As my field is biomedical optics, I probably ought to have heard of this, but I hadn't. A quick survey of the field suggests the following:
1. Scientific evidence is contradictory, some experiments have shown an effect, some haven't.
2. There's a whole load of bad science done on this, there are lots of parameters to vary in the light applied (let alone what you are trying to treat with LLLT) which have generally been ignored, which means that any conclusions reached are fairly meaningless anyway. The general approach seems to be just to point a laser at an injury and see what happens.
3. As ever, the big problem on working on in vivo targets is that they very variable - enough so that any small effect will be masked by the variability.
4. As the wavelengths and powers used, light won't do any damage to the body (except the eyes).
So as things stand, my opinion is that it won't do any harm and might just do some good. But as no-one's actually worked out the power density/irradiance/exposure time/wavelength that will encourage healing, nor what tissues it will be effective on, it's a long shot. But it's unlikely that there will be much difference between the effects on dogs and humans.
