Animals that go on fasting 

Elephants Elephants go on fasting when they are seriously injured. 

Dogs Whenever they suffer injury, dogs go on fasting till they recover. 

Horses  Horses go on fasting when they are sick. They lose their appetite when they fall sick.  

Penguins  Penguins fast in order to improve the quality of their sperm. 

Seals  Seals fast to improve the quality of their sperms and and eggs to produce healthy young generation.

Bears  Bears go into hibernation during winter and sleep for long hours. It is during that time that they go on fasting. 

Crocodiles  Crocodiles go on fasting during summer due to the rarity of food. 

Snake  Snakes fast after consuming preys and keep them in their intestines especially when the preys are larger than their bodies.