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Home , Animal bite, Cat bite

BITES AND MANAGEMENT

AIan S. Banks, D.P.M.

Podiatrists may occasionally be consulted to care for bite tilis, and Beta Sfreptococcus. was not isolated either in an emergency room or local office setting. from a single wound, despite a concerted effort to identify The majority of bites occur at home or in association with this organism.3 "friendly" usually known to the patient. Therefore, many individuals may delay seeking medical attention until More recently, discussion has been held as to whether or has already developed. Patients who have sus- not bite wounds may be sutured primarily upon initial tained spider envenominations may wait until early signs of examination. Classically, of this nature have been skin necrosis are evident. As with any traumatic wound, cleansed and closed at a Iater date after careful examination thorough debridement, irrigation, and adequate tetanus to ensure infection had not developed. However, Callaham prophylaxis are the most reliable means of preventing later states that wounds can be safely sutured with an complications. However, a basic understanding is important infection rateof only 5-10o/", which iscomparabletothe rate in instituting appropriate therapy for bites as each type of of infection for clean, non-bite lacerations. However, the wound may have its own idiosyncracies based upon the same author identifies the foot as a high-risk location for offending . This paper will discuss the primary treat- complications.a Perhaps a more conservative approach for ment concerns for the cond itions most I ikely to bre of interest podiatrists is warranted until clinical studies dictate other- to the podiatrist. Human bites will be purposely omitted as wise. the incidence of such lesions in the lower extremitv is extremely rare. Cats generally produce a more characteristic puncture wound which has a greater tendency to become infected Dog bites are the most common form of this encoun- than injuries for dogs. More than likely this is due to the tered, occurringl-2 million times each year.l In addition to difficulty in achieving adequate cleansing of puncture ver- the obvious puncture and tearing, dogs can produce enough sus open lesions. The primary organism implicated in subse- force ('150-450 lbs./sq. in.) to significantly crush tissues.2 quent is Pasteurella multocida. This gram nega- Such wounds may be susceptible to infection due to direct tive bacillus can be isolated in the oropharynx of 5O-74'h o{ inoculation of into this compromised area. There- healthy cats.2 scratches may also inoculate this organism fore, basic wound care is of utmost importance. due to the routine cleaning habits of felines.2 Pasteurella is apparently rather virulent and infection usually presents Several studies have been performed to evaluate the fairly soon following the injury. Other infectious organisms organisms likely to cause infection following dog bites. A commonly encountered after cat bites are wide variety of organisms have been cultured from the oral aLtreus, , and Staphylococcus epidermidis.s cavity of dogs. Although early authors generally focused upon the presence oI Pasteurella multocidal more recent More recently, another unnamed bacteria has been asso- studies have found this to be present in only 25% of dog bite ciated with both dog and cat bites. Designated as DF-2 wounds.2 Ordog, et.al., cultured wounds in 420 patients (dysgonic fermenter), it seems to have a predilection for upon initial presentation to the emergency room following patients who are asplenic, cirrhotic, or immunocompro- injury. 48% ol the specimens demonstrated no bacterial mised.6 growth. Of the organisms cultured, Staphylococcus epider- m i d i s w as noted most com mon ly (2O5%). Th i s was fe lt to be a contaminant. Multiple bacteria were present in 15.5% of PROPHYLAXIS the patients. 50o/" ol those individuals with clinically in- fected wounds showed multiple pathogenic organisms. The prophylaxis for bite wounds is still a topic of predominant bacteria were of the family Enterobacteri- controversy. Antibiotic concentrations need to be present in aceae/ Pseudomonas, Staphylococcus aureus, Bacil lus sub- the tissues prior to contamination to be maximally effective.

16 Each minute which passes following the inoculation of clinically infected following canine bites were treated suc- bacteria theoretically limits the effectiveness of "prophylac- cessful ly with Cephradine (Velocef).3 tic" . Callaham states that dog bites do not require antibiotics. However, as noted earlier, the foot is considered As previously mentioned, Pasteurella is a major considera- a high risk area for complications.a Certain patient groups tion in wounds. Although penicillin is very effective listed as being high risk are listed in Table 1. in treating this organism, less than optimum coverage is provided lor Staphylococcus. Empiric therapy with Di- lf administered, these agents should provide adequate cloxacillin or Cephalexin still seems to be a good compro- coverage for the most likely organisms to precipitate infec- mise. ln one clinical study 4 of 6 individuals receiving a tion. No single drug will be sufficiently effective against all placebo following cat bites developed infection, three of pathogenic bacteria. The recent recommendations of Cal- which were due to Pasteurella. Five patients receiving laham are listed in Table 2. Dicloxacillin or Cephalexin Oxacillin did not develop infection.s lnterestingly, these (Keflex) appears to adequately cover most organisms in- same authors found no brenefit from the use of Oxacillin in volved in dog bites.a In another study 95% of patients dog bites.T

Table 1.

HIGH RISK PATIENTS FOTLOWINC ANIMAL BITES

Location Hand, wrist, or foot

Type of wound Punctures Tissue crushing that cannot be fully debrided.

Patient Older than 50 Asplen ic Chronic alcoholic Altered immune status Diabetic Peripheral vascular insufficiency Chron ic corticosteroid therapy Prosthetic or diseased cardiac valve Prosthetic or seriously diseased joint

Modified from Callaham (4)

Table 2.

PROPHYLACTIC ANTIBIOTICS FOR BITE WOUNDS

Organism unknown Dicloxaci I I in or cephalexin Penicillin allergic -

Cat bites Penicillin or dicloxacillin Penicillin allergic - erythromycin Resistant to initial treatment- culture and consider tetracycline (ex- ceptions -pregnant women and children)

Modified from Callaham (4)

17 Clinically, erythromycin has also been effective against The initial bite may be imperceptible, or produce a very this organism, despite in vitro evidence to suggest that minor stinging or burning. Therefore, the patient may not oxacillin and erythromycin have questionable activity. Al- have any idea as to the exact cause of the lesion unless the though there may be some resistant strains, the recommen- actual spider is noticed. A central pimple with an irregular dation atthis time is to use dicloxacillin initially and change red reaction may be noticed in 6-12 hours, followed by to other antibiotics only if the clinical response dictates that formation. A blue-gray macular halo surrounding the it is in order.a puncture site is said to tre characteristic of necrotic arachni- dism and may appear within a few hours to days. However, ln dog and cat wounds one also needs to determine other authors have described a more variable appearance whether or not the animal has been adequately vaccinated with central blanching surrounded by erythema. Blebs or for . lf the risk of rabies is high, it has been suggested purpura, a central purplish discoloration, or blood filled thatthe wound be irrigated with 1% benzalkonium chloride nearly always indicate impeding necrosis and ul- (Bactine, Zephiran) due to an apparent virucidal action ceration which may take months to heal. against the rabies . Local health officials should be contacted immediately to determine further appropriate Treatment of reactive sprder bites is still a subject of measures. controversy. Wasserman states that the "benign neglect" approach almost always results in a suitable outcome.ll NECROTIC SPIDER ENVENOMATION Antipruritics, analgesics, tetanus prophylaxis, cold com- presses, and immobilization are all measures with which most authorities will concur. Aspirin-type agents should be Despite the irrational fear many have of spiders, the vast avoided as these drugs may tend to potentiate majority of these species are either harmless or beneficial to compl ications. Topical, i ntralesional, and system ic steroids man. In the past few years more attention has been directed have been used, as has early surgical excision of the bite towards necrotic changes following spider bites. For many area. All of these measures have generally failed to provide years the role of these animals in the development of suitable results. Early surgical excision appears to be the one dermonecrosis was not appreciated. The animal most often modality that most agree is contraindicated due to the poor associated with these lesions has been Loxosceles reclusa, or results witnessed to date. Many times the full extent of the the brown recluse spider. Bites from this arachnid may at necrosis can not be fully appreciated early in the process. times result in extensive necrosis of tissue. Until recently Better results have been noted with delayed excision after effective treatment measures had been lacking for these full demarcation of necrosis.e'12'13 more severe envenomations.

The use of Dapsone has been proven to be helpful in both The brown recluse has a very wide distribution and is seen experimental and clinical studies. Traditionally, this agent mainly throughout the south and midwest, east from Texas has been used in leprosy or by dermatologists in other to South Carolina, and south from lndiana to Alabama, dermonecrotic processes. Dapsone was shown to be effec- excluding FIorida. The most common areas for identification tive in reducing surrounding brown recluse are Missouri, Arkansas, Oklahoma, eastern Kansas, and injection.r3 In a comparative study, the results of Tennessee.e,r0 However, with central heating, it would be early surgical excision versus the use of dapsone and de- possible to discover these spiders in more northern states. layed surgical excision of the skin defect were evaluated. Specimens have already been identified as far away as Pretreatmentwith dapsone resulted in fewerwound compli- Idaho, Montana, Arizona, and California.e The adult size cations, reduced objectional scarring, and reduced the need ranges lromT-12 mm in length to 3-5 mm wide. Some color for future surgical excision.l2 However, judicious use of this variation may be evident, but most are light to medium agent is appropriate, especially in children. Severe adverse brown with a characteristic violin shaped marking on the reactions may occur and include hemolysis, methemo- body of a somewhat darker color. globinemia, and Ieukopenia. Wasserman recommends that adults with rapidly progressive severe bites (early blistering, As the name implies, the brown recluse spider is a shy hemorrhage, or necrosis) be started on a low dose and animal which does not bite unless provoked by direct gradually increased from 50mg to 200m9/day, divided twice human contact and disruption of its habitat. Despite their a day, for 2 weeks.11 Fortunately, most envenomations will timid nature, they have readily adapted to dwellings which not progress to this extent. Therefore, dapsone should be place them in close proximity to man. Loxosceles has been used judiciously, and if in doubt, a period of close observa- identified in all types of buildings and prefers darkened tion employed prior to the institution of its use. storage areas such as closets, garages/ basements, attics, and cupboards. Other preferred hiding places are utility boxes, under Iogs, hay bales, inner tubes, furniture, boxes, papers/ bricks, in feed sacks, and behind picture frames.l0

18 References

1 . Douglas LC: B ite wou nds, Am Fam Physician,l l :93-99 , 197 5. 2. Coldstein EJC, Richwald CA: Human and wounds. Am Fam Physician, 36:1 01 -109, 1987 . 3. OrdogCJ:The bacteriologyofdog bitewoundson initial presentation . Ann Emerg Med, 1 5:1324-1329, 1986. 4. Callaham M: Controversies in antibiotic choices for bite wounds. Ann Emerg Med, 17:1321-1 330, 1 9BB. 5. Elenbaas RM, McNabney WK, Robinson WA: Evalu- ation of prophylactic oxacillin in cat bite wounds. Ann Emerg Med,13: 155-157, 1984. 6. Carpenter PD, Heppner BT, Cnann JW: DF-2 bactere- mia following cat bites. Am J Med 82:621-623, 1987. 7. Elenbaas RM, McNabney WK, Robinson WA: Prophy- Iactic oxacillin in dog bite wounds. Ann Emerg Med, l1 :248-251 , 1982. B. Callaham M: Human and animal bites. Iopics Emerg Med, 4:1-15, 1982. 9. Wong RC, Hughes SE, Voorhees JJ: Spider bites. Arch Dermatol, 1 23 :98-1 04, 1 987 . 10. Williams HE, Breene RG, Rees RS: The brown recluse spider. PB1 '1 91 , The University of Tennessee lnstitute of Agriculture. .l 1 . Wasserman GS: Wound care of spider and en venomations . Ann Emerg Med, 17:1331-1 335, 1 9BB. 'l 2. Rees RS, Altenbern DP, Lynch JB, King LE: Brown recluse spider bites. A comparison of early surgical excision versus Dapsone and delayed surgical excision. Ann Su rg, 25 :659-663, 1 985. 1 3 . King LE, Rees RS: Dapsone treatment of a brown recluse bite. JAMA, 250:648, 1983.

Additional References

Chapple CR, Fraser AN: Pasteurella Multocida wound infections - a commonly unrecognized problem in the casualty department. lnjury, 17:410-411 , 1986.

Rees R, Shack RB, Withers E, Madden J, Franklin J, Lynch JB: Management of the brown recluse . P/ast Reconstr Surg, 63:768-773, 1981 .

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