Why are blood hounds called by this name?

Nothing in the History of the Bloodhound is more remarkable than the way in which it has become accepted that the derivation of the word ‘Bloodhound’ is from the meaning ‘pure-bred hound’. This idea seems to have been first put forward in the 19th Century, by Le Couteulx de Canteleu, quite without any etymological justification, in support of his idea that the Bloodhound was the St Hubert Hound kept pure in Britain. Etymology, however, is not a matter of guesswork: it requires evidence like any other study, and all the relevant linguistic and historical facts need to be sifted through. If this is done, it becomes totally clear that the original meaning is ‘blood-seeking hound’.

https://vcahospitals.com/know-your-pet/dog-breeds/bloodhound

Primarily because of their use as scenthounds, able to follow scents for hours or even days. This may or may not mean following the scent of actual blood trails, although that was apparently the meaning intended when the term was first used by Caius in 1576.

‘Bloodhound’ is a compound word, made up of two nouns ‘blood’ and ‘hound’. With this kind of word the semantic (meaning) relationship between the two parts is not obvious; we are expected to know it from our experience. ‘Bloodhound’ means ‘hound associated (in some way) with blood’, but what ‘blood’ could mean to the speaker of Middle English demands historical investigation."

"The earliest person actually to consider how the word was derived is Caius (1576). To him, Bloodhounds derive the name from their ability to follow blood-trails. In the absence of any earlier discussion, or any contradictory evidence, there is no reason to doubt Caius."
https://www.yumpu.com/en/document/read/11533992/aspects-of-bloodhound-history-bloodhoundsorguk

"A bloodhound (also known as the St. Hubert hound) is a large breed of dog bred for the specific purpose of tracking human beings. Consequently, it is often used by authorities to track escaped prisoners or missing persons. It is a scenthound, famed for its ability to follow a scent hours or even days old, over long distances."
https://en.wikipedia.org/wiki/Bloodhound
http://www.dogbreedinfo.com/bloodhound.htm

I've run across that very question on "Who's the Smartest?" several times. The question is wrong, then.

"This breed, the best of the cold-trailing hounds (hounds that follow an old scent) received its name from its fine pedigree.

Bloodhound. It's a blooded hound- as in blue-blood."


The American Bloodhound Club says,

The name Bloodhound was derived from the expression "blooded hound", meaning a hound of pure breeding.
http://www.bloodhounds.org/page2/page22/history.html

and
"Blood," in the breed name "bloodhound," probably comes from "blooded" - meaning a hound of pure breeding.
http://www.bloodhounds.org/page2/page22/history.html

There exists, of course, the possibility that the club doesn't care to entertain the alternate idea.

This illuminating article also supports the 'blood-line' origin of the name, although again without etymological evidence. In fact the story seems to involve much cross breeding in the early days.
Also it doesn't nmake much sense, does it? Surely ALL dog breeds recognised by the AKC must be pure bred, so why single out bloodhounds for this description?

https://www.akc.org/dog-breeds/bloodhound/