Dogs are known for forming such strong connections to their humans. On the spectrum between farmed-for-food and totally-off-limits, it's not hard to guess where we would put dogs.
It's just like indians and cows. Cows have a special place in their culture, therefore they don't eat beef.
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.
If you've read the studies I did, they're not very good. For instance, the test that asserted a pig is smarter than a dog was where they were tasked with moving a joystick designed for a monkey that controlled a cursor that they wanted moved into a blue region on a screen. I'll let you make your own judgements about how sound the testing with respect to the assertion is. My dog certainly has eyes that can be tuned to manipulate me, but she also has a sizeable vocabulary, a lot of tonal intuition, and this little heat seeker in her nose that quite literally syncs her heart rate with mine. There's a good amount of theory that says this adds up to empathy.
Now, with pigs, you have a point. They're indeed very smart.
I justify eating pigs by reasoning that pigs will happily eat humans if they get a chance (a few pig farmers lose their lives that way every year, plus there's the occasional serial killer...). Turnabout is fair play.
Think in general this holds to animals seen as pets. Like in the West with adorable little guinea pigs, which in the Andes Mountain regions are a food source. And it makes sense too if you live high in the mountains that get snowed in in the winter, to have a bunch of them living in your home.
You can have a relationship with animals and raise them but they are also food. You can ride horses and eat them, to me that isn't contradictory because killing for sustenance isn't an evil act, and if the animals are raised well and kept in good conditions and live happy lives there's no issue.
I think the psychological issues are mostly about anthropomorphizing animals and not having personal experience with the food chain, killing animals for sustenance or quite frankly death which most people now have a completely pathological relationship to.