Cantering Leads.
The canter is a controlled, three-beat gait performed by a horse. It is a natural gait possessed by all horses, faster than most horses trot but slower than the gallop. A variation of the canter, seen in western riding, is called the lope and is generally quite slow.
The "lead" of a canter refers to the order in which the legs are placed, and is determined by which leg is the last to ground before the suspension phase. If the left hind leg is placed first (beat one), which would then be followed by the right hind and left foreleg (beat two), before the right foreleg (beat three), the horse is said to be on the "Right Lead." If the right hind leg is beat one, then the left foreleg will be the last leg to ground, and the horse will be said to be on the "Left Lead." Therefore, a person on the ground can tell which lead the horse is on by watching the front and rear legs and determining which is the last one to touch the ground, but may also simply watch to see on which side the legs are literally "leading", landing in front of the opposing side.
When the horse is on a lead, the legs on that side (usually the inside front and hind) have greater extension than those on the other side (usually the outside front and hind). Therefore, a horse on the Right Lead will have its right hind (beat two) come slightly further under its body than the left hindleg had when it grounded (beat one), and the right foreleg (beat three) will reach further out from the horse's body than the left foreleg had extended (beat two).
In general, the horse is on the "correct" lead when it matches the direction it is going. So a horse turning to the right should be on the Right Lead, a horse turning to the left should be on the Left Lead. However, just as people find it easier to write with one hand or the other, most horses have a "better side", on which they find it easier to lead at a canter. In limited circumstances, mostly in dressage training, a horse may be deliberately asked to take the lead opposite of the direction it is traveling. In such cases, this type of canter is called a counter-canter.
A variant canter, involving the same sequence of beats but variant footfalls in beats one and two, is often referred to by equestrians as cross-firing, cross-cantering, or disunited canter, among other terms. To the observer, the horse appears to be leading with one leg in front, but the opposite leg behind. It is produced by an improper sequence of footfalls.
The problem with this sequence is in beat two: the grounded hind and foreleg are NOT diagonal pairs, but are on the same side of the horse (in this case, the outside). This means that the horse is balancing on only one side of its body, which is very difficult for the horse, making it hard to keep the animal balanced, rhythmical, and keeping impulsion. A horse that is cross-firing cannot perform to the best of its ability, and can even be dangerous (such as an unbalanced, cross-firing horse who must jump a huge, solid cross-country obstacle). Additionally, it makes for a very uncomfortable, awkward ride, producing a rolling movement often described as riding an eggbeater, which makes it difficult for the rider to perform to the best of his or her abilities.
The most important function of the correct lead is for balance. While they are unimportant on a straight line, they can greatly influence the athletic ability of a horse on turns, especially if the turn is tight or performed at speed. Horses naturally lean in to the direction they are turning. Since they extend their lead-side legs further out, they may use them to balance themselves as they lean into that direction. So, if on the Right Lead while taking a right turn, the right hind will be positioned more under the body, and the right foreleg more in front of the body, to act as a stabilizer as the horse turns.
When on the incorrect lead, the horse is usually left unbalanced. In this case, correct riding can make the difference in the horse's performance. Good riding can keep the legs positioned correctly enough so that the horse is still able to perform the turn. Poor riding will hinder rather than help the horse, and in extreme situations such as a tight turn at speed, the horse may lose its legs footing and fall.
Source: Wikipedia
Pictures of the Models detailed below can be found here
CLASSIC SIZEAction Stock Horse Foal - Right Lead
Alborozo - Left Lead doing a Pirouette
Andalusian Stallion - Right Lead
Black Beauty - Cross Cantering (Left Lead in the rear legs, Right Lead in the front legs)
Cantering Welsh Pony - Right Lead
Cigar - Left Lead
Cody - Left Lead - Note this model is not doing a true canter. It's kind of like a stutter step
Etheral - Left Lead
Flash - Left Lead (above picture)
Gem Twist - Left Lead - Note this mold was sculpted as taking the last stride before jumping. He is not doing a true canter
Haflinger - Left Lead
Phar Lap - Right Lead
Roemer - Left Lead
Roxy - Right Lead
Ruffian - Left Lead Photo
Running Stallion - Cross Cantering (Left Lead in the rear, Right Lead in the front)
Show Jumping Warmblood - Left LeadSmarty Jones - Right Lead
AQHA Foal - Left Lead
AQHA Mare - Left Lead
AQHA Stallion - Left Lead
Andalusian Foal - Right Lead
Andalusian Stallion - Right Lead
Arabian Stallion - Left Lead
Black Beauty - Right Lead
Ginger - Cross cantering (Right Lead in the rear, Left Lead in the front)
Hobo - Left Lead
Keen - Left Lead
Might Tango - Several show this model at the canter. He is really walking.
Morgan Foal - Left Lead
Polo Pony - Left Lead
PADDOCK PALS/LITTLE BITS
Clydesdale - Left LeadSTABLEMATES
Thoroughbred Stallion - Left Lead
MINI WHINNIESCantering Foal - Cross Cantering (Left Lead in the rear, Right Lead in the front)
Cantering Stock Horse -Cross Cantering (Right Lead in the rear, Left Lead in the front)Cantering Warmblood - Left Lead
Clydesdale - Right Lead
Endurance (Arabian) - Left Lead
Mustang - Right Lead
Seabiscuit - Left Lead
Thoroughbred - Right Lead
Warmblood - Right Lead
Cantering Morgan Mare - She's really trotting and not cantering
Cantering TWH Gelding - Right Lead
Cantering TB mare - Left Lead
Galloping Mustang Stallion - Cross Cantering (Left Lead in the rear, Right Lead in the front)
Loping Stock Horse - Left Lead
Running TB Stallion - Right Lead (could be cross cantering, but it's hard to tell)
Article Re-printed here with kind permission from Randa Garret.