It is not unusual for a slight swelling to occur at the site of a vaccination. The small bump is usually a result of a localized reaction to the vaccine and will normally subside within five to seven days. The bump is usually firm and remains small. If, however, the site seems to be soft and getting larger due to swelling or is tender, it may be an abscess. This would require a follow-up exam by your veterinarian, and he or she can advise what needs to be done, if anything. Swelling at the vaccination site is not normally a serious situation, but if there is any doubt in your mind, you should not hesitate to call your veterinarian and bring your cat in for an exam.
