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Demodicosis 245

• In adult-onset demodicosis, signs caused by scrapings, acetate tape preparations, and
underlying disease (e.g., hyperadrenocorti- fecal flotation are negative, treatment trials
VetBooks.ir can be present. TREATMENT Diseases and Disorders
have been used.
cism) or by immunosuppressive treatment
PHYSICAL EXAM FINDINGS
Canine: Treatment Overview
• Localized demodicosis: several small areas • Treatment of canine demodicosis has been
of patchy alopecia, mild erythema, scaling, revolutionized by the use of the isoxazoline
and variable hyperpigmentation on the face drugs: fluralaner (Bravecto), afoxolaner
or forelimbs (NexGard), sarolaner (Simparica), and
• Generalized demodicosis: lesions can lotilaner (Credelio).
be similar but are usually more severe, • Generalized demodicosis requires miti-
extensive, and complicated by pyoderma. cidal therapy, but most cases of canine
Comedones, papules, pustules, follicular localized demodicosis resolve without
casts, crusts, edema, and deep folliculitis/ treatment.
furunculosis are common. Hyperpigmenta- • Treat for underlying or concurrent disease,
tion of follicular ostia is suggestive. Peripheral or discontinue immunosuppressive therapy
lymphadenopathy, pain, pruritus, and malaise in adult patients.
may also be present. In adult-onset cases, • Treatment of secondary pyoderma is essential
physical changes associated with underly- for reducing pruritus and restoring normal
ing disease (e.g., hyperadrenocorticism, skin appearance. Unless deep or severe
neoplasia) may be found. pyoderma is present, antibacterial shampoo
• D. injai: greasy skin and pruritus on dorsal therapy is often sufficient, and systemic anti-
trunk (or face) DEMODICOSIS Pododemodicosis resembles many biotics are not needed if effective miticidal
Feline: other conditions. Skin scrapings and trichograms should therapy is given.
• D. cati: patchy alopecia and scaling or be collected in dogs of any age presenting with pedal • Cure is achieved when there has been no
lesions.
ceruminous otitis relapse for at least 1 year after treatment
• D. gatoi: symmetrical, self-induced truncal completion.
alopecia
○ Squeeze skin to extrude mites from hair Acute and Chronic Treatment
Etiology and Pathophysiology follicles immediately before and/or during • Localized demodicosis does not require treat-
• The immunologic defect leading to canine scraping; scrape until mild capillary bleed- ment. The rationale for not treating these
demodicosis is poorly understood. ing is seen. mild cases is that their resolution indicates
• In adult dogs, consider underlying cause, ○ Subjective assessments of mite numbers adequate immune function (and has positive
including corticosteroid administration (0-4+) and the proportion of live mites implications if the dog is to be used for
(common), spontaneous hyperadrenocorti- and juvenile mites/eggs are important for breeding).
cism, hypothyroidism, leishmaniasis, neo- baseline and subsequent monitoring of • Therapy for generalized canine demodicosis is
plasia, and immunosuppressive treatments. therapy. continued for several months. All treatments
• Poor nutrition, estrus, parturition, and stress • In sensitive areas, trichography (microscopic should continue for at least 1 month after
can contribute. examination of 50-100 hairs forcefully two consecutive sets of skin scrapings are
plucked using forceps or hemostats) is negative.
DIAGNOSIS an easier but less sensitive method. If the • Response to therapy is monitored by clinical
trichogram is negative, consider sedation for improvement and skin scrapings approxi-
Diagnostic Overview scrapings in these areas. mately every 4 weeks.
In most cases, canine demodicosis is a straight- • Acetate tape impressions with skin squeezing • Isoxazoline drugs likely represent the safest
forward diagnosis as long as skin scrapings are are an alternate technique but less often used. and most effective therapy. One report of
not overlooked. The diagnosis rests on finding successful treatment with extralabel oral
mites in affected skin. Although D. canis is a Advanced or Confirmatory Testing fluralaner for D. gatoi; the licensed topical
normal skin inhabitant, it is rare to find mites • Be sure to collect deep skin scrapings and product may also be effective. The use of
unless they are causing disease. trichograms before performing biopsies other treatments, including macrocyclic
because histopathologic evaluation usually lactones, is becoming less common.
Differential Diagnosis is not necessary to diagnose demodicosis. Options for treating canine demodicosis:
Uncomplicated demodicosis resembles other Skin biopsies may be needed to find • Oral isoxazoline drugs
skin disorders: mites when extensive scarring is present ○ Extralabel use for this condition: very
• Dogs: bacterial folliculitis, dermatophytosis, (e.g., feet). convenient with an excellent safety profile
dermatomyositis, pemphigus foliaceus and • In adult-onset demodicosis cases, recommend when used as labeled. Note that minimum
other immune-mediated diseases, sebaceous diagnostic workup for internal disease as age for some products is 6 months.
adenitis deemed appropriate (e.g., CBC, chemistry ○ Sufficient published and anecdotal evidence
• Cats: hypersensitivity disorders and other profile, urinalysis, imaging, screening tests exists to recommend the use of these
ectoparasites (D. gatoi), psychogenic (sym- for endocrinopathies, FeLV/FIV evaluation). drugs as first-line therapy for canine
metrical) alopecia (D. gatoi), dermatophytosis • In pruritic cats with D. gatoi infestation, generalized demodicosis. Studies of D.
(D. cati), otodectic acariasis (D. cati) mites are easy to miss because the cat removes injai are lacking.
them by licking. ○ Rapid clinical and microscopic improve-
Initial Database ○ Less pruritic housemate cats and fecal ment is expected. Negative skin scrapings
• Deep skin scrapings from at least three flotations can yield the mites. are attained quite rapidly; typically mite
sites for follicular-dwelling Demodex mites ○ In geographic areas where D. gatoi numbers are dramatically reduced at 1
(p. 1091) is endemic: if broad superficial skin month and negative at 2 months.

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