I have a conscious awareness of children, and parenting. Animals evolved sexually but if you remove those organs the hormones driving those instincts usually goes away. Hence why the horses we geld from a young age never even try to exhibit breeding behavior. In turn, my horses aren't thinking, "Oh, darn. I'll never be a parent. That's so sad." It simply doesn't occur to them. If I were to sterilize myself, I have a higher level of awareness in which I would know I was missing out on parenting. A female dog who has been spayed does not look at other dogs and go, "Oh, man, I really wish I was a mother!" It is absolutely ridiculous to think so. Furthermore, even if they did, as humans it is our responsibility to keep their breeding behaviors in check, save we let them roam free, starving, and diseased as they do in countries that cannot afford to do so. Please stay away from animals, people with your mindset is the reason millions of cats and dogs are euthanized each year. They think Fluffy longs to be a mother so they breed her four times and you end up with 20+ dogs that don't need to be in existence, many of which will end up killed in a shelter at one point in their lives. Cheers.