Pip and Squeak the miniature horses, Farmyard Friends series, by Lisa Mullarkey,  published by Calico (an imprint of Magic Wagon, a division of ABDO), 2019.

About the book:

Introduce young readers to the world of Storm Cliff Stables and Pony Girls! Meet Pip and Squeak the miniature horses, Silo the dog, Patches the cat, and Sweet Pea the sheep. They face challenges from friendship to gift giving. Luckily, these farmyard friends always know just what to do!

Pip and Squeak are best friends. They do everything together! Then Squeak makes a new friend, and Pip gets upset. But soon he learns it’s great to have more than one friend!