There is an ongoing debate over whether a miniature horse should possess horse or pony characteristics. This is a common controversy within the miniature horse world and also is a hot debate between mini aficionados and other horse and pony breed owners. While technically any member of Equus caballus under 14 hands 2 inches (58 in; 150 cm) is termed a “pony,” many breeds, including some miniature breeds, actually retain a horse phenotype and their breed registry therefore classifies them as horses.
Some miniature horse breed standards prefer pony characteristics such as short, stout legs and elongated torsos, while others prefer ordinary horse proportions. Even the name is in dispute, terms such as “Midget Pony” and “Pygmy Horse” used in addition to “Miniature horse” and breed-specific names such as Falabella. The level of controversy is reflected by the presence of over 30 different registries for miniaturized horses or ponies just within the English-speaking world.
A Shetlands height starts at 38 inches tall. A Miniature horses height limit is at 38 inches tall. If a horses height is exactly 38 inches, they can be register in both American Miniature Horse Registry (AMHR) and American Shetland Pony Club (ASPC). There IS a difference between the two breeds. A Shetland can be ridden. People often do ride their minis, but its not safe to, it can easily hurt their backs. I highly recommend not riding a miniature horse.
A Miniature Horse can be registered in two registries, AMHA and AMHR.
In AMHR there are two divisions, A and B. A horse under 34 inches is clearly a Division A mini. A horse over 34 inches is clearly a Division B mini.
However, AMHA only recognizes miniatures under 34 inches. A mini cannot be registered in AMHA until the age of 5 when they are fully grown.
Miniatures and Shetlands are shown in different classes, and never in a class together. Classes are set up from the different height and age.
For Example “AMHR Mare 3 & Older – 30 & Under” ,
“AMHR Mare 3 & Older – Over 30 to 32” , OR
“AMHR Mare 3 & Older – Over 32 to 34” .