Extension of folliculitis -> rupture of hair follicle wall -> microbes + free keratin in dermis -> provokes a foreign-body reaction
What type of inflammation is present in furunculosis?
Usually pyogranulomatous reaction - see macrophages, neutrophils +/- rbcs - NB organisms may be hard to find - do not assume is sterile.
Are the lesions of furunculosis always pruritic?
Lesions often painful, variably pruritic.
How do you treat furunculosis?
Usually require extendedsystemic antibiotic course based on culture + susceptibility testing (culture of tissue (ideally) or exudate). Continue to 2 weeks post-resolution (minimun 4 weeks, often 6-8 weeks total).
Topical chlorhexidine shampoos/foams also.
What are the clinical manifestations of furunculosis?
Chin/muzzle folliculitis/furunculosis
Nasal folliculitis/furunculosis
Interdigital folliculitis/furunculosis
Acral lick dermatitis/granuloma.
Post-grooming folliculitis/furunculosis
GSD pyoderma (rare)
What are the diagnostic considerations for furunculosis?
Allergies
Ectoparasites - NB demodicosis
Infections - NB Dermatophytosis
Systemic immunosuppression/endocrinopathy
Pressure driving hair back into skin
Interdigital folliculitis/furunculosis
Very common in bulldogs.
Chronic pododermatitis with interdigital folliculitis/furunculosis - common and complex problem.
Multifactorial pathogenesis - starts as sterile process but become infected when lesions rupture and are licked.
What are the primary causes of interdigital folliculitis/furunculosis?
AD/AFR
Conformation
What are the predisposing interdigital folliculitis/furunculosis?
Breed - includes EBD, FBD and mastiff types.
Increased weight-bearing - fore more than the hindlimb.
Altered weight-bearing
Congenital limb deformity
OA
Cruciate disease/other joint problems
Restrictive harnesses?
How do you treat interdigital folliculitis/furunculosis?
Consider primary cause - NB always rule out demodicosis/ treatment as indicated.
Investigate and treat secondary infections.
Control inflammation once infection controlled:
GCCs - topical/systemic
Ciclosporin/ 0.1% tacrolimus
Not oclacitinib/lokivetmab!!!!
Address predisposing triggers, where possible:
Reduce weight, analgesia if underlying pain, corrective surgery
What is Acral lick dermatitis/granuloma?
A deep pyoderma that does not present with sinus tracts - a d/d for cutaneous masses.
Localised folliculitis/furunculosis on lower limbs due to self-trauma.
What are the underlying causes of Acral lick dermatitis/granuloma?
Pruritus - allergies, Ectoparasites.
Pain - small injury/ underlying orthopaedic/ neurological disorder.
Neoplasia - uncommon.
Anxiety/boredom.
What are the clinical signs of Acral lick dermatitis/granuloma?
Usually large breed, middle-aged/ older dogs.
Lesions
Plaque-like, firm +/- ulceration
Often hyperpigmented, lichenified.
Often forelimbs
Initial deep infection but, with chronicity, can develo:
Ongoing inflammation/pruritus due to FB reaction to intradermal keratin.
Obsessive-compulsive behavioural component.
How do you diagnose Acral lick dermatitis/granuloma?
Often visually distinctive, especially when small.
Cytology (squeeze lesion) and deep bacterial culture ideal.
Biopsies if unsure regarding diagnosis - d/d neoplasia, deep fungal infection.
Post-grooming folliculitis/furunculosis
Uncommon but distinctive furunculosis of dorsal trunk.
History important for diagnosis: acute onset within few days of bathing/traumatic grooming procedure. Skin lesions may be preceded by fever, depression.
Very painful - d/d back pain.
A 9 year old Rottweiler presents with discharging sinuses on the muzzle. Which investigations will you perform first?
1 Examine an impression smear of the exudate and deep skin scrapes.
2 Examine an impression smear of the exudate and submit a sample for fungal culture.
3 Take biopsies of the lesion and examine deep skin scrapes
4 Take biopsies of the lesion and submit a sample for fungal culture.