Dermatology - Pruritis Flashcards
What is the pathogenesis of Flea Bite Allergic Dermatitis?
type 1 hypersensitivity reaction
What are the clinical signs/findings of Flea Bite Allergic Dermatitis?
- lumbo-sacral distribution
- pruritis crusting eruption and secondary erythema
- seborrhea, alopecia, excoriations, pyoderma, hyperpigmentation, and lichenification
- cats: miliary dermatitis
How is Flea Bite Allergic Dermatitis diagnosed?
- distribution of lesions: lumbo-sacral, tail base, caudo-medial thighs, ventrum, flanks
- presence of fleas or flea dirt
- flea antigen test
- elevated serum flea allergen specific IgE
How is Flea Bite Allergic Dermatitis treated?
- flea eradication: knock down product, insect growth regulator, and environmental control
- monthly spot-on for dogs
- prednisone for severe pruritis
What is the pathogenesis of Atopy/Allergic Dermatitis?
- type 1 hypersensitivity reaction
- hypersensitivity to aeroallergens
What are the clinical signs/findings of Atopy/Allergic Dermatitis?
- pruritis
- distribution: paws, face, distal extremities, elbows, ventrum, otitis externa
- secondary infections common: staph, malassezia, otitis, lick granuloma
How is Atopy/Allergic Dermatitis diagnosed?
- history and clinical signs
- rule out other causes
- allergy tests (intradermal or serum)
How is Atopy/Allergic Dermatitis treated?
- allergen specific immunotherapy (hyposensitization)
- symptomatic relief
- allergen avoidance
Which drugs show strong evidence for symptomatic relief of Atopy/Allergic Dermatitis?
- glucocorticoids
- cyclosporine A
- Oclacitinib
- recombinant canine interferon gamma
What is the most common food antigen causing allergies?
beef protein
What are the common locations of food allergy lesions in the dog and in the cat?
dog - muzzle, ears, distal limbs, inter-digital, axillae, groins
cat - head, face, pinnae, neck
How are food allergies diagnosed?
- positive response to elimination diet is the only definitive diagnosis
- intradermal skin testing (inaccurate)
- ELISA serology
- skin biopsy
What are the treatments for food allergies?
- change in diet: hypoallergenic, hydrolyzed
- prednisone for pruritis
What is the pathogenesis of contact dermatitis?
- type 4 hypersensitivity reaction
- cellular injury through macrophages and T lymphocytes
What are the clinical signs associated with contact dermatitis?
- intensely pruritic lesions
- hyperpigmentation, lichenification
- hairless areas most commonly affected
What are the clinical signs associated with Sarcoptes infection?
- intensely pruritic
- papules, alopecia, erythema, crusts, excoriations
- areas: hocks, elbows, pinna, ventrum, and chest
- secondary weight loss
How is Sarcoptes infection diagnosed?
- response to treatment
- fecal float
- difficult to find mite on scraping
How is Sarcoptes infection treated?
- topical dips (Lime, Amitraz)
- topical spot-on or system (Ivermectin, Selamectin)
- clean all bedding/kennels
- treat all affected and in-contact animals
Describe the features of localized demodecosis
- young patients
- one to several well-circumscribed erythematous, scaly, non-pruritic areas of alopecia
- < 6 lesions
- face, forelimbs
- often resolves spontaneously
Describe the features of generalized demodecosis
- animals < 18 months
- lesions are usually coalescing and extensive, often with secondary pyoderma
- > 12 lesions
- immunosuppressive disease
How is demodecosis diagnosed?
- deep skin scrape
- biopsy and histopathology
How is local demodecosis treated?
- often resolves spontaneously
- local antiparasitic ointment
- monthly follow-ups
How is generalized demodecosis treated?
- Amitraz dip/baths
- Ivermectin
- always avoid steroids
What are the clinical signs of a Cheyletiella infection?
- “walking” dandruff
- scaling
- pruritis is variable
How is Cheyletiella diagnosed?
- seen with naked eye on fur
- Acetate tape test
- flea comb under microscope
How is Cheyletiella treated?
- treat all in-contact animals and the environment
- topical (shampoo, spot-ons, dips)
What are the clinical signs of a hookworm infection?
- interdigital areas affected
- intensely pruritic
- erythema, alopecia, thickening of skin
How is a hookworm infection diagnosed?
fecal float
What are the clinical signs associated with chigger infestation?
- Chiggers found around legs, head, and abdomen
- inside the ears in cats
- pruritis, papules, erythema
How is a chigger infestation diagnosed?
- skin scrapes
- red color
How is a chigger infestation treated?
- two pyrethrin dips spaced two weeks apart
- topical antiparasitics
- topical or oral prednisolone for the pruritis
What are the general clinical signs of pyoderma?
pustules
papules
crusts
When is a culture indicated with pyoderma?
- if < 50% improvement after 2 weeks of tx
- new lesions after 2 weeks of tx
- residual lesions at 6 weeks
- intracellular rods on cytology
- history of MRSA/MRSP
What are the clinical signs of mucocutaneous pyoderma?
- mucocutaneous swelling, erythema, and crusting
- lips and commisures affected symmetrically
- painful, pruritic
- fissures, depigmentation
How is mucocutaneous pyoderma treated?
- clip and clean area
- topical ab: Mupirocin
What are the clinical signs of pyotraumatic dermatitis?
- red, moist, exudative, crusting lesions
- lesions in areas of primary irritation
What is impetigo?
Who normally gets it?
- bacterial disease caused by Staph spp.
- young dogs
What are the clinical signs of impetigo?
- vesicles/pustules
- mainly affects ventral hairless areas
How is impetigo treated?
- antibacterial shampoos (Chlorhexidine, Benzoyl peroxide)
- topical antibiotic creams (mupirocin, flucidin)
What is superficial pyoderma?
folliculitis caused by Staph pseudointermedius
What are the clinical signs of superficial pyoderma?
- pustules with hair shaft protruding from center
- patchy focal alopecia
- epidermal collarettes
- scaling, seborrhea
- hyperpigmentation or excoriations if chronic
What is found on cytology of superficial pyoderma?
degenerative neutrophils, phagocytosed cocci, and proteinaecous background
What is the treatment for superficial pyoderma?
- antibiotics for 21-28 days, and 1 week past resolution
- antibacterial shampoo
What are the general clinical signs of a deep pyoderma?
- deep, draining tracts
- clusters of ulcers
- necro-hemorrhagic purulent bullae or abscesses
Which breeds are predisposed to deep pyoderma?
GSDs and Bull terriers
How is deep pyoderma treated?
- topical rinses/shampoos
- topical steroid/antibiotic combinations
- systemic antibiotics (beta-lactam resistant penicillins) for 6-8 weeks
Which antibiotics are used as 1st tier empiric therapy?
- 1st gen cephalosporins
- amoxicillin/clavulanic acid
- clindamycin
Which antibiotics are used as 2nd tier empiric therapy?
- sulfas
- erythromycin
- lincomycin
- doxycycline
Which antibiotics are used as 2nd tier based on C/S results?
- chloramphenicol
- rifampin
- amikacin
Which antibiotics are used as 3nd tier based on C/S results?
- fluoroquinolones
- 3rd gen cephalosporins
How is actinomycosis acquired?
infection following trauma or penetrating wounds
What are the clinical signs of actinomycosis?
- subcutaneous abscesses, draining tracts
- exudates (thick, yellow, hemorrhagic, foul smelling)
How is actinomycosis diagnosed?
- anaerobic culture
- histopathology
- cytology
What is the treatment for actinomycosis?
- surgical debulking
- long-term antibiotics (penicillin G, erythromycin, clindamycin)
How is nocardiosis acquired?
wound contamination, inhalation, or ingestion
What are the clinical signs of nocardiosis?
- similar to actinomyces
- pyothorax
How is nocardiosis treated?
- surgical debulking, drainage
- long term ab: TMS, ampicillin, erythromycin, minocyline
What are the clinical signs of opportunistic mycobacteriosis?
- slowly developing, subcutaneous nodules, non-healing abscesses, ulcers, and fistulas
- serosanguineous/purulent exudate
- regional LN enlargement
How is opportunistic mycobacteriosis treated?
- wide surgical excision
- long term ab: clarithromycin, enrofloxacin, doxycycline
What is intertrigo?
skin fold pyoderma
How is intertrigo treated?
- shampoos, rinses, topical antibiotics
What are the clinical signs associated with Malassezia infection?
- pruritis
- rancid odor
- erythema, greasy, scaly plaques
- otitis externa (black wax)
- hair turns red-brown
- chronic: lichenification, hyperpogmentation, hyperkeratosis
How is Malassezia infection treated?
- anti-yeast shampoos
- creams, lotions, and sprays
- systemic: Ketoconazole, Itraconazole
What is dermatophytosis?
fungal infection of keratinized tissues, claws, hair, and stratum corneum
- Micosporum spp.
- causes a folliculitis
Which animals are predisposed to dermatophytosis?
young and/or immunosuppressed
What are the clinical signs of dermatophytosis?
- focal alopecic lesions
- circular alopecia with scaling
- pruritis rare
How is dermatophytosis diagnosed?
- Wood’s Lamp
- hair pluck
- fungal culture
- biopsy
How is dermatophytosis treated?
- topical and systemic therapy
- topical: shampoo, ketoconazole
- systemic: Grisofulvin, ketoconazole, itraconazole
What is Notoedres cati?
What are the clinical signs of this infection?
- feline scabies
- alopecia, wrinkled skin, papular rash and crusts
How is Notoedres cati diagnosed?
skin scrapes
How is Notoedres cati treated?
- Lime sulfur dip
- Ivermectin Selamectin
- Imidocioprid/Moxidectin
What are the clinical signs of fur mites in the cat?
- “salt and pepper” appearance
- hairs epilate easily
- eggs on hairs
Which endocrine diseases cause non-pruritic lesions in the cat?
- hyperthyroidism
- hyperadrenocorticism
What are the 3 presentations of eosinophilic granuloma complex?
- indolent ulcer
- eosinophilic plaques
- collagenolytic granuloma
Describe the indolent ulcer presentation of eosinophilic granuloma complex
- well-circumscribed, proliferative inflammatory lesions with central dish-shaped ulcer
- upper or lower lip
- non-painful and non-pruritic
Describe the eosinophilic plaque presentation of eosinophilic granuloma complex
- well-circumscribed, red-yellow, ulcerate, edematous plaque
- intensely pruritic
Describe the collagenolytic granuloma presentation of eosinophilic granuloma complex
- well-circumscribed, linear or raised, nodular, firm, yellow-pink lesion
- non-painful, non-pruritic
What is the treatment for eosinophilic granuloma complex?
- prednisolone
- cyclosporine A
What is feline acne?
What is the clinical appearance?
- idiopathic disorder of follicular keratinization
- comedones on chin and lower lip
- papules and pustules
- furunculosis and scaring
What is the clinical appearance of feline leprosy?
- chronic draining nodules
- pus and fluid oozing out of skin
What are the possible causes of feline leprosy?
- bacterial or fungal
- panniculitis
- collagenolytic granuloma
- foreign body
- neoplasia
