I believe it is a malnourished Staffordshire Terrier (my girlfriend has one) with a brindle coat. The specifics on the breed can be found at the AKC website or by Googling. The tail is tapered and stiff like a Staffordshire and, assuming an injury had been experienced in the past, a crook would be evident.
Regardless on whether I'm right about the breed, I am 100% certain it is a terrier of some variety (but not a British Bulldog -- that would be mistaken for a hog, "pac man" frog, or Jabba the Hut).