How do I know if my Miniature horses are to thin?

If you can see the bones of their spine or if you can see the peeks and dips of their hipbone they are too thin. But like all animals, you get your old Minis that just can't keep the weight on anymore (take inside for winter), or you get your young stud that is just too dumb to stop strutting for the girls and eat (sometimes needing separated so they don’t see any other minis). There are always exceptions. If you worry about a potential perches ask if you can bring a local vet that they don't use, or a vet you trust, out to see the animal in question. If the seller is unwilling then you don't want to buy from them anyway.

This is an example of a mini that is to thin with a winter coat, I do not know this mini personally and it could be to thin for many reasons. If it's because of old age try FAST-TRACK. It helps with the digestive proses so that they get the most out of their food. Also as your vet to check their teeth to see if they need floating, or evening out so they can chow better. 

(Kay Baxter http://voices.yahoo.com/conditioning-miniature-horse-show-7602552.html?cat=53)

This is a show body weight. As you can see the hoses is trim, has good muscle and nice round hips. Looks like he could use some muscle building in the shoulders and chest but he looks to be very young, about 1 or 2. Young animals like people will build muscle as they grow, as we girls know, the bottom can develop before the chest. And our mothers where right when they said, "it will come when your ready."

http://www.ferrandstriplekfarms.com

Her is another show ready stallion that is 28" tall. Thank you Zig Zag of Ferrands Tirple K Farms.

http://www.ferrandstriplekfarms.com

Here is a mini mare that is just about to have her baby. You can see that her belly is large but her hip, butt, and chest are much smaller. She's at a good weight for having babies and do keep in mind that the weight of a mother is always better larger than smaller. You don't want to curb the nutrition that baby would get before being born. Poor nutrition can be as much a contributor birth defects as genetics. Thank you Spotted babe of Ferrands Triple K Farms for letting us use your pic honey.

http://www.ferrandstriplekfarms.com

Here is a photo of a mini mare only 3 days after having her baby. Great weight, good chest, and a healthy baby girl at her side. The body standers of a brood mare are very different than those of your show horses. We should always be just a little more voluptuous for that baby. Thank you Viceroy of Ferrands Triple K Farms for letting us use your pic. The baby is precious. 

http://www.ferrandstriplekfarms.com

Here is a stallion that is a bit overweight, but better overweight than thin. Overweight just means exercise and less grass. But you can see the major weight gain in his neck area. Especially along the top where you can see the layers of fat building. This is a crown and happens often in middle aged or older stallions. As you can also see his hip and but area is very nice so keep in mind, just like people, minis can gain weight in a variety of areas. Some of us get it on our butts, other in their face, and some only on their thighs. Thank you Toby of Ferrands Triple K Farms for letting us use your pic big boy.

Now here is a case of obesity. The legs seem shorter because of the weight making them look wider, crown is large, and shoulders are invisible. This boy is a pony but we have had the same trouble with another girl that we just can't keep the weight off of and she has to stay in the barn to keep from foundering. 

Mini weight problems are just like people. You can have one that can never keep a good weight, looks like a supper star their whole life, or has a tendency to over eat. If you have any questions about a horse you are looking at feel free to email me a photo and I will do my best to help you out

Check out this sight for more depth http://www.docstoc.com/docs/91851497/Feeding-the-Miniature-Horse