I have been using equine chiropractics, acupuncture, and massage off and on my horses since 1994.
Yes it does all work, but like human chiros and doctors, not all practitioners are created equal.
While having someone show their "sheepskin" is a step in the right direction, two of the recent equine chiropractors I have used are both veterinarians. One is so good at chiropractics and acupuncture that she doesn't even practice medicine. The other one isn't worth that proverbial "hill of beans"
One of the best equine chiros to have ever worked on my horses was an endurance rider in SoCal who learned the art to keep her own horse "together". She didn't have any fancy papers but she had been taught and had a natural instinct --- instinct is important no matter how much schooling someone has for this venue.
Hope this helps you with your decision