Most of time we do not keep the dogs or cats to stay overnight in the hospital after OHE or castration. We always perform surgery in the morning, so we have enough time to observe the animals recovering from anesthesia for at least 3-5 hours. I believe let owner takes their pet home after such a minor surgery is good because owner can give the best watch on their pets especially there is no doctors or assistants stay in the facility at night in most of the hospitals.(same as in USA).
I have no idea about the hospital you ask. Please ask someone has been there before.
Dr. Lee
Most of dog had castration should recover well in 24 hours. There shouldn't be any severe swollen on surgical site especially we removed both testicles from the area cranial to scrotum(I don't know where the surgical lesion is on your dog). We didn't cut the scrotum to perform the surgery so there is no any trauma on it. We saw few cases shown swollen of scrotum due to bleeding problem. If you think your dog's swollen is too severe, please take him back to the hospital for recheck. The pain for this surgery shouldn't be very severe. They may feel a little bit of uncomfortable for the first 24 to 36 hours. They should walk OK when they go home and run OK in 1-2 days later. Sometimes the dog will lick the surgical lesion in a few days after surgery due to itching of skin healing. You can apply some antibiotics/hydrocortisone ointments twice a dy for a few days. The stitches will be removed in 10-14 days if there are stitches.
Dr. Lee
The surgical lesion looks OK, Only shown mild sign of irratation. When you go back to recheck, please make sure there is no fever on Shaw-pon. It is not normal for dog still vomiting 2 days after surgery especially for such a small procedure.
Good luck!
Dr. Lee