A domesticated dog is an animal on a「taut leash」under the control of human masters.「A big condition, two-handed」(as contrasted with the 'smaller' condition) appears in many fonts today, and it may require two hands to restrain a big DOG on a taut leash. See related glyphs for the source of this glyph meaning MALE CANID, a DOG as a「hand with whacking motion, crossover」perhaps depicting rather intense training of the animal, or as a「hand petting and stroking」(犮), or「tapered stiff wood for driving into soil, a stake」(弋, the Chinese astrological sign of the Dog). Others say the old glyph is「marked hand holding taut head and neck」as a dog on a short leash, not able to run freely as he wishes…
　「Adult male person and rod with emphasis」requires little if any imagination to grasp in all these analogies that DOG, a male canid, is euphemistic of human male genitals (female canids are 'bitches'). Note the English term 'dick-dog' expresses a redundancy, no matter how it is spelled.
　In the case of a dog, perhaps 'man's best friend' is actually the ability to give himself a selfie with his own two hands in crotch (see 友, 犮, 犬, and 然) while「big, two-handed.」…literal dogs are noted for the ability to self-fellate at will, but human males must settle for the next-best thing, a「hand petting and stroking.」
　As an element, DOG is often associated with the「condition or appearance」of something or someone, presumably due to their extreme acuity of physical senses, including sight, smell, hearing, but especially their ability to hunt as a pack and being highly aware of all the pack members and their respective conditions during a hunt, and probably other senses that humans cannot even begin to understand. This is why humans often use dogs as guards, particularly at night, and for tracking.
　「Adult male human being in line and marked」or a「line of adult male human beings」with the emphasis on being in that line and waiting for one's turn at doing something also describes a domesticated dog, or dogs, as animals awaiting their turn mounting a bitch, such as the queue outside the entrance to a shaman's cave o' wonders, or, the gateway and inspection station with access to the brothel quarter, and so on.

Modern definitions (that generally disregard history) …excluding politically incorrect concepts and other meanings deemed offensive today; may list only pigeonholed definitions, euphemisms, or meaningless mnemonics)
Chinese: dog
Japanese: dog familiaris), snoop, loser, asshole, counterfeit, inferior, useless, wasteful, dog paddle, pup, puppy, whelp, dog sled
Unihan extended: dog
EDRDG: dog