17.—(1) Any person who—
(a)where he is not the holder of a dog licence, keeps a dog; or
(b)where he is the holder of a dog licence, keeps a dog of a description not authorised by the licence;
shall be guilty of an offence and shall be liable on summary conviction to a fine not exceeding £200.
(2) A person shall not be guilty of an offence under paragraph (1)(a) where he is the holder of a block licence which is valid in relation to the dog in question.