Hi there!
The timing of the problem and the pulse you're seeing suggest either Damp Heat or Blood + Wei Qi deficiency as the two most likely differentials. If the pulse seemed feeble and slippery, then I'd wonder about the latter. If it seemed kind of excess and slippery, I'd wonder about the former.
The problem is that they are kind of opposite conditions, meaning if we guess wrong, we've theoretically aggravated the problem. You'd have to monitor the tongue and especially the pulse every couple of weeks, to make sure you were on the right track.
As long as you're in a position to do that, and chemo is a ways off, then I'd try Bu Yang Huan Wu Tang first, and see if you can tackle the problem that way. I've used it before for nasal adenocarcinoma and it has promoted long term stability. It also helps protect against some of the adverse effects of chemo.
If in a couple of weeks, the pulse is more slippery and broader, then you could change courses and try a Damp Heat approach, maybe using something like Hoxsey-Like Combination. Meanwhile, watch for symptom changes as clues. If the dog seems less dog aggressive on BYHWT, it suggests you're on the right track. If that gets worse instead, or if new problems appear, it suggests BYHWT is the wrong way to go.
Hopefully that helps you out!
Steve