Or alternatively, is that a horse or an agglomeration of awkward limbs masquerading as an equine?
Horses are made up of lines and angles, some of which can be a bit surreal. All of these will affect how the horse moves and lives its day-to-day life, and will particularly affect what you can actually do with them if you decide to ride. Some problems will stand out immediately i.e. one leg points in a different direction to the others. But some problems will only be obvious if you spend a lot of time watching horses and drawing lines all over their photographs.
Here is an example of a well-designed horse:
The dotted lines drawn here are on the shoulder blade (scapula) and humerus. The relative length of the humerus tells us a lot about what kind of stride action the horse will have, and so does the angle that these two make when they meet.
In addition, the slope of the shoulder blade compared with the horizon can help determine how high the horse can lift their knees.
In this picture, the horse is suitable for dressage. She has a laidback shoulder slope of around 45 degrees (the line has been cut off a bit by the saddle), which is ideal for the kind of lift and expression in dressage horses. If she were designed for jumping, the slope would be closer to 55 degrees.
Her humerus is long, at around 50% of the length of her scapula, which means that she has room for large, expressive movement. The angle at which the two meet is not very vertical, so she is not ideal for jumping, since this means that she will have a harder time snapping up her knees to get over jumps.
Note as well that her back and rump, as far as can be seen under saddle, have long smooth coats of muscle. She is level to the horizon and evenly balanced.
Compare her now to this horse:
First reaction: what even is this. This image taken from google is of a quarter horse stallion, apparently fully grown and used for breeding (though can’t imagine why). The line drawn near his scapula isn’t actually the angle drawn in the previous horse (they’re measuring how downhill he is), but it’s distressingly close to reality. He has a very upright shoulder of around 60 degrees. His entire frame is built towards pushing him flat onto his face. The scapula doesn’t make it any easier. The angle between the humerus and scapula isn’t all that bad, but their feeble efforts to let his knees come up aren’t enough to make the whole horse look like he can stay vertical. It’s hard to tell what he’s been designed for, other than dental realignment surgery.
His back and rump were clearly built by two different contractors. The former is working like a kiddie slide and the latter is perhaps intended as a launch pad for rockets.
From the same stable…
Sadly, this is being advertised as a breeding prospect. I can only imagine the resulting Franken-horses. Just like the previous stallion, this one is trying very hard to land flat on his nose. His shoulder is painfully vertical and his humerus embarrassingly short. His knees are stuffed underneath his hugely overbalanced body. His backside is built like a peaked tent and if you were to put a saddle on his back, it would slide straight down his neck and off his face.
One of these things is not like the other! If you’re in the market for a new horse, study up on conformation. If you’re a casual (i.e. might go for a trail ride once every ten years) look for the horse not built like a slide with pogo-stick shoulder action. You’ll have a more comfortable time!