also lap-dog, 1640s, from lap (n.) + dog (n.); figurative sense of "subservient person" is by 1950.
Senator McCarthy (R-Wis) renewed his Communists-in-Government charges today and called Senator Tydings (D-Md) the Truman administration's "whimpering lap dog." [AP news story, Aug. 7, 1950]
A rough, somewhat stupid and crude man; gorilla, strong-arm: the tendency of some covert agents, ''the knuckledraggers'' of the Special Operations Group, to revel in deception
[1970s+ College students; from the image of a gorilla whose knuckles drag on the ground when it walks]