Cruelty to animals is a crime, and refers to the abuse or killing of animals when it is unnecessary. Necessary circumstances would include killing animals for food or putting a suffering animal out of its misery.
An example of cruelty to animals would be dog fighting rings.
Cruelty to animals is the maltreatment of animals. It could range from beating a dog to killing horses for sport.
Those found guilty of cruelty to animals can be prosecuted by a court of law. Lengthy jail sentences can be applied if the cruelty is severe enough.
Legal hunting is not classified as cruelty to animals; however, hunting seasons are regulated by the government. Note that the appropriate use of force as a training tool does not qualify as cruelty to animals.