The most important first aid after an animal bite is to wash the wound immediately and thoroughly with plenty of soap and running water for at least 15 minutes. This step can remove or kill a large amount of the rabies virus before it enters the nerves. After washing, apply an antiseptic like povidone-iodine or alcohol, and seek medical attention right away for evaluation and rabies vaccination. Avoid covering the wound tightly or using caustic chemicals. Prompt cleaning is the single most effective first defense against rabies infection.