From an AAEP press release in The Horse.com:
The body systems that followed in order of importance under the same criteria were gastrointestinal (82%), respiratory (74%), endocrine (67%), and nervous (62%).
Specific conditions they cited included:
Tendon injuries 44%
Navicular disease 36%
Racing injuries 34%
Suspensory ligament injuries 32%
Foot problems 31%
Osteochondritis dissecans (sic) (OCD) 28%
Rhinopneumonitis (herpesvirus) 26%
Recurrent lower airway disease 24%
Foal pneumonia 23%
I am really surprised to see zero interest in learning behavior, the equine brain, or social, emotional and bonding behaviors among horses and between horses and humans. This focus on physiological issues alone reinforces the prevalent view of horses as mechanical means to a human end.