I did a non-scientific test a few years ago with 3 lights, all the same made and model, but with different LEDs in them (white, red, green). That was as comparable as I could do the test between the colors. I then proceeded to spotlight animals as they walked up to a water hole. I was on a water tower, approximately 40 yards away.
Basically what I found was that generally speaking, red seemed to bother them the least. Red also offered the least clarity for me to see. I understand that is a product of the longer wavelength. Green seemed to bother animals less. White bothered them the most. It was not uncommon to illuminate the animals with each color and have one or more lift its head and look at the light. So they did see the lights. The worst reactions were when they got lit up and they just ran.
Keep in mind that these are generality statements and NOT absolutes.
All colors of light were seen by the animals, though they likely cannot see red as red, but probably see it as a gray illumination. Keep in mind that being red/green colorblind (as many animals apparently are) does not mean things of a given color are invisible to you, just that you don't see them in their distinctive color.
I have seen the videos for folks selling lights where they claim a proprietary color that animals "can't see" and they offer proof by shining their light on an animal that does not react. This is an ignorant conclusion at best and likely balls-out deceitful statement. I have lit up hogs, coyotes, raccoons, and deer with white light and they didn't respond. That doesn't mean that they were blind to the light, only that it did not bother them at that time.
It was suggested above to use a wide beam. That isn't bad advice. Also, slowly lowering the beam down on animals seems to spook them a lot less than suddenly lighting them up which seems to illicit a startle response, sometimes causing them to run away.
Not only can animals such as hogs see red light (though as noted, not see it as red), they can also see the dull red glow emitted my infrared illuminators. While the light shown from such lights may be truly invisible to the hogs, the illuminators themselves produce a small amount of visible light that can be seem, even if it doesn't shine with any intensity on the targets.
Powerful lights will get noticed by animals more than weak lights as well.