Hi again,
Don't you ever sleep?
The information is a little sketchy to prescribe upon, but I'll give it a go.
Heat intolerance can be due to body-wide heat symptoms or just to heat in the upper burner. Heat in the upper burner would create a dry thin tongue as well. In this case, then, the erratic pulse would indicate Heart Fire, but in a deficient sort of way.
At the same time, the benefits of lasix imply a Damp draining influence is needed. Unless it's the hypotensive drug. But I'm betting the lasix had the most benefit, because I can tie it quite well to the Heart Fire. Basically, I'm wondering if the connection between the Heart and the Kidney has become weakened, leading to Heart Fire, and increased Damp (pathological Yin) in the lower burner. If this is the case, then a formula like Rehmannia Eight might allow the Heart and Kidneys to reintegrate. The earliest discussion of Rehmannia Eight was in reference to its ability to treat pulmonary edema. This might be even more powerful an effect if Gui Zhi is subbed for Rou Gui, or at least added in. Gui Zhi (Cinnamon twigs) promotes better peripheral circulation and the mobilization of edema. It was the original form of Cinnamon advocated for the formula. Given that the dog is on a hypotensive drug, to some extent, it is conferring that effect. But you could add it all the same.
Good luck and I hope I'm right!
Steve