CRACKCast E061 – Mammalian Bites

In CRACKCast, Podcast by Adam Thomas3 Comments

This episode of CRACKCast covers Rosen’s Chapter 61, Mammalian Bites. From dogs to seals, this episode covers a solid chunk of the pathogens, risk factors for infection and first line treatments for a number of different bites that you may encounter in your ED.

Shownotes – PDF Here


Rosen’s in Perspective

Can be a big problem: Dogs can bite down with over 310 pounds of force. Dog bites most common domestic animal bite; cats are second

The breeds most frequently responsible for fatalities include Pit Bull (59%), Rottweiler (14%), American Bulldog and Siberian Husky (5% each), and German Shepherd Dog (3%)

Bites can damage all sorts of tissue and structures: Watch out for head and neck injuries in children less than 4


1) List at least 5 pathogens responsible for infection from dog bites

Aerobic bugs: Staphylococcus aureus, alpha-hemolytic and beta-hemolytic streptococci, Klebsiella, Bacillus subtilis, Pseudomonas, Enterobacteriaceae, and Capnocytophaga canimorsus

Anaerobic bugs: Bacteroides, Fusobacterium, Peptostreptococcus, Porphyromonas, and Prevotella species

NOTE: Pasteurella multocida likely has been overstated as a primary causative pathogen


2) List 4 risk factors for overwhelming sepsis from dog bite

  1. Alcoholic liver disease
  2. Functional or surgical asplenia
  3. Lung disease
  4. Corticosteroid use

3) What first line antibiotic is a good choice for cat and dog bites?

Amox-Clav 875mg PO BID

For penicillin allergies:

  • Moxifloxacin

4) What species are known to cause infection with Pasteurella multocida?

  • Dogs & Cats
  • Opossum
  • Rat
  • Lion
  • Rabbit
  • Pig
  • Wolf
  • Monkey
  • Cougar

5) What are the risk factors for infection with animal bites?


6)  Describe the treatment of monkey bites

  • Highly virulent virus
    • Herpes virus simiae
  • Case fatality of 70% without antiviral therapy

Treatment: Mechanical debridement and vigorous irrigation immediately for 15 min


Valacyclovir: 1g orally PO q8h x 14 days


Acyclovir 800mg PO Q5 times daily x 14 days

Note: These bites are also high risk for bacterial infection
-> Amox-Clav for covering S. aureus and Bacteroides


7) When is anti-viral prophylaxis NOT indicated for a monkey bite


8) Describe the recommendations for bite wound closure and antibiotics in bite cases




1) What about seal bites?

UptoDate: Nada.


It’s authored by the one and only Dr. McDreamy! (Dr. Colin White)

Punch line: Mycoplasma phocacerebrale can mess you up! Don’t forget about possible Vibrio vulnificus infection as well.  Mycoplasmas lack a cell wall, the major site of action for beta-lactam antibiotics. No cell wall, no worky worky, no good for seal finger.

Doxycycline for two doses and then switched to tetracycline 500 mg four times a day for two weeks


2) What about rabies in BC?

CALL BC Public Health Vet: 604-829-2110

“Epidemiology of rabies in BC: The only known reservoirs for rabies in BC are a number of bat species. Because of altered behaviour, infected bats are considered more likely to come into contact with humans and subsequently be tested. Between 4 and 10% of the bat specimens sent for testing to the CFIA are positive (1). It is estimated that less than 0.5% of bats are actually infected.

Other species that have tested positive for rabies in BC include (except as noted, all were found to have bat-variant rabies): 1 cat in Maple Ridge (2007), 4 striped skunks in Stanley Park (2004), 3 cats in Delta (one cat had skunk strain) (1992), 1 beaver (skunk strain) (late 80s), 1 horse in the Sorrento area (1984), 1 cat on Vancouver Island (strain unknown, but presumed to be bat-variant) (1969).

A wildlife survey in Delta (prior to 1989), following the isolation of the skunk strain rabies in a beaver, intense testing of cats following the Delta incident as well as a study examining raccoons indicated that the skunk and other specific strains of rabies are not enzootic in BC.

Human cases of rabies in Canada are very rare. In BC, there has only been 1 human case diagnosed since 1983: an adult male who died of bat-variant rabies in 2003 (2).”



3) Waterhouse-Friderichsen syndrome & Capnocytophagia related Gangrene sepsis

Adrenal hemorrhage from overwhelming sepsis: this is BAD! Super high mortality rates. (30% overall, with 70% of these deaths in immuno compromised)

If you see gangrene at the site of a cat or dog bite, think about this. These patients can get SICK. DIC, renal failure, refractory hypotension. You can get metastatic endocarditis and meningitis.

Replace steroids early (eg Hydrocortisone 50-100mg IV Q6hrs). Look for adrenal hemorrhage on CT: not very sensitive. Cultures can be negative, even after 14 days of running the plates. Think about running a PCR for C. canimorsus


This episode was edited and uploaded by Colin Sedgwick (@colin_sedgwick)

Adam Thomas

CRACKCast Co-founder and newly minted FRCPC emergency physician from the University of British Columbia. Currently spending his days between a fellowship in critical care and making sure his toddler survives past age 5.
Chris Lipp is one of the founding Fathers for CrackCast. He currently divides his time as an EM Physician in Calgary (SHC/FMC) and in Sports Medicine (Innovative Sport Medicine Calgary). His interests are in paediatrics, endurance sports, exercise as medicine, and wilderness medical education. When he isn’t outdoors with his family, he's brewing a coffee or dreaming up an adventure…..