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Domestic animals, like dogs and cats, are responsible for most animal bites. While dogs cause more bite injuries, cat bites are more likely to become infected. According to the American Academy of Pediatrics, infection occurs in about 10 to 15 percent of dog bites and up to 50 percent of cat bites.
One reason that animal bites often lead to infection is that bites often occur on the fingers or hands. These areas are where the body may have a harder time fighting infection. Also, the bacteria often come from the animal’s mouth or may be present on the human’s skin. The infections are often caused by these bacteria penetrating the skin.
As the bacteria multiply, the body’s immune response causes common symptoms of infection. Swelling and inflammation are two examples. Animal bite infections are serious and can even be life-threatening if left untreated.
Animal bites that don’t break the skin are not at risk for infection. Scrapes or scratches that just graze the skin’s surface have a minimal risk of infection. Cuts or lacerations have a higher risk of infection. Puncture wounds caused by cats are considered to have the highest risk of infection.
Even the gentlest dog can bite if injured, scared, or overexcited. And all dog breeds have the potential to bite. Most of the time a person is bitten by a dog they know.
Injuries from a dog bite make up 85 to 90 percent of animal bites in the United States, and 1 percent of injury-related visits to the emergency room, according to American Family Physician.
Children are more likely than adults to experience dog bites.
Cat teeth can cause deep puncture wounds that are hard to clean. Since the teeth are sharp, a wound can be deep yet small, making it easier for it to heal over. This can trap bacteria inside the wound.
Of all animal bites reported in the United States, 5 to 10 percent are from cats. Most people bitten by cats are women. And most cat bites are the result of intentional contact, like attempting to feed or pet the cat.
In rare cases, bites from wild animals like bats, raccoons, foxes, skunks, and wild dogs can cause rabies infections. Rabies is a life-threatening viral disease. Seek medical attention for any wild animal bite that breaks the skin’s surface. Also seek medical attention if a bat is found in a room you were sleeping in, even if you do not see visible bites.
You should clean all animal bites thoroughly. And watch them closely. Seek medical attention if symptoms of an infection develop.
Infection from animal bites is caused by bacteria. The bacteria can be found in the mouth or saliva of the animal. The bacteria then enter the wound after being on the skin. The bacteria can also be present in the environment.
Animal bites are often polymicrobial, which means that multiple species of bacteria are involved.
Tetanus, a bacterial disease affecting the nervous system, can develop from the bacteria. This is a serious condition. Puncture wounds from animal bites are the most likely to lead to tetanus.
The most common symptoms of infection from animal bites are redness, pain, swelling, and inflammation at the site of the bite. You should seek immediate medical treatment if any of these symptoms continue for more than 24 hours.
Other symptoms of infection include:
You should also seek medical treatment as soon as possible if any of these less common symptoms are present, particularly if the symptoms are not improving on their own.
Cat bites carry a much higher risk of infection than dog bites.
Other risk factors that increase the chances of a bite turning into an infection include:
To diagnose infection from an animal bite, your doctor will ask about the bite. Questions to expect from your doctor include:
Your doctor might also order an X-ray to determine whether the infection has spread to the bone, especially if the bite is on the finger or hand. Blood tests can also diagnose a spreading of the infection, known as sepsis. Sepsis and infection of the bone are life-threatening concerns.
The first step with an animal bite is to properly clean and assess the wound. This could help prevent infection in an animal bite. To properly clean an animal bite, take the following steps.
For a minor wound:
For a deep wound, suspected rabies, or a wound showing symptoms of infection:
If an infection develops, your doctor will prescribe antibiotics. A typical round of treatment will last five to 10 days. However, the length of your treatment may vary based on many factors, including:
For infected bites, your doctor may recommend intravenous (IV) antibiotics until the infection clears. But most infected bites will only need oral antibiotics.
Your doctor might also suggest a tetanus booster shot. This depends on how severe the bite is and your vaccination status.
After performing blood tests to determine the extent of the infection, your doctor might need to stitch the wound. They may also ask you to return for a follow-up visit after 48 hours to monitor the wound.
If left untreated, infection from animal bites could spread and cause serious medical problems. Infection generally develops within 24 to 48 hours.
You should seek immediate medical treatment if:
You should also contact your doctor immediately if the animal that bit you starts showing symptoms of illness. Potential complications of animal bite infections include tetanus and rabies.
Symptoms of the bacterial disease tetanus include:
Because of the tetanus vaccine, tetanus infection is rare in the United States. According to the Centers for Disease Control and Prevention (CDC), children should receive five tetanus shots by the time they reach the age of 6. Teens and adults should receive the vaccine every 10 years. If you are uncertain how long it’s been since your last shot, you should opt for another dose of the vaccine. There is no cure for tetanus.
Human rabies is a rare occurrence in the United States. According to the CDC, there are only one to three cases each year. The symptoms of the viral disease rabies are:
Once symptoms are present, rabies can lead to death. For this reason, medical professionals will have people begin rabies treatment if they have been bitten by an unvaccinated animal (wild or domestic) that shows any symptoms of the disease. If the animal that caused the bite or scratch is wild, it’s important to capture it but not kill it. If the animal is a pet, the doctor will want to check its vaccination records first. And they may still want to observe the animal for a period of time.
An infected animal bite should start to look and feel better within 48 hours of treatment. If you do not notice an improvement, be sure to contact your doctor immediately.
It is particularly important that you follow up with your doctor to ensure that the infection and wound are healing properly. They will also let you know if any adjustments may need to be made to your treatment plan.
Written by: Amber Erickson Gabbey and Diana K. Wells
Medically reviewed on: Nov 15, 2016: Nancy Choi, MD
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