Horse (Franchise)

The Horse is an animal only mentioned in How to Train Your Dragon Franchise. Its smaller form, the Pony, is also mentioned in the Franchise.

Horse
The Horse (Equus ferus caballus) is an odd-toe ungulate animal - having one "toe" it walks on - of the Family Equidae, making it related to zebras and donkeys. Horses were domesticated at least 4000 years ago, possibly from the now-extinct Tarpan (Equus ferus ferus) or some other unknown extinct horse species. The domesticated horse only has one other subspecies, the Przewalski's horse (Equus ferus przewalskii), which is critically endangered.

Female horses are called mares and the young horses are called foals. Stallions are intact male horses, while a "gelded" horse, or gelding, is one which has been castrated. A filly is a juvenile female, while a colt refers to a juvenile male. The lifespan of a horse is usually between 25 and 30.

Pony
A pony is an arbitrary term for a small horse, or a variation of it. Typically a pony is defined as a horse how measures 14.2 hands or less, though the measurement can vary in different place around the world. A "hand" is 4 inches in length, and the horse or pony is measured from the bottom of its hooves to the top of its shoulder blades, or "withers". However, ponies are not always defined by height alone, but sometimes also physical traits. Their differences from horses (excepting the height) are shorter legs, wider barrels, heavier bones, thicker necks, and shorter heads. Many people confuse ponies with foals.

Function
As mentioned by Gobber, horses were used by Vikings for transport. This exists in reality too, along with sports and entertainment purposes.

Ponies are mentioned to be pets by Hiccup. In reality, they are also used for work and to be ridden by children. Some bigger ponies can be ridden by adults for sport activites.

Historical Vikings were known to eat horses, as well.

How to Train Your Dragon
"This is Berk. ... The only upsides are the pets. While other places have ponies or parrots, we have... dragons!"

- Hiccup at the end of the film

During the closing narration, Hiccup describes the Berk, saying that while other places may have ponies or parrots, their pets are the dragons.

Dragons: Riders of Berk
"I've made a lot of saddles in my day. Horse, donkey and now, dragon."

- Gobber in Viking for Hire

Gobber mentions horses as animals he has made saddles for.

Toothless
Toothless, and perhaps the Night Fury as a species, has been inspired by many animals, including horses, according to Dreamworks' Youtube Video Series, "The DreamWorks Download". "His [Toothless] design, behavior, and personality were inspired by cats, dogs, and horses." Further, "the noises Toothless makes are a combination of elephant seals, elephants, tigers, horses, and domestic cats."