Animals that are both higher intelligence in our perception and closer to us day to day will fall into the category of disgust, imo. For instance, I've had dogs my whole life. They're pretty deep creatures with emotions, intelligence, and personalities all their own. If you tell me that you ate what I have a personal connection to, what I consider my family - It's hard not to look at you in disgust. Similar to the disgust that people feel when they hear someone ate human flesh. The case with horses is similar.
Cows, chickens, turkeys, pigs, and fish on the other hand are not similar at all. They often have short memories, and live pretty simple lives. Thus, it's a bit easier to look at them as purposes for lunch. I'd be curious if Hindus feel relative disgust over seeing folks eat cow, I think that might bolster this theory a bit.
That said, although I feel disgust over that stuff I don't really say anything. If offered, I'd probably smirk and say, "That's not for me". Other cultures are allowed to, in my mind, enjoy things that might disgust me and vice versa.
Edit:
I'm also curious that if one day when all meat is lab grown if we'd ever feel those feelings of disgust. If the loss of what we view as potential personal connection is removed, it's entirely possible we wouldn't feel disgust at all.