Joining a long list of alleged animal prodigies is "Mascot the Talking Horse" (shown in a cabinet-card photo about 4¼" x 6½").
In seventeenth-century France, for instance, a famous "talking" horse named Morocco could perform mathematical calculations and other feats. He was charged with "consorting with the Devil," but he saved his and his master's lives by kneeling, seemingly repentant, before Church authorities.
Other sapient creatures included a "Learned Pig" and a "Wonderful Intelligent Goose" that appeared in London in the late eighteenth century. Such animals responded to secret cuing from their trainers.
(See Joe Nickell, The Mystery Chronicles. Lexington, Ky.: The University Press of Kentucky, 2004, chapter 33: "Psychic Pets and Pet Psychics," pp. 277-288.)