Without some alterations, a lot of quadruped mammals that are land-based end up looking rather alien, probably too alien to go unaltered in most cases. With horses and especially antelope and deer, the leg proportions compared to human limbs get a little crazy, so toning the amount of elongation of those parts is acceptable. The important thing is to not start with a human "blank"--otherwise you end up not with a non-human animal that has been given a more human form, but a human body with some non-human features stitched on. Some non-human features do not look right on a human blank--i.e., the basic human "blank" may not have the structures to support things that non-humans have, like whiskers, prehensile tails or any tail with a broad base that streamlines into the body, fins, large horns, tusks, etc. Above all, stick with the non-human animal as the base, then compare the proportions, think about what physical features need more support or balancing features, and then conceptualize the animal onto a humanoid form appropriate for the animal's original anatomy--leave nothing out, and add very little!

Another tip that is bird-specific--most birds have incredibly short torsos compared to humans, though this may not be apparent through the thick coat of down feathers that most birds possess. Don't measure the feathers for basic anatomical shapes! Like a poodle with a lot of poofy fur, the actual body of the bird isn't as big as the poof makes it appear. XD