Request #24

 I am trying to remember the title and author of a book I read in c. 1986, when I was about 11. It was about a girl who goes to stays with her relative for a period of time. She meets a woman who, it is revealed later in the book, is her recovering alcoholic mother. She befriends an elderly man who has a German Shepherd named MacDuff. MacDuff is swept out to sea when the girl almost drowns, but is later found safe and brought home.  Now Is Not Too Late by Isabelle Holland identified by Lost Classics reader ninyabruja!