Whenever your dog needs surgery it is very important to do full blood work prior to be sure all organs are functioning properly.
For example if the liver or kidney levels are off (and you don’t know it) the anesthesia during surgery could produce more problems for these organs that could later be fatal.
This is also true of younger dogs going in for spay or neuter. Vets will give you the option of doing the work up or not.
I highly recommend y0u spend the extra money to be on the safe side.
If your vet does not suggest this, question them. If they say its not necessary please find a new vet.
*Even if you have no surgery planned and you have a senior dog (age 7 and up) yearly blood work is important to check all organ function. If something is elevated you can reverse it with meds or natural supplements or at least keep it in check (from further elevation).