My horses are a hobby, not a business therefore my expenses far out weigh any income. However I've noticed that in entering barrel races lately that they are requiring a W-9.  My concern is identity theif, I don't know how the information is handled and how secure it is kept. Thinking about applying for a EIN with the IRS to use on these W-9 with the barrel producers.  If I was to win enough to get a 1099, I would offset the income with expenses (always keep receipts and records) and file a Schedule C with my personal taxes anyway. Wonder if anyone else has used an EIN instead of SSN on W-9.  

Once you start filing using the fed schedule C than you are basically saying you do have a business. 

An EIN is used to identify a business. I am not sure that you could use an EIN and file as a hobby. You also cannot offset hobby expenses through your taxes. You can only offset expenses, as you are describing, as a business.