cracked heels

[0]

why do horses get cracked heels?
my horse has her legs washed as soon as she comes in every day whether they look muddy or not, she is ten and has never had them before (had her since baby) but she has just got cracked heels - why would this be?
she has moved to a new area so can different soil etc cause it??
vet has looked and she is on anti-biotics i just want to understand how she got it when her legs are washed every time she has been out (field and ridden)

ETS: i meant to put this in veterinary, so i have just put it there aswell as i don't know how to delete this!!

 

[debonhorse]

personally, I think you are better off not washing the feet every time, but actually letting them dry off naturally and then brush the mud off. by washing every time, the bacteria breeds better on wet hair, which can turn to mud fever, also, if you are continually washing, its like washing your hands all the time, if you dont cream them up occasionally they will get sore. even vaseline on the heels after washing can help.