How To Be Your Own Veterinarian (sometimes) - A Do-it-yourself Guide For The Horseman by Ruth B. James, DVM. (Used)
From the introduction:
"I have tried to emphasize preventative measures which may be taken to keep many problems from occurring so that you may never need to treat them. Many illnesses, such as founder, are in large part preventable, but may be nearly incurable or permanently damaging once they have occurred. Preventative medicine is the cheapest form of veterinary care- and the most effective in the long run!"