"Does the CDH taste better when it is made with HCL than with Citric Acid?"
To my taste buds, there is a huge difference in taste between CA and HCL. And, CA can cause stomach problems for some people and maybe animals, too. Andreas Kalcker says in his recent book, Forbidden Health, on page 71:
"Precaution 7
Using citric acid as an activator can provoke intestinal acidosis in sensitive individuals causing diarrhea, discomfort, and Citro-bacteria (bacteria that feeds on citrates). This mix is never used anymore, although it is equally effective. Note: Citric acid can be used to make CDS because it doesn’t go in the final mix. We only use the gas created."
The reason you are making CDH with citric acid is because sellers of MMS products keep selling it! I have tried to discuss this and other problems with some of the products sellers market, but they ignore my advice. The other problem is that Jim continues to say it is okay to use CA as an activator, yet he also says HCL is the preferred activator.
I would be careful using DMSO. A little goes a long way. Since your dog doesn't like taking CDH now, I would stop adding DMSO, use HCL to make CDH and see what happens. I am assuming that you are adding DMSO to each dose and not to the bottle of CDH. DMSO will reduce CLO2 content in a short time.
When treating those lymph nodes topically, using CLO2 gas and applying CDH directly to the skin should be okay. But, don't leave the solution on her skin too long.