HorseNetwork.com - Full Article
December 30 2017
ELEANOR KELLON, VMD
It happens every winter. A horse that may not even have a prior history of laminitis is found to be very lame and reluctant to move. It’s more than the typical hesitation horses show on hard, frozen ground. Looks like laminitis but the feet aren’t hot. What’s going on?
Cold-induced hoof pain strikes horses with insulin resistance. IR is a well described risk factor for laminitis and even when the horse is not glaringly lame it is causing damage to the laminae. We haven’t uncovered all the mechanisms behind laminar damage from high insulin levels but one known factor is elevated levels of endothelin-1.
Endothelin-1 is a peptide (small protein) produced by the cells lining the interior of blood vessels. It is the most potent vasoconstrictor known and is normally balanced by production of the vasodilating chemical nitric oxide. Cold-induced reduction in blood supply to the hoof when superimposed on the pre-existing high endothelin-1 activity may explain why some IR horses develop hoof pain in cold weather but normal horses do not...
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