Anything that causes pain in people can be expected to cause pain in animals. Pets may not show the same symptoms of pain as people do; they usually don't whine or cry, but you can be sure they feel it. Pain medications needed will depend on the surgery performed. Major procedures require more pain relief than things like minor lacerations.
For dogs, we may recommend oral anti-inflammatories/analgesics for a few days after surgery to lessen the risk of discomfort and swelling. We use newer medications, which are less likely to cause stomach upset and can be given even the same day as the surgery.
Because cats do not tolerate standard pain medications such as aspirin, ibuprofen, or Tylenol, we are limited in what we can give them. Recent advances in pain medications have allowed for better pain control in cats than ever before. We administer an analgesic/anti-inflammatory prior to surgery. After surgery, analgesics/anti-inflammatories are given on a case by case basis. Any animal that still appears in discomfort will receive yet additional medication(s).
Injectable pain medications, CRI's (intravenous), nerve blocks and/or narcotic patches may also be used after surgery on both dogs and cats. Providing whatever pain relief is appropriate is a humane and caring thing to do for your pet.