狗 is used to refer to the animal dog. It is a common and neutral term for dog.

In Chinese, classifiers (量词) are used before nouns to indicate the quantity or type of the object. 隻|只 and 條|条 are classifiers used for counting dogs in different contexts. 隻|只 is used for general counting of animals, while 條|条 is used for long and flexible objects like dogs.