« Listen, Hound of Sauron ! he cried. ‘Gandalf is here. Fly, if you value your foul skin ! I will shrivel you from tail to snout, if you come within this ring ! »
J.R.R Tolkien, The lord of the rings, Part one, The fellowship of the ring, Chapter 4, A journey in the dark
"The very impressive musculature of the Wargs is not just a visual fantasy designed to impress. Cattle breeders are aware of a natural mutation which results in muscular hypertrophy and is caused by the ‘mh’ (muscular hypertrophy) gene.
As muscle is the most valuable part of a bovine carcass, breeders have selected animals with a mutation in the ‘mh’ gene, allowing for greater muscle development.
In Tolkien's work, Wargs are the more or less the pets creatures of the forces of evil. Their overdeveloped musculature, their reflective eyes and their aggressiveness are not the result of chance but the result of a fine selection by the orcas and Saruman.
They would have been "like cattle breeders, fine observers, able to select and crossbreed individuals with the most interesting characteristics for the use they had in mind, in this case crunching heroes".
The species we know as pets are all descended from a remote, wild species.
For example, all dog breeds originate from the domestication of a wolf population, while the pig originates from the wild boar.
Over the generations, breeders have selected useful morphological and behavioural characteristics to create new ones, very different from those present in the wilderness, as shown for example by the differences observed between the muzzles of a dog and that of a wolf.