Vol. 14 •Issue 7 • Page 44
Treating Dog and Cat Bites
General Principles for Care
Between 4 million and 5 million animal bites occur each year in the United States, most inflicted by dogs and cats.1,2 Almost half of all dog bites involve an animal owned by the victim’s family or neighbors. About 50% of all dog bites are experienced by children younger than 14.1-3
Dog and cat bites are common presentations in emergency departments and primary care office settings. Prompt assessment and treatment are vital, and aggressive management can prevent most complications.
Assessment
A complete history of the bite wound is crucial. Find out what type of animal caused the injury and whether the attack was provoked or unprovoked. Tetanus and rabies immunization status for the patient and pet are key pieces of information. The overall health and location of the animal are also important. In some communities, notification of an animal control officer, game warden or other law enforcement officer may be required.
The most common wounds caused by cats and dogs are punctures, lacerations and avulsions. Both dogs and cats have sharp incisors that easily penetrate soft tissue. Bite wounds can be deep, depending on the force with which the injury occurred.4 Note size, depth and classification of the wound, and determine any nerve, tendon, bone or ligament involvement. A plane radiograph may be necessary to rule out bone penetration. Assess range of motion, vascular and gross motor function. Photographs and diagrams are helpful, especially in cases that may involve litigation.5,6
Facial and other highly visible wounds may require consultation with a plastic surgeon. For injuries that suggest abscess formation or nerve, tendon or vascular compromise, refer the patient to a surgeon.3
Clinical Presentation
Patients usually present to primary care offices or emergency departments for treatment and evaluation of a dog or cat bite wound because the injury is painful, red and swollen.4 In healthy patients, signs and symptoms of infection frequently occur within the first 24 hours. Signs and symptoms may develop earlier in patients with comorbid conditions such as diabetes, who take ongoing steroid therapy, are immunocompromised or have peripheral vascular disease.4,5,7 Cellulitis is the most common clinical manifestation after a dog or cat bite wound.4
Irrigation
Most patients require analgesia before thorough wound cleansing and irrigation can take place. Copious irrigation with high-pressure normal saline through a syringe will help reduce infection risk.3 Remove any foreign bodies, such as fur or fragments of teeth, during irrigation.
Infection
Between 15% and 20% of dog bites result in infection.3,5 The most common infectious organisms associated with dog and cat bites are Pasteurella multocida in the first 24 hours, then Staphylococcus aureus or Streptococcus the following day.3,8 Anaerobic organisms such as Bacteroides fragilis, Veillonella parvula and Fusobacterium species have also been implicated in infected dog bite wounds.3 Wound culturing may be necessary if the wound appears infected or is slow to respond to appropriate antibiotic therapy. If a culture is indicated, collect aerobic and anaerobic cultures. The lab should observe them for 7 to 10 days, to allow for slowly growing pathogens.3,5,9
Because they are usually puncture wounds that inject pathogens deep into tissue, about 28% to 80% of cat bite wounds develop infection.5,8 The inability to effectively irrigate deep tissue only adds to the risk of infection. Pasteurella multocida bacteria are the cause of 75% of all cat bite infections.5,8 Some patients may present with evidence of lymphangitis in progress. Low-grade fever and axillary or cervical chain lymphadenopathy may also be present.4,5
Wound Closure
Whether to close a wound resulting from a cat or dog bite is the subject of debate. The general consensus is that clinically infected wounds, puncture wounds and wounds that are older than 24 hours should be left open.3,5,6,9 The belief is that these wounds will have a better outcome if they heal by secondary intention. Many providers prefer to close wounds that are less than 8 hours old or are located on the face.3,5 Facial wounds may require repair by a plastic surgeon. These wounds usually heal well due to the enhanced blood supply in the face and the lack of dependent edema.3,5,6 Bite wounds to the hand require elevation and immobilization. Splinting is recommended for 3 to 5 days, or until recheck.3-5,9,10
Rabies
Dogs and cats account for only 10% of human rabies exposure, with wild animals such as skunks, raccoons, foxes and bats accounting for the other 90%.11 Patients who sustain a bite from an unprovoked animal are at higher risk for rabies infection than those who are bitten by a provoked dog or cat.3,5,11 If the pet owner is unable to confirm the animal’s current rabies vaccination, or if the status of the animal cannot be determined, the pet should be quarantined for 10 days at a veterinarian’s office for behavioral observation. If the animal is wild or unable to be quarantined for 10 days, the patient should receive the vaccination.3,5,11 Treatment with rabies immune globulin, as well as the vaccination, is recommended.11
After the initial vaccination, the four remaining doses should be administered on days 3, 7, 14 and 28.11 Patients who have been previously vaccinated for rabies need not receive rabies immune globulin and only require the initial rabies vaccine at the time of incident, followed by another dose 3 days later.3,11 Provide written and verbal instructions reinforcing the importance of the subsequent vaccinations.
Antibiotic Therapy
Prophylactic antibiotic treatment for bite wounds ranges between 3 and 7 days, depending on the risk of infection and depth of the wound.3,5 The regimen of choice for treating dog and cat wounds in adults is amoxicillin-clavulanate (Augmentin) 875/125 mg orally twice a day or 500/125 mg orally three times a day. Children should be dosed at 25 mg to 50 mg orally per kilogram, divided into three daily doses.3,5,12 For adult patients who are allergic to penicillin, prescribe clindamycin (Cleocin) 300 mg orally four times a day, plus a fluroquinolone after a dog bite. Children who are allergic to penicillin can take clindamycin and trimethoprim-sulfamethoxazole (Bactrim DS) as an alternative.3,5,12 In the case of cat bite, adult patients who are allergic to penicillin can take cefuroxime (Ceftin) 500 mg orally every 12 hours or doxycycline (Vibramycin) 100 mg orally twice a day. Children with penicillin allergy can also take cefuroxime and doxycycline, but doxycycline is contraindicated in children younger than 8 years.3,5,12
In cases of cellulitis, treatment for 10 to 14 days, as well as hospital admission, may be necessary.3,5 Inpatient care may also be needed for inadequate response to outpatient treatment, osteomyelitis, joint involvement, tendon or nerve involvement, and signs of systemic infection.3,5,6
Tetanus
It is important to ascertain tetanus status with each patient. Dog and cat bites contain saliva and correspond with tetanus-prone wound classifications.12 According to current guidelines from the Centers for Disease Control and Prevention, patients who have had at least three prior tetanus immunizations and who present with a tetanus-prone wound should receive a tetanus and diphtheria toxoid booster if their last booster was more than 5 years earlier.5,12,13 If the patient has received fewer than three tetanus immunizations or the immunization history is unknown, the patient should receive both the tetanus immune globulin and tetanus diphtheria toxoid.5,12,13
Emotional Distress
Both children and adults experience increased anxiety after a bite injury. Children may have nightmares in which they relive the event. Books and videos about dogs and cats may help children overcome their anxiety. If a child exhibits excessive fear and stress longer than a month after a biting incident, psychological consult may be necessary.14 Permanent scarring and disfigurement may lead to depression and decreased self-esteem.
Putting It Into Practice
Patients should return 24 to 48 hours after treatment for inspection of the wound. Emphasize the need to elevate and immobilize the injured area. Explain the signs and symptoms of infection, and thoroughly explain medication dosing.
Dog and cat bites require rapid treatment. Provide each patient with a working knowledge and understanding of what his or her individualized plan of care will be.
References
1. Sacks JJ, et al. Dog bites: how big a problem? Injury Prevention. 1996;2:52-54.
2. Weiss HB, et al. Incidence of dog bite injuries treated in emergency departments. JAMA. 1998;279:51-53.
3. Presutti RJ. Prevention and treatment of dog bites. Am Fam Physician. 2001;63(8):1567-1574.
4. Patton C. Animal-inflicted hand wounds. ADVANCE for Nurse Practitioners. 2003;11(7):57-63.
5. Bower MG. An update on managing dog, cat, and human bite wounds. Physician Assistant. 2003;27(8):38-46.
6. Goldstein EJC. Bite wounds and infection. Clin Infec Dis. 1992;14:633-638.
7. Blumm RM. Wound care in the emergency department. ADVANCE for Physician Assistants. 1998;5(1):37-42.
8. Patton C. Hand wounds: assessment and treatment issues. ADVANCE for Nurse Practitioners. 2001;11(2):91-95.
9. Lewis KT, Stiles M. Management of cat and dog bites. Am Fam Physician. 1995;52(2):479-485.
10. Presutti R J. Bite wounds: early treatment and prophylaxis against infectious complications. Postgrad Med. 1997;101(4):243-252.
11. Hankins DG, Rosekrans JA. Overview, prevention and treatment of rabies. Mayo Clin Proc. 2004;79:671-676.
12. Gilbert DN, et al. The Sanford Guide to Antimicrobial Therapy. 34th ed. Hyde Park, Vt.: Antimicrobial Therapy Inc. 2004;35:129,139.
13. Immunization Practices Advisory Committee. Diphtheria, tetanus, and pertussis: recommendations for vaccine use and other preventative measures. MMWR. 1991;40(RR-10):1-28.
14. Scott A. When dogs bite. ADVANCE for Nurses. 1999;July26:12-15.
Nadine Villani is a family nurse practitioner student at the University of Maine in Orono.
