For a nice little breakdown of the transformations in each part:
part i - horse
part 2 - rabbit and sheep
part 3 - dog and gender swap
part 4 - cow and horse
part i: fresh air
"this is exactly what we need," jessie told her husband
Adult Content, Alchemy, Aroused, Authority, Bad Language, Ball Growth, Balls, Betrayal, Bisexual, Blackmail, Bovine, Breeding, Canid, Character Development, Cisgender, Cock, Cock Growth, Collar, Consensual, Corruption, Couple, Cow, Cum, Deep Penetration, Dick, Dishonesty, Doberman, Dog, Doggystyle, Domination/Submission, Ejaculation, Emotion, Equine, Erection, Explicit, F/F, Fantasy, Farm, Feeding, Female Ejaculation, Feral, Flirtation, Forced, Forced Sex, French Kissing, Gender Shifting, Gender Transformation, Growth, Heartbreak, Heat, Heterosexual, Hooves, Horse, Humiliation, Impregnation, Kinky, Knot, Knotting, Lagomorph, Leash, Lesbian, Licking, Love, Lust, M/F, Magic, Mammal, Master/Pet, Mastiff, Mate, Mating, Mature, Messy, Milking, Modern, Morphing, Naked, Naughty, Never Seen Sex Act, Novel, Nude, Nudity, Orgasm, Ownership, Passion, Penetration, Pheromones, Pregnancy, Public, Pussy, Rabbit, Relationships, Riding, Role Reversal, Romance, Secret Love, Seduction, Seductive, Seed, Semi Consensual, Sex, Sexy, Sheath, Sheep, Story, Straight, Submissive, Tail, Teasing, Temptation, Third Person, Transformation, Vagina, Various Species, Voyeurism, Vulva, Weight Gain