Clinical Notes : Dermatology

199. Cat and Dog Bites

 

Definition

 

An animal bite is an injury caused by the mouth and teeth of an animal (including humans).

Specific attention must be paid to :

  • possible bruising

  • deep anatomical structure disruption

  • introduction of infectious agents

  • envenomation (injection of toxin by a bite or sting)

Risk factors

 

Factors That Increase the Risk of Infection from an Animal Bite include :

  • Bite in extremities with underlying venous and/or lymphatic compromise

  • Bite involving the hand

  • Crush injuries

  • Puncture wounds

  • Cat bites

  • Delayed presentation

    • Greater than 6 to 12 hours for bites to the arm or leg

    • Greater than 12 to 24 hours for bites to the face

  • Victim with diabetes mellitus or immunosuppression

  • Bite near or in a prosthetic joint

 

Wound management

 

  • Thorough cleansing is adequate for contused, intact skin.

  • If the skin is penetrated, copious irrigation is warranted.

  • irrigation with an 18-gauge needle catheter and a 20-30 ml syringe should provide adequate pressure for irrigation

    • between 100 and 200ml of saline should be irrigated for each inch of wound

  • soaking the wound is not recommended due to the consequent higher risk of introducing and/or spreading infection

  • administration of appropriate anesthetic agents facilitates exploration of the wound to its base

 

Squirt bottle irrigation

 

Equipment :

  • A 500 cc bottle of sterile water or normal saline (bottle of drinking water could even work if not in a clinical environment)

  • Eye protection

  • Alcohol swab

  • 18- or 20-gauge needle

Method :

  • Clean the side of the bottle with an alcohol wipe

  • Use the needle to puncture the top or side of the irrigation bottle 10-20 times in an evenly spaced pattern. If you are having trouble puncturing the side of the container you can luer-lock the needle onto a syringe for a better grasp.

  • Firmly squeeze the container to get a strong stream of pressurized fluid until the bottle runs dry

This irrigation trick works particularly well for cleaning out scalp wounds with a densely matted blood.

 
 

Wound closure

 

Dog bites may be closed if necessary, because the open nature of these bites renders them less conducive to deep-tissue infection than puncture wounds such as cat bites.

 

In general, the following types of wounds should not be closed because they are at significant risk of infection :

  • cat, primate and human bites

  • lower-extremity and hands wounds

  • puncture wounds

  • crush injuries

  • contaminated or heavily soiled wounds

  • wounds older than 8-12 hours

  • wounds infected at presentation

  • wounds in patients with immunosuppression ( e.g. diabetes mellitus, HIV, chemotherapy, asplenic)

 

Antibiotic prophylaxis

Antibiotic prophylaxis should be considered for all bites requiring closure and for high-risk bites.

The microbiology of infected bite wounds from dogs and cats is similar to that of the organisms that colonize the animal's oral cavity. Less frequently, isolates may also come from the environment and patients' skin.

 

Common pathogens associated with animal bites include :

  • Staphylococcus

  • Streptococcus

  • Pasteurella

  • Enterococcus

  • Moraxella

  • Corynebacterium

  • Neisseria

  • anaerobic bacteria

  • Pasteurella multocida

    • common bacterium in the mouths of cats, but it can also be present in dogs

    • can cause a fast-growing infection in humans

    • causes wounds to become infected within 24 hours of the bite

  • Capnocytophaga canimorsus

    • an emerging human pathogen that has been isolated from the mouths of 24% of dogs and 17% of cats

    • a fastidious gram-negative bacterium that can cause septicemia, meningitis, and endocarditis

Amoxicillin/clavulanate (Augmentin) is generally considered the first-line prophylactic treatment for animal bites.

 

Tetanus vaccination

Tetanus vaccination is recommended after an animal bite if it has been more than five years since the patient has been immunized (10 years for clean, minor wounds).

 
 

Rabies

Rabies is a virus that can infect any mammal.

Postexposure prophylaxis is indicated in all persons who were possibly exposed to a rabid animal.

Saliva, brain tissue, and nervous system tissue are considered infective. Blood, urine, and feces are not infective, and contact does not warrant postexposure prophylaxis

Postexposure prophylaxis is generally not needed in patients with a dog or cat bite as long as the animal is not showing signs of rabies, such as inappetence, dysphagia, abnormal behavior, ataxia, paralysis, altered vocalization, or seizures; however, the animal should be monitored for at least 10 days.

If the animal shows signs of rabies, becomes sick, or dies, immediate postexposure prophylaxis is recommended. No animal should be euthanized within 10 days of biting someone so that it can be properly observed.

If there is a question about whether postexposure prophylaxis should be given, physicians should contact their local health department.

Preexposure prophylaxis should be considered in persons with higher risk of rabies exposure, such as certain laboratory workers, veterinarians, spelunkers, and international travelers to areas where they are unlikely to receive treatment within 24 hours of a possible exposure.

 
 
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Animal Bites to the Head and Neck

Medscape

Updated: Oct 24, 2018

Access

Dog and Cat Bites

Ellis R, Ellis C

Am Fam Physician. 2014 Aug 15;90(4):239-243.

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Animal bites

World Health Organisation

5 February 2018

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Animal Bites: What You Need to Know

Becker JU

Medscape 

October 28, 2019

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Animal bites

BMJ Besyt Practice.

Last reviewed:December 2019

Last updated:January  2019

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Bite Wounds

American Academy of Pediatrics

Red Book Online

February 2020

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Rabies: risk assessment, post-exposure treatment, management

Public health England.

Gov.UK

Last updated: 19 July 2019

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Rabies

Wallace RM

Centres for Disease Control and Prevention

Yellow Book, Chapter 4(78) 

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Animal Bite - Antibiotic prescribing

HSE Ireland

Online February 2020

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Ireland is considered rabies free and practises strict quarantine of imported animals.

In Ireland there have been no indigenous rabies cases reported since 1903, and in Northern Ireland since 1923.

 

However, in January 2020 the Department of Agriculture confirmned that a sable (a species of marten) had been exposed to rabies.

The infected pet is believed to have been imported from Russia via Italy and England, by a homeowner who lives in Riverstick, near Kinsale in County Cork.

Concerns were first flagged on January 7 when the department said it was made aware of a sable that was intermittently displaying “atypical behaviour”.

It is understood that the animal's owner raised concerns about their pet with a local vet who immediately recognised the symptoms.

The Department said it is satisfied that the animal was kept securely confined at a private house and there was no evidence of contact with animals outside the household.

But the animal was euthanised when the initial investigation could not rule out rabies infection.

While initial screening tests by the department’s Central Veterinary Laboratory and the European Reference Laboratory in France were negative, further test results found evidence of low levels of lyssavirus genetic material in brain samples taken from the animal. The Department said that based on these results, rabies cannot be ruled out in the sable.

 

While no contact with any other animals outside the household has been identified, and the likelihood of spread to other animals in the area is extremely low, the Department has imposed precautionary measures in the surveillance zone, prohibiting the gatherings of dogs, cats or ferrets, including hunting, sales and fairs, for a month.

 

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