What happens to the Mechanical Hound?

The Mechanical Hound attacks Montag, and Montag destroys it with the flamethrower, but not before it stabs him with a needle full of anesthetic.

There are two. The original, Montag sets on fire, along with Beatty and the other firemen (I hope you've read the book :)). Then, one is brought in from another city, but Montag escapes that one and it gets blown up along with the city.