I am so sorry to hear about Tucker. I went through something similar with Emma. When they gave her hydromorphon as a painkiller prior to anesthesia, she went deeply asleep. I had to take her to another vet to have the spay done. Even then, she had body flushing with the anesthesia. She is MDR1 normal/normal. Good idea to have this done. She was diagnosed with a heart murmur.