Miniature horses are a breed determined solely by their height. To qualify as a miniature for the American Miniature Horse Association, the horse must be no taller than 34 inches from the last hair of the mane to the ground at age 5. The American Miniature Horse Registry accepts horses that measure 38 inches or less at age 3. True miniature horses have the same features and proportions as full height horses. With proper care, they can live to be more than 40 years old.
A healthy diet is important to the quality of life and longevity of all horses, but since miniature horses are so much smaller, it's also important that they don't overeat. Their diet should be made up of foods similar to that of full-size horses -- hay and grain -- but less of it. Due to their small intestinal tract, they'll need to be fed twice daily to keep food flowing through their digestive systems. They need fresh water every day, too.
If your miniature horse is eating less than usual, food is falling from his mouth or is undigested in the manure, or you notice him chewing only on one side, he has facial swelling or bad breath, he could have a dental problem. Other signs include if he balks at the bit when he hasn't before, or in general acts upset or ill. Improper eating affects digestion and can make a horse uncomfortable. Consult an equine veterinarian or dental technician.
Roaming and Resting
To stay healthy, miniature horses need sunshine and time to run in the pasture every day. At day's end -- and for resting and feeding during the day -- they need shelter that includes a roof over their heads. Since miniatures are low to the ground, the shelter should have good ventilation so they get enough air. The more open it is, the better. Just like regular size horses, miniatures should be able to poke their heads out and look over their stall doors or out a window.
Keeping miniatures groomed regularly and properly is also important to their health and well-being. Their coat, mane and tail need to be combed and brushed -- and their hooves checked for debris and picked out -- every day. Every six to eight weeks, a farrier who specializes in miniatures horses should come in to check and trim their hooves. This is important for their balance, which can affect their gait.
Miniature horses are about the size of a large dog, and they need regular medical care much like a dog would, with at least annual visits. Be sure the veterinarian has experiences with horses, and preferably with miniature horses. He can advise you on what immunizations are needed in your area, and give you deworming medication to administer on a specified schedule.
Miniatures also need regular dental checkups twice a year until age 5, and annually after that. They can suffer gum disease and absesses just like humans. Horses also regularly need to have their teeth "floated," which means grinding down the points that occur on their teeth from eating. These can cause painful mouth sores if left untreated.
Miniature horses are not dwarf horses. Their features are in proportion to that of a full size horse. Their head is in proportion to their neck, their legs are in proportion to their height, and so on. In a photo, where no height is given or visible background that indicates the horse's height, the miniature looks like a full size horse. However, proportionate miniatures can carry the dwarf gene and, if mated with another carrier, could produce a dwarf miniature, which is considered an undesirable genetic abnormality. Labs can perform genetic tests to see if a miniature horse carries the dwarf gene. Other genetic tests can determine if the miniature is at risk for diseases that could shorten the horse's life.