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Finally got my grades turned in, so back to the fray. Was thinking about the long hold/running out of gas issue over the weekend. John, Sue: do you know how those horses were managed at the check? One of the most frequent complaints I've heard about short holds is that the horses don't have time to eat. Could it be that they had more time to consume more grain than usual? (again, please note I said "than usual" -not implying that grain at a check per se would "stop" a horse). Chromium: I have done research with chromium in horses (old horses with pituitary dysfunction and insulin resistance)and have read most of the literature available, both human and animal. Chromium does seem to increase the efficacy of insulin's action on glucose, thereby somewhat reducing the amount of insulin released in response to a given carbo load. No one seems to know exactly where in the metabolic pathway it works nor what the actual "requirements" are. However, the effects are seen (at least in the literature)are only after chronic daily dosing, not with a single jolt. Tom, have you compared the glucose/insulin response to your CC with and without chromium? I'd be interested in seeing the data. In our work, reported this year at the Equine Nutrition and Physiology Meetings, we found that the old mares responded after about three weekes of a low (0.02mg/kg) dose with a slight improvement in glucose tolerance but they also had some mild decreases in immune function. Not that I would expect to see this after a single dose, but chromium is a trace element -ie: very minute amounts needed. How much is in each dose of CC? Just curious, not flaming. I would be very interested in seeing the science on Tom's statement a awhile back that heart rate has been shown scientifically NOT to be correlated with an animal's ability to continue. I was under the impression that heart rate recovery was one of the best metabolic indicators of a horse's fitness to continue, though obviously not the only one we use and obviously can be falsely elevated (ohmigod-my buddy is leaving me! Omigid-a mare! (for stallion owners!;-). The biggest crash I ever had with my mare was when I did try something new at a ride. Look at the archives for the summer of '98 for my descriptions of how stupid a rider can be. I'm not afraid to admit my mistakes (though it was awfully embarassing at the time) and hopefully others learned something from them! Tying up is like colic-multifactorial. The technical name, rhabdomyolysis,means "lysis (or breakdown) of muscle cells". So just cramping or muscle spasms, unless there is actual muscle damage, is technically not true tying up. Causes can be from over exertion/dehydration/electrolyte imbalance in any horse. Dehydration, changes in pH (ie: due to lactic acid accumulation), free radical accumulation, etc can cause cell membrane disruption. The cell contents contain myoglobin, which is then excreted in the urine, turning it brown/black (which is why we are the only group of people I know who are obsessed with the color of our horse's urine!). To my knowledge low blood sugar does not cause disruption of muscle cells. Nor do glucose/insulin serve as antioxidants or buffers. So I am at a loss to explain why CC would prevent a reoccurence of true rhabdomyolysis the next day, as Tom insists it does. (if a horse had truly tied up, I doubt if I would WANT to work him the next day-let those muscle heal!) Stephanie Valberg (Minnesota)and Beth Valentine (now at Oregon) (sorry, they are dreaded academics but they really have come up with something interesting) have characterized a polysaccharide storage myopathy (PSM, Duncan, not PSS) that appears to be genetic in draft horses, Quarterhorses (not related to periodic hyperkalemia AKA:Impressive syndrome) and even the occasional Arabian. As pointed out before these horses do well only if fed a high fiber, high protein (which really surprised me) and high fat ration with severely limited access to grain or other feeds high in simple carbohydrates. If fed a high carbo diet they tie up big time at the drop of a hat. But not every horse that ties up has this problem-again a tremendous amount of variability. Some horses are much harder to manage metabolically than others. Fling, for example, is extremely prone to cardiac arrhythmias that I am assuming (though we haven't yet taken blood when she's doing it-will try to catch her next season) are due to a Ca and potassium acute deficit. Only happens when she's had some major mind farts (omigod-there's a horse in front of me-gotta pass him, oh-there's another one, gotta catch up etc-she has Tom's mentality but I love her anyway) on the trail. Since I started adding more potassium and calcium to my electrolyte mix it seems to help. Since nervous sweat has a different sodium/potassium balance than heat dissipation sweat (work done a long time ago), my question is: has anyone else noticed this-if horses are particularly nervous they are more likely to get into electrolyte related problems even if on a "good" electrolyte supplement? I know the conventional wisdom at the race track is that nervous young fillies will tie up more than calmer ones or colts. Sarah (who will leave off my academic credentials from now on since they only seem to inflame certain people on the list and will use only my "practical credentials") Working at and vetting endurance and competitive trail rides since 1978, including 8 years of Old Dominion and the first 5 ROC's. Manager of the Horsetooth Mountain 50 mile Endurance 1984-1988. Actively competing with my mare, Fling for the past two years (we had been able to train for only one or two limited distance rides a year for her first 5 years of being eligible to compete). We have done over 1000 miles of competition together, not always successfully (pulled 3 times now at 3-day 100's, once for metabolic, the last two for lameness), but always enjoyed the feeling of coming across that line "WE DID IT!". It's taken me a awhile to figure Fling out and how to "rate" her on a ride. 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