Do histiocytoma usually get larger if bumped or licked by dog. Had ours reduced by 50 percent and he played too rough and now we are back at square one. How do we keep an 18 month old boxer from playing and busting this thing all over. He requires a ton of exercise but even walks have been hard because it’s on his left hind paw pad on the upper side. Any suggestions. We play in the house almost all the time but I am exhausted. There is no way we can keep a boxer puppy quiet for 2 to 3 months. When he accidentally hits it, he will limp then want to lick because either it starts itching or has started to bleed. We have been spraying gentamicin on it twice a day per our vets advice due to location and constant exposure to ground and it looked a bit infected. It helped reduce it down to the size of the tip of my finger but now it is the size of a nickel. It was confirmed by needle biopsy to be histiocytoma but is this normal? He is also on famotidine for bilious vomiting occasionally and she said it may help with this also. He takes amitriptyline for severe anxiety so is benedryl safe and possibly effective in controlling the itching and release of histamine when he bumps it?