Being aware of certain things during the winter months is important for all of our horses, but especially true for broodmares. Over the last 3 or 4 months of gestation your broodmare needs a very balanced ration.
Protein, minerals, carbohydrates, and vitamins are being competed for by the developing foal. Therefore, just good quality hay will not generally suffice for what your broodmare really needs. For example; for every one degree below freezing the amount of energy required for maintenance increases by one percent. That long winter hair is good but it can easily cover-up your horses body condition score.
I highly recommend palpating the ribs and hip areas plus use a weight and height tape to frequently calculate your horse's body weight. Adjust the amount of grain they are given if your horse can not maintain an adequate body weight. The ration can also be fortified with fatty acids, minerals and vitamins.
Another often over looked area is water. Your horse probably will drink that ice cold water but water that is heated to 45 degrees Fahrenheit is a healthier choice. They will drink more warm water than cold water which in turn decreases digestive issues such as impaction.
Finally, do not forget about vaccinations! Broodmares should be boostered with the sleeping sickness or encephalitis series and tetanus about a month or more before foaling. This will help increase the colostral protection when the foal first nurses. Other vaccines can be given such as rabies, strangles, rotavirus, Potomac horse fever, equine influenza and herpes virus type 1. Your veterinarian can advise you on which additional vaccines should be used. Everyone has different or unique situations to deal with. Not every broodmare needs the same type of vaccine protocol.
Other areas to additionally consider or evaluate are inventory needed to assist in the foaling process, the foaling stall and bedding, individual health checks, dewormers and parasite control, and veterinarian emergency numbers. It is much better to be prepared than have a panic attack because your regular veterinarian cannot be reached so now who can I call. Remember, even with an excellent plan that broodmare somehow gets the job done without you being there.