I read the British Horse Society Complete Manual of Stable Management (2000) because a depressing number of people are told that this is the way to deal with horses and pass BHS exams.
On page 17 they give this information "A well known saying is that "Blood carries weight". Thoroughbred and Arab horses have much denser bone structure than a horse of common breeding, ie of carthorse blood. Horses with this denser bone are capable of carrying more weight, relative to their size, than the commoner breeds."
The well known saying "Blood carries weight" isn't actually that well known. Try Googling it and it crops up three times,
Yes, so many people think if a horse has lots of bone, it can carry more weight but, as the old saying goes; "blood carries weight", TBs and Arabs have much denser bone and can carry relatively more weight, for the size of the animal.
Don't forget the old saying "Blood carries weight". Blood horses have denser bone than draught breeds and their crosses, so a 15.2hh Arab can carry far more weight than a 15.2hh Irish Draught.
The third time it appears is on my website asking just how well known this is. The other more pertinent question is whether it is just complete nonsense. It does crop up in a fascinating article entitled The bloody shouldered Arabian and early modern English culture. This states It had been known since the mid-seventeenth century that the bone density of the Eastern breeds known as "blood horses" was much greater than that of the heavier northern European breeds. The Duke of Newcastle had observed (in his French treatise of 1658, translated into English in 1743), "I have experienced this difference between the bone of the leg of a Barbary horse and one from Flanders, viz. that the cavity of the bone in one shall hardly admit of a straw, whilst you may thrust your finger into that of the other."
Since this cavity in the bone to which Newcastle refers, is the location of the bone marrow, the source of blood, it would appear that "blood" horses were LESS capable of producing blood than their common relatives.
There is no other backing for this ludicrous theory so why is it appearing in the BHS Manual, and being quoted by people trying to make decisions about the right type of horse or pony to buy.
The first page of chapter one has another well known quotation, "no foot, no horse". This gets 8,190 hits on google, so at least it is a genuinely well known phrase. This chaper is on conformation and states
"Front feet and hind feet should be matching pairs. Any difference obvious in outline, angle of foot to the ground, or size of frog, should be viewed with suspicion. The only exception is the horse whose foot has been worn down through losing a shoe."
Is the BHS really suggesting it is reasonable when a horse has lost a shoe to do enough exercise to wear the foot down. Or is it possible that the senior members of the BHS don't bother to read what is put out in their name because it is only for grooms and amateurs.