American Miniature Horse weight and height, and why a weight tape is the wrong tool

Minnesota measured height at a different spot than the mane rule, so its averages and the registry limit do not line up.

A height breed built like a larger horse

Oklahoma State says the Miniature is bred down in size while keeping the conformation of its larger cousins, and that the horses look like Quarter Horses, Arabs, Thoroughbreds or draft horses in small scale. The University of Kentucky adds that Miniatures are the only breed measured at the last hair of the mane, and that the limit runs from 34 to 38 inches depending on the association. Weight therefore follows height and frame more than breed.

Daily hay for a 257 pound Miniature Horse

The arithmetic uses 257 pounds, the Minnesota adult average. Replace it with your own horse’s weight.

Oklahoma State says care is the same as for larger horses on a much smaller scale, with grain measured by the cup and roughage by a flake of hay. Merck gives 2 to 2.5% of body weight in dry matter as the usual daily maximum, with at least 1.5 to 2% from forage. These figures are our arithmetic, counting hay as 90% dry matter.

• 1.5% of body weight: 3.9 lb (1.7 kg) of dry matter, about 4.3 lb (1.9 kg) of hay
• 2% of body weight: 5.1 lb (2.3 kg) of dry matter, about 5.7 lb (2.6 kg) of hay
• 2.5% of body weight: 6.4 lb (2.9 kg) of dry matter, about 7.1 lb (3.2 kg) of hay

Why a tape is the wrong tool

Merck says weight tapes are not suitable for miniature horses. It gives its equation for adult horses and says nothing about miniatures, so treat the result as a rough check. Using the University of Minnesota’s adult miniature averages, a heart girth of 45 inches and a body length of 38 inches gives 45 x 45 = 2,025, times 38 = 76,950, divided by 330 = about 233 lb (106 kg). The scale average was 257 lb, so the equation came out about 9% low.

Minnesota fitted separate equations for adult and young miniatures, which add neck circumference and height, and found that miniature owners guessed within about 35 pounds, or 15%, of scale weight. A 35 pound error is more than 10% of a horse this size. Ask your vet to weigh on a scale, and use the same method each time for the trend.

Skeletal atavism

UC Davis describes skeletal atavism as an inherited bone development disorder of Miniature Horses and Shetland Ponies, with short legs, clubfoot and impaired movement. Matings between two carriers give a 25% chance of an affected foal, and the DNA test uses a hair sample with roots.

Night blindness with the leopard pattern

UC Davis says horses with two copies of the leopard complex spotting variant have congenital stationary night blindness, and lists the Miniature Horse among the breeds that can carry it. Its laboratory adds that such horses are at elevated risk of equine recurrent uveitis, the leading cause of blindness in horses. A Miniature with the symmetrical white pattern over the rump may be worth testing, and an eye problem is a call to your vet.

Body condition and weight

The University of Minnesota found that 20% of adult miniatures scored 7 or more on the 9 point scale, against 2% of juveniles, and that adults averaged 6.1. Merck advises a score of 4 to 6. Do not starve a small horse to fix it: Merck warns that prolonged fasting or intake under 1% of body weight in dry matter risks hyperlipidemia in obese equids. Log the score and a scale weight together.