as far as effect on the animal, no. But you can have something resembling a placebo effect with the owners of the animal. The animal can improve or worsen in their eyes, but on retest, there was no change.

As far as acupuncture goes, I again haven't read any exact studies, but the clinician discussed with me what she had learned about it. Some of the theories about the "science" of acupuncture relate to the "energy nodes" used for acupuncutre being "coincidentally" near or directly associated with nerve bundles. There can be no doubt if you look at a full meridian network, that there is certainly an uncanny resemblance between them. So that association along with some studies have presented the theory that acupuncture directly stimulates particular nerve nodes that help alleviate whatever associate symptom. This makes a lot of sense to me, as you could see muscles twitching a bit while the horses were having their acupuncture. It also makes sense why it could alleviate symptoms of many disorders, if indirectly. Even if all acupuncture did was create a "deep tissue massage" relaxation benefit, it would lower the stress of the patient.