There are three basic types of horse trailers: stock, straight-load and slant load. But, these trailers come in so many variations, it is impossible to list them. (This is especially true considering many manufacturers will build to the customer’s specifications.) Each of these trailers has advantages and disadvantages.
Stock trailers
Stock trailers are open, often with slatted sides, and can be used for a variety of hauling needs. Some horses prefer stock trailers because of the openness and because they can find the most comfortable way to stand.
The openness, however, becomes a drawback during bad weather. These definitely are not for long-distance trailering.
Straight-load trailers
This is the most common horse trailer. It often is equipped with a manger for hay. It is the same width as the tow vehicle so its tires follow the truck tracks.
The manger, however, can restrict the horse’s forelegs. Also, the horse must do most of its bracing with its front legs. The manger prohibits the horse from lowering its head and clearing its respiratory tract.
Slant-load trailers
Horses ride diagonally in a slant-load trailer. Many believe this is more comfortable for the horse, especially during acceleration and deceleration. Slant-load trailers are shorter but slightly wider. If the horse is tied with a long lead, it usually can lower its head. Also, slant-load trailers offer more design options for living quarters and equipment rooms.
Because of they generally are wider than the tow vehicle, slant-load
trailers can be prone to dropping off the edge of the pavement or striking
a curb.