Fox
Foxes are present in The Sims 4: Cats & Dogs as a small dog breed with a unique fox voice. They can be adopted by Sims and can mate with dogs. The default traits for foxes are independent and troublemaker. Aside from their appearance and voices, however, they behave like normal dogs.
Like other dog breeds, foxes and fox crossbreeds occasionally appear as randomly generated strays in Brindleton Bay, as well as pets in randomly generated households.
A fox can briefly be seen interacting with a bloodhound in the reveal trailer for Cats & Dogs, as a possible reference to the 1967 novel The Fox and the Hound, or the 1981 film adaptation by Disney.