Papules, pustules and crusts Flashcards
what do papules, pustules and crusts often represent
a progression of a lesion
major differentials for papules, pustules and crusts
pyoderma demodicosis dermatophytosis miliary dermatitis (cats) flea allergy dermatitis sarcoptic mange contact dermatitis pemphigus foliaceus superficial necrolytic dermatitis zinc responsive dermatosis calcinosis cutis
true or false; pyoderma is one of the most common cutaneous conditions of dogs but is uncommon in cats
true
characteristics of the staphylococcal organisms typically involved in pyoderma
not highly virulent and need an abnormality in the host in order to proliferate excessively
examples of host abnormalities that may predispose to pyoderma
impaired barrier function of skin and impaired immune function
examples of impaired barrier function of skin
atopic dermatitis, dry skin, swimming, poor nutrition
example of impaired immune function
hyperadrenocorticism
which bacteria is common in a majority of canine bacterial skin infections
staphylococcus pseudintermedius
what other bacteria is currently being recognized as a cause of canine bacterial skin infection that is inherently more resistant
staphylococcus schleiferi
what are the different subtypes of staphylococcus schleiferi
staph schleiferi schleiferi (coag neg) and staph schleiferi coagulans (coag positive)
is pyoderma contagious
transmission is not common
what two things must you consider with a patient with a resistant staph in your clinic
hygiene and environmental cleaning
what do we do differently now with more resistant staph infections
rely more on bacterial cultures for antimicrobial choices and use topical treatments rather than systemic
which gram negative can be involved in skin infections
pseudomonas
3 classifications of pyoderma
surface, superficial and deep
distribution of superficial bacterial folliculitis
most common on trunk but can be anywhere on body
clinical signs of superficial bacterial folliculitis
elevated hair shafts or patchy alopecia; pustules or papules on the ventral abdomen
where does the saying “in dogs, if it looks like ringworm it’s probably pyoderma” result from
superficial bacterial folliculitis commonly has lesions that are considered classic for ringworm in dogs
definition of furunculosis
rupture of hair follicles
factors of deep pyoderma
deep folliculitis, furunculosis and cellulitis
which bacteria are commonly involved in deep skin infections
E. coli, proteus or pseudomonas
where do you commonly see deep pyoderma in german shepherd dogs
trunk
where do you commonly see deep pyoderma affect in boxers and pit bull terriers
interdigital skin
what should always be considered as a possible underlying cause of deep pyoderma
demodicosis
what causes deep pyoderma associated with grooming or bathing (post-grooming furunculosis)
shampoos contaminated with bacteria (pseudomonas)
what can also be a name for pyotraumatic dermatitis
hot spots
cause of pyotraumatic dermatitis
self-trauma (scratching or biting)
lesions seen with pyotraumatic dermatitis
circular alopecia or matted erythematous, moist, exudative area of skin
which types of dogs is pyotraumatic dermatitis most common in
thick-coated dogs – golden retrievers
description of fold pyoderma (intertrigo)
surface infection with bacteria, yeast or both seen in a body fold
what is an indication to check the folds of a dog
bad odor
which breed and at what location does mucocutaneous pyoderma affect
german shepherd in the haired skin near the lower lips
definition of bacterial overgrowth syndrome
surface bacterial proliferation without any pyoderma lesions
presentation of bacterial overgrowth syndrome
pruritic and malodorous dogs
definition of impetigo
superficial infection not involving hair follicles
what body location is impetigo seen in
inguinal and axillary regions of young dogs
what is your best diagnostic tool for pyoderma
cutaneous cytology
what are the best lesions to sample with pyoderma
pustules (next would be edge of an epidermal collarette, draining lesion or from greasy or moist skin)
what is observed with classification 0
no bacteria or inflammatory cells
what is observed with class 1+
occasional bacteria or inflammatory cells but slide must be scanned carefully for detection
what is observed with classification 2+
bacteria or inflammatory cells present in low numbers but detectable rapidly without difficulties
what is observed with classification 3+
bacteria or inflammatory cells present in large numbers and detectable rapidly without any difficulties
what is observed with classification 4+
massive amounts of bacteria or inflammatory cells present and detectable rapidly without difficulties
when are bacterial cultures useful
when rods are present on cytology, with deep or severe pyoderma, when infection doesn’t respond to first line therapy or relapses frequently
what is the minimum treatment length for superficial pyoderma
3-4 weeks
what is a major cause of recurrences of pyoderma
inadequate length of therapy
3 other causes of recurrence of pyoderma
inappropriate drug selection, inadequate dosing and poor compliance
first choice antibiotic for pyoderma
cephalexin or clavamox
what antibiotic can be a good choice for pyoderma in cases with extensive scarring
clindamycin
example of topical therapy that can be used with pyodermas in addition to antimicrobials
shampoos containing chlorhexidine and benzoyl peroxide
what are 3 things that can be useful in pyotraumatic dermatitis
clipping, topical astringents such as aluminum acetate (burrow’s solution) and short courses of corticosteroids in select cases
two examples of topical antibiotics
mupirocin or fusidic acid
cause of demodicosis
demodex canis – normal resident of dog skin
where do demodex mites reside and what do they feed on
reside in hair follicles and feed on skin cells, sebum and epidermal debris
when does demodicosis occur
when host-mite balance is tipped in favor of the parasite
forms of demodicosis
localized or generalized; juvenile onset or adult onset;
localized demodicosis
one or several areas only, 6 or less lesions, does not progress to generalized
generalized demodicosis
large areas of body, entire body region, 2 or more feet, 12 or more lesions
juvenile onset demodicosis
less than 12 months old in small dogs, less than 18 months in large breeds, less than 2 years in giant breeds
adult onset demodicosis
above the cut-offs for juvenile onset
true or false: dogs with generalized demodicosis are okay to be bred
false: there is a genetic predisposition
what should dogs with adult-onset demodicosis be screened for
immunosuppressive conditions: cushing’s disease, steroid or other immunosuppressive drug therapy, hypothydroidism and neoplasia
clinical appearance of demodicosis
highly variable: alopecia, erythema, scaly, hyperpigmented areas
clinical appearance of demodicosis when complicated by secondary pyoderma
comedones, papules, pustules follicular casts, crusts and deep folliculitis
diagnosis of demodicosis
deep skin scrapings – 3 or more collected while squeezing the skin and draw capillary blood; can also use trichogram in sensitive or painful areas
when can skin biopsies be useful to diagnose demodicosis
in chronic cases when there is extensive scarring
what should be done in addition to skin scrapings when suspecting demodicosis
cutaneous cytology for secondary pyoderma
treatment of localized demodicosis
benign neglect – usually have spontaneous resolution within 6-8 weeks as puppy immune system matures; can do mild topical therapy (benzoyl peroxide) but not necessary
duration of treatment of generalized demodicosis
need to be treated, likely will last several months, skin scrapings every 2-4 weeks;
treat for one month past two consecutive skin scrapings
when is a patient considered cured of generalized demodicosis
when there has been no relapse for 12 months after treatment has stopped
treatments of generalized demodicosis
oral isoxazolines, oral or topical macrocyclic lactones and topical amitraz
example of an oral isoxazoline
fluralaner (bravecto)
benefit of using fluralaner to treat demodicosis
safe in ABCB1 deletion dogs and excellent efficacy
common adverse effects seen with macrocyclic lactones
neuro side effects: early signs are mydriasis, salivation and ataxia
which drug should not be used in patients with demodicosis
corticosteroids
dermatophytosis
fungal infection affecting keratinized tissues of the body – superficial skin layers, hair and claws
causes of dermatophytosis
microsporum canis, trichophyton mentagrophytes and microsporum gypseum
most common cause of dermatophytosis
microsporum canis
what can predispose an animal to a dermatophyte infection
mechanical disruption of the stratum corneum
which breeds are predisposed to dermatophytosis
persian and himalayan cats; yorkshire terriers, dalmatians, and jack russell terriers
major differential diagnosis for scaling, crusting and alopecia in the cat
dermatophytosis
appearance of lesions of dermatophytosis in the cat
one or more roughly circular areas of alopecia with or without scaling and erythema
why is a definitive diagnosis of ringworm/dermatophytosis crucial
it is contagious and zoonotic
diagnosis of dermatophytosis
wood’s light;
trichograph;
fungal culture
what is the most reliable diagnostic test for dermatophytosis
fungal culture of affected hair and scales
how long can M. canis spored remain infective in the environment
18 months
why are antifungal dips more effective than shampoos in treating dermatophytosis
dips have a longer residual activity
how long should pets be treated for dermatophytosis
systemic antifungal treatment until 2 to 3 consecutive fungal cultures are negative – may be up to 4-20 weeks
two examples of dips that can be used to treat dermatophytosis
lime sulfur and enilconazole
systemic treatment of dermatophytosis
ketoconazole
what is miliary dermatitis
a reaction pattern in cats referring to the way the lesions feel on palpation – multiple etiologies
lesions of miliary dermatitis
fine papules and crusts often scattered over the dorsal trunk
what is miliary dermatitis often associated with
underlying hypersensitivity dermatitis
examples of causes of miliary dermatitis
feline nonflea-induced hypersensitivity dermatitis, fleabite hypersensitivity, cheyletiella, pemphigus foliaceous
