Definition order of adjectives of noun
'黑小狗' = 'black small dog' (small in size)  or 'black puppy' (small in age)

小黑狗 = small black dog

Some breeds of dog can be held with one hand. They are 小狗 (small dogs) too, but it doesn't mean they are not adult dogs

To be specific, you can use '幼犬' (infant/small dog) for 'puppy'.