Our Dog Arie has a fatty tissue (according to vet) on his side near his upper back leg – Should we get it x-rayed to make sure it is benign?

Of course, any growth may be removed. If you are concerned, the first step would be to do a fine needle aspirate of the growth and submit cytology to confirm the presumptive diagnosis. Even if the growth is a benign lipoma, it may be your desire to have it removed. If Arie is in good health there is no reason not to remove the growth. This is always a question of “risk vs benefit”. So as long as the risk to Arie is low, proceed with the surgery if you want the growth removed. Once it is removed it may be biopsied to confirm complete excision and cell type.