The phrase "a young dog" is correct and usable in written English.
You can use it when describing the age or stage of development of a dog, typically indicating that it is not yet fully grown.
Example: "The shelter had several animals available for adoption, including a young dog that was full of energy and playfulness."
Alternatives: "a puppy" or "a juvenile dog".
A young dog called Sid is so filled with happiness that he flies!
Asked to recommend a possible mate for Jean, he sized up one young woman as "tall, well made, limbs a bit long — sprawling movements like a young dog — intelligent, very gifted and very reserved".
Ms. Rossellini is a "puppy walker," someone who will spend a year with a young dog teaching rudimentary skills and habituating the animal to crowds, bright lights, cats and, yes, pigeons.
His first self-portrait in particular: it is the artist as a young dog, an etching of himself snarling at the mirror, rejecting the viewer's (and by implication, society's) gaze.
Then again, given how intensely taboo the condition has been for most of history, it may often have been desperation that drove some epileptics to eat the testicles of a bear, pulverised camel's brain, a young dog, maggots from a rotting sheep's nose or earthworms during coitus (yours, not theirs).
A young dog found wandering the streets during the violence in Hackney was saved by a riot police officer.
One afternoon, amongst a pack of stray dogs was a younger dog of about 4 to 5 months old.
Having adopted very old dogs fifteen years ago, this time I think I would like a younger dog.
It's easier to teach a younger dog, however, older dogs will learn with enough repetition.
If your family does not have the time or energy to meet the needs and responsibilities of a younger dog, find a dog that is over 2 years old.
He knew he was playing his young doggishness for all it was worth, and was even conflicted about it, resolving not to act the "jolly dog," but lapping it up when Johnson calls him "a wild young dog" or a "drunken dog".
