After a long, cold winter, the animals of Isabella County are getting testy. Dr. Pol and Charles head out on a farm call to treat an angry bull with a deadly case of bloat. Dr. Pol must act quickly, or the bloat could block the bull's diaphragm and lead to death. Back at the clinic, a cat injured while birthing kittens inspires Charles to volunteer at HATS, the Humane Animal Treatment Society, whose goal is to keep the animal population in check by way of spaying and neutering animals.