The American Red Cross has this on their website:
Q: I’m a heavy cannabis user. Can a transfusion recipient fail a drug test if they receive my blood?
A: No.
They don’t care if you’re high as a kite as long as it doesn’t impair your memory or comprehension (probably for legal reasons).
Somewhat related, there is a vaccine for cats in the works meant to prevent feline chronic kidney disease. If successful it could massively increase the lifespan of domestic cats.
https://www.boredpanda.com/medicine-cats-live-longer/