Look up what happens when someone puts rubber bands around a watermelon, and then imagine putting that on a puppy's tail to achieve cheap tail docking, or cheap neutering of goats, sheep, horses, cows, etc. Obviously the organs won't explode, but it puts extreme pressure on the tissues and destroys them.
These practices are not only inhumane, but extremely painful, and more prone to infections. Please do not do this. Spaying and neutering is expensive, I know, but I'd rather have it safely and humanely done versus cruelty and trauma.
