Liz Buchanan BVSc MRCVS
Sometimes, when sutures can't be seen, it is because the vet placed them internally - it makes them less likely to be pulled out - or even that the wound has been glued. However, the redness around the wound may indicate inflammation / dermatitis and the scrotal sack may be slightly filled. Particularly if being bothered / licked / rubbed by the patient, this can at times lead to concerns. Many vets ask for post op checks or phone calls if you are worried, so this may be a good place to start.