The Fifth-Book Hounds, or simply Hounds (pt: Cão do Quinto Livro or Cão) are a race of mutated wild dogs in Brazil.
They are a mutated variant of the more common canis fammiliaris, and can be distinguished from their brethren by their larger size, elongated nose, bulging teeth and far more aggressive behavior toward humans. Also, they seem to be slightly less perceptive to their environment then the common dog; this has not yet been proven, however, due to difficulties in obtaining test subjects.
Their most notable development, however, would be that they have allegedly developed superior brain function. According to some field researchers, they seem to have developed a primitive growl-based language, and to now develop societies more complex than families or packs. In fact, these researchers claim these hounds now build small multiple-family clans, complete with initiation rituals and identifying symbols.
Before the Great War, dogs were the most widely spread domestic animal in Brazil - both for their use as guard animals as well as for being relatively easy to tame and keep - and as such were commonplace throughout both urban centers and farmsteads.
When the bombs fell, many of the country's dogs died, either immediately due to the blast or subsequently by the hands of the famished survivors. Most of those who survived were farm dogs, safely distant from the nukes or the countless refugees - this being the reason most living dogs are of larger races, descendants of the big Shepherd and Labrador species favored in farms at the time.
Not all dogs, however, met one of those two fates. Those who lived along the Stripe were, as happened with most creatures there, hit by the worst the nuclear fallout had to offer, and were mutated accordingly, becoming the resilient, ravaging beasts they are known for.
Some theorists claim that it was during this period they acquired their new level of intelligence. As their body increased size, so did their brain mass, allowing for more complex thought. And big as they were, they were still no match in one-on-one combat for other local predators, such as the guatirica and the radliggator, and needed to band in groups in order to obtain food. These two factors combined led to a more complex social organization, and eventually to a quasi-vocal communication system.
The term "fifth book hound" is actually older than the species it names. Back before the war, in the Brazilian northeast, collective public school was mandatory, and as such all kids received the same textbooks. One of those books, the one of the fifth-grade, depicted a hound who was strong, mean and exceptionally skilled. When the mutated giant dog was first seen in the region, it was understandably associated with the folklore.
In modern day, an idiom separation occurred. While originally the terms were similar and interchangeable, "dog" (pt. "cachorro") now refers exclusively to the original species, and "hound" (pt. "cão") now refers solely to the mutated variant. It may also be noted that the portuguese term "cão" also refers to the christianity's Devil.
The Fifth-Book Hound may be found all over Brazi, having successfully spread from their birthplace at the Rad Stripe.