Although cat bites account for only 10 to 15 percent of animal bites treated in emergency rooms, they pose special infection risks. Dog bites, the most common bites treated, can tear flesh and break bones, but they create open wounds that are easy to clean and less likely to become infected than the puncture wounds created by cats, which usually affect the hand and can inject bacteria into tendons and bones. In a three-year retrospective study published in the February issue of The Journal of Hand Surgery, researchers reviewed records of 193 people who came to Mayo Clinic Hospital with cat bites to the hand. Thirty-six victims were immediately admitted to the hospital, where they stayed an average of three days. Another 154 were treated with oral antibiotics as outpatients, although 21 of them eventually had to be hospitalized. Complications included nerve involvement, abscesses and loss of joint mobility. The most common cause of infection was Pasteurella multocida, an aggressive bacterium found in the mouths of many animals and up to 90 percent of healthy cats. Amoxicillin is commonly used to treat it.