Preliminary Info on Foaling

Obviously, another very important aspect of equine reproduction is gestation and foaling. The farm that I worked at did not foal out any mares due to the laborious nature of foal watching and care. This in itself gives you an idea about how important foaling is, and how many complications are possible. The woman in the article from the previous post mentions that she has a set up where she can put a mattress in her SUV and camp out in her barn so that she can watch her mares that are close to foaling. I have also herd tales that it is Murphy’s law that a mare will be watched for twenty three hours and will foal in the twenty fourth.

A mare will only have one foal a year (without participating in embryo transfers), and therefore if a lot is invested in the breeding and pregnancy, the success of the foaling is very important. There are many signs that a mare mare be ready to foal. They are listed in detail on this website (http://equisearch.com/horses_care/health/breeding/breedingbusiness_122004/) and any site on general horse care. Some signs are a mare bagging up, which is a term that means that she is producing milk and starts to have a bag look in her mammary area. Bagging will happen several weeks before foaling. Waxing occurs up to two days before foaling and this is when a syrup like material comes out of the teats and hardens at the ends like wax. Mares may also be more solitary before foaling, if they are in a herd, and the muscles and ligaments in the pelvic area will soften and widen before foaling as well.

Common problems that happen in a foaling situation can range from a foal being oriented the wrong way in the mare, to red-bagging. Red bagging is when the membrane doesn’t brake soon enough for the foal to get out and it is trapped inside of the mare without any oxygen. This can cause severe or mild problems with the foal in its development. For these reasons, foaling season tends to employ many people watching the mares to make sure they don’t have any problems delivering and that the foal is healthy once it comes out. It is also very important for the person on foal watch to make sure the foal suckles in the first hour of its life.

A Breeding Business

I ran across an interesting article on breeding horses. The article tells the story of a woman who was a successful realator and one day decided to own a horse. She did ride horses before she started to own them. The breed she chose to purchase and later breed were Sweddish Warmbloods. He first stallion was named Brando and managed to begin her farm and business until he died at the ripe old age of 24. There is no telling why Debora Borra chose to go into the business of breeding horses, but she did so with incredible energy a quality that seems to be necessary for a beginner to run such an enterprise successfully. Two veterinarians named in the article, claim that they did not think she would last a year. She has, however, more than tripled her business and now owns two stallions as well. Her farm is located in New York state. The location of a ranch or farm is an important consideration in management because of all the different considerations like buildings, feed availability etc. If you are in an area that gets a lot of snow, NY state for example, your barns will need to be insulated enough to keep the horses protected. Barns like this will cost more than wooden barns that can be constructed in a more moderate climate.

Ms. Borra lists some of the more important considerations required for running an equine breeding facility. They include; a realistic business plan, consistent organization, good help that stays around, regular follow-up, and honesty. Some of the overall ideas behind theses elements are keeping things very consistent on the farm and treating both employees and clients alike with respect and consideration. I think that these things can help any business to succeed but the article emphasizes that reputation in the horse industry is worth a lot. Since clients are spending a lot of money, no matter what kind of service they have done, it is mandatory that they feel like their money and horses are safe and well cared for.

The last thing that struck me about this horse breeder, is that she has taken the time to take courses and gain experience from the veterinary college at Cornell University. Ms. Borra says that without this experience, she would not be prepared to handle problems in foaling and also would not be familiar with the care involved with stallion collecting and semen processing and shipping. The article lists the lab equipment that this novice breeder has. She has a microscope, a tool for counting sperm cells, centerfuge, refrigerator and incubator. I think that these items are a very good starting point for a lab because they are just the basics but still enough to accomplish enough to run a successful business.

The tale told by this article interested me because the farm and breeding practice were started and maintained by someone without a veterinary background and mostly just an interest in horses. The article makes it sound like anyone with a little dedication and some good business practices can run an equine breeding facility. I would wonder how often she has mares checked by a licensed veterinarian and how much of an interest other parties play in her operation.

Lutalyse and Sulpiride

Estrus synchronization is a term used to describe the phenomenon of getting mares to ovulate at the same time, or close to the same time. It is slightly different from using desorelin or another agent to make one mare ovulate, because both mares are treated or monitored from the start. The product that is used the most, and is probably the oldest, is called Lutalyse. I have also used this quite a bit on dairy cows. Lutalyse is given to a mare intra muscularly and we gave 2cc of it. What it does is lyses the corpus luteum if a mare has ovulated recently, and essentially restarts the mare building follicles. The time given for her to come back into heat is about 2-4 days. If this is given to two mares, no matter what stage of follicle development they are in, you will know that they will both be coming into heat around the same time. Lutalyse is also given to donor mares. Once the embryo has been flushed from the donor mare, she may have follicles present and she will definitely have a corpus luteum. The CL is lysed and will bring her back into heat much more quickly than if her body is given the time to realize she is no longer pregnant. The process of bringing a mare into heat that has just ovulated is known as short-cycling, and is very helpful when you are trying to get many embryos from a donor mare during a season, or if you would like to breed more than one mare (or cow) at a time.

At my facility, another practice we had this year was administering IM injections of sulpiride to the recipient mare herd. When I googled the drug sulpiride, it came back with information that it is a drug used for schizophrenia and as an anti-psychotic. This was very interesting to me because on the farm, sulpiride is used to cause mares to begin to come into heat and grow follicles earlier in the year than they normally would. In the scope of our practice this is necessary because there are some donor mares that naturally start the breeding season early, so there are potential embryos in February that must have recipient mares. So here’s how it works; sulpiride inhibits the release of dopamine in the brain. This neuro-transmitter has been shown to control the time when an animal is not ready to breed. By stopping the release of dopamine, veterinarians have been able to cause mares to begin heat cycles much earlier in the year than they normally would.

Encouraging Ovulation

Ovulatory agents and drugs that synchronize estrus affect the size and development of the follicles on the ovary. For those of you that don’t know, some basic physiology: a follicle will develop for every egg that is released by the horse. When a mare ovulates, this means that the follicle bursts and releases an egg into the ovuduct. The egg can them be fertilized in one of the uterine horns and then finally the embryo moves into the body of the uterus. When the follicle bursts, it leave a corpus luteum, which the veterinarian can also see on the ultrasound and this body produces progesterone, a hormone that helps maintain pregnancy. Progesterone is given intra muscularly to mares that receive embryos from the recipient herd, and also to mares that have a low progesterone level in their blood.

Sometimes mares will not ovulate their large follicles and the follicle can actually regress in size. In order to encourage a mare to ovulate, veterinarians can implant an Ovuplant which is made of desorelin, an analog of GnRH which is a hormone leads to follicle release. The Ovuplant is supposed to cause the release of an egg within 36-48 hours of use (if there is an appropriate follicle). This makes it possible to know that if you breed a mare before ovulation, that the chances are high the mare will ovulate before the semen is dead. It is also easier to know when the mare will ovulate to breed after ovulation. Ovuplant is also useful in estrus synchronization because if one mare has already ovulated, then by making the other ovulate ASAP, the gap between days of the donor and recipient will be small.

Other methods of causing a mare to ovulate include shots of desorelin, and HCG injections. GnRH is produced by the body and causes the release of LH, the hormone that directly causes the follicle to erupt. HCG acts in the same way as LH, causes release of the follicle and desorelin, acting as GnRH, causes the natural increse in production of LH. GnRH will help a mare that is not building follicles to begin to do so. All of these injections and implants can cause a change in the mare’s hormonal level and make her ovulate sooner than she would naturally.

Getting the Mare Ready

So, once the method and means by which the semen is available is determined, the next step is to worry about the mare. If you are simply breeding a mare that will carry her own foal, the timing is not as critical as embryo transfer donor mares. Mares will not come into heat or go into estrus during the off season, so once breeding season has begun, you will know because your mares will be cycling. When mares are cycling and getting ready to breed, they will be able to tease with a stallion. If a mare is visibly in heat then a veterinarian should check her with an ultrasound. To walk you through this step by step, the veterinarian wears a palpation sleeve, which is clear plastic like saran wrap but does not cling. This sleeve goes all the way up the arm. The veterinarian pumps a handful of lubricant onto the sleeve and insert it into the rectum of the mare. The mares that are being checked are situated in a stocks which is a large structure with poles that are about 8-10 feet high. The poles are welded to create a box-like canopy which has two doors, one on either end. The mare is led through one door and stopped before going through the other door. When both gates are closed, the horse’s head is usually tied (unless the horse will freak out). The back gate is closed and on an average sized mare this will reach mid-flank. There is also a chest rope that goes across the chest of the mare and holds her back so that the veterinarian is able to reach deep enough. Once the horse and the veterinarian is ready, he or she cleans out the rectum and lower colon simply by reaching in and removing any fecal matter. This is done so that when the ultrasound is used, it is able to detect objects through the walls of the intestine. The ultrasound probe is inserted into the rectum and by precise positioning, the veterinarian can view the uterus and ovaries.

When a mare is in heat and getting ready to be bred, she will start off having many small follicles on both of her ovaries. As time goes on and depending on the particular horse, one or two of the follicles will grow while the others shrink. At the time of breeding, there will be one dominant follicle larger than 35mm. The veterinarian is able to find the follicle with the ultrasound and can measure it using tools on the screen. To the untrained eye it will look like a large, black bubble. As discussed earlier, sometimes to have a better likelihood that the mare will get pregnant on the first time, breeders will breed before and after ovulation. To tell if a mare has ovulated, the veterinarian must check the ovary with the dominant follicle many times a day.

Quick notes

For more information on cooled vs. frozen semen visit: http://www.equine-reproduction.com/articles/faqfro.htm, and http://www.thehorse.com/viewarticle.aspx?ID=6406.

Frozen vs. Cooled Semen

Now that you know the basic process involved for cooled semen, the desicion of whether or not to use it (given you have the choice) is a big one. Frozen semen, even the technology is now fairly common, is still considered "new" by many equine producers. For this reason, a lot of people are reluctant to use it. These skeptics do have some good points.

Frozen semen can be cost prohibitive for some. In order to freeze semen you must have all the proper equipment, and if your farm can not afford this (many cannot) then you must pay someone to collect and freeze the semen for you. Depending on how much you would like to freeze, this can be several thousand dollars. Another, almost more obvious negative quality of frozen semen, is that the first-heat pregnancy rates are lower than fresh or cooled-shipped semen. However, these rates are increasing and, if the semen is frozen by the right person many think that the pregnancy rates are higher. Another factor that affects the cost of using frozen semen (for the mare owner) is how much constitutes a dose and how many doses you need to get your mare pregnant. Another downfall is that some stallions are unable to be frozen because their sperm isnt high enough quality and by the time it were frozen and thawed, there would be no viable sperm left. It is theoretically possible for a farm to have someone skilled enough to depodit frozen semen into the mare, but it is probably a good idea to have a veterinarian on site so that you have the option of breeding pre, post or both pre and post ovulation. This will figure into cost and convenience of using frozen semen.

Some benefits of frozen semen, and I believe they outweigh the risks, include the ability to breed to many stallions, even those that are deceased. Also, because of growing use and proficiency by veterinarians and technicians, I think that there will be national rates higher than those of cooled shipped semen. Frozen semen is convienent because it can be used at any time, there is no necessary coordination between the mare and stallion owners.

So, the use of frozen vs. cooled semen is a personal choice. I think it makes a lot of sense to freeze a valuable or high performing stallion because lots of people have access to it and they can breed to him any time, it does not hinder the stallion's ability to work or perform during the time.

The Next Step

Once the stallion is collected, the next step is evaluation of the semen. At this point, there are three main places that the semen can go. If there is a mare that is ready to be bred on site, she will be inseminated with all but a very small drop of the sample collected. This is usually about 50mL, depending on the stallion. The small drop left over is looked at under a microscope and the percent of motile sperm is estimated. A "good" stallion's number of progressively motile sperm (these are the ones that have a movement in a forward direction and do not only turn in circles) will probably never be above 80%. 50% is pretty good and the cut off as far as how comfortable my facility was using it was about 28%. A few things affect a sample that have horribly low numbers (like 5 and 6%). One of these could be the age of the stallion, we saw some two year olds that did not have many mature sperm yet. Also, for a stallion that is not collected often or ever, sometimes we did a depletion collection to get rid of any mis-formed or bad sperm. The idea behind this was that the second collection would be sperm that were more recently made and the numbers for the stallion's motility would be higher and a more true indication of how the stallion will perform in the future.

So, once the collection is finished, if the semen is not being put into a mare on site, that is the mare that is ready to br bred and waiting for that semen, it is either shipped as cooled semen or frozen. Semen that is being shipped fresh, that is by air, to be used ASAP, gets centerfuged once and put into an extender. In a collection the majority of the volume is a liquid called seminal plasma. The study of the benefit and purpose of this liquid is a topic of much research today. The gist of it is that seminal plasma not only lends some nutrient to the sperm, but also helps it to deal with the environment of the mare's uterus. It is theorized that seminal plasma also helps to reduce infection in the mare, though this has yet to be solidly proven. As far as storage or shipment, the plasma does not keep the sperm alive as long as other nutritious extenders developed by man. So once the sample is centerfuged, the seminal plasma is poured off. In some facilities they do it very precisely so that all they get is the pellet of sperm. However, with the uncertainty that seminal plasma is all together useless, the technician at my facility only poured off most of the plasma. For fresh semen, it was centerfuged once and then a extender was added and it was put on ice and sent out.

Horses that were being frozen, that is their semen was being frozen, were centerfuged twice and a greater amount of the seminal plasma was removed. The point of the extender is to offer nutrients to the sperm and keep them 'happy' when they are thawed and put into the mare. In order to determine which extender is the best for any given stallion, we would do a test freeze. For this the stallion was collected, the sample centerfuged twice and the seminal plasma poured off. The semen is then separated into four equal parts and each part received an extender (we used four though there are many more than that available). The semen samples are them put into half mL straws and these are then frozen with liquid nitrogen by a machine with a computer. The computer regulates how fast the semen is frozen and this is dependant on the extender used. There were two curves on the machine I am familiar with, a short and long. Two of the extenders we tested were short and two long, so that when testing extenders there were really only two variables being tested. Once these test straws were frozen, they were thawed (50 degrees celcius for 7 seconds) and looked at again under the microscope. The extender that yielded the most viable, progressively motile sperm compared to the original count of the fresh semen was the one that any subsequent samples were frozen with.

More on the benefits of frozen compared to fresh semen later.

Stallions!

I think I will take a break from the mare side of things and discuss stallion reproduction. Stallions are unique and important in the horse industry because as a male horse matures he can become aggressive towards other horses and humans and he can be harder to keep. Usually stallions are bred because they have won lots of awards on the race track or show ring and mare owners desire foals with their genetic attributes. Male horses that do not have desireable genetic lines are often castrated (gelded) either when they are young or older for aggression purposes or if breeding is not a possibility.

Basic Anatomy

Dr. Janet Roser gives some physical guidelines to a fertile horse. In the article “Is Your Stud a Dud”, which thoroughly discusses all aspects of the breeding soundness exam, she describes physical attributes specifically related to the reproductive organs. Stallions have external testicles and erectile tissue makes up the largest percentage of the penis (there is no bony tissue). I learned interestingly, that the only land mammal with internal testicles is the elephant, just think what an elephant would look like with external testicles! So, back to horses… The penis should be free of lesions and sores and a normal scrotal size for a stallion (dependant on age and time of year) is 9 to 11cm in diameter. Dr. Roser also recommends a rectal palpation of the prostate, ampulia, and seminal vesicles. For many if not all stallions, this would require a set of stocks not in the direct vicinity of any mares and a tranquilizer. A rectal palpation was not preformed on any stallion during a breeding soundness exam at the facility I worked at.

Although the physical characteristics of the reproductive organs are important, Dr. Roser agrees that the stallion must be overall in good physical shape to breed. Some of the things to check for include blindness, lameness or bad conformation. Basically, the horse must be able to mount the mare or phantom (I’ll explain that later) and ejaculate safely. Believe it or not, even though it is a natural process, breeding takes a lot out of a stallion and the breeding technician at the clinic I was at has actually had a horse die while breeding of heart related problems.
Another very essential physical characteristic is presence of libido. This can be detected with a mare that is in heat or a teaser mare. At the farm I was at there were two teaser mares that had their ovaries removed and received shots of estradiol (estrogen) which made them act like they were always in heat and could respond to stallions appropriately. The physical signs of a stallion’s libido are whinnying, nudging, sometimes biting or nipping, pawing and others. Sometime during the teasing, the stallion will “drop” his penis from the prepuce and will be ready to be washed and breed the mare.

Collecting the Stallion

There is a significant population of mare owners who breed with artificial insemination (AI) instead of live cover, which is the “natural” way of breeding. There are certain breed associations, for instance with registered thoroughbreds, that are not allowed to breed using AI. However, if allowed, it is becoming the preferred method of breeding. Its benefits include the reduction of disease and decreased injury to the stallion and mare during the actual breeding process. Stallions must be collected for the purposes of artificial insemination or for semen evaluation. There are two common ways of collecting a stallion. One is letting him tease and mount a tease mare. This involves taping the tale of the mare and making sure she is very calm. It is difficult to collect this way if the stallion likes to bite or thrash his front legs while breeding because this is very uncomfortable for the mare and she will probably not stand long enough for the collection. However, if you do use this method, once the stallion has jumped the mare, an artificial vagina is slipped over the penis before he is able to enter the mare and until he ejaculates.

The second and in my opinion more preferable method of collecting is with the use of a phantom mare. This is a large, padded, block like object that is mounted on an adjustable pole and is built to represent the height and general size of a mare standing to be bred. It is not necessarily intuitive for a stallion to want to breed a phantom and so he must be taught. There was one stallion at my clinic that, upon seeing the phantom, thought it was another stallion and was threatened by it and rushed it and took a bite out of the padding. Anyway, for many stallions (that I have experience with) a teaser is still used to excite the stud and sometimes also to teach a young horse how to jump. Once the horse is excited he is led up to the base of the phantom and will usually mount on instinct. Immediately, when the collector sees that the stallion is on, in the right angle, and it is safe to approach, they grab the penis and guide it into the AV. After this, the stallion will usually ejaculate on his own and dismount.

There is a third way and some veterinarians and stallion owners claim that there is a specific way to teach a stallion this method and it works the best, it is not a commonly held belief. The method is collecting the stallion on the ground, that is, without him mounting anything but standing on all fours. I think this process is more dangerous for the collector and handler because it is circumventing the natural movements of the horse. I think the reasoning behind this is that it does not put as much physical strain on the stallion and some say that it is easier. We did collect one or two stallions like this for a specific client, but in general shied away from it.


So that’s it! The basic procedures for collecting semen from a stallion. There is one aspect I did not mention though and that is the different typed of AV. The two common types are the Missouri and Colorado AVs, named for their state of origin. The Missouri is a soft latex pouch and the semen is deposited into the end of it. The Colorado (I am most familiar with this one) is made of hard fiberglass and has a double latex liner, one which is removable. The ejaculate is collected in a bottle in the end. Both liners have a chamber that is filled with hot water to simulate a mare’s body temperature (<100>

I know it’s a lot of information, so here is an overview of the process to physically evaluate and collect a stallion:
-Check general physical soundness
-Examine external genitalia (penis and testes)
-Rectally palpate internal organs
-Tease stallion to drop
-Wash penis
-Lead stallion to phantom or teaser
-Collect ejaculate with AV once stallion mounted
-Make sure horse dismounts safely



The next process in using and evaluating semen occurs in the lab. There are many checks and steps that the ejaculate will go through depending on what it is being used for. I will go into this at a later time.