"The Center for Equine Health at UC Davis is dedicated to advancing the health, well-being, performance and veterinary care of horses through research, education, and public service"
This Minimum Standards of Horse Care document was published in 2010, written by experts in equine care to establish the minimum accepted standards of horse care in regards to water, feed & body condition, shelter and space, health care, and transportation, for California.
http://www.vetmed.ucdavis.edu/ceh/sp_standards.cfm
http://www.vetmed.ucdavis.edu/ceh/docs/special/pubs-HorseCareStandards-bkm-sec.pdf
