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[RC] calcitonin (was Mares Tying Up) - Susan E. Garlinghouse, D.V.M.Heidi, your explanation is right on, but you have your hormones switched. The substance which releases calcium from bone storage depots is parathyroid hormone (PTH), not calcitonin. Calcitonin's job is to take excess circulating serum calcium and stash it into storage for mobilization later. Thus, if the ration is consistently too high in calcium, then calcitonin is produced in excessive levels (hypercalcitoninism) and the parathyroid gets lazy and produces too little PTH for mobilization. Anyway, your explanation of the process is perfect, just substitute "parathyroid hormone" for "calcitonin". :-) Susan Garlinghouse, DVM -----Original Message----- From: ridecamp-owner@xxxxxxxxxxxxxxxxx [mailto:ridecamp-owner@xxxxxxxxxxxxxxxxx] On Behalf Of heidi@xxxxxxxxxxxxxxx Sent: Sunday, December 12, 2004 2:57 PM To: karenellis3@xxxxxxx Cc: rainbow@xxxxxxxxxxx; ridecamp@xxxxxxxxxxxxx Subject: Re: [RC] Mares Tying Up I must have missed something - calcitonin? Karen Calcitonin is a hormone produced by the parathyroid glands that regulates the body's ability to mobilize calcium in times of stress or greater need. The body is very dependent on keeping calcium levels fairly constant in the bloodstream, so when serum levels of calcium drop, calcitonin is released, and calcium is released from the bones to keep blood levels from falling too far. Unfortunately, when calcium levels are comfortably adequate to excessive in the daily diet, sometimes the parathyroid gets "lazy" and does not produce enough calcitonin. When this happens, and then there is a stress that requires more calcium, the blood levels drop too low and begin to jeopardize various body functions. The classic example of this is milk fever in dairy cattle--if they are fed too much calcium during their dry period, then when they suddenly begin to produce milk just prior to calving, their blood calcium drops and they literally collapse. The scenario in horses is a bit less dramatic--but nonetheless, some horses are far more apt to have low calcitonin levels on good to slightly excess calcium levels in their diets, and then get into trouble at rides. They generally don't display the collapse that the dairy cattle do, but various things can happen, including tying up. The suggestion that was given to Drin in view of slightly low calcium levels in her mare's bloodwork at the time of the tie-up was that perhaps she could avoid this in the future by supplementing a wedge of alfalfa the day or two prior to a ride to provide the extra calcium that will be needed, since perhaps her mare is not producing sufficient calcitonin to mobilize it from the bones. Heidi =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Ridecamp is a service of Endurance Net, http://www.endurance.net. Information, Policy, Disclaimer: http://www.endurance.net/Ridecamp Subscribe/Unsubscribe http://www.endurance.net/ridecamp/logon.asp Ride Long and Ride Safe!! =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Ridecamp is a service of Endurance Net, http://www.endurance.net. Information, Policy, Disclaimer: http://www.endurance.net/Ridecamp Subscribe/Unsubscribe http://www.endurance.net/ridecamp/logon.asp Ride Long and Ride Safe!! =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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