Here's a post I made earlier today on the DRF FormBlog hosted by Dan Illman:
I’m pretty sure that I read in Horsebreeding In Theory And Practice, which was written by Burchard Von Oettingen and published in 1909, that if a horse bleeds it is a sign that the horse is not fit. The horse’s lungs have not been properly developed through training and when the horse is called upon to perform in an extreme circumstance such as a race the capillaries will burst causing bleeding.
But I can not remember where I read that in the book. If I find it, I will give you the quote.
Oettingen was a world-renowned expert on horses and especially Thorougbreds. He was the Director of the Royal Stud of Trakehnen Germany and here’s some more tips he had about the fitness of a horse that I thought you would appreciate:
Besides a horse’s galloping performances, there are several other very remarkable signs to show how far its condition has improved. To commence with, notice must be taken how long it takes the horse to snort (clear the wind) after it has been pulled up. The sooner this happens the more forward is its condition, especially the breathing. If the horse, for example, requires a minute or two to snort, it is a sure sign that the horse has been asked to do too much in the gallop in question, i.e., a mistake has been made. If the horse is very fit and the gallop has been too short, i.e., it has been easy work for it, it takes a long time to snort, or it does not snort at all. The length and pace of the gallop must fit the condition, so that if it clears the wind by snorting 10 to 30 seconds after being pulled up, it is a sure sign that everything is all right.
In the case of a horse which is fit the skin becomes thinner, the hair more shiny, and the flesh firmer. The latter, as well as the disappearance of useless fat, can best be noticed at the mane and on the ribs. A little easy sweating is by no means a sign of bad condition, on the contrary, a fit horse certainly sweats less but more readily, as its sweat is more liquid and its skin thinner and more readily penetrated. The sweat of a fit horse looks like clear water; on the other hand, that of an unfit one like lather, which can be most distinctly seen between the hind legs, and dries up less quickly.
Finally, I must add that before the race, and in order to get a perfect condition, in most cases several gallops at full speed, over not more than 2,000 metres, are required, and that the last gallop – which often works wonders – must be undertaken two or three days before race day. …On the day of the race itself, early in the morning, give the horse 1 to 1 ½ hours’ walking excersie, a short canter of 800 metres, and a so-called sprint for the same distance. If desired, you can do as the Americans like to – let the sprint follow the canter without any interval. – page 404