Demodicosis Flashcards by Brittany Jermalovic

Canine demodicosis

What is it?

Inflammatory skin disease caused by follicular mite Demodex canis

Normal habitant of skin’hair follicles (lives in the follicle) generally found in small numbers
When numbers increase and cause clinical signs = demodicosis

NOT contagious; although obtained when they are a few days old from nursing on mom

Not considered pruritic disease but can be associated

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Canine demodicosis

Lifecycle (broad)

Spends entire life on skin of host

Found in hair follicles and occationally sebaceous glands

Cycle = 20-35 days

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Canine demodicosis

Lifecycle (stages)

Fusiform eggs
Six-legged larvae
Eight-legged nymphs
Eight-legged adults

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Canine demodicosis

Immunopathologenesis

Hereditary gene defect (juvenile onset, generalized disease)

Probable T-cell defect (generalized disease condition)

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Canine demodicosis

Clinical lesions

Alopecia (patchy) 
Comedones (scrape these)
Papules
Pustules
Crust
Draining tracts
Nodules
Erythema; can be severe

Overproliferation of mites; build up in hair follicle and rupture causing deep pyoderma

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Canine demodicosis

Location of lesions

Face
Periocular area
Commissures of the mouth 
Forelegs
Trunk
Rear legs
Paws; demodectic pododermatitis

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Types of canine demodicosis (2)

Localized

Generalized

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Canine demodicosis
Localized
Age

Juvenile (3-6 months)

Rarely progresses to generalized

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Canine demodicosis
Localized
Lesions

1 to 6 small areas (patchy, scales); anymore than considered generalized

Face and forelegs most common

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Canine demodicosis
Localized
Treatment

Typically benign

Typically resolves spontaneously within 6-8 weeks

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Canine demodicosis
Generalized
Onset

Juvenile (do NOT breed)

Adult (>4 years)

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Canine demodicosis
Generalized
Adult

Uncommon-rare

Suspected to develop secondary to immune suppression:
Drugs (pred, apoquel, chemo)
Disease (Cushing’s, Hypothyroidism, neoplasia, parasites)

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Canine demodicosis
Generalized
Lesions

Many localized lesions: head, trunk, legs, 2+ paws

Patchy

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Canine demodicosis

Diagnosis

Deep skin scrapings (must get to the hair follicle) - multiple scrapings

Observe under 10X

Hair plucks not as sensitive as skin scrape

Tissue biopsy not necessary; will yield folliculitis/furunculosis

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Canine demodicosis
Diagnosis
Rule out tests

CBC, Chem, UA
Heartworm and fecal
T4/TSH
ACTH Stim or LDDST 
Radiographs +/- ultrasound for neoplasia

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Canine demodicosis
Treatment
What to avoid

STEROIDS; can make disease a lot worse

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Canine demodicosis
Treatment
Goal

Treat underlying disease to keep Demodex at bay

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Canine demodicosis
Treatment (broad)
Localized disease

Usually wait 1 month
90% will spontaneously resolve

If puppy need to wait and see if will develop generalized if planning to breed

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Canine demodicosis
Treatment (Topical)
Localized disease

Topical treatment used to treat secondary bacterial pyoderma:
Chlorhexidine
Mupirocin ointment

Benzyl peroxide
Follicular flushing properties
Antibacterial/anti-staph

Canine demodicosis
Treatment (Golden Rule)
Generalized

Treat one month beyond 2 negative skin scrapings, one month apart

Usually get a clinical cure before parasitologic cure

Canine demodicosis
Treatment (#1 choice)
Generalized

Isoxazoline (flea and tick product); safe for herding dogs

Inhibits GABA and glutamate gated chloride channels

Treat for a minimum of 3 months

Canine demodicosis
Treatment-Name Brands
Generalized

Isoxazolines:
Bravecto
Simparica
Nexgard
Credelio

Canine demodicosis
Treatment: Amitraz/Mitaban
Generalized

Weekly Dips-has to drip dry
Monoamine oxidase inhibitor and Prostaglandin inhibitor

Alpha-2 adrenergic agonist so can cause sedation (Antisdedan if too many side effects)

Unknown MOA

Canine demodicosis
Treatment: Ivermectin
Generalized

Not a licensed/approved treatment; not as effective as Isoxazoline class

Only use in dogs negative for heartworm disease; dosage is higher than Heartgard dose

Canine demodicosis | Monitoring treatment

Monthly skin scrapings: Evaluate live:dead mites, immature:mature, eggs Evaluate dog Usually requires 3 months of treatment Treat ONE MONTH BEYOND 2 negative skin scrapings, one month apart

Canine demodicosis | All possible treatments

Wait a month to see if it resolves (if puppy) Isoxazoline Amitraz (Mitaban) Ivermectin

Canine demodicosis | Clinical Cure

Cured if no clinical signs and mites are found 1 year after discontinuing treatment

Canine demodicosis Demodex injai Clinical signs

Long bodied mite Follicular mite that also lives in sebaceous glands Usually occurs/found along dorsum Seborrhea oleosa (greasy dermatitis)

Canine demodicosis Demodex injai Treatment

Same as D. canis | Isoxazolines

Canine demodicosis | Demodex cornei

Short-bodied mite Can be pruritic Treat like D. canis (Isoxazolines)

Feline demodicosis | Species

Demodex cati

Feline demodicosis | Background

Follicular mite similar to D. canis Rare Non-contagious Not considered to be pruritic but can be

Feline demodicosis | Types

Localized | Generalized (rare)

Feline demodicosis | Localized background

Most cases | Self-limiting

Feline demodicosis Localized Lesions

1 to 6 small areas (patchy)

Feline demodicosis | Pathogenesis

``` Look for underlying disease/immune-suppression: Drugs Diabetes FeLV/FIV SCC ```

Feline demodicosis | Clinical Signs

``` Alopecia Erythema Scaling Crust Ceruminous otitis May get miliary dermatitis ```

Feline demodicosis | Location

``` Eyelids Periocular area Head Neck Ear canals Trunk Limbs ```

Feline demodicosis | Diagnosis

Deep skin scraping Also rule out underlying disease (drugs, diabetes, FeLV, etc.)

Feline demodicosis | Treatment

May be self-limiting Isoxazolines Lime-sulfur weekly dips until 1 month free

Feline demodicosis | Demodex gatoi background

``` Contagious! Highly pruritic (most of the time) ``` Very small mite that lives on the surface (stratum corneum)

Feline demodicosis Demodex gatoi Clinical lesions

Alopecia (excorations) | Erythema

Feline demodicosis Demodex gatoi DfDx

Allergies Psychogenic alopecia Feline scabies

Feline demodicosis Demodex gatoi Diagnosis

Broad superficial skin scrapings on 10X power Fecal float; low yield but possible

Feline demodicosis Demodex gatoi Treatment

Difficult to treat Historically: Lime sulfur weekly dips Will have to treat all cats in household