Your sister's guinea pig lives in a cage, this makes sense. But what about that empty cage in the corner? The door is swung open and a peek inside tells you that there is a well-loved chew toy and a blanket. The conclusion is quickly reached that this is a 'cage' for Molly, the beautiful white Bulldog puppy.
Is this cruel? Your sister explains to you that it is not a cage, but a crate, and that she is training Molly to use it. Back to the question, is this considered a cruelty? Those who say it is use the argument that it is like a prison cell to your pet or only a means to 'get the dog from underfoot'. When used properly, crating Molly is not a cruelty, but can become a haven to her.
As den animals, dogs have a natural desire to have a space of their own where they can retreat. You will witness this behavior in dogs that are not crate trained, they will pick a spot in the house that they will consistently return to and consider their own. Crate training Molly has benefits to her owner as well. Because dogs are highly reluctant to soil their dens, using a crate is helpful in the housetraining process. Letting Molly learn to trust and feel comfortable in a crate at home makes traveling with her simpler. It is safer for you to have her in a crate while driving, and she will be somewhere that she already feels secure.
Your puppy's crate should be large enough that she can stand up, turn around and lie down. A too small space could lead to Molly panicking and potentially hurting herself trying to get out. Also be aware that some of the more intensive chewing puppies may chew their way out of a fabric crate. Place inside a water bowl that attaches to the side or door, a blanket and a favorite toy. Puppies are very curious creatures, and your puppy may crawl into her new haven as soon as you place it on the ground. Leave the door off, or at least propped open while she gets used to the space. If little Molly is unsure of this new space and reluctant to go inside use the following steps.
Toys and Treats
Let Molly see you place a treat inside. If she just runs in, grabs it, runs out, still praise her and give her positive reinforcement. Continue daily with placing treats inside; eventually she will associate the crate with the treats and see it as positive thing. Praise your brave little puppy whenever she goes inside on her own. Resist the urge to nudge or force her into the crate. There is an exception to this rule, and that is when your puppy has to sleep in her crate from the beginning. Gently put her and if possible keep the crate in the room with you.
Closing up the Crate
Staying in the room with Molly those first few times that she's in her crate will help her to not associate being closed in with you leaving. If Molly starts to fuss, don't yell at her and don't immediately let her out. Wait until she stops, and then open the door. If you open the crate back up right away, she'll learn that whining gets the door open.