chapter 19 Demodicosis (Canine and Feline)...........................
DEFINITION/OVERVIEW
An inflammatory parasitic disease of dogs and, less frequently, cats that is character-
ized by an increased number of mites in the hair follicles, adnexa, and on the surface
of the skin.Often leads to superficial or deep folliculitis and furunculosis, and alopecia.
May be localized or generalized.
Juvenile-onset generalized form (dog) has a heritable basis; certain DLA haplotypes
associated with disease in one study.
ETIOLOGY/PATHOPHYSIOLOGY
Commensal organism in the dog; frequently colonizes the skin of cats.
Normal immune system tolerates mite presence and may have an inhibitory effect on
mite populations.
Pathology develops when mites proliferate and produce inflammation within the fol-
licle (dogs):D. gatoimay cause a hypersensitivity reaction (cats).
Demodexmites may change from commensal to pathogenic parasite to produce
disease.
Initial proliferation of mites may be the result of a genetic or immunologic disorder.
Mechanisms of disease include disruption of cutaneous barrier; disruption of follic-
ular integrity (furunculosis); proliferation of bacteria; T cell exhaustion.
Dead or degenerate mites may be found in noncutaneous sites (e.g., lymph node,
intestinal wall, spleen, liver, kidney, urinary bladder, lung, thyroid gland, blood, urine,
and feces) and are considered to represent drainage to these areas by blood and/or
lymph.Dogs
Demodex canis: most common mite identified; transferred from bitch during nurs-
ing; typically present in small numbers; resides in the hair follicles and, rarely, in the
sebaceous glands of the skin (Figure 19.1).Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Dermatology, Third Edition.
Karen Helton Rhodes and Alexander H. Werner.
©2018 John Wiley & Sons, Inc. Published 2018 by John Wiley & Sons, Inc.
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