My cat was neutered and on the first night the wound looks like this; is it serious, is this normal?

The photo shows the male cat’s scrotal wound has opened a bit, exposing tissue and reddening, which may cause poor healing. Watch for bleeding or redness; if present, take it to a vet.

If not, disinfect with iodine and spray antibiotic. Most vets do not stitch such small neuter wounds, but stitch if the cat is very active; after healing, remove stitches. Always keep a proper E-collar to prevent licking and infection.