Small Animal Dermatology, 3rd edition

212 DISEASES/DISORDERS

The normal flora can be altered by pH, temperature, salinity, moisture, albumin,

fatty acid levels, etc.; age, sex, diet, hygiene, and environment also play a role

Bacterial counts in the normal individual vary greatly; counts are further affected

by pathology; resident populations of staphylococci play a role in the bacterial

dybiosis of disease.

 Transient:
Bacteria that may be cultured from “normal” skin but do not multiply or establish

colonies

Not of significance unless associated with disease (i.e., infection).

 Different strains of the same organism may be either resident or transient; non-

pathogenic strains ofS. pseudintermediusmay be cultured from normal skin (resi-

dent) whereas methicillin-resistant strains ofS. pseudintermediusmay be eliminated

from the skin by treatment of reservoir sites (transient).

 Infection versus colonization:
Infection: the organism is present and causes an immunologic reaction (degener-

ating neutrophils and/or phagocytized bacteria noted in a direct smear or aspirate

of a pustule)

Colonization: the organism is present on the skin but does not produce an

adverse reaction by the host.

 Primary resident bacterial microbiome of the skin surface and hair follicle:
Dog:
Micrococcus
Corynebacterium
Coagulase-negative staphylococci (S. epidermidis,S. xylosus)
Alpha-hemolytic streptococci
Acinetobacterspp.
Clostridium perfringens
Propionibacteriumacne
Staphylococcus pseudintermedius(often identified in hair follicle)
Cat:
Alpha-hemolytic streptococci
Micrococcus
Coagulase-negative and -positive staphylococci (S. pseudintermediusandS.
aureus)
Acinetobacterspp.

Primary Causes

 Cutaneous bacterial infections are more common in dogs compared to other mam-

malian species:

Thin compact stratum corneum

Relative lack of intercellular lipids in the stratum corneum

Lack of a lipid-squamous epithelial plug in the ostia of the canine hair follicle

Relatively high cutaneous pH (basic, 7.5).