While crates are extremely useful even when you're only dealing with your own dog, many people get by just fine without them. I did. Pongu whined and scratched and was so noisily pitiful whenever I put him in his crate that after the third day I just let him sleep on a towel next to my air mattress. (We were poor and furniture-free in those days, which was one of the reasons I was so cavalier about not crating him: even if he had been inclined to destroy my stuff, I didn't own anything he could chew.) The primary crate I use for foster dogs was a donation from a couple at my local dog park, who never used it with their dog for similar reasons.
If you only have one dog, and you can keep an eye on your dog all the time until you're sure he can be trusted, and your dog isn't terribly prone to chewing on furniture or making messes in the house, you can get by without a crate.
If you're fostering, a crate is an absolute lifesaver.
Most dogs in rescue networks have big question marks in their backgrounds. Many have never known a stable home -- or, for that matter, any kind of home at all. Some dogs have spent their entire lives on a chain outdoors or in a cramped puppy mill cage; to them, everything about living inside is new and confusing. They often aren't housetrained. They might not know the difference between a dog toy and a $300 pair of shoes... or an electrical cord for a plugged-in appliance. And, because most of these dogs are coming out of crowded, understaffed shelter environments (where stress and anxiety may create problems that the dog didn't have before going in), no one can tell you ahead of time if the dog knows these things or not. Crate training can save a lot of damage to your home, your patience, and the dog's confidence in the early days.
If you're dealing with a multi-dog household, a crate is even more important. It gives the foster dog a safe place that is immediately "hers" in another dog's territory. It allows you to separate the dogs for feeding, and to keep them separate while you're away from home. (No matter how good the dogs are together while you're around, it's unwise to leave them unsupervised until you can completely trust both or all of them -- and with an ever-changing foster rotation, that day may never come.) If they play together every waking moment, the crate may be the only way to grab a moment's peace and quiet for yourself.
Finally, as a foster parent, your ultimate goal is to help the dog get adopted into a suitable, loving forever home. Everything you can do to make the dog more "adoptable" helps, and crate training gives the dog one more point in its favor. And if the dog can't tolerate being crated, no matter what you do, then at least you know that and can match it to adoptive families accordingly.
Crates come in two main types: wire-sided collapsible ones and plastic-sided airline-approved crates. My personal preference is for the wire-sided type, which is easier to clean and easier to see into (so you can tell at a glance if your foster dog's getting into trouble), but either kind works. There are also fabric-walled crates, wooden crates, and crates that look like artistic sculptures, if you're not into wire or plastic.
Whatever kind you choose, the crate should be large enough for the dog to stand up, turn around, and lie down comfortably, but not big enough to tempt the dog to potty in one corner and sleep in another. Fill up some of the empty space with boxes or block it off if the crate is too large. Put in an old blanket or towel as bedding. If possible, the crate should be in a quiet spot in a frequently-used room (we use a corner of the living room that's under a flight of stairs), so it feels safe but doesn't feel like banishment to Siberia.
|Our crate is under the stairs in the living room: a quiet corner, but close to the family.|
Always feed the foster dog in its crate. This both helps the dog to associate good things with its "den" and serves the functional purpose of keeping dogs separate so they don't squabble over dinner. Similarly, when you hand out long-lasting treats like rawhides or stuffed Kongs, always give the foster dog its treats in the crate.
Don't keep a dog crated too long. A few minutes here and there over the course of the first days, plus mealtimes and bedtimes, is plenty. You can gradually increase the duration, but a dog shouldn't be crated for more than three or four hours at a time (consider a midday dog walker if you have to be away longer for work), and if possible, tire the dog out with a good bout of exercise before and after such long spells in the crate.
NEVER use the crate as punishment or for a "time out." Even if you're frustrated beyond all human endurance and need to get every four-legged furball in the house out of your sight before you strangle every last one of them a la Homer Simpson with Bart, NEVER send the dog to its crate in anger. Put on a smile, hand out the rawhides, send everyone to their assigned places with singsong delight... and then go punch a hole in the wall and/or pour yourself a drink. But never, ever do anything to make the dog think of its crate as a bad place instead of a safe warm den filled with treats and snuggle blankets and happiness.
And voila!, you have mastered crates, the #1 tool for fostering dogs without losing your mind.