How Kalhoun came to have an Iron Horde wolf by his side was through an act of desperation on the battlefield. His rifle jammed, his wolf companion dead, he found himself separated from his battalion. 

When attacked by a houndmaster and his beast of war, Kalhoun had no choice but to throw a Tame onto the charging beast and set it upon its owner. It’s lucky that he was able to keep the required eye contact long enough.

That’s also how he acquired an Iron Horde weapon; the houndmaster no longer needed his.