How much do it cost to have a dog put to sleep

I forgot call the human society and ask them.

Hello Greg! Euthanasia fees depend on the dog's weight, your preferences with his remains, and whether you'd like to be present during the procedure. If you'd like to be with your pet, please call 314.951.1534 for an appointment. If you do not wish to be with your pet (and the fee is a little lower) you may bring him to either of our adoption centers between 10am and 5pm. We're sending our sympathy during a tough time ❤

Last time I did it was 75 I think but call them

I've never used them for that and it's to hard to remember. And, I think you meant, does it cost; not "do it cost".