I wouldn't want to be without Benadryl in case of an allergic reaction. Children't liquid is fine and figure your pup's dose before a problem comes up.
Playpens do come in handy and a carseat would be a good idea.
For shampoo, I'd look into the John Paul and Tigi lines.
Some other things you might want are nail clippers, dog friendly nail polish
, towels for bath time unless you're sharing yours, robe, washcloths for eye gunk, eye wash (sterile water not contact solution), ear cleaner, thermometer with KY jelly and disposable covers, a bell for her harness, Snuggle Safe heated disc, treat jar, brush, Tick Twister (depending on your area), stroller.............................. I guess it depends on how much you want to spend.
