"the former refers to little dogs while the latter is for bigger dogs"
No this strict distinction when using 只 or 条.
“is one used by speakers of a certain age or from a certain region?”
No
The emotional color is different:
一只狗, neutral word
一条狗, negative word
The stylistic color is different:
一只狗, written language
一条狗, spoken language
Extended meaning:
Describe someone whose life or character is like a dog's (negative), eg,
活得还不如一条狗。
Live is not better than a dog's life.
as measure words, the 只 vs 条
只: a quantifier used to describe the number of animals
条: is widely used, which can be roughly divided into 4 categories:
- For thin, long, and narrow things, such as 一条线 (a line), 四条黄瓜 (four cucumbers), 一条香烟 (a carton of cigarettes); 一条狗 (a dog)
- Used of rivers and streets, such as 一条河 (a big river) or 一条街 (a street);
- Items used to itemize, e.g., 一条建议 (one suggestion), 两条新闻 (two pieces of news), 三条办法 (three methods);
- Used of human: 一条人命 (a life)