Originally posted by YellowLabLover
My guesses:

1) Clydesdales- I got to pet them at the Missouri State Fair
2) Saddlebreds & Quarter Horses
3) A coggins test is when they screen the blood for the nasty virus called " Equine Infectious Anemia". All horses traveling through other states, and for events must have a coggins test done.
4) If I remember correctly a Thoroughbred and Quarter Horse makes an Appendix Quarter Horse.

I'll leave some questions open for others.
Good job YLL!
All are correct! For number 2, I was just thinking of the Saddlebreds but he probably has some QH's too.
For number 3, I just want to add that the test is required by law on any horse to be sold, shown or brought across state lines.(like you said)
The 2nd part of question 4 and question 5 still need to be answered as well as my previous question about the cowboy artist.