Septic arthritis is a severe joint infection caused by bacteria that migrate through your bloodstream from another region of your body. Septic arthritis can also arise when bacteria enter the joint by a penetrating injury, such as an animal bite or trauma. The bacteria proliferate inside the joint causing inflammation and destruction of cartilage and bone. Antibiotic therapy should be started immediately after diagnosis to prevent further damage to the infected joint. In some cases, surgery may be necessary to remove all of the damaged tissue and place an antibiotic-laden implant into the site to kill any remaining bacteria. If you are bitten by an animal, it is important to seek medical attention immediately. Failure to do so may lead to serious complications for you down the road.