Hi Michelle,
That's a pretty bizarre finding. I can't think how it might relate to the TCC. Certainly it's not a typical herb side effect.
My first thought is that this is a new problem. When dependent edema suddenly appears affecting the dog anywhwere (but more commonly the neck and forelimbs), I wonder if this is the very earliest stage of glomerulonephritis. So I'd check the urine P/C ratio.
Meanwhile, though, the formula we use to address that is one called Fang Ji Huang Qi Tang (Stephania and Astragalus). In humans, it deals with Wind invasion creating sudden edema in the upper body (most commonly seen in acute nephritis), usually the face. In animals, their entire periphery counts as the upper burner, as per the discussion of where the burners are exactly in the Nan Jing. So acute onset of superficial and dependent edema anywhere would have me thinking of Wind invasion.
The idea is that Qi must descend from the upper burner to the Kidneys, carrying water down to the Bladder with it. Wind invasions disrupt the natural movement of Lung Qi. Sometimes we see it as a cough. Sometimes it is this disrupted descent of Lung Qi to the Kidneys, with subsequent superficial edema formation.
Regardless of the metaphoric diagnosis, I'd try the FJHQT. It restores normal filtration in the early stages of renal disease, as well as being somewhat of a diuretic (Damp drainer). It improves liver function, too, in the event there is a problem there. Has albumin been checked and the dog had a blood profile? I'd advise that, too, so we have all the facts there are to have.
All the best in your strange case.
Steve