Miff,
Unfortunately, my job often gets in the way of my passion--horse racing. So, there will be long periods of time when I won\'t be able to follow all the discussions on the board. However, this is the best place I have found to discuss these issues, biases, passions and ad hominem responses notwithstanding. Jerry Brown is to be complimented for providing such a forum no matter what your view is on his figure making methodology. IMO, his is the most grounded in scientific principles, e.g. see all the work on the potential for changing race surfaces during the course of a day.
As to your first question, note that I am not an equine vet who would better answer your questions. Nonetheless, after doing my own research, on a simplistic level, it seems logical that bleeding a horse will force its spleen to inject newly high oxygenated blood into its system. Timing would be crucial. As with all complex regulated physiologic systems though, I don\'t know what other detrimental effects if any, might ensue as a result of repeated bleeding.
As to the second question, simplistically a \"milkshake\" is an attempt to add a basic pH buffering agent (sodium bicarbonate) to combat the acidic effects of lactic acid buildup in muscles which causes their fatigue. A vet would know better but, IMO, the positive effects should be minimal--you\'d need one hell of a lot of bicarb to buffer the lactic acid produced in a 1000 lb race horse running at high speed.
The key concept for both questions is that all physiologic systems are highly and tightly regulated to combat wild swings up or down. It would be good for the board to have an articulate equine vet who was not connected to the racing industry post to answer such questions more authoritatively.