In order to have a breed speciality for both horses and dogs/2 horses or 2 dogs, why are you allowed only one breed specialization tag when you edit your profile? Therefore, does one always have to create another account to specialize in another breed and receive the benefits for that specialization? Is it a plus to the player and breed to have each breed specialization on different accounts? *did that make any sense*

You get one breed specialty of your choice.

So if you want to have a breed specialty for a horse and a dog, you would need two accounts. 

The breed specialty gets you some extra points when you place in shows and 10 extra shows a week that you can train in, so it does benefit you to have the breed specialty set. Plus the "enter all" button for them, which makes training easier.

What Adranth said.

It benefits the game as a whole to only have 1 per account, because the perks for it are a major reason that people upgrade so if you could have more than one on an account then people would upgrade fewer accounts and we woudln't make as much income. And the income we make goes into supporting the game and keeping it open, as well as getting updates. And in additino, I live off of the income, which makes me able to work on HP full time, which might not be possible with fewer upgrades.