The initial stress from being confined can give way to "increased feelings of security, safety, and comfort" after repeated exposure to the crate.
"[1] On the other hand, if properly done, crate training can play a major role in housebreaking a dog as fast as possible.
[1] Borchelt (1984) states:[1] Nevertheless, a dog can learn to tolerate confinement in a crate and accept it as a place of comfort and safety.
[1] The Humane Society of America recommends crate training to create a place of security and comfort for a dog, while cautioning that it is not the best solution to animal behavior problems.
The correct size for a crate is just enough room for the animal to stand up without hitting their head, lay down and stretch out their paws and to turn around unimpeded.
[7] Likewise, crates that are too small pose a health risk by restricting and preventing proper air flow and ventilation.
Due to their shortened airways and limited ability to cool themselves through panting, overheating while traveling poses a risk to the health of such breeds.
The crate is the only space in the entire house that truly belongs to the dog, and if used appropriately, will become a safe haven for years to come.
The pet will attribute any emotional responses such as raised voices or other nervous behaviors to the foreign object in their normal environment.
It is important for the owner not to create any negative associations with the cage in order for the pet to accept the crate in a calm manner.
Long term or excessive crate confinement "may lead to emotional and behavioral deterioration over time."
[1] Steven Lindsay in Handbook of Applied Dog Behavior and Training states that while "the role of crate confinement in the etiology of behavior problems has not been scientifically established [...] empirical impressions and logic dictate that it probably plays an important role in the development or exacerbation of many adjustment problems.