Holly Webb is great for Year 3 girls. She writes lots of different animal stories but also has some other series like Maisie Hitchins, which are mystery type books, and another called Museum Kittens
The Jasmine Green animal series by Helen Peters is also perfect for this age, and Zoe's Rescue Zoo.
Bear and Rabbit series is funny and full of coloured illustrations.
Isabella Moon is aimed at age 6-8ish so she might still enjoy them, and the Kitty series by Paula Harrison (she's a superhero with cat powers).
Dick King Smith wrote loads of animal stories and age 7-9 is the perfect age for them. The Hodgeheg, The Sheep Pig, The Invisible Dog, The Mouse Family Robinson etc. George Speaks is another favourite Dick King Smith book of mine, although that one isn't about animals
Lots of girls start getting into Jacqueline Wilson at this age too. Many of her books are aimed at slightly older, due to more mature themes, but some of her earlier stuff like The Suitcase Kid, Double Act, Mum Minder, The Bed and Breakfast Star, Tracy Beaker etc are fine for Year 3/4 age.