The abuse is based on harmful effects caused by not having all things that are necessary for the animal. Or not feeding them or brushing them. One of the main kinds of abuse is neglect. The definition for this would be doing something to the animals that would hurt their health, or their well-being. Neglect is a big problem in the United States.
People think that they can leave their animals in a crate, or tied up all day.
For instance, dogs are pack animals, they need to be around other animals or humans. It is wrong and cruel if you don't spend time with your animals. Also, there are more adult animals abused than young ones. The reason for this is because people will see a puppy in a pet store, and go ahead and buy it even though they aren't prepared for them. Most of the time they don't even think about the future of the pet.