Case Study: Your next patient in clinic has arrived with a chief complaint of “animal bite”. Steve is a long-time patient of yours. He is retired and spends his time volunteering at the animal shelter. This is not the first time he has been bitten by an animal. When you walk into the examination room, you see an older gentleman in minimal distress. He is holding his right arm, and his forearm has a piece of gauze covering it. After exchanging greetings, you ask Steve what happened this time. He tells you, “Doc, a garbage truck drove by, and the large dog I was walking got scared. Anyway, he turned around and bit me.”
You ask Steve for additional details, and he tells you the dog chomped down on his right arm and would not let go for a minute or two. The bite broke the skin on Steve’s forearm, and it also bruised the tissue around his arm. As soon as help arrived, Steve immediately washed the wound with soap and water, placed a piece of gauze over the bleeding wound, and came to the clinic.
What do you want to do now?
You remove the gauze and examine Steve’s wound. You then use a 20 ml syringe to copiously irrigate the wound with saline. The skin and underlying tissue are torn but there does not appear to be any bone or tendon involvement, so you do not need to call a specialist. You explore the wound to make sure there is no foreign material left behind, such as tooth. Steve’s wound does not appear to need much debridement.
Do you close the wound?
Dog bites are responsible for the majority of animal bites, and studies show that no single breed is responsible for most dog bites. Animal bites are contaminated and standard of care in the past used to involve leaving the wounds open to heal by secondary intention. However, this might only be necessary for wounds that have a high likelihood of becoming infected, such as bites on the hand or near a prosthetic joint, crush injuries, puncture wounds, cat bites, delayed presentation, or bites on an immunocompromised patient. A plastic surgery consult may be in order for face bites. This particular bite is near the wrist and involves a crush component, so you decide to leave it open due to the high risk of contamination.
Do you prescribe antibiotics?
A Cochrane review found that antibiotic prophylaxis only reduced infection in bite wounds to the hand. However, you should prescribe antibiotics for wounds at high risk of infection and if you close the wound. Also, consider prescribing antibiotics for wounds at moderate risk of infection. The usual course for adults is 3-7 days of treatment with Amoxicillin/Clavulanate 875/125 mg every 12 hours.
How do you approach a bite made by a potentially rabid animal?
Rabies is a significant concern if the domestic animal appears rabid or if a wild animal has inflicted the bite. In this case, the dog that bit Steve had already been under observation for 10 days and had not shown any signs of rabies. The dog was placed under an additional 10 days of observation after biting Steve. At this time, it is highly unlikely that the dog has rabies. However, if there is a possibility that an animal is rabid, the patient should undergo prophylaxis with immune globulin if he or she presents with an animal bite. The patient then receives a rabies vaccination on days 0, 3, 7, and 14 after the bite. This regimen is almost 100% effective at preventing rabies; but if a person does not receive prophylaxis and develops symptoms of rabies, the disease is almost universally fatal.
After irrigating the wound and leaving it open, you prescribe 7 days of Amoxicillin/Clavulanate and tell Steve to call back if his wound does not improve. A week later, he calls back to let you know his wound is healing well and has returned to his volunteer work at the animal shelter. You suspect that you will be seeing him again soon.
Share your interesting cases and experiences below in treating animal bites.
Ellis, R and Ellis, C. Dog and Cat Bites. Am Fam Physician. 2014;90(4):239-43.
Dr. V. Silverstein
Published on 4/3/18