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RE: [SPAM] Re: [SPAM] Re: [RC] Thumps - heidiI had a horse that was prone to thumping, but was one of those on which it meant nothing. He could be absolutely normal at every perimeter, but still have that slight tic in his flank. I controlled it with extra doses of calcium. Which will certainly work, if calcium is the issue. In some horses, the problem seems to be magnesium. In researching some of the reasons this particular horse was prone to thumps, I came up with some interesting information. One of the very well known Endurance vets told me this horse had a large heart for his body size. This was a very small horse, less than 13.3. It seems to me since the nerve in question runs near the heart and fires in rythym with it, that an extra large heart in a smaller body cavity would be more likely to cause thumps as the nerve would be positioned closer to the heart. Is this false reasoning? I suspect so. The nerve runs right across the heart, and the heart discharges an electrical potential with each beat. The size of the heart really has nothing to do with it. Think of the nerve instead as being like an electrical wire. If there is a hole in the insulation, the wire will short out. The problem is with the myelin sheath insulating the nerve itself--not with any sort of anatomical size differences. Another factor that I felt contributed was, this horse was raised in an area where the grass is very high in calcium. Cows pastured in the area often develop milk fever in the spring due to the high level of calcium in the soil. I was given this information from a local large animal vet who treated these cows so I assume it is accurate. I know when a horse is given an excess of calcium, his system loses the ability to source it from his skeleton which I believe is what the normal horse does under stress. So it stands to reason if a horse was raised in an area with an over abundance of calcium available in the grass, his system is probably not well developed to pull calcium from his bone. This ability usually comes back when the diet is corrected, though. This scenario could certainly be a factor as long as the horse is on the improper diet--provided his phrenic nerve is susceptible to the problem. This seems to be as much genetic as anything. Horses that are not going to thump won't do it no matter how bad the diet or how badly they are overridden or dehydrated. Horses that are prone to thumping will do so with very little provocation. And there are all "shades of gray" in between. I participated in a study conducted by Dr. Nagota back in the '80's. He was researching calcium levels and how they related to thumps. At a 105 mile ride in Ohio, blood was drawn from horses participating in the study 6 different times throughout the ride. This particular horse finished that ride in 3rd or 4th place so I was not riding conservatively. After the ride was completed and all the data collected and reviewed, Dr. Nagota called me as my horse was the only participant whose calcium levels stayed stable or even elevated a little throughout the ride. Since this was inconsistent with the results from the other horses, he wanted to know why. The answer, of course, was the extra calcium supplementation I was doing. But did the other horses thump? This sounds like an interesting project, but unless one has already determined that a given horse is prone to thumping, I don't think it has much application across the board to other horses. I've seen too many horses "clear off the charts" that don't thump, while others thump with very little variation. The only time this horse was ever pulled from a ride for thumps was at the World Championships in Front Royal. A Swedish rider had leased him and did not follow my instructions on administering calcium during the ride. The horse was thumping slightly at 60 miles, but was absolutely normal in all other perimeters. Had we had another 15 minutes in the check, I could have eliminated the thumps, but as I was unable to administer the extra calcium until the check and he'd had none for 60 miles there wasn't enough time to get the thumping under control. Therefore, he was pulled. The rider could not have continued any way. She was in far worse condition than the horse, but the horse could have finished easily barring other unforseen events. Sounds very typical of a horse that will thump with very little variation--and as you've found out, some of these individuals can be controlled by very careful e-lyte regimens. One other thing of note, at a convention where Valerie Kanavy was a guest speaker. During her presentation, she talked about horses that recover to extremely low pulse rates, stating, that in her experience, these horses often have issues in other areas. One of the issues she mentioned being thumps. My horse had extremely good recoveries under extreme conditions. He was often recovered to 32/36 BPM at a vet check very quickly. I wonder if the large heart may have contributed to the low recoveries and the thumping as well. I'd have to disagree. I've seen thumpers in all sorts of pulse brackets, and have seen far too many low pulsing horses that NEVER thump to think that there is any correlation. Yes, the large heart will contribute to the low recoveries--but as I already stated, I think it has nothing whatsoever to do with the thumps. Just coincidental traits that in this case happen to occur in the same individual. Heidi =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Ridecamp is a service of Endurance Net, http://www.endurance.net. 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