Boxers have been nicknamed "cancer factories" by some. As distasteful or offensive it may sound, it does illustrate that Boxers are prone to cancer. And while other dogs may develop cancer, Boxers seem to develop them at a younger age.
We lost Rocky to cancer. As heartwrenching as it was, we did not hesitate to get another. The sorrow is but a reflection of the joy they have brought to our lives. Not to miss them would mean that they didn't mean much to us.
Regarding wild animals being healthier than domestic. How do we know that to be true? Wild means that there are no health records on any given species. In nature, the weak and sickly become food for predators, or are driven from the group. Those not fit for breeding are eliminated, not only by predators, but also by the hierarchy within their groups.
Disease does decimate wild animals. Rabies is the one that immediately comes to mind, but there are others such as distemper, and many of the other diseases that we innoculate against.
However, those that remain after an epidemic has claimed many, do so because they have a natural immunity, or strong immune systems that enable them to overcome the disease. This is a trait that can be passed on to their offspring.
How much of a role did "developing" the various breeds play in determining what their health issues would be? Can anyone answer that? Breeds were developed for specific purposes, or for a particular appearance to some arbitrary standard. They were bred to arrive at a specified physical appearance. It may have been size or shape, but those were the prime considerations in breeding them.
Little thought was given to health considerations.
In the wild, canine species may gorge themselves after a "kill", then go several days without eating. While some recommend fasting a dog periodically, I have heard no one suggest not feeding them for several days, then stuffing them with food.
In fact, many recommend feeding two or three meals daily rather than one. Do a search on feeding here, and some will feed their dog a small snack before their regular feeding to reduce vomiting or regurgitation.
As much as we know about cancer, there is much more that we don't know. There are known carcinogens, and there are suspected carcinogens. Some foods seem to inhibit the development of cancer, while others are suspected of causing, or "encouraging" cancer to develop in certain parts of the body.
Since Boxers have a relatively short life, it is our responsibility to make the most of the time we have with them. Enjoy them, and make their lives enjoyable. Doing that will help to improve their health and ours.
Tom