The safest way to do this with your dog is to work with a holistic vet. They know the products that work, the manufacturers who are careful about the products they make, and can give you a customized treatment plan for your little guy.
This site may help you find a holistic vet near you
http://www.holisticvetlist.com/#search
I usually search based on state and small animal to get the biggest listing of vets to check out.
Just trying things that are advertised over the net may not be the best choice for your dog.
Another possibility is to have a consult with a veterinary oncologist. Many of them are open to and prescribe alternative treatments as well as traditional ones. This site may help you locate one near you
http://www.acvim.org/Specialist/Search.aspx
I usually search it by specialty and state.
Hope this helps you!
Dog Expert:Rescue, Train,Breed,Care
30+ yrs dog home vet care & nursing, rescue, behavior&training, responsible show breeding, genetics
I think your changes may be fine for him. Sometimes the pain med Piroxicam can help shrink tumors so you might want to talk to your vet about that. Often you need a stomach protecting med when using it.
But I think a holistic vet consult would be excellent as you might find a chinese herb, or another alternative medicine choice will help him even more.
My personal view on dog care is that I want to keep the dog happy, comfortable, as pain free and able to do the things the dog loves as I can. Then when we get to the point the dog is no longer comfortable or is unable to do the things he loves to do that is when I consider euthanasia. With his senior age getting a few more good weeks or months may be worth the effort.