Animal Bites, Mammalian
Definition
A.A bite from any mammalian animal to a human can be potentially dangerous. Bites from human to human are included.
Incidence
A.Account for two to five million ED visits each year.
B.About 80% to 90% of bites are dog bites.
C.About 6% of bites are cat bites.
D.From 2% to 3% are human bites.
E.The elderly are especially prone to bites.
Pathogenesis
A.Mechanical trauma and break to skin and/or underlying structures.
B.Infection from transmission of bacteria:
1.Pasteurella multocida is primarily associated with cat bites but may also be associated with dog bites.
2.Staphylococcus aureus, Staphylococcus epidermis, and Enterobacter species can be transmitted with dog and cat bites.
3.Streptobacillus moniliformis can be transmitted with rat and mice bites.
4.Streptococcus, Staphylococcus, and Eikenella can be transmitted with human bites.
5.Human bites can transmit diseases such as actinomycosis, syphilis, tuberculosis, hepatitis B, and, potentially, HIV.
C.Rabies, an acute viral infection, may be transmitted by means of infected saliva or by an infected animal licking mucosa from an open wound. It is rarely contracted by means of airborne transmission, but this has been reported to occur in bat-infested caves.
Predisposing Factors
A.Elderly.
B.Entering an animal’s territorial space and/or surprising an animal.
Common Complaints
A.Bitten by an animal.
B.Pain.
C.Redness.
D.Swelling.
Subjective Data
A.What person or type of animal bit the patient?
B.Was this a provoked or an unprovoked attack?
C.Did the patient identify and contact the owner of the animal?
D.What was the behavior of the animal? Unusual, strange, or ill-appearing?
E.How much time elapsed from being bitten to seeking treatment?
F.Did the patient start any self-treatment?
G.What is the patient’s tetanus immunization status?
H.Review history for any prior rabies immunizations.
I.Does the patient know if the animal was a domestic animal? Is the animal’s vaccination status known?
J.If the bite is of human origin, determine if it is a closed-fist injury (a human bite/injury that occurs when the closed fist is injured, with teeth penetrating the skin, joint, and possibly bone, over the metacarpal heads) or plain bite.
Physical Examination
A.Check blood pressure, pulse, and respirations; observe overall respiratory status.
B.See Table 7.1.
Diagnostic Tests
A.Refer to Table 7.1.
Differential Diagnoses
A.Animal bite: Dog, cat, human, and so forth:
1.Cat bites more frequently become infected.
2.Bites on the hand have the highest infection rates. Bites on the face have the lowest infection rates.
B.Cellulitis and abscesses.
C.High-risk potential for rabies from bites from the following:
1.Skunks, foxes, raccoons, and bats are primary carriers.
2.Rabbits, squirrels, chipmunks, rats, and mice are seldom infective for rabies.
3.Properly vaccinated animals seldom are infective.
Plan
A.General interventions:
1.Control bleeding.
2.Wound care:
a.Immediately wash wound copiously with soap and water.
b.Irrigate wound with saline, benzalkonium chloride (Zephiran), or 1% povidone-iodine (if the patient is not allergic to iodine).
c.May use Waterpik.
d.Use 150 to 1,000 mL of saline solution.
e.Direct stream on entire wound surface.
f.Scrub entire surrounding area.
g.Debride all wounds.
h.Trim any jagged edges to prevent cosmetic and/or functional complications.
i.Cover with dry dressing.
3.Do not suture wounds with high risk for infection:
a.Hand bites, closed-fist injuries.
b.Bites older than 12 hours.
c.Deep or puncture wounds.
d.Bites with extensive injury of surface or underlying structures.
e.Immunocompromised patients.
4.Rabies control measures:
a.Consult with the local health department regarding risk of rabies in the area.
b.The domestic animal should be identified, caught, and confined for 10 days of observation. If the animal develops any signs of rabies, it should be destroyed and its brain tissue analyzed. No treatment is necessary if results are negative.
c.The wild animal should be caught and destroyed for brain tissue analysis. No treatment is necessary if results are negative.
d.If the bat or wild carnivore cannot be found, rabies prophylaxis is instituted.
B.Patient teaching: Instruct the patient how to keep site free from infection.
C.Pharmaceutical therapy:
1.Antibiotic prophylaxis is controversial, but it is generally recommended for wounds involving subcutaneous tissues and deeper structures:
a.Agent of choice: Amoxicillin-clavulanate acid (Augmentin) 875/125 mg every 12 hours.
b.Alternatively you can prescribe (aerobic and anaerobic agents together to cover):
i.Doxycycline 100 mg twice daily.
ii.Trimethoprim/sulfamethoxazole (TMP-SMX) double strength (DS) twice daily.
iii.Ciprofloxacin 500 to 750 mg twice daily.
iv.Levofloxacin 750 mg once daily.
PLUS an anaerobic agent:
i.Metronidazole 500 mg three times daily.
ii.Clindamycin 450 mg three times daily.
c.Alternatively, prescribe erythromycin (E-Mycin) 250 mg four times per day for 3 to 7 days.
2.Tetanus prophylaxis:
a.Tetanus immune globulin and tetanus toxoid to all patients who have had fewer than three primary immunizations.
b.Tetanus toxoid alone can be given to those who previously have had the primary immunization, but have received a booster five or more years ago.
3.Rabies prophylaxis:
a.Active immunization: Human diploid cell vaccine (HDCV), 1 mL, is given intramuscularly on first day of treatment, and repeat doses are administered on days 3, 7, 14. For persons with immunosuppression (corticosteroid use, immunosuppressive drugs, and immunocompromising illnesses), they will receive an additional dose on day 28.
b.Passive immunization: Rabies immunoglobulin (RIG; human); should be used simultaneously with first dose of HDCV; recommended dose of RIG is 20 IU/kg. Approximately one-half of RIG is infiltrated into wound, and the remainder is given intramuscularly.
Follow-Up
A.Evaluate wound and change dressing in 24 to 48 hours.
B.Reevaluate as indicated. If the patient is on immunoprophylaxis and has no signs of infection, see in 1 week.
C.Instruct the patient to return immediately for any signs of infection.
Consultation/Referral
A.Refer all patients with bites of ears, face, genitalia, hands, and feet to plastic surgery.
B.Consult with a doctor if suspicion of rabies is involved.
C.Contact the local health department.
D.Wounds involving tendon, joint, or bone require hospitalization and surgical consultation.
Individual Considerations
A.Pregnancy: Use appropriate antibiotic management.
B.Geriatrics:
1.Consider chronic conditions (chronic kidney disease, diabetes, etc.) when prescribing the patient antibiotics.
2.Pet therapy has been allowed in long-term care facilities, and studies suggested that 75% did not report health and safety concerns or had policies in place for animals. Be sure to discuss pet precautions (i.e., bite prevention, how to treat bites if they occur, and safety issues) with geriatric patients whether they live at home, assisted living, or are residents of a long-term care facility.
Insect Bites and Stings
Definition
A.Bites and/or stings on the skin come from commonly encountered insects, bees, hornets, wasps, mosquitoes, chiggers, ticks, fleas, and fire ants.
Incidence
A.Bites are seen in all age groups, more commonly in summer months.
Pathogenesis
A.Some bites elicit local tissue inflammation and destruction due to proteins and enzymes in the poison or venom of the insect.
B.Serum immunoglobulin E (IgE)-mediated allergic reactions (immediate or delayed) may occur.
C.Serum-sickness reaction may appear 10 to 14 days after a sting with venom. Toxic reactions can also occur from multiple stings, yielding large inoculation of poison or venom.
D.With tick bites, exposure to Rocky Mountain spotted fever, Lyme disease, ehrlichiosis, and babesiosis disease may occur.
Predisposing Factors
A.Exposure to areas of heavy insect infestations.
B.Warm weather months.
C.Outdoor exposure with barefoot, bright clothes.
D.Use of perfumes and/or colognes.
E.Previous sensitization.
Common Complaints
A.Local reaction: Pain, swelling, and redness at site after insect bite.
B.Toxic reaction: Local reaction plus headache, vertigo, gastrointestinal symptoms (nausea, vomiting, diarrhea), syncope, convulsions, and/or fever.
Subjective Data
A.Did patient see what bit or stung him or her?
B.If the patient felt the bite or sting, was he or she bitten or stung once or multiple times?
C.How long ago did it occur?
D.Where was the patient when the injury occurred (environment)?
E.Has the patient ever been bitten or stung before? If so, did he or she have any reaction then? If so, what was the treatment?
Physical Examination
A.Check temperature, pulse, respirations, and blood pressure. Observe overall respiratory status.
B.Inspect:
1.Inspect site of injury for local reaction; note erythema, rash, or edema.
2.Perform ears, nose, and throat exam.
C.Auscultate: Assess heart and lungs.