Evolutionary ethologists don't think there was one dog in the beginning. Dogs evolved from wolves, but wolves like dogs also have many breeds. Various breeds of dogs have evolved from the different types of wolves.
The table below outlines all the different groups of dogs and where they came from. We're not sure how long ago this all was, but dogs were first domesticated around 14,000 years ago.
Clutten-Brock, J. (1999). A natural history of domesticated mammals. Cambridge University Press.
1.Canis lupus chanco (small Chinese wolf) > Early Chinese and Mongolian Dogs
2.Canis lupus lycaon (large Northern wolf) > Eskimo breed of spitz type
3.Canis lupus Arabs (small western Asiatic wolf)
>European and Southern Asiatic Dogs
>Canis familiaris metris-optimae (Shepard dogs)
>Canis familiaris inostranzewi (Northern Indian moloses)
>Canis familiaris intermedius (braques)
>Canis familiaris leineri (harriers)
My guess would be to look into the Kennel Club, as they are the registered organisation that deals with dog breed definition: when they started was when dog breeds were defined as they are today. All others from art, or literature in history are simply close resemblences physically to the breeds we have today, but they may not actaully be the same or related breeds
The Border Collie is a breed of dog known for its intelligence and loyalty.
The breed of dog known for its loyalty and intelligence is the German Shepherd.
Vizsla is a breed of dog that first originated in Hungary. The Vizsla is a medium-sized sporting and hunting dog, which has also become known for its suitability for being a family dog.
The dog breed known for having distinctive brown eyebrows is the Rottweiler.
The dog breed known for having distinctive eyebrows is the Bouvier des Flandres.
The breed of dog known for its distinctive facial features and eyebrows is the Siberian Husky.
The dog breed known for its expressive facial features and eyebrows is the Siberian Husky.
The breed of dog known for carrying a barrel around its neck is a St. Bernard.
Chiuauha.
The breed of dog known for its fluffy white coat resembling a snowball is the Samoyed.
I think the Dalmationthe Dalmatian.
Dalmation