split hooves

I have an older quarterhorse who is not shoed but gets regular visits from the farrier. She is kept in a pasture and she rides great. the only problem is here since it has been warmer her hooves have taken a turn for the worse. they have multiple cracks and chips in them. It is to the point that some of the cracks are so bad you can no longer trim them for fear of making them worse.We have put the hoof oil on and her food has hoof supplement in them. How can i fix this, she is a wonderful horse and i have not been able to ride her since this has occured. any advice is needed.

The warmer weather has dried the ground out and this is putting pressure on her hooves and they are cracking. Unfortunately it soudns like her horn quality isnt as good as it once was as she has gotten older. Shoeing her may help this as the shoe will prtect her feet. Biotin will help her horn quality. Also make sure she is getting a balanced diet with plenty of vitamins, minerals and protein to reapir those feet.