Good quality, dry food is the most healthy. If your bag of food ingredients starts out with a meat product you can almost always bet it is a better quality food. Unspayed females have about 7 times greater chance of getting mammary tumors than spayed females. When your pet is spayed, the uterus and ovaries are removed to prevent pyometra disease. Neutered males are usually less aggressive, better behaved and easier to train because they are more attentive to their owners.
Neutering can also help prevent certain types of cancer.
Spaying and neutering improves hunting instincts. Unaltered pets usually have their minds elsewhere, such as mating or fighting. Unspayed hunting dogs have heat cycles every six weeks during the year. Females in heat are not physically up to hunting. As long as these birth rates exist, there will never be enough good homes for all the animals.