Can I Give My Dog household 3%?

No
Outdated practice: peroxide damages healthy tissue and slows healing. Flush wounds with plain saline instead. (Peroxide's only modern use is vet-directed emesis, see its own entry.)
Source: Veterinary Partner (VIN)
Already ingested? Pet Poison Helpline 855-764-7661

Skip it or ask a vet first if

all wound care

The safe habit

Confirm any medication decision with your veterinarian, who knows your dog's health history and other medications. VetDose shows published reference data, not prescriptions.