I was driving to work today and I was following a truck pulling a horse trailer. On the back of the trailer was a bumper sticker that said “Real Women Ride Warmbloods” with a silhouette of a woman riding a horse. Obviously from the context a warmblood is some kind of horse. But I’ve never heard the term before. What exactly is a warmblood?
A warmblood is a breed of horses that is warmer than the coldblood breeds but cooler than the hotblood breeds. Obvious, right? 
Now, to be a bit more informative. The hotbloodedness/coldbloodedness refers to the breeds temprament, excitability, tendency to be more alert & active (and nervous and jumpy).
Typical hotblooded horse breeds would be those like Arabians, Thoroughbred racing horses, Standardbred trotting racers, Morgans, Saddlebreds, Hackneys, etc. Most of your common pleasure riding horses are in the “hotblood” class. They were bred to be this way: the gent out for a ride thru the park or the lady out in her carriage wanted a stylish, high-stepping, alert horse to put on a good show in front of the neighbors.
Coldblooded horses cover most of the work or large draft horse breeds: the Shires, Clydesdales, Percherons, Belgians, etc. These, too, were bred to be this way. With a team of huge horses pulling your wagonload of goods down a narrow alley and backing it up to a loading dock, you do NOT want them to be at all excitable or jumpy – calm & collected is the goal. Nor do you want them wasting energy on stylish high stepping – they’re work horses; you want all their energy going into the work.
Warmbloods are the breeds that are basically a mix of the above. They have some of the energy & alertness of the hotblood breeds, but still retaining a godd deal of the calm nature of the coldblood breeds. Also sizewise, they are in between the smaller hotbloods and the very large coldbloods.
Most of the horses you see in the Olympics & Dressage events are warmbloods. (Except the jumpers – those are hotbloods.)
Hot blooded horses are those such as Arabians and Thoroughbreds that are known for their “feisty” personalities.
There is not really a “cool blood” designation, but draft horses are known for their (generally) placid dispositions.
Around 20 years ago, the dressage folks picked up a fad of breeding thoroughbreds to some of the lighter draft breeds, producing a horse that was well-muscled, but having a personality that was neither as jumpy as a hot blood nor as sluggish as a draft horse. They began calling such critters “warmbloods.” (The most popular warmblood breed, the Trakehner, is a lot older than 20 years, but that was when the warmbloods really got popular among U.S. dressage and cross-country event partiipants.)
Damn, I had a long reply all typed and I was the first in…and then the peculiar log-in process for this board spat me out again.
Here’s the reply anyway.
At last a question I can answer!
“What is a warmblood horse?” is the kind of question that can keep equine enthusiasts going for days and days. Warmbloods, as a collective breed name, refers to the European breeds of horse which were originally bred as good all-round riding and carriage horses. Some of the specific breeds are Hanoverians, Trakehners, Oldenburgs, Swedish and Dutch Warmbloods and others.
It makes a bit more sense if you know that the draft breeds (big horses bred for pulling) such as Clydesdales, Shires, Percherons, Belgians and the like are collectively know as “coldbloods” and the Arabian and Arabian-derived horses such as Thoroughbreds are know as “hotbloods”.
The terms have nothing to do with the warmth or otherwise of the animal’s blood, but is a kind of short-hand way of referring to temperament. Because of their size, the draft breeds are deliberately bred for calmness of temperament, placidness and docility, while the Arabian-derived horses are noted for their sensitivity and reactiveness. Obviously horses differ in temperament almost as much within breeds as between breeds so it’s not as simple as it might seem.
Trakehners, for example, have had a largish infusion of thoroughbred, so by reputation are “hotter” than some of the other Warmblood breeds, while Hanoverians are reputed to be very calm and level-headed horses. But of course there are hot Hans and placid Traks and laid-back Arabians and hotter than hot Percherons.
There are lots of arguments about whether or not a Warmblood is simply a cross between a “coldblood” and a “hotblood”, such as the popular draft X thoroughbreds, or whether the word refers to specific breeds of horse.
I’d come down on the side of specific breeds myself, but there are lot of arguments for and against, and almost as many registries for the various breeds as there are arguments. Certainly many of the Warmblood studbooks are still open to outside breeds, such as thoroughbreds, which makes it a more complicated issue.
Warmbloods are often bred nowadays for performance, mainly dressage and showjumping, although you can find them doing almost anything. They are generally largish, solid horses and it’s not unusual to find them well over the 17h mark (a hand is four inches), but again, it depends, there are fine, elegant WBs as well as the 18.1h Goliath who I saw competing in the Sydney Olympic dressage competitions.