shoe has to be changed

Question
hello sir, how does a farrier get to know that the shoe has to be changed for a horse?? i meant, that shoe is no longer in use. a new one should be shod to the horse.  

Answer
HELLO EASY...

You have sent me 5/6 questions a few mins. apart. I am trained to do Veterinary farriery and
work with some of the finest veterinarians in the West/Southwest. I am here to give "solid" advice and help people get out of problems to make both their's and their horses lives better.

I NOT HERE to write "volumes or essays" on "how to or shoe your own horse and cripple him/her
so that you can mess it up yourself"!!!

It is NOT fair to me or my readers who DEPEND on my knowledge and accuracy with this web-site.

I WILL answer your one question out of kindness...

Two reasons for changing a shoe. The thickness of the shoe. Excess wear at the toe or heel area
or maybe wear on one side more than another.
Nail holes will be bigger from wear and tear and cannot hold a suitable nail.
Also...the hoof capsule itself will be long in the toe or too much heel growth so as the horse
will have to be trimmed and another shoe will be applied back on after proper trimming
is done.

Thank You...
Joepaul Meyers,C.J.F.