Learn English – Where does the word “totty” come from

The Online Etymology Dictionary and myEtymology mention:

1520s (implied in puppetry),

• from Old French poupette, dim. of poupée "doll" (13c.),
  • from Vulgar Latin root *puppa,
    • from Latin pupa "girl, doll" (see pupil).

Metaphoric extension to "person whose actions are manipulated by another" first recorded 1540s.

More details in this "Word of the day" entry, including about the related word puppy:

In the middle ages lap dogs were also called poupée because they were thought of as playthings—not working dogs.
Poupée morphed to puppy and so with time any little dog began to be called a puppy.

Note: the origin of the word puppeteer is more recent (1915).

The Wiktionary entry for "docga" suggests a possible origin in the root of a word originally meaning "power, strength, muscle" along with a diminutive suffix -ga.

It occurs to me that single-syllable words (or single syllables plus a suffix) can come about onomatopeoiacally. The root "dog"/"doc" doesn't necessarily have had to have come from "somewhere".

If the Wiktionary entry is correct that there is only one known attestation of "docga", it is striking that it became the word that eventually ousted "Hund" (as the generic word). On the other hand, I guess it's possible that "docga" was widely used, just not in the kinds of register that tended to be written down. (It's quite common for words to shift register over the years.)