A few reasons:
It's illegal:
1.) You can't buy dog-hunting licenses.
2.) Dog meat is not rated fit for human consumption by the government.
3.) Dogs are domesticated, which means the dogs you hunt will most likely be owned by someone other than you.
4.) Dogs are domesticated, so it's considered unsportsmanlike.
It goes against western values:
5.) Specifically, canines and humans have had a symbiotic relationship for as long as 400,000 years. [
1]
6.) As an immediate consequence, dogs and humans both consider each-other to be members of their immediate family.
7.) As a further consequence, mentally-stable humans of European descent are programmed not to harm domesticated dogs. Most of us have extreme difficulty even
watching a dog being killed (moreso than humans, in my case). See below for why this may not apply to Asians.
Dog meat isn't very good:
8.) Cultures that consume dog meat eat strays exclusively. There are no wild dogs in North America. Koreans differentiate strongly between food-dogs and pet-dogs.
9.) Cultures that consider dog meat to be food have, within the past 17,000 years, experienced severe famines that made the consumption of dog meat a matter of survival.
10.) Extending upon the last point, Asian cultures did not develop with the dog as a symbiotic organism as we did.
11.) In spite of this fact, dog meat is only commonly found in China because China is a living hell full of monsters and dragons [2]. In Korea the practice has been banned, but the ban is not yet being enforced. Buddhism, Islam and Judaism all teach that dog meat is unclean.
12.) Even if the Chinese people believed that eating dog meat is wrong, they would have no way of telling the world [
3]. Seriously though, the Chinese believe that dog meat has extremely potent medicinal value so it is eaten very rarely, and never in the larger westernized metropolises (Bangkok, Shanghai, Hong Kong).
And that's why.