As nouns the difference between dog and giraffe

is that dog is a mammal, Canis lupus familiaris, that has been domesticated for thousands of years, of highly variable appearance due to human breeding while giraffe is a ruminant, of the genus Giraffa, of the African savannah with long legs and highly elongated neck, which make it the tallest living animal; yellow fur patterned with dark spots, often in the form of a network; and two or more short, skin-covered horns.

As an acronym DOG

is digital on-screen graphic.

As a verb dog

is to pursue with the intent to catch.