It is very important to pick a crate that is the right size for your pet and is suitable for its purpose. Often larger crates come with some kind of divider so that a crate can grow with the pet. The right size for a crate is simply enough space for the animal
to remain true without hitting their head, lay down and loosen up their paws and to turnaround unimpeded.
A crate for use in the home can be bigger than one used for travel. Crates used for international transport should stick to international regulations stipulated by IATA. If the crate is too big your pet will have a way to use one end for rest and sleep while using the other as a toilet, that'll undermine among the purposes of crate training.
A dogs natural instincts are to get rid of from the region in that they eat and sleep. So if a crate is small enough which they cannot possibly defecate whilst having enough space to sleep well from it, your pet dog will'hold it'as long as they possibly can. It's this instinct we make the most of when using a crate as an aid for house training.
During air travel, a large cage does not permit your pet to use the sides easily as a brace during turbulence. Likewise, crates which can be too small pose a health risk by restricting and preventing proper air-flow and ventilation. This is of particular concern to domestic pets of a brachycephalic (short-headed) breed where in fact the requirement is allowing extra room because of the high incidence of death in these pets during transport. Because of their shortened airways and limited ability to cool themselves through panting, overheating while traveling poses a risk to the health of such breeds.