Looking at the picture in different light now that my blinds are closed, I notice that the animal is a darker shade than I thought, and it appears that it may have the characteristic nilgai hump (looks like a smaller, less pronounced version of a bull buffalo hump). It also appears that the critter has comparatively thin fur that lies flat against it's skin, signifying that it's a warm-weather animal.
I've gonna cast my vote for Nilgai.
If you ever get a glimpse or better picture of it, observe how it runs(they bounce as they run-it's comical).
If it has 2 horns, 3-8" in length and sloping back, and it has a beard like a tom turkey(seriously!), then it's a Nilgai.