contradict other aids, the horse gets confused, crooked, or offers other feedback that telegraphs the message, “What did you say?”
At the halt, the horse’s spine should be straight from poll to tail. The rider’s nose, chin, breastbone, belly button and spine all align with the horse’s spine. From the side, the rider’s ear, shoulder, hip and heel should align. As the horse begins to move, the rider keeps equal weight on both seat bones to indicate a straight direction of travel. Or she weights and unweights her seat bones in nuanced ways that influence the direction of travel in bends, circles, canter leads, lateral movements, etc. To get a square halt, she needs to put her weight equally on both seat bones again.
If the rider pays attention, the horse broadcasts clear feedback about as to how he feels the weight distribution in her seat bones and what it suggest that he do with his body. Take the example of a crooked rider whose default position puts more weight on her left seat bone than on her right. When going to the left, the horse probably bends and circles correctly. However, when the rider asks the horse to circle right, the horse may drift out to the left, fall in through the right shoulder, or have difficulty picking up the right lead. Ridden continually this way, the horse may develop more muscle on the left side to carry the rider’s crooked weight and become asymmetrical in the pelvis or hips.
Small things can make a huge difference for the horse. I recall one horse whose rider trained him correctly to turn on with the rider’s weight slightly heavier on the inside seat bone. He was sold to a rider who used a ‘spiraling seat’ to turn her horse. While this is very useful seat imagery, the rider misunderstood the full concept and overturned her shoulders, pushing her weight onto her outside seat bone. The horse was confused and the new rider was frustrated. (Sit on a swivel chair and try it.)
If rider sits heavily on the left seat bone, horse may dive to right or may drift to left to get more underneath the rider. The horse may have difficulty getting the right canter lead, refuse to yield from the right leg because the left seat bone is blocking the request. A jumper may run out to the left in front of a jump or drift to the left on landing. Unequal weight may put a lazy horse behind the leg and slow him down. Given confusing signals, a hot horse might get hotter and run from the pressure.
Understanding how to sit with equal weight on both seat bones, understanding how to weight and unweight each seat bone independently of the other, and keeping shoulders aligned with the hips can make many riding problems go away. A very slight shifting of weight onto one seat bone or the other can help the horse give the right answer as he follows the rider’s weight. For example, when the rider starts from the halt sitting straight with equal weight in both seat bones, she can give the horse clear communication when they start circles and eventually lateral work. Later on in the training scale, the rider’s ability to shift slightly from one seat bone to the other while staying straight and centered over the horse’s spine is essential to correct flying changes.
Many riders blame the horse when he goes crooked rather than considering that he may be giving them feedback about their own crookedness. A horse may act out because of a sore back and the rider may blame the saddle instead of realizing that continual riding with her seat bones unequally weighted could be the cause.
The question “Is it me or is it my horse?” can be hard to answer when you ride the same horse all the time. The rider with just one horse will benefit from the help of an instructor or experienced observer who can give them feedback about whether the rider’s crookedness is making the horse crooked or vice versa. Gradually, both horse and rider can develop a feel for ‘straight’ and help each other stay centered. Our students have the opportunity to test their seat skills by riding horses of all sizes, personalities and training levels. They learn a lot from their mounts as they adjust to these differences.
Riders with their own horse might take lessons on other mounts from time to time to help them figure out, “Is it me or is it my horse?”
Certainly a horse with unevenly developed musculature, saddle soreness, teeth issues, or dozens of other major or minor issues may compensate in ways that put the rider crooked in the saddle. Regardless of the cause, however, if the rider matches the horse’s crookedness, it will never go away. The rider that becomes responsible for being ‘straight’ herself, helps her horse feel what ‘straight’ should be so that he can figure out how to get there.
Riders ambitious to get to the next level in their sport sometimes hope that buying a horse that is at or above that level is the way to move up. Once they are in the saddle, however, they find themselves stuck right where they were. Worse yet, the higher level horse they thought would be their ticket to ribbons winds up ‘dumbing down’ its performance to the rider’s lower level. Often, the problem is very basic. The rider has never really learned how to sit truly straight with equal weight on both seat bones.
The seat bones are literally the seat of all communication with the horse. Correctly or incorrectly they are always sending information to the horse. Riders who pay attention to their seat bone messages and the feedback their horse gives about them will become able to truly influence their horse stride by stride. Remember, nothing replaces a correct, independent, influencing seat.
What to expect when she’s expecting: Foaling 101
Part I – Managing the late pregnant mare and preparation for foaling
Foaling season is an exciting time of the year for both veterinarians and breeders. For first time breeders the pregnancy, foaling, and neonatal periods can be stressful, as they should be. Proper care for the pregnant mare and appropriate preparation for foaling and potential complications are key in an uneventful foaling and healthy newborn. This guide is meant to be an overview of some key components and to allow the expecting horse owner to develop a plan and questions for their veterinarian. It is not meant to be an exhaustive checklist, so we encourage you to consult with your veterinarian with plenty of time before foaling is expected.
Normal gestational length in the horse can be highly variable, but is 330-345 days on average. There are a wide variety of causes of a longer gestational length. Some mares tend to carry foals longer than average, and some may consistently carry foals out to a year or longer. Mares that are due earlier in the year typically carry foals longer than those due in the late spring, which is thought to be due to photoperiod (the amount of time in the day the horse is exposed to sunlight). Some pregnancy abnormalities may also lead to longer pregnancies, including dysmaturity (a foal that is less mature than what it should be for a given gestational age) or a previous twin that resulted in slowed development of the remaining foal. It is very rare for a long gestation foal to be large enough to cause dystocia (a difficult birth), and typically long gestational lengths are required for adequate development of the foal and preparation for life outside the mare. Rarely is it a good idea to induce labor in a horse, so taking advantage of ways to predict foaling will help to reduce the number of sleepless nights the owner has to endure! Foals born before 320 days gestation are considered premature and may face a variety of hurdles, so if foaling is looking imminent in a mare that hasn’t neared her due date, notify your veterinarian immediately as a team approach will be required for any chance of survival of the foal.
Early in pregnancy management of the mare can typically continue as normal. Vaccinations and deworming should be kept up to date, and teeth floating should be performed regularly to ensure the mare can maintain adequate nutrition through pregnancy and lactation. Typically their caloric intake does not need to be increased significantly until around the last month of gestation, when they are going to begin lactation. However, it is important to maintain mares in adequate body condition (around a 6/9 on the body condition scoring system). The major changes to vaccinations early in pregnancy are the type of vaccine. Typically pregnant mares should be vaccinated with killed vaccines or those tested and approved for use in pregnant mares. Be sure to tell your veterinarian if your mare is pregnant so they can choose the appropriate vaccines.
Later in pregnancy some additional vaccinations are recommended to protect the foal both before and after birth. One significant concern in pregnant mares is equine herpes virus-1 (EHV-1) which can cause late-term abortions or significant disease in the newborn. Vaccination of the mare for EHV-1 is recommended at 5, 7, and 9 months of gestation to prevent disease or abortion. In addition, antibodies are key proteins involved in preventing disease in all animals by binding to pathogens, and foals are born with extremely low levels of circulating antibodies due to the type of placenta present in the horse. The early immune system of the foal relies heavily on antibodies that they gain by ingesting colostrum, or the mare’s first milk, within the first 24 hours of life when their gut can absorb these intact large proteins. By vaccinating the mare for EEE/WEE, tetanus, WNV, and other pathogens (as deemed necessary by your veterinarian) approximately 4-6 weeks prior to the expected foaling date, antibodies for these pathogens will be produced and present in high concentrations in colostrum, thereby protecting the foals against these diseases. In addition to the mare’s standard vaccines, rotavirus vaccination is recommended in the last couple months of pregnancy as well. This is a virus that does not affect adult horses, but is a common cause of diarrhea in youngsters. By vaccinating the dam late in pregnancy it will increase antibodies against this pathogen in the colostrum, thereby conferring protection to the foal.
A wide variety of cues can lead us to predicting when a mare is going to foal. Obviously, having an exact ovulation date with confirmed pregnancy off of that cycle is ideal. If an exact date of conception is not known, some fetal measurements, including ocular or aortic diameter, can be measured using transabdominal ultrasound by your veterinarian and used to estimate gestational age. These tend to become more sensitive as pregnancy progresses, but it can become more difficult to locate these structures transabdominally as the fetus gets larger depending on its location in the mare’s abdomen. Below are some other changes to monitor that can indicate when she is getting closer to foaling.
- Around 1 month before foaling the mare’s udder will begin to show some enlargement, and you can get some watery milk out of it.
- About 2 weeks prior to foaling you will notice relaxation of the pelvic ligaments. You will notice that the muscles and ligaments of the hindquarters, tail head, and perineum will begin to soften. Her hindquarters may begin appearing more sunken.
- 1-2 weeks prior to foaling you will see significant enlargement of her udder. As she gets closer to parturition the milk present in her udder will become thicker and more yellow in color. This is the transition to her producing colostrum. This is the antibody rich milk that will provide foals with the essential components to an early healthy immune system. Some mares, particularly multiparous mares (those who have had multiple foals) may leak colostrum prior to foaling. If you notice this occurring during this period, be sure to notify your veterinarian and save as much as you can in the freezer to ensure that the foal has a colostrum stock that can be fed immediately after birth
- In the 24-48 hours prior to foaling a variety of changes occur. The first that you may notice is the udder will “wax” over with a bead of colostrum as it gets thicker just before foaling. In addition, milk calcium can be measured daily with a variety of commercial kits. The milk calcium will increase to greater than 10mmol/l when the mare is within 48 hours of foaling.
Preparing the Foaling Area and Mare
The foaling area should be prepared about 4-6 weeks prior to the expected foaling date, and the mare should start being put in there to allow her to get used to the area and prevent any “surprise” foalings in a less-than-ideal area. Foalings can occur either indoors or outdoors, and there are pros and cons to each. Whether it is going to be inside or out, the major considerations are having an area that is clean, dry, and free of hazards. For outside foalings, this means a wide open area where the mare is by herself. There should be no standing water, hazardous fencing, or bushes/trees that could pose a threat to the newborn foal. For indoor foalings, a large (at least 12x12) stall with straw bedding is important.
A few considerations for the mare should be addressed at this time, well in advance of the anticipated foaling date. If the mare has had a caslicks procedure, this should be opened about 1 month prior to foaling. In addition, neonatal isoerythrolysis (NI) is a potential risk that should be screened for in mares that have had multiple foals or received any blood products (whole blood, plasma) in the past. NI results when the mare possesses antibodies against the foal’s red blood cells. When the foal ingests colostrum, these antibodies will cross the gut and gain access to the foal’s blood stream, allowing incompatible antibodies to attack the foal’s red blood cells. The mare will only develop antibodies against these different blood groups if she has been exposed to them in the past, so it is only a risk if the mare has had previous foals or been exposed to different blood groups due to blood products. Horses have a large number of blood groups, but the groups Aa and Qa are the 2 that tend to cause NI reactions. At risk mares should be tested for antibodies against these blood groups prior to foaling to determine whether additional steps need to be taken to avoid a problem in the foal.
Foaling monitoring systems will help the anxious horse owner get a bit more sleep during this stressful time, help reduce anxiety in both the owner and mare, and make for a more natural and undisrupted birth. Many farms have cameras in foaling stalls and a closed circuit TV set up elsewhere in the barn or a nearby house so someone can be sleeping there and periodically wake up to check the camera without going into the barn and disrupting the mare. In addition there are a wide variety of systems that will send alerts when they detect a mare is going into labor. These include systems that monitor how the mare is laying down, sweating, or separation of the vulvar lips and will send a signal to selected people when labor has started. These foal monitoring systems should start being utilized if you begin to see signs of imminent parturition, or around a week or so before the expected foaling date as some mares will not give you much notice.
Stay Tuned for Part II of Foaling 101 coming next month!
If you have any questions regarding foaling or any medical issues affecting your horse, please contact your veterinarian or the veterinarians at New England Equine Medical & Surgical Center.
Erica Secor, DVM
Jacqueline Bartol, DVM, DACVIM
What to expect when she’s expecting: PART II
What to expect when she’s expecting: Foaling 101
Part II – Foaling and the Early Neonatal Period
The day has arrived… Your mare is looking like she is about to pop, and you are sure foaling is going to happen tonight. Knowing the normal progression of parturition and the immediate post-foaling period will be pivotal to ensuring a healthy foal. By having a thorough understanding of normal foaling, you will be able to more easily identify when something is amiss and in need of veterinary attention. Normal labor in horses progresses very quickly, so early intervention is required if a problem arises.
The Stages and Normal Progression of Labor
Stage I of labor can take minutes to hours (generally an hour or two, but it can be up to four). Often the mare will appear to be colicky. They often pace, look at their sides, will get up and down frequently, and urinate often. During this period the foal will be turning to the correct foaling position, which involves it’s front feet extended towards the cervix and their head between their front legs. Uterine contractions begin during this stage, which causes much of the discomfort. In addition, cervical dilation is occurring during this time, which is essential for uncomplicated foaling. Horses are one of very few species that can halt labor early in this stage if they feel threatened, so it is very important to not disrupt the mare during this period or you can expect to be up another night! If she isn’t already, be sure to put the mare in the foaling area during this time. In addition you can wrap the mares’ tail with brown gauze to minimize contamination of the foal during labor. Depending on how far away your veterinarian is located and how comfortable you feel with the foaling process, you may want to notify your veterinarian at this time. This should be discussed with your veterinarian ahead of time.
Stage II of labor begins when you see her water break (which is due to rupture of the chorioallantois portion of the placenta and release of allantoic fluid). This stage should progress very quickly (no more than 30 minutes) and is associated with significant pushing by the mare. After the water breaking you will see the white amnion surrounding the foal. You should be able to see two front feet followed by the foal’s muzzle at the level of their knee. Often the mare will get up and change positions periodically during this phase. In addition, once the foals’ hips are engaged in the pelvic canal the mare will often stop pushing for a period to rest, then finish delivering the foal. Once the foal's nose is delivered, break the white amnion if it hasn’t already broken, and clear the fluid and membrane from around its nose by massaging the nasal passages a few times and pushing the fluid out. Then as long as everything is progressing normally, you should step back and let the mare do the work. Resist the urge to pull the foal if all is going well, as it can result in trauma to the mare or foal as well as premature umbilical rupture. Once the foals chest is delivered ensure the foal is breathing on its own, even if the mare takes a break. If there is any concern about the foals viability, ensure the nose is clear first, then rub the foal briskly with towels. Often this is enough to stimulate breathing on the foal’s part and will help dry them off and warm them up. Once the foal is delivered and everyone appears happy and healthy, give the mare and foal some time alone to bond. This period is very important for maternal bonding, and is often forgotten as everyone is excited about the new foal. Within two hours, and more typically in the first hour, the foal should be up and nursing.
Stage III of labor is expulsion of the fetal membranes, aka the placenta. This should be completed within three hours after birth, and the mare is put at significant risk of infection and serious illness if she experiences a retained placenta. Do not wait to contact your veterinarian if you suspect she has a retained placenta, as early intervention is key. Be sure to save the placenta for examination by your veterinarian. They will look closely at the placenta to ensure that it is intact, for any evidence of placentitis, or indication of placental insufficiency.
These stages are summarized with a “1-2-3 rule”. This makes the general timeline of events easier to remember. The foal should be delivered within 1 hour of the beginning of stage II labor. Within 2 hours of birth the foal should be up and nursing on its own. The placenta should be expelled in its entirety within 3 hours after birth. By keeping this rule in mind you can more easily decide if a foaling is progressing in a timely fashion.
With horses being the fragile creatures they are, it’s amazing that most foalings go as smoothly as they do. However, if problems should arise they need to be dealt with promptly to give the mare and foal the best chance at survival. We recommend learning as much as you can about what to do in a foaling emergency before the situation should arise so you can be as prepared as possible.
“Red bag”, or premature placental separation: In a normal delivery the red chorioallantois ruptures, resulting in the “water breaking” and you see the white amnion directly around the foal. If the chorioallantois separates from the uterus prematurely it will not rupture. The result is that you see a red, velvety membrane first instead of the white amnion. Since this is caused by premature separation of the placenta from the uterine wall, the foal becomes oxygen deprived during delivery. If you see this, you have to immediately rupture the sac and pull the foal out. The easiest way to do this is with a sharp pair of scissors, so be sure you have a clean pair in your foaling kit. Since it is difficult for the foal to breathe on its own until its thorax is through the birth canal, you will have to help deliver the foal as quickly as possible until it is to a point where normal respiration is possible.
Dystocia, or “difficult birth”: This refers to any birth that is difficult or prolonged due to poor positioning of the foal, anatomic abnormalities in the mare, or congenital defects resulting in an inability for the mare to deliver the foal normally. Normal foal position is front feet and nose first, in a “diving position”. A breech birth, or when they come hindquarters first, is particularly important to deal with and resolve quickly, as the umbilical cord will be compressed prematurely as it enters the pelvic inlet, resulting in oxygen deprivation to the foal. The most common cause for simple dystocia is shoulder lock, and is something that most owners can deal with quickly. The widest point of a foal is at their shoulders, and they frequently become stuck in the pelvic canal at this point. To resolve this, gently pull one forelimb at a time in synchrony with the mare’s contractions. This will help to pull one shoulder through at a time. If they get caught at the foal’s hips, you can try rotating the foal 45* to have them align diagonally with the mare’s pelvis, which is the widest point of the pelvic canal.
Times to Call Your Veterinarian Immediately
There will be some obvious foaling emergencies that require immediate veterinary attention. However, there are some situations where the foal may appear healthy, but urgent care can prevent serious consequences.
- Dystocia or red bag delivery, even if the foal is alive and out: these foals often have experienced some degree of oxygen deprivation, depending on how severe the dystocia and how prolonged the delivery was. Hypoxemic-ischemic encephalopathy (HIE) also known as "Dummy Foal Syndrome" is a potential consequence of oxygen deprivation in utero or during delivery, and may not manifest until hours to days after birth. However, preemptive steps may be taken to prevent complications, and serial neurologic assessments will be important to catch any problems early.
- Meconium staining of the foal and/or placenta: if there is any evidence of dark meconium (first manure) during delivery the foal should be assessed immediately. These foals are at high risk to develop aspiration pneumonia, and early treatment will be key for survival
- The inability to stand and nurse on their own within 2 hours (most normal foals are able to accomplish this within an hour): this can be an early sign of problems, including HIE or sepsis. While they often look too leggy and uncoordinated, normal foals will be able to get through the uncoordinated phase quickly and be able to get up and down on their own.
- Evidence of broken ribs: broken ribs are fairly common in foals, as their shoulders are tight through the pelvic canal and their elbows can press in with extreme pressure, resulting in rib fracture. Unfortunately the most common site is directly over their heart. Any foals that have swelling, soreness, crackling sounds, or you can feel crepitus (a rough feel of the bone ends moving over each other) should be evaluated quickly by a veterinarian to ensure there is no damage to the underlying structures or an imminent risk of the fractures causing injury to the heart or lungs. Foals that are suspected to have rib fractures should be handled with extreme care to not cause further shifting of the fracture ends.
All postpartum mares and newborn foals should be evaluated by a veterinarian about 12 hours after birth. The mare should be evaluated for any injuries and general health and condition. The placenta should be closely inspected for any evidence of placentitis, placental insufficiency, or incomplete expulsion. The foal should be evaluated for any congenital abnormalities and general health. In addition, blood should be drawn at 12-18 hours of age to test for IgG concentrations. This is a measure of the antibodies absorbed from colostrum. Inadequate IgG results in failure of passive transfer and needs to be addressed quickly by administering further colostrum (if the foal is less than 24 hours old, when they still absorb antibodies from the gut) or intravenous plasma (if the foal is greater than 24 hours old). The umbilicus should be evaluated thoroughly, and dilute chlorhexadine should be used to dip the umbilicus a few times a day for the first 3-5 days of life.
Foaling season is an exciting time for any horse owner, but much anxiety can be reduced by taking the appropriate steps ahead of time to ensure you are well prepared for potential complications. Specific steps to take and what is applicable for your situation should be discussed early on with your veterinarian, so you both have a good game plan for when that day comes.
Some good resources for expecting owners
- The Complete Book of Foaling: An Illustrated Guide for the Foaling Attendant by Karen E N Hayes DVM MS
- A foaling guide from the Veterinary School at Kansas State University http://www.vet.k-state.edu/VHC/equine/pdf/Foaling_guide.pdf
If you have any questions regarding foaling and what to expect or questions about any equine health issue please speak with your veterinarian or any of the veterinarians at New England Equine.
Erica Secor, DVM
Jacqueline Bartol, DVM, DACVIM