The other type of cacti are jungle cacti, and they do need humidity. These plants are more succulent-looking, and lack real spines, similar to 'Christmas' cactus. If this is the type you have, they like a bit more water, and during spring and summer, water plentifully to keep the potting mixture thoroughly moist.
There are about 3-4 million animaks euthanized each year by shelters. There actually are about 4-6 million animals euthanized in shelters in America each year. The above are just estimates. Shelters don't always keep accurate records, and no thorough surveys have been done. No one knows the real numbers.
In the 1990s, there are approximately 120,000 adoptions of children each year. This number has remained fairly constant in the 1990s, and is still relatively proportionate to population size in the U.S. (Flango and Flango, 1994)