Messy horse stands in her manure

[samp]

My mare's pretty filthy has bed of mats with shaving banks. She has a large stable but being lazy she insists on depositing her poohs where she stands so ends up standing in manure which are not doing her hind hooves any good. Any advise? If someone told me a huge bed i'm not convinced as she'd still stand in it. Tried moving her hay etc

 

[Sarah Sum1]

Chippings in the middle may help a bit, as they will be kicked bout and some will cover said poo.