How Long Do Animals Stay Pregnant Elephant: 22 months The longest pregnancy of any land animal. Baby elephants take their time! 玲 Walrus: 15 months These marine mammals carry their pups for over a year before giving birth. Dolphin: 10 months Smart and social, dolphins have pregnancies similar in length to humans. Cow: 910 months Cows, like humans, have relatively long gestation for a farm animal. 鍊 Hippo: 8 months These water-loving giants have a shorter pregnancy than cows. Goat: 5 months Goats multiply quickly thanks to their relatively short gestation. Cat: 2 months Cats are fast reproducers with just a two-month pregnancy. Dog general: 2 months Most dog breeds have a quick 2-month turnaround. 輦 Kangaroo: 45 weeks Surprisingly short! Joeys are born tiny and develop in the pouch. Mouse: 3 weeks Mice multiply rapidly with one of the shortest gestations in mammals.