Here is the site I think you are talking about.  They are also available at most TSC (Tractor Supply Company) stores.

http://www.cautionhorses.com/

Steve

You can have them custom made at your local sign shop.  I had decals with my name and hometown put on my trailer in the color and font of my choice.  They can do anything you can think of given enough time.

See ladies, I always tail-gate trailers that don't have the caution signs on them just fo fun  and to see the drivers sweat!

I've seen lots of trailers with Caution show animals, or Caution live animals instead of Caution show horses like we used to see everywhere.

Maybe on my next one I'll put:

Caution, crazy horse lady.

I've got more insurance than you.

My horse bucked off your honors student.

Caution, hayburners inside.

If I didn't have horses this would be a _____________. (Dragster in my case.)

 "I always tail-gate trailers that don't have the caution signs on them just fo fun  and to see the drivers sweat!"

My trailer's 8'W and 37' nose to tail so I can't see tailgaters!  I figure a tailgater will tail gate no matter what they follow so no use sweating what's behind me.  Like your tail signs though.  I know someone who used to have a sign on the back of her trailer that said "Organized Confusion!"  Man was that appropriate!

What would even be better if you have the half back doors....Have the horses tail on the outside with a sign that says "s**t happens".

I bet they wouldn't tailgate then.

"My horse bucked off your honors student."  

LOVE that one!

I have a bumper sticker that a friend gave me years ago for my 2h bumper pull.

                 CAUTION

If you can read this then your following to closely

We are not responsible for horse buns on your hood.