I might agree with you about the blood but I said "in a situation of a past presence of a cadaver ...." The body (the cadaver) would have a different set of factors compared to decomposing blood IMO.
Davel is trying to say that when blood decomposed it would not produce cadaverine. That is his problem, for we don't know what chemicals a dog recognises when they alert to a cadaver. Would a cadaver dog recognise decomposed blood. I imagine that would depend on the training it got.
To be honest, I don't really care. And here's why.
If you research cadaver decomposition, it normally goes through 5 stages. Each of these stages gives off a different set of volatile organic compounds. Or to put it more simply, a different smell.
I have little idea what Eddie was trained on / tested on. Ditto Keela.
I know that Eddie would alert to blood. Cite already provided.
From research, it appears that a decomposing chicken produces the VOCs closest to human decomposition.
My cadaver dog, Gonçalo, has alerted to two cadavers, neither of them a chicken.
Should I get one of our neighbours chickens to test him?