[QUOTE=Colibri]
John has this exactly right. Whether wolves and dogs are
the same species is a matter of definition. Since the definition of species according to the Biological Species Concept does not apply to domestic animals, it is impossible to settle the question by invoking the BSC. As with other cases where the BSC can’t be applied, one must use other criteria to decide species status. While in the past the convention was to class domestic animals as species separate from the ancestral species, the modern convention is to include them in the same species. The only thing to be “settled” is whether you accept that convention or not.
[/QUOTE]
Do we do this with all species? Cows, Sheep, Horses, Cats, Pigs, and so forth?
As far as the cat goes, it still seems to be a matter of debate (Wiki) "*The domestic cat was named Felis catus by Carolus Linnaeus in his Systema Naturae of 1758. Johann Christian Daniel von Schreber named the wild cat Felis silvestris in 1775. The domestic cat is now considered a subspecies of the wild cat: by the strict rule of priority of the International Code of Zoological Nomenclature the name for the species thus ought to be F. catus since Linnaeus published first. However, in practice almost all biologists use F. silvestris for the wild species, using F. catus only for the domesticated form.
In opinion 2027 (published in Volume 60, Part 1 of the Bulletin of Zoological Nomenclature, March 31 2003[5]) the International Commission on Zoological Nomenclature “conserved the usage of 17 specific names based on wild species, which are predated by or contemporary with those based on domestic forms”, thus confirming F. silvestris for the wild cat and F. silvestris catus for its domesticated subspecies. (F. catus is still valid if the domestic form is considered a separate species.)
*"
http://www.iczn.org/BZNMar2003opinions.htm#opinion2027
"OPINION 2027 (Case 3010)
Usage of 17 specific names based on wild species which are pre-dated by or contemporary with those based on domestic animals (Lepidoptera, Osteichthyes, Mammalia): conserved
Abstract. The Commission has conserved the usage of 17 specific names based on wild species, which are pre-dated by or contemporary with those based on domestic forms. The majority of wild progenitors and their domestic derivatives share the same name, but in the 17 cases considered (1 Lepidoptera, 1 Osteichthyes and 15 Mammalia) the wild and domestic forms have been separately named and this has created confusion.
Keywords. Nomenclature; taxonomy; Mammalia; Perissodactyla; Artiodactyla; Rodentia; Carnivora; Lepidoptera; Osteichthyes; names for wild species with domestic derivatives; Equus africanus; Equus ferus; Camelus ferus; Lama guanicoe; Vicugna vicugna; Bos primigenius; Bos gaurus; Bubalus arnee; Bos mutus; Capra aegagrus; Ovis orientalis; Cavia aperea; Canis lupus; Mustela putorius; Felis silvestris; Carassius gibelio; Bombyx mandarina; ass; tarpan; Bactrian camel; guanaco; vicuña; aurochs; gaur; water buffalo; yak; bezoar; Asian mouflon; guinea pig; wolf; polecat; wildcat; Prussian carp; gibel carp; mulberry silk moth."
And from what I can see, the Horse remains Equus caballus, and not Equus ferus.
Sheep remain O. aries, and not O. orientalis or several others (perhaps that’s the reason, they aren’t 100% sure of what ancestors the domestic sheep really does come from).
And of course, Humans remain Homo Sapiens, not Homo erectus or something else. We’re “domesticated” too, aren’t we? Or are we? 
So, it’s a new (2003) ruling by the International Code of Zoological Nomenclature, it goes against established rules of priority, and it’s applied unevenly. We’ll see if it sticks. They have changed their minds before (in fact this is them changing their mind).
But I’ll point out, this isn’t quite the same thing as the Commission and Zoologists agreeing that all Wild species and the domesticated species are the very same species- it’s a naming convention. There is no rock solid line between “species” and “sub-species”, and here the Commission has just thrown their hands up in the air and ruled that most domesticated species are the same as their wild forebears, without doing a lot of genetic material work, etc.