SA Dermatology Dz/ Allergies Flashcards
Ctenocephalides felis (flea)
Hypersensitivity to flea salivary Ags
Seasonal (warm)
CS of Ctenocephalides felis (flea)
Pruritus, crust, alopecia, erythema, papules
Found on dorsal lumbar area/ caudomedial thighs
Miliary dermatitis (cats)
Life cycle (14d): egg →larvae (3 stages) →pupae (most resistant)→ adult
#1 cause of flea allergy in cats
Dx of flea allergies
CS/ Lesions/ presence of fleas
Response to therapy
Allergy testing (Intradermal skin test)
Eosinophilia
Therapy to eradicate fleas
Activly (topical, Indoxacarb)
Nexguard (oral, afoxolaner)
Bravecto (oral, fluralaner)
Simparica (oral, sarolaner)
Credelio (oral, lotilaner)
Atopic dermatitis
Genetically predisposed inflammatory and pruritic allergic skin dz, clinical features associated with IgE directed against environmental allergens
Atopic-like dermatitis
Patients with clinical features of atopic dermatitis and no detectable IgE
Atopy
Inherited type 1 hypersensitivity
Pruritic face, feet, Axillary, groin
6m-3y
Atopy pathogenesis
Mediated by IgE → attaches to mast cell in epidermis → Ag cross links IgE → causes degranulation
Atopy dx
History, PE findings
IDST (doesn’t confirm Atopy) and serum allergy testing
Therapy for Atopy
Antihistamines, fatty acids, topical anti-itch meds, steroids (if responsive), immunotherapy, avoid allergens, to secondary infections, cyclosporine, oclacitinib, cytopoint
Apoquel (oclactinib)
Control of acute and chronic pruritus, flea, food, Atopy and contact allergy
Inhibits the IL-31
Itch relief within 4 hrs
IL-31
Mediator of itch
Key cytokine associated with atopic dermatitis, sending the itch signal to the brain
When shouldn’t apoquel be used?
Dogs under 12m
Breeding, pregnant or lactating dogs
Side effects of apoquel
V/D
May worsen parasitic infections and cancers
Cytopoint (Lokivetmab)
Injectable monoclonal Ab designed for dogs
Targets and neutralizes IL-31
SC injection for 4-6w
Food allergies
Dx with food elimination diet: 8 weeks of cleansing pets system with novel protein, then individual diet challenge
Tx: avoidance
CS of food allergies
Dogs: generalized pruritus, ears, rears and paws
Cats: Facial pruritus, miliary derm and EGC
Allergic contact dermatitis
Type 4 hypersensitivity rx
Hairless areas of contact
Pruritic, papular eruption
Dx: patch test and change environ.
Allergic contact dermatitis causes
Wandering jew
Commelinceae spp. (spreading day flower) → poison ivy for dogs
Minimal data base for skin infections
Skin scraping (parasites)
Skin cytology (secondary bacterial infections)
Ear cytology (fungal growth)
+/- fungal for cx (ring worm)→ always for cats!!
Bacterial pyoderma (secondary bacterial infection)
S. psuedintermedius common in dogs
Mild to severe pruritus, pustule
Bacterial pyoderma dx
CS, cytology, cx and sensitivity, histopath
Tx for bacterial pyoderma
Abx: cephalexin, cefpodoxime, clavamox, clindamycin, SMZ-TMP, chloramphenicol, enrofloxacin
Abx shampoos, sprays, creams and wipes
Surface pyoderma
Pytotraumatic dermatitis (hot spot, fleas common source)
Skin fold pyoderma (brachys deeps folds)
Bacterial pyoderma in different species
Cat, horse and goat: S. pseudintermedius and aureus
Sheep, cattle: S. aureus
Pig: S. hyicus (Greasy pig dz)
Superficial pyoderma
Imeptigo puppy pyoderma: abx
Bacterial foliculitis: abx
CS: papules, pustules, crusts, alopecia, epidermal collaretes
Deep pyoderma
Demodex, dermatophytes, FB
Callus pyoderma
Furunculosis (ruptured hair follicles)
Abx: 4-6w
CS of deep pyoderma
Bulla, draining tract, ulceration, crusts, +/- fever, lymphodenopathy
Methicillin Resistant Staph
S. aureus
Resistant to B-lactam abx and methicillin
Been replaced with oxacillin
What is methicillin-resistance due to?
MecA gene that encodes for the production of the altered penicillin binding protein (PBP2a)
Low affinity for all B-lactam abx
Malassezia dermatitis (yeast infection)
M. pachydermitis
Severe, non-steroid responsive pruritus
Erythema, alopecia, lichenification, greasy scale, malodor, hyperpigmentation
Where is Malassezia dermatitis common?
Ventral neck, axillae, inguinal area, flexural surfaces of elbows, tarsus
Predisposed breeds to Malassezia dermatiti
Westies, cockers, bassetts
How to dx Malassezia dermatiti
CS, r/o demodex, pyoderma, dermatophytes, cytology
Tx of Malassezia dermatiti
Topical therapy: 4% chlorhexidene, benzyl peroxide, miconazole/ ketoconazole shampoo, lime sulfure dip, enilconazole
Systemic antifungals: Ketoconazole, fluconazole, itraconazole 3-4 x week
Dermatophytosis (zoonotic- ring worms)
Fungus that invades keratinized structures
Primary host is man
Transmission direct or fomites
Different types of fungal infections
Geophilic (inhabits soil)
Zoophilic (animals)
Anthrophilic (humans)
invades hair follicles or S. corneum
Lesions of fungal infections
Broken stubby hairs, scaling, erythema
Kerion (nodules rx with ulceration and drainage and extreme inflamm.)
Different species fungal infections
M. canis: feline reservoir, asymptomatic
M. nanum- pigs
T.eqinum- horses
T. verrucosum- cows and sheeps
Fungal infection dx
Fungal cx/ DTM (sabourauds dextrose agar with clycoheximide, gentamycin, cholrtetracycline)
Macroconidia (microscopic ID)
Wood’s lamp
KOH prep
Fungal infection tx
Spontaneous remission in 4m
Itraconazole, clean environ./ clip hairs. topical therapy to reduce contamination
Papillomaviruses
Nonenveloped DNA virus transmitted by direct and indirect contact (benign)
Infects epithelial cells @ site of damaged skin or mm
Incubation: 1-2 m
What do papillomaviruses turn into?
Squamous cell carcinomas in some K9s
PV regression
Humoral immunity protects against viral challenge
Cellular immunity important in PV regression and infiltration with CD4 and CD8+ lymphos for viral clearance
Five syndromes of cutaneous papillomas
K9 oral papillomatosis
Cutaneous inverted paps
Multiple pigmented, papular, cutaneous paps
Multiple pigmented plaques
Multiple paps
K9 oral paps
Common and affects young dogs
White flat smooth shiny papules and plaques → gray pedunculated or cauliflower hyperkeratotic mass
What do K9 oral papillomas affect?
Buccal mucosa, tongue, palate, pharynx, epiglottis, lip, nasal planum, skin, eyelids, conjunctiva, cornea
Cutaneous inverted papillomas
Dogs 8m-3y
Lesions on ventral abdomen and groin
Small, raised and firm with central pore opening to skin surface
Multiple pigmented plaques
Mini schnauzers, pugs and shar-peis
@ 2-4 yrs of age on ventrum and medial thighs
Characteristics of pigmented plaques
Melanotic macules and plaques becomes progressively scalier and more hyperkeratotic
Multiple papillomas
Foodpads of adult dogs
Firm, hyperkeratotic, horn-like appearance, larger lesions= lameness
Feline papillomaviruses
Oral (FdPV-2) and skin (FdPV-1) forms
Melanotic macules → plaques progressive and scaly, hyperkeratotic, greasy
Oral feline papillopaviruses
Causes tongue lesions
6m-9y
Multifocal, small, soft, light pink, oval and slight raised flat topped lesions
Multiple viral papillomas (feline papillomaviruses)
Middle aged to old
Lesions anywhere on the body (esp. head, neck, dorsal thorax, ventral abdomen and proximal limbs)
Dx of Papillomavirus
PCR (no sensitive to ID of viral DNA)
Southern blot (specific and sensitive, long time)
Dot blot and reverse blot (sensitive, laborous, accurate)
Clinical management for papillomavirus
Sx excision, cryosx, electrosx, CO2 laser ablation and observation without tx (spontaneous regression)
Retinoids
Autogenous vx (injection site squamous cell carcinoma)
Demodicosis (Red Mange, parasite)
Demodex canis
Mom to pup via nursing
Entire life cycle on the dog
Periocular, lips, forelimbs
Tx for demodicosis (localized form)
Resolve over 6-8w
Tx: none, benzoyl peroxide, goodwinol
Juvenile onset demodicosis (generalized)
Immunosuppression
Guarded prognosis
Onset <1.5 yrs
Breeds predisposed to juvenile onset demodicosis
Dobes, GSD, Sheltie, pitbull, Shar pei, boxers
30-50% spontaneously resolve
Generalized adult onset demodicosis
Most > 4 yrs of age
Look for underlying cause: hypothyroid, allergies, stress, immunosuppression
Feline demodicosis
Demodex cati (in hair, not contagious) or gatoi (contagious)
Dx for demodicosis
Deep SS in dogs/ superficial inc cats
Bx for pododermatitis/ Shar pei
Demodicosis in other species
Rabbits: D. cuniculi
Hamsters: D. criceti
GP: D. caviae
Demodicosis tx
Tx pyoderma
Amitraz (mitaban) → clip long hair dogs
Ivermectin (contrain in MDR1 gene dogs)
Milbemycin
Lime sulfur dips
Sarcoptic Mange/ Scabies (dogs)
Sarcoptes scabiei var. canis - zoonotic
Papular eruption, extremely pruritic
Ears, hocks, elbows and ventrum
Dx sarcoptic mange
SSS, CS, Hx, Pinnal-pedal*
Tx for Sarcoptic mange
Lime sulfur, selamectin, ivermectin, paramite, amitraz, fipronil spray
Scabies in cats
Notoedres cati (zoonotic)
Cheyletiella (walking dandruff)- zoonotic, entire life cycle on host, not species specific
Abscesses in cats (parasites)
Anaerobes: Bacteroides, fusobacterium
Aerobes: P. multocida, Strept.
Lance good ventral drainage, abx
Feline acne
Bacterial or Malassezia
MC location chin
Tx: benign neglect, topical astringents, abx, benzyl peroxide
Mycobacterial infections
Internal/ SQ granulomas: M. bovis, M. tuberculosis, M.avian/ intracellulare
Feline leprosy: M. lepraemurium
Sx excision
Spreading, SQ, pyogranulomatous in cats
Opportunistic (atypical) mycobacteria
M. fortuitum, M. chelonei most common in US
Dx with cx and sensitivity
Tx for mycobacterial infections
Doxycycline, tetracycline, enrofloxacin, clarithromycin
Mosquito bite sensitivity
Symmetrical, papular/ erosive dermatitis
Nose, muzzle, ears,
Seasonal occurrence
Tx: steroids, avoidance
Indolent ulcer
Rodent/ eosinophilic ulcer
MC on upper lip
Tx: steroids
Eosinophilic plaque
Erosive patch/ plaque lesions on the lateral thighs, inguinal, perineal regions
Intense pruritus, onset may be acute
Tx: underlying allergies and steroids
Eosinophilic granuloma
Cd./ medial thighs or lateral thorax, chin, oral cavity, interdigital spaces
Conjunction with ulcers, heritable
Tx: steroids, immunosuppressive drugs, tx allergies
Autoimmune Dz in dogs and cats
Pemphigus complex (4 types)
Ab formation of IC desmosomes
Loss of IC adhesion and ancanthoytic cells
Hereditary, drug induced, UV light, stress
What are the 4 types of Pemphigus complex?
P. foliaceous: intraepidermal/ subcorneal pustules
P. erythematosus: IE/SQ pustules/ lichenoid inflamm.
P. vulgaris: suprabasilar clefts, vesicles
P. vegetans: IE microabscesses
Dx Pemphigus complex
Cytology: PMNs with acantholytic cells, no bacteria
Histopath: pustule
Direct immunofluorescence and IHC
Therapy for pemphigus complex
Corticosteroids
Azathprine in dogs
Chlorambucil in cats
Chrysotherapy (gold salts)
Tx pyoderma and avoid UV light
Hypothyroidism
Naturally occurring or idiopathic
Caused by primary hypothy or lymphocytic thyroiditis
CS associated with hypothyroidism
Bilaterally symmetric truncal alopecia, dull dry haircoat, thick pitting skin (myxedema), hyperpigmentation, lack of pruritus, susceptible to skin infections
Dx hypothyroidism in dogs
TT4, FT4 and TSH
Primary dz: low TT4 and FT4, TSH variable
Natural hyperadrenocorticism
Bilateral adrenocortical hyperplasia
Middle-age to older dogs
Iatrogenic hyperadrenocorticism
Misuse of exogenous glucocorticoids
Predisposed breeds to hyperadrenocorticism
boxer, boston terriers, poodles and dachshunds
CS of hyperadrenocorticism
PU/PD/PP, systemic hair loss of trunk and extremities, lacker luster hair coat, thin hypotonic skin, bacterial pyoderma, easy bruising
Dx of hyperadrenocorticism
ACTH response test, skin bx
Elevated liver enzymes (ALT, ALKP, AST), cholesterol, triglycerides and glucose
High dose dex suppression test
Tx hyperadrenocorticism
Adrenal tumors: sx excision
Pituitary dependent: bilateral adrenolectomy, radiation therapy, trilostane, lysodren, cyprohetadine
Otitis externa
Inflamm. of the externa ear canal
Unilateral and bilateral, acute or chronic
Erythematoceruminous or suppurative
Perpetuating factors causing otitis externa
Inflamm. and pathology in the ear that prevents the resolution of otitis
Otitis externa pathology
Acute inflamm. and edema in ear → chr. inflamm.
Glandular changes, fibrosis and scarring, stenosis and occlusion of the ear canal
Calcification and ossification of cartilage
Possible sequela to otitis externa
Otitis media and aural cholesteatoma
CS of otitis externa
Head-shaking, pruritus, pain, excoriations, erythema, edema, exudate, odor
Otitis externa dx
Cytology: ID the number and morphology of bacteria and yeast, fungal hyphae, parasites, number and type of leukos, excessive cerumen…
When should culture and sensitivity be done?
Rods on cytology
Systemic abx required
Failure to repsond to initial tx
Otitis media dx or suspected
Pseudomonas infection
Myringotomoy
Rupturing of the tympanic membrane and useful dx tool for otitis media
Dx otitis media
Rads, CT or MRI (acute) and bx (neoplasia)
Otitis externa tx
Ear cleaning
Corticosteroids
Topical otic solutions (abx, antifungal, steroid)
Systemic abx
Which abx are safe with ruptured tympanic membranes?
Enrofloxacin, ticarcillin, ceftazidime
avoid ototoxic abx aminoglycosides
