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50 February 4, 2016 New column! Dr. Grove has breeding season insight by daniel h. grove, dvm W

ell, it’s February, and breeding season is here. This is a great time to review equine reproduction and

some of the options available to horse own- ers. Three things to consider in preparation of get ing your mare in foal are:

• mare preparation • how you will receive your semen • who is going to be inseminating the mare

Mare preparation is important for a suc- cessful pregnancy. The goal for the horse owner usually is to get the mare in foal as soon as possible for an early foaling. Also, the more times you need to breed the mare, the more your costs go up. Whether you are shipping in semen or taking your mare to the stallion, it all adds up. First, starting in late November or early December, you should have started having your mare under lights. Between the natural sunlight and the artifi cial light you provide, there should be about 15-16 hours per day. The mare should not be able to have her head in any spot in that time that is dark. The next step in get ing her ready would be to have a culture and/or biopsy of her uterus. Whether one or both of these are necessary is up to your veterinarian. I choose whether or not to do them based off of the history of the mare—the ones who are prone to problems are more likely to get the works! Finally, any vaccines you want your mare to have, get them done before trying to breed her. The infl ammatory response to the vaccine can be detrimental to an early preg- nancy. It is very frustrating to get a mare in foal in February just to lose the pregnancy in April and have to start over. Just like us humans, to get your new foal, it

takes two to tango. Selecting the stallion that best suits your mare is going to be your fi rst priority, but you need to know some of the advantages and disadvantages of the diff erent ways to get his genetic material into your

The more times you need to breed the mare, the more your costs go up. Whether you are shipping in semen or taking your mare to the stallion, it all adds up.

mare. First is the tried-and-true natural way of live cover. The stallion breeds your mare directly and leaves his DNA in the process. You get the whole ejaculate, so sometimes you get higher fertility rates. Also, it is less costly than assisted reproduction. Two dis- advantages to live cover, though, are (1) the mare or the stallion are more likely to get injured—a mare can kick and hurt the stal- lion or some stallions are very aggressive and can injure your mare, and (2) both the mare and the stallion are at increased risk of con- tracting sexually transmit ed diseases (STDs). The second and probably most common

method is cooled shipped semen. The stal- lion is collected at his farm, and either your mare is present and inseminated right there, or the semen is shipped to you via overnight courier or an airline. Your veterinarian will be checking your mare to determine when she will be close to ovulating and will order the semen accordingly. With the veterinary fees and shipping costs, this process is more expensive, but fertility rates are oſt en very high—and the stallion has zero risk of dis- ease from your mare. Your mare can still get some of the STDs out there from him, and although there is no risk of injury to your mare from the stallion with this method, anytime you ask a veterinarian to check your mare there is a small risk of injury to her. If the stallion cools and ships well, this is an excellent way to go. Since some stallions’ semen will survive for several days this way and some others’ don't do well at all, always inquire about the quality of the shipped semen when choosing this way. The last way to receive semen is when it

is frozen. There is no overnight shipping charges, but oſt en times the extra veteri- nary costs surpass that. Ideally, the mare is inseminated just before and just aſt er ovula- tion. It requires more frequent checking of the mare. Just as with cooled semen, some stallions freeze well and some do not. An additional benefi t is that you can get semen from overseas since it does not have to be overnighted. Fertility rates tend to be lower than with live cover or cooled. Also, some of the stallion contracts do not off er a live foal guarantee. Instead, they sell you a given number of doses of semen and you get that many chances to breed your mare. That covers a lot about the stallion’s con-

tribution, but what about the mare’s? The semen has to get to the oviduct to fertilize the egg. It needs to travel through the uterus to get there. If the uterus is not a hospitable environment for the sperm cells, they can be killed before ever making it there. If the

Ask the Vet

A monthly column by Daniel H. Grove, DVM

sperm do make it and fertilize the egg, then the uterus needs to be ready to receive the fertilized ovum and nurture it as it grows into an embryo—and then, a fetus. Any of a number of factors can disturb these from occuring, and if that becomes the case, fear not—you do have options. The fi rst is embryo transfer. Aſt er approximately seven days post ovulation, the mare is fl ushed and the resulting fl uid is collected and searched for an embryo. That embryo can then be either implanted into a recipient mare, or frozen to be implanted later. If you have a mare that has uterus problems,this allows for a healthier uterus to carry the foal. If you want multiple foals from the same mare in the same year, this makes that possible, too. An additional option for those mares that

may have problems is ICSI. This stands for intracytoplasmic sperm injection. Here is where you can get your “test tube” foals. The eggs are harvested directly from the ovary and are manually fertilized by a reproductive specialist. This is an expensive procedure with increased risk to the mare during oocyte collection. If you have a great mare with a damaged uterus or oviduct that cannot get you a seven-day old embryo to fl ush out, this is your last stop. Also, if you have a stallion that is either deceased or has very limited semen, this may be an additional tool to help. A single straw of frozen semen, which is usually just a partial breeding dose, can be used over and over to fertilize many eggs. This is just a brief overview of the diff er-

ent possibilities in equine reproduction. As you can see, there are diff erent avenues you can travel down in the process. It may not always be successful, or as inexpensive as you may want, but the result is a new life that you get to raise and mold into hopefully the horse of your dreams!

Dan Got a question for Dr. Grove? Send your

inquiries to, and it could be answered by Dr. Grove in a future column. Dr. Grove is based at West Coast Equine Medicine, headquartered in Falbrook, Calif., where he lives with his wife Kristen.

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