I'm sorry
Never let the sun set on a pyo. If that is in fact what it is and the uterus is this noticeably diseased the surgery is needed today. waiting could cost her her life very easily. Spinal arthritis should not complicate a spay. There are many vets that would be okay doing this. Please find one today. Cancelation or no cancelation..it's not right that they aren't doing this on an emergency basis.