Editing Horse breeding (section)

=== Care of the pregnant mare ===
Domestic mares receive specific care and nutrition to ensure that they and their foals are healthy. Mares are given vaccinations against diseases such as the [[Equine herpesvirus 1|Rhinopneumonitis]] (EHV-1) virus (which can cause miscarriage) as well as vaccines for other conditions that may occur in a given region of the world. Pre-foaling vaccines are recommended 4–6 weeks prior to foaling to maximize the [[immunoglobulin]] content of the [[colostrum]] in the first milk.<ref>{{cite web|url=http://www.aaep.org/vaccination_passivetransfer.htm |url-access=subscription |title=Vaccination and Passive Transfer |website=American Association of Equine Practitioners}}</ref>  Mares are dewormed a few weeks prior to foaling, as the mare is the primary source of parasites for the foal.<ref>[http://www.aaep.org/health_articles_view.php?id=140 "Expectant Mare: Assuring the Health and Well-Being of the Pregnant Mare"] {{webarchive|url=https://web.archive.org/web/20080415220750/http://www.aaep.org/health_articles_view.php?id=140 |date=2008-04-15 }}</ref>

Mares can be used for riding or driving during most of their pregnancy.  Exercise is healthy, though should be moderated when a mare is heavily in foal.<ref>{{Cite web|url=http://www.esdaw.eu/horse---breeding.html|title=Horse - breeding|website=ESDAW|language=en|access-date=2019-06-11}}</ref> Exercise in excessively high temperatures has been suggested as being detrimental to pregnancy maintenance during the embryonic period;<ref>Mortensen C, Choi YH, Hinrichs K, Ing N, Kraemer D, Vogelsang S, Vogelsang M. 2006. Effects of exercise on embryo recovery rates and embryo quality in the horse. Animal Repro. Sci. 94:395-397</ref> however ambient temperatures encountered during the research were in the region of 100 degrees F and the same results may not be encountered in regions with lower ambient temperatures.{{original research inline|date=August 2014}}

During the first several months of pregnancy, the [[equine nutrition|nutritional]] requirements do not increase significantly since the rate of growth of the fetus is very slow.  However, during this time, the mare may be provided supplemental vitamins and minerals, particularly if forage quality is questionable.  During the last 3–4 months of gestation, rapid growth of the fetus increases the mare's nutritional requirements. Energy requirements during these last few months, and during the first few months of lactation are similar to those of a horse in full training.  Trace minerals such as copper are extremely important, particularly during the tenth month of pregnancy, for proper skeletal formation.<ref>{{cite web|url=http://horse.purinamills.com/products/pregnantlactatingmare.asp|title=Nutritional Management of Pregnant and Lactating Mares|website=purinamills.com}}</ref> Many feeds designed for pregnant and [[lactation|lactating]] mares provide the careful balance required of increased protein, increased calories through extra fat as well as vitamins and minerals.  Overfeeding the pregnant mare, particularly during early gestation, should be avoided, as excess weight may contribute to difficulties foaling or fetal/foal related problems.