well like in a shelter situation, not 100 dogs at your house unless you had a few acres and the money to feed them and get them doctor care and the time to throw balls for them sometimes.
I would donate to these places if instead of gassing them, they put them on a farm with lots of other dogs. If the people cleaning up after them, feeding them and playing with them were all volunteers it couldn't cost that much to run it and if every town had one or two of these then way way less dogs would have to die
We have a "no-kill" shelter in our county. It's called "All God's Creature," and it survives on donations. But, although someone donated a couple of acres of lands, and an old house, it takes a lot of money to build kennels, buy food and medication, and spay and neuter. Local veterinarians offer very low cost spay and neuter services, and even medical care, and neighbors (including our neighborhood) give bags of dog foods, toys, old towels, bedding and all that. The local grocery store also helps by selling them dog food at reduced prices, and by collecting dog (and cat food, obviously) from their customers for them.
We had a big fund raiser where the "dog whisperer," (don't remember his name) came, with an auction, etc. . .they were going to build a new big kennel on the 2 acres of land, but they never got enough money.
So they bought an old farm house and made a kennel out of it. To keep it going, they offer boarding for people who want to leave their dogs while they go on vacation, and also grooming. They also go to gas stations on weekends, etc. .. and instead of a "carwash" sale, they have a "dogwash" sale! It's kind of fun, and many people volunteer. They also go to malls (like near PetSmart) about once a month with a 1/2 dozen dogs and offer them for adoptions. . .they can usually place 2 or 3, which allows them to take in a few more. They are doing really well for a lot of dogs, but could NEVER take as many as 100 dogs at a time. . .so they do have to say no sometimes, especially if the dogs are aggressive.
Still they are doing a great job, and I always give them a check at the end of the year, and a couple of bags of food, flea products, etc. . .during the year, as do most of my neighbors.
But there is NO WAY they could take in all the dogs that are dropped at the SPCA, in addition to the dogs that are dropped at their place. A dog lives 12 to 16 years. . .and they NEVER put a dog to sleep, unless he is terminally ill or is suffering.