The Two Bites Hand Surgeons Take Most Seriously Are the Two That Look Like Nothing
A dog bite to the hand looks alarming. Torn skin, bruising, blood. People go straight to hospital, which is correct.
The two that reliably cost people function are the ones that look trivial:
- a cat’s needle-thin puncture, and
- a small split over a knuckle from someone’s tooth.
Both bury bacteria deep and seal them in.
Both are frequently downplayed by the person who has them.
Any bite that breaks the skin of the hand needs to be seen the same day. The hand is the worst place on the body to be bitten, because tendons, joints and sheaths sit millimetres under the skin with very little blood supply and very little room.
The fight bite
Someone punches someone else in the mouth. A tooth splits the skin over a knuckle. The wound is maybe half a centimetre, barely bleeds, and everyone goes home.
Here’s the mechanism that makes it dangerous, and it’s worth picturing.
The tooth goes in while the fist is clenched, so it can pass through skin, through the extensor tendon, and into the knuckle joint itself, all in one movement. Then the hand relaxes. As it opens, all those layers slide back to their resting positions, and they no longer line up.
Now the bacteria are locked inside the joint with the skin closed over the top of them, and there’s no path out.
A day later the knuckle is swollen, hot and won’t bend, and what started as a nick is now an infected joint with a partially cut tendon in it.
Any wound over a knuckle after a punch is a tooth wound until proven otherwise, no matter what the patient says happened.
I’m not raising that to embarrass anyone.
Fight bites get missed mostly because people are reluctant to say how it happened, and the treatment depends entirely on knowing. Say it. The staff have heard it before and they’ll treat it properly.
Proper treatment is exploration of the wound, often washing out the joint in theatre, and antibiotics that cover mouth bacteria. Stitching it closed without exploring it is precisely the wrong move.
The cat bite
Cat teeth are thin, sharp and long. They don’t tear, they inject. A cat bite to the hand is a deep, narrow puncture that reaches structures a dog’s blunter teeth usually can’t, and it closes over within hours.
Cat mouths also carry organisms, Pasteurella in particular, that move fast. The distinctive feature is speed: redness, swelling and pain appearing within 12 to 24 hours rather than over several days.
Cat bites to the hand infect at a strikingly high rate compared with bites elsewhere on the body, and the puncture over a joint or a tendon sheath is the one that turns into a hospital admission.
Same day assessment, antibiotics started early, and a low threshold for exploring the wound.
Dog bites
More tissue damage, lower infection rate. A dog bite crushes and tears, which is ugly but at least leaves the wound open enough to drain and wash out.
The concerns here are the visible ones: skin loss, damaged tendons, fractures underneath, and in children, injuries far deeper than the skin suggests.
That being said…it still needs medical attention, still needs thorough washing out, and still needs a conversation about antibiotics and tetanus.
What to do in the first hour
- Wash it. Running water, generously, for several minutes. This is the single most useful thing you can do and it’s almost free.
- Let it bleed a little. Don’t clamp down hard on a puncture wound trying to stop a small ooze.
- Don’t close it. No butterfly strips, no superglue, nothing that seals bacteria in.
- Cover loosely, elevate, and go seek medical attention. Emergency department or urgent care, same day. This isn’t the time to save money. Better still, if you have medical or accident insurance, it’d usually cover you.
- Say what actually bit you. Cat, dog, human, tooth in a fist. It changes both the antibiotic and the decision to operate.
Take your tetanus status with you. If the animal was unknown, stray, or you’re overseas, rabies has to be part of the conversation depending on where you are.
Signs it’s already infected
- Redness spreading beyond the wound, particularly if it’s advancing hour by hour.
- A knuckle or joint that won’t bend, or hurts sharply when moved.
- The whole finger swelling evenly with severe pain on straightening. That’s the tendon sheath, and it’s a surgical emergency.
- Fever, chills, or feeling generally unwell.
- Any pus, or a wound that starts hurting more after day two rather than less.
Recovery, and why the stiffness lingers
An uncomplicated bite that’s washed out and treated early: dressings for a week or so, back to normal use over 2 to 3 weeks.
A bite that reached a joint or a tendon and needed surgery is a different recovery, and the problem shifts from infection to stiffness.
Infection inside a joint or around a tendon will 100% produce scar. Scar around a knuckle produces a finger that won’t fully bend or fully straighten. And the natural response, protecting a sore hand, is exactly what locks it in.
- Week 1: elevation constantly, gentle movement as soon as the surgeon allows it. Swelling controlled now is stiffness avoided later.
- Weeks 2 to 6: daily range of motion work, scar management once the wound is closed, splinting if a joint is settling into a bad position.
- Weeks 6 to 12: strengthening and return to full use.
- Beyond: a knuckle that was infected can stay slightly thickened and slightly stiff permanently. Early movement is what decides how slight.
The short version
The impressive-looking dog bite is usually the least dangerous of the three. The cat puncture and the split knuckle are the ones that cost fingers.
Wash it, don’t seal it, go the same day, and tell them exactly what happened.
Written by Nigel Chua, hand occupational therapist in practice since 2005. Tens of thousands of hands, wrists and elbows assessed and treated. My credentials are here. This article explains; it doesn’t examine. Any bite that breaks the skin on a hand needs seeing today, and a swollen knuckle after a punch needs seeing tonight.