Approach to alopecia 1 Flashcards
What is spontaneous alopecia?
*No animal involvement
*Various aetiopathogeneses
What is self induced alopecia?
*Animal removes hair
*Pruritus (ectoparasites, allergic skin disease
*Psychogenic (behavioural, internal pain/inflammation)
How can you check if alopecia is self-induced or spontaneous?
Self induced = look for hair in teeth / litter trays
=Trichograms - shows broken hair shafts in pruritic animals
how does inflammation cause spontaneous hair loss?
Inflammation within hair follicle = damaged hair = hair loss
How would you approach diagnosis?
1.History
2. Physical examination - needs to be thorough
3.Differentiate spontaneous vs self-induced
4.Differentiate inflammatory vs non-inflammatory
5.List differential diagnoses
6.Make diagnostic plan
What skin conditions are puppies predisposed to?
*demodicosis
*dermatophytosis
*growth hormone deficiency
What alopecia causes are adults predisposed to?
Immune mediated disease (sebaceous adenitis)
What alopecia causes are older dogs predisposed to?
*hypothyroidism
*Hyperadrenocorticism
*Neoplasia
When making differential diagnoses- what should you prioritise?
*Common things are common
*Zoonoses - any other animals in the household
What are the infectious agents causing inflammation causes of spontaneous alopecia?
*bacterial folliculitis
*dermatophytosis
What are the parasites causing inflammation causes of spontaneous alopecia?
*Demodicosis
*Leishmaniasis
What are the immune mediated causing inflammation causes of spontaneous alopecia?
*alopecia areata
*dermatomyositis
*sebaceous adenitis
What is the most common cause of spontaneous alopecia in cats + dogs?
Bacterial folliculitis
What is the agent causing bacterial folliculitis?
Staphylococcus pseudintermedius
What can be associated with bacterial folliculitis?
*Pruritus
*Alopecia
*Scale
*Crust
*Deep infection
How should you take a sample of a dry/wet lesion?
Dry = tape strip
wet = impression smear
What is the most common agent causing ringworm?
Microsporum canis (zoophilic)
What are less common agents causing ringworm?
Microsporum gypseum
Trichophyton mentagrophytes
Trichophyton benhamiae
What animals are predisposed to ringworm?
*Young / Immunocompromised
*Puppies + kittens
*Persian cats
*Yorkshire + jack russel terriers
What are reservoirs for ringworm?
Asymptomatic carriers
Where are ringworm lesions mosrt common?
Head
Ears
Chin
If a vet suspects ringworm what should be done?
Wear protective clothing to prevent contamination
How is ringworm diagnosed?
*Wood’s lamp examination - apple green fluorescence of hair
*Trichography - on x100 magnification w oil immersion can see arthrospores (looks like soap bubbles)
*Culture = gold standard
What is the mackenzie sampling technique for culture?
Use nylon brush to create electromagnetic charge which attracts spores
-then submit brush to lab / inoculate on fungal culture medium - RED=fungal
What special stains can be used to detect hyphae?
Silver
PAS
How is ringworm treated?
*Spontaneously resolve (12-20wks)
*Topical Tx = reduce scale = reduced contamination + shedding (miconazole / lime sulfur dip)
*environmental decontamination
What are systemic treatments of ringworm?
*Itraconazole - licensed in cats
*Ketoconazole - licensed in dogs - can cause neurological disease
What are the species of demodex?
Demodex canis (dog)
Demodex injai (dog)
Demodex cati (cat)
What will happen if commensal demodex is not controlled?
Will proliferate + cause disease
What are the 2 clinical syndromes of demodicosis?
*juvenile onset demodicosis
*Adult onset demodicosis
What is seen with juvenile onset demodicosis?
*Localised to generalised patches
-Alopecia
-Scaling
-Comedones
-Blue-grey hyperpigmentation
-Follicular casts
*+/- secondary bacterial infection
*Mild cases spontaneously resolve
Why is generalised juvenile onset demodicosis a problem?
Serious problem as can lead to secondary infections
What is seen with adult onset demodicosis?
*Often generalised
*Often secondary bacterial infection
*Papules, pustules, draining sinus tracts, enlarged lymph nodes, +/-pyrexia
*Pruritic or painful
*Require aggressive treatment
Is demodex cati contagious?
No - demodex gatoi is
Demodex cati = commensal gone wrong
What does it mean if a condition is idiopathic?
Can never be cured - only handled/ lifelong treatment
How do you confirm demodicosis?
*positive skin scrapings
*hair plucks
When would you use biopsy to confirm demodicosis?
Only if skin is thickened
When is a hair pluck useful to do?
On a conscious patient
What do you need to do when doing a skin scraping and why?
Always squeeze the skin to bring the mite to the surface
How would you observe demodex mites under a slide?
*Mount in liquid paraffin + use cover slip
*Most found on x4 or x10 magnification
What is the difference micrscopically between D. canis + D. injai + D. cati?
D. injai = long tail
D. cati = pointy tail
What is the treatment of demidicosis?
*clip long haired animals + bathe to remove debris
treat 2 bacterial infection
*Treat underlying immunosuppression
*Imidacloprid / moxidectin
*isoxazoline - afoxolaner / flurolaner
Why do they advise spaying dogs with juvenile onset demodicosis?
*increased chance of disease in offspring
*periparturient reduction in immunity can result in return of disease
How would you treat demodicosis in cats?
*Isoxazolines - Flurolaner
*Treat underlying disease
How would you perform a biopsy if you suspected non-inflammatory alopecia?
Take a biopsy of the full alopecia, partial alopecia (edge) and a sample of the normal skin
