The Arrival Trilogy by Lucy Daniels
Jenny Miles lives with her family on a farm in the Scottish Borders. Money is always tight, running a sheep farm. Even a new puppy has to earn its keep. But when Nell the sheepdog gives birth to a tiny puppy with a twisted leg, Jenny begs to keep him. Because there's something special about Jess ...
These stories have an element of Lassie about them - warm hearted adventures of Jenny, and Jess whose always ready to help in an emergency.