Animal Bite
Causes
Animal Bite
Millions of animal bites occur worldwide each year. In the United States, dogs cause most animal bites. Other common animals that may cause hand injuries include cats, rodents, rabbits, ferrets, farm animals, bears, birds (domesticated and wild), bats, monkeys, and reptiles, such as snakes, alligators, and crocodiles. Marine animals, such as eels, fish, and sharks, can also cause bite wounds.
The major concerns with these bites are infections and tissue damage to the skin, muscles, joints, nerves, and tendons. When an animal bites, bacteria from its mouth can enter the wound and begin growing. An infection can cause pain, tissue damage, limb-threatening problems, or sometimes life-threatening problems. While bacteria are the most common, viruses and fungi are also possible infections that are associated with bites.
The seriousness of a bite depends on the location and depth of the wound, the type of animal, and whether a foreign object is left behind in the wound. Bites from large animals often cause more damage to soft tissues. These can tear or crush muscles and tendons, and even cut nerves and blood vessels. The severity of the bite often determines the treatment, with the worst outcome being amputation for the most severe injuries.
Infections are more common in cat bites due to the sharp teeth that can penetrate deeper into the hand. The skin usually closes quickly over the bite, trapping bacteria inside the hand (Figure 1). Pain and swelling within hours are common after a cat bite. However, quick and proper treatment often can prevent or minimize the risk of infection.
Other problems can be due to toxins or venoms from a bite wound. Snake bites can be very dangerous. Knowing the type and species of snake can be very helpful in treating the toxin, because venoms vary between different snakes. Venoms can affect body parts not associated with the wound area, like nerves, muscles, eyes, and kidneys.
Rabies is a rare but potentially fatal infection that may result from an animal bite. In the United States, wild animals such as bats, skunks, raccoons, and foxes are most likely to spread rabies. Bites from these animals should be reported to your public health department.
Human Bites
Human bite wounds contain a lot of bacteria and carry a high risk of infection. Many times, these bites are the result of a fight. The human teeth can penetrate the hand when a punch is delivered to the face. The tendon and the large joint at the base of the finger are often involved in this situation. Infections from human bites can progress quickly if not treated in a timely manner. An infection inside the joints of the hand may destroy the joint within days (Figure 2).
Signs and Symptoms
Signs that your bite may be infected include:
- Swelling
- Redness
- Warmth
- Continued pain beyond 24 hours
- Drainage from the wound
Signs that your infection may be spreading include:
- Red streaks up the arm or forearm
- Swollen glands around the elbow or in the armpit
- Fever
- Tiredness
- Night sweats
- Shakes
If these develop, you should seek emergency treatment in your physician’s office or the emergency room.
You should also seek emergency treatment if you think that the bite may have caused damage to other important structures such as the bone or nerves. Some signs that this may have happened include:
- Bleeding that is difficult to control
- Pale or numb finger(s)
- Swelling or bruising
- Deformity
- Loss of finger motion
Treatment
Prevention is the best form of treatment. If you are traveling to an unfamiliar place or country, it is wise to research the area about animal safety. This may help you learn about what different animals to look out for and avoid places where animal bites may occur. It may also help you to choose appropriate protective clothing and shoes.
Getting treatment quickly can minimize the risk of problems. Your physician will examine the wound and ask about how the injury occurred. A complete and honest account of the events will help your physician treat you properly. For animal bites, it is helpful if you can describe the type of animal, its general health and behavior, and any known rabies vaccine status.
Treatments for poisonous snake bites often require an anti-venom. Since these treatments are often specific to the type of snake, your description (color, pattern, location of the snake when attacking [woods, desert, swamp]) can help medical personnel to choose the best anti-venom.
X-rays may be used to identify any damage to the hand to look for broken bones, joint injuries, or tooth fragments. Other kinds of imaging, like an MRI or ultrasound, may be used based on the severity of the bite.
All bites to the hand require careful cleansing. Your physician or other medical personnel will wash the wound and might trim away damaged skin, blood clots, or other debris that could cause infection. If a wound is infected, a culture swab may be obtained. This can help identify the type of bacteria causing the infection and determine which antibiotic would be most effective for treatment.
Depending on the bite, some will require the use of antibiotics through an IV, while others may be treated with oral medication. Sometimes people need to stay in the hospital for treatment, with serious bites usually requiring surgery.
Follow-up care is crucial in the case of animal or human bites to ensure that infection is controlled and that the function of the hand is optimized.
© 2025 American Society for Surgery of the Hand
This content is written, edited, and updated by hand surgeon members of the American Society for Surgery of the Hand.Find a hand surgeon near you.