If this is something you don't know to much on its certainly not the time to be to lazy to look it up, Google is a wonderful place :)
DO YOUR RESEARCH! Loosing a little one and or mommy would be devastating. Miniatures are tricky and more prone to complications IMO.
Mini mares carry on average 326 days however they can go as early as 300 days and as late as 365 days. Maiden mothers like your three year old tend to carry longer and foal with little warning.
There are little heath concerns to watch for in your pregnant mare however there are MANY complications she can have at the time of foaling, as I've said more so with a mini IMO. It is also recommended for mares to receive a pneumabort K vaccine at 5, 7 and 9 months of pregnancy. The vaccine will help the foal from aborting... This is in addition to the regular vaccines. A tetanus toxoid vaccine four to six weeks prior to foaling is very important to both the mare and foal also!
As far as the mares feed it doesn't need to change much until nearing the end of her pregnancy. I'm not familiar with your feed so I cannot say much but good quality hay and a salt or mineral block is a must. I would also add a little beet pulp and oats in there. |