Demodicosis (Marsella) Flashcards
Demodex canis Life Cycle
- 25-30 days
- Egg → larvae (6 legs) → Nymph (8 legs) → adult (8 legs)
Demodex transmission
- Mites transmitted from bitch to pups
- Present in low numbers in healthy, post-natal dogs
- NOT contagious
- NOT zoonotic
Demodex pathogenesis
- Deficient cell-mediated immune response
- Genetics (autosomal recessive)
- Immunosuppression
- Bacterial folliculitis (Staph is an immunosuppresant)
Common causes of immunosuppression in juveniles
- Poor nutrition
- Stress
- Estrus
- Endoparasites
Common causes of immunosuppression in adults
- Steroids
- Endocrinopathies
- Neoplasia
(Demodicosis usually presents before the underlying disease does)
Clinical signs of demodicosis
- Papules/pustules
- Erythema
- Scaling
- Crusting
- Comedones
- Patchy alopecia
- Hyperpigmentation
Differential diagnosis list for comedones
- Demodex!!!
- Endocrine disease
Demodicosis diagnosis
- Deep skin scrapes
- Hair plucks (negative does not R/O)
- Biopsy (Shar peis, scar tissue, pododermatitis)
Onset of juvenile onset demodicosis
- Small breed < 12 mos
- Lrg breed < 18 mos
- Giant breed < 24 mos
Onset of adult onset demodicosis
- Small breed > 12 mos
- Lrg breed > 18 mos
- Giant breed > 24 mos
Juvenile onset localized demodicosis
Evidence of mites in one area based on 5 deep skin scrapes. Benign.
Questions to ask with deep skin scrape of demodex
- Is it generalized?
- Scrape 5 places total
- If not, will it become generalized?
- Don’t tx, wait and see
Prognosis for localized demodicosis
- 90% will clear spontaneously in 6-12 wks
- 10% will generalize
- Prognosis good
Treatment for juvenile onset localized demodicosis
- Benign neglect
- Abx (esp. if pustular)
- Topical 2% mupirocin, benzoyl peroxide gel/shampoo
- Systemic
- De-worming, HW prevention
- Good diet
- Supportive
Treatments to avoid in juvenile onset localized demodicosis
- Steroids
- Anti-mite therapy
Why not treat localized demodicosis w/ miticides?
- To know if it will become generalized
- Prevent unnecessary medical treatment
Localized demodicosis recheck
- 2-4 wks later
-
Deep skin scrape in same 5 spots
- mite counts decr: lesion resolving, recheck in 4 wks
- mite counts incr. +/- other positive sites: may be progressing to generalized