Dermatology pt.2 Flashcards
T/F: for every food allergic dog, there are probably 10-20 atopic dermatitis dogs
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Food Allergy (Etiology)
- unknown
Food Allergy (History)
- recent change in diet is uncommon
- most affected animals have been on the same food for > 2 years
Food Allergy (Dog - Signalment)
Age: 4months - 13 years (none)
Breed: retrievers, terriers
Food Allergy (Dog - Clinical Signs)
- pruritus (generalized, pododermatitis, otitis externa)
- scaling, papules, erythema
Food Allergy (Cat - Signalment)
- no age or se predilection
- breeds: Burmese, mainecoon, himalayan
Food Allergy (Cat - Clinical Signs)
- pruritus, alopecia (face and neck @ 40-50%)
- papules, miliary dermatitis
- eosinophilic granuloma complex
- self-induced alopecia
»> same as for Atopic Dermatitis <
Food Allergy (GI signs)
- diarrhea, vomiting (10%)
- gi + pruritus in cats = food allergy
- mild colitis (dogs)
- lymphocytic, plasmacytic colitis (cats, cheetahs)
Food Allergy ( Neuro, Resp)
Neuro: malaise, epilepsy
Resp: asthma-like signs
Food Allergy (Diagnosis)
- hypoallergenic diet
- Serologic Testing ( not all allergies are IgE mediated)
Food Antigens
- typically attributed to protein sources
- the common food antigens often reflect what is commonly eaten by animals
Elimination Diet Selection
- get a thorough diet history
- ingredients must be novel to the pet
- no single diet will work for every pet
Elimination Diet Selection Options
- home-cooked
- commercial hydrolyzed
- commercial limited/ uncommon antigen diets
Concerns with OTC novel diets
- a ton of undeclared antigens in OTC
- OTC also tend to have extensive ingredient lists
Vet. Therapeutic Diets
- > 90% ability to diagnose food allergy
- no one will work for every animals
Food Allergy Diagnosis via Diet
- after 8-12 weeks of new diet (with subsided symptoms), revert back to og diet
- signs should reoccur w/in 2-3 weeks
Pemphigus Foliaceous
- antibodies target the transmembrane proteins
- Dogs: desmocollin - 1 [humans have desmoglein-1]
Pemphigus Foliaceous (Clinical Presentation)
- curst and pustules on nasal planum, peri-orifical, foot-pads, pinna
- whole body crusts in retreivers, chows, cats
- +/- pruritus, febrile, depressed
- peripheral edema
- 2* pyoderma
Pemphigus Foliaceous (Predisposed breeds)
- chows, akitas, bearded collies, chines SharPei
Pemphigus Foliaceous (HIsto)
- Acantholytic Cells
- subcorneal pustules, often spanning multiple follicles
- usually neutrophils, sometimes eosinophils
- rafts
- superficial pyoderma (fewer and smaller) [trichophyton spp. (requires special stains)]
Drug-Related Pemphigus
- reported in dogs and cats
- removal of drug = resolution
- transient immunosuppressive tx may be necessary
- drug ‘triggers’ genetic predisposition to pemphigus
Paraneoplastic Pemphigus
- 2* to neoplasia, often lymphoma
- histo: PV + apoptotic cells
- removal of neoplasm may not be helpful = poor prognosis
Rx for PF in dogs
- pred/ prednisolone/ methylpred
- azathioprine
- cyclosporine
Factors affecting survival for PF
Pos - abx w/ immunosuppressive therapy?
Neg - neg side effects from Rx
Discoid Lupus Erythematosus (DLE)
- more common than PF
- Etiology: antigen-antibody complexes @ basement membrane zone
DLE (Diagnosis)
- clinical presentation and history
- histopathology
- other: IHC, ANA, CBC, serum
DLE (Clinical Presentation)
- depigmentation, alopecia
- nasal planum, periocular, pinna, muzzle
- collies, shelties, other
DLE (Histo)
- Interface Dermatitis
- thickening of basement membrane
- basal cell edema (Hydropic degen.)
- pigmentary incontinence
- mononuclear inflammation just below BMZ
DLE (Treatment)
- prevent sunlight exposure
- Niacinamide & Doxycycline
- Tacrolimus ointments
- topical corticosteroids, sunscreens, EFAs
Exfoliative Cutaneous Lupus Erythematosus (ECLE)
- german shorthaired pointer, viszlas
- usually < 1 year of age
- scaling and alopecia on face, hocks, generalized
- histopath: interface derm, w/ apoptotic cells, sebaceous adentitis
- ANAs may be (-)
- Rx: cyclosporine is best
Vesicular Cutaneous Lupus Erythematosus (VCLE)
- ulcerative dermatosis of collies and shelties
- ulcers in inguinal area, axilla, ventral abdomen, medial thighs
- Rx: poorly responsive, corticosteroids and cyclosporine
Canine Demodecosis
- demodex is a commensal in mammalian hair follicles
- transmitted via direct contact w/in 2-3 days of liffe
- it is an opportunistic pathogen
2 species of demodex in dogs
demodex canis - commensal in hair follicles
demodex injai - mostly found in sebaceous glands
D. Canis (gen. clinical signs)
- lesions ass. w/ folliculitis
- focal to multifocal alopecia
- papules, pustules, comedones
- pruritus only present w/ 2* bacterial infection
D. Canis (Clinical Presentation)
- Localized
- Generalized
A. Juvenile-onset ( <2years old)
B. Adult-onset ( >2years old)
D. Canis (localized lesions)
- generally restricted to juvenile-onset
- < 4 areas of focal alopecia that are no greater than 2.5 cm
D. Canis (generalized lesions)
- juvenile or adult onset
- multifocal patchy, generalized alopecia
- erythematous, +/- pruritus
- 2* infections are common
D. Canis (unusual clinical presentation)
Pododemodicosis (erythema, swelling, nodules, draining tract)
Otitis Externa d/t demodex
D. Injai
- not considered a commensal spp
- mainly live in sebaceous glands
- mostly seen in terries
- mild to sever pruritus
- characteristic greasy dorsal stripe on the trunk
Demodex (Diagnosis)
- deep skin scraping
- trichoscopy
- acetate tape prep (best for exudative)
- histopathy (expensive, but useful of D. injai)
Demodex (Treatment - localized dem.)
- benign neglect (90% spont. resolve)
- topical therapy to ‘treat the owners’
Demodex (Treatment - generalized dem.)
- Ivermectin (considered antiquated) (Ivermectin tox)
- Moxidectin (Advantage Multi = Moxi + Imidacloprid)
- Isoxazolines
- Amitraz dips
- Pyoderma treatment
Ivermectin (demodecosis)
- considered antiquated treatment
- can cause toxicity w/ ‘white feet don’t treat’
- Ivermectin tox = mydriasis, ataxia, tremors, seizures
Demodex (Treatment: monitoring)
- identify and treat concurrent 2* infections
- repeat skin scrapings from the same locations once monthly
- dead mites =/= neg skin scraping
Demodex (Treatment: Prognosis)
- cure rate is >90% if owner compliance is good
Feline Demodicosis (species_
- Demodex cati (commensal)
2. demodex gatoi (stratum corneum)
D. cati (clinical signs)
- usually seen in sick cats
- non-pruritic
- patchy, regional, multifocal alopecia
- can be localized or generalized
- very uncommon
D. gatoi (clinical signs)
- variable pruritus
- contagious (cat-cat)
- alopecia from self-trauma or overgrooming
D. cati (diagnosis)
- superficial skin scrapings
- incidental finding on biopsy
D. gatoi (diagnosis)
- superficial skin scrapings
- acetate tape method
- fecal float
- empirical treatment and response
Feline demodicosis (treatment)
- lime sulfur dips q1-2 times weekly
- moxidectin (advantage multi)
- ivermectin
- fluralaner
D. cati can resolve spontaneously if underlying disease is addressed
T/F: skin disease in less common in cats than dogs
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T/F: prednisolone is the preferred corticosteroid in cats
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Feline Miliary Dermatitis
- reaction pattern - multiple etiologies, most are hypersensitivities
- -> flea allergies, food allergy, AD, ectoparasites
- crusted papules +/- pruritus and self-trauma, alopecia
Feline Miliary Dermatitis (Rx)
- treat underlying cause
- flea control
Feline Eosinophilic Reaction Patterns
- eosinophilic reaction patterns are not specific diseases
- -> eosinophilic plaque
- -> eosinophilic granuloma
- -> indolent lip ulcer
Eosinophilic Plaque
- most common on abdomen, medial thighs
- pruritic
- often associated w/ FelineAD
Eosinophilic Granuloma
- caudal thighs, oral cavity, chin, foot pads
- may have genetic basis in some cats and not associated with allergy
Feline Lip Ulcer
- bad other names: rodent ulcer, indolent ulcer
- upper lip
- symmetrical lesions on either side of philtrum
Mosquito Bite hypersensitiviity
- dorsal muzzle, pinna, footpad
- crusts, papules, ulcers, swelling
- Rx: corticosteroids and keeping cat indoors
herpes Virus (FHV-1) Ulcerative Dermatitis)
- often dorsal muzzle lesion
- Biopsy: often eosinophili inflammation w/ visible inclusions
- PCR skin biopsy: sensitive and specific test
Diagnostic Approach to Eosinophilic Lesions
- impression cytology: eosinophils
- Therapeutic trials to evaluate for underlying hypersensitivity
- possible infectious etiologies = biopsy
Clinical Presentations of the Pruritic Cat
- head and neck pruritus/ excoriations
- self-induced alopecia
- miliary dermatitis
- eosinophilic lesions
Why are pruritic cats challenging to treat?
- overlapping clinical presentations require a systematic approach
- may take time to determine etiology
Feline Dermatophytosis
- ubiquitous infectious skin disease
- Diagnosis - fungal culture, PCR, wood’s lamp, trichogram, biopsy
Feline Dermatophytosis (treatment)
Systemic: Itraconazole, fluconazole, terbinafine
Topical: lime-sulfuer
Environment: bleach
Feline Degenerative Mucinotic Mural Folliculitis
- presumptive immunologic disease
- generalized alopecia and exfoliation
- facial skin is thickened, shiny, w/ narrowing of eyelid margins
- Prognosis: poor
Feline Paraneoplastic Alopecia
- older cat, often unwell
- marked ventral alopecia w/ very shiny appearance
- foot pad lesions
- abd u/s = pancreatic or hepatic mass
- skin biopsy: marked atrophy of follicles and epidermal hyperplasia
Feline Thymoma-Ass. Exfoliative Dermatitis
- rare, cutaneous marker for underlying thymoma
- erythema, dramatic exfoliation, alopecia, sheets of scale, begins head and neck
- Systemic - coughing, dyspnea, lethargy anorexia
Plasma Cell Pododermatitis
- distinctive foodpad lesions
- Dx: confirm w/ biopsy
Feline Acne
- comedones present on chin and mandibular lip region
Common Pruritic Parasites for Rabbit, Guinea Pig, Rats and Hamsters
Rabbit: Psoroptes cuniculi
Guinea Pig: Trixacarus caviae
Rats and Hamster: Notoedris muris
Lice as Vectors for Disease
Polyplax serrata (mice) and Polyplax spinulosa (rats):
- -> mycoplasma muris
- -> encephalitozoon cuniculi
- -> eperythrozoon coccoides
Mites and Lice Treatment
- Selamectin
- Isoxazolines
- Ivermectin
- Do not use fipronil (frontline) for rabbits or hamsters
Causes of Alopecia w/out pruritus in small mammals
- dermatophytes
- barbering/ shedding
- demodicosis (most common in hamsters)
- endocrine
Small Mammal Dermatophytes
- Trichophyton menoagrophytes
- microsporum canis
- M gypseum
Chinchilla
- fur slip –> frightened or stress causes shedding of tufts of hair
- ear trauma including frostbite
- avoid aminoglycosides
Demodicosis in Hamsters
- demodex aurati (long, follicular)
- demodex criceti (short, stratum corneum)
Endocrine Diseases in small mammals
- hyperadrenocorticism (hamsters)
- cystic ovaries (guinea pigs)
- dx of both probably done most easily w/ ultrasound
Treponema paraluiscuniculi
- crusts, erythema, edema, vesicles, ulcers, proliferative lesions; face and perineum
- painful, not pruritic
- metritis, abortion, and neonatal death
- rabbit syphilis is not zoonotic
Treponema paraluiscuniculi (Rx)
- Penicillin G
- monitor for signs of abx-ass. enterotoxaemia
- Choramphenicol
- Azithromycin
Causes of scaling and crusting in small mammals
- sebaceous adenitis
- cutaneous lymphoma (hamsters, rabbits, guinea pigs and mice)
- thymoma
Chelitis in Guinea Pigs
- rough forage and/or acidic fruit
- hypovitaminosis C
- pox virus (myxoma virus)
Myxomatosis
- arthropod transmission
- morbidity and mortality high in pet rabbits, approaching 100%
- edema of head, ears, eyelids, and genitalia
- firm, non-pruritic, erythematous nodules
Abcsesses in Rabbits
- pasteurella multocida
- rabbit heterophils are myeloperoxidsase-deficient: abscesses are more inspisated
- better results in abscess removed surgically
Mouse pox
- infectious ectromelia, orthopoxvirus
- usually in colony situations
- transferred from infected serum
- EM, IHC, animal inoculations, serologic testing, virus isolation, PCR
Otitis Externa (Signalment)
- Dogs: 5-8 years old, allergic dermatitis most common
- Cats: 1-2 years old, ear mites most common
Otitis Externa ( Clinical Signs)
- head shaking
- scratching
- pain
- erythema, excoriations, alopecia
- exudate, odor
Otitis Externa (Causes)
- most cases have mutlifactorial etiology
- Predisposing Factors, Primary Factors, Perpetuating Factors
Otitis Externa (predisposing factors)
- Breed conformation ( hairs w/in ear canal, narrow canal conformation, large number of apocrine glands)
- Humidity in the ear (leads to maceration of tissue)
- Inappropriate therapy
- Contact Rxn (non-haired pinna and canal, rxn to drugs)
Otitis Externa (Primary Factors)
- Atopic Dermatitis
- Cutaneous Adverse Food Rxn
- Parasites
- Foreign Bodies
- Cornification disturbances
- Neoplasia
- Immune-mediated dz (pinnae > ear canal)
Common Otitis Externa parasites
- Otodectes Cynotis
- demodex canis
- otobius megnani
Otitis Externa (Perpetuating Factors)
- bacterial organisms
- Yeast/ fungal organisms
- Otitis media
- chronic pathological changes
Otitis Externa (bacterial perpetuating factors)
- Staph pseudintermedius (most common)
- pseudomonas (causes ulceration)
- strep
Otitis Externa (Otitis Media)
- not ruled out by intact TMb
- Tx w/ systemic abx +/- myringotomy and flush of middle ear
- 1* Secretory Otitis Media (PSOM) = middle ear effusion only, rarely ext. ear canal dz
Otitis Externa ( Diagnosis)
- History and PE
- Otoscopic inf
- myringotomy
- cytology
- imaging studies
- biopsy
- culture and sensitivity (sens only for serum, not topical)
Otitis Externa (treatment)
- use ear cleaner prior to treating w/ appropriate topical +/- systemic therpaies
- Ear Cleaners: antimicrobial and ceruminolytic (always flush after use)
- Glucocorticoids: use as sole agent (topical) in allergy or ceruminous OE; otherwise used in combination
- Systemic therapy: Abx, glucocorticoids, anti-fungal
Otitis Externa (Keys to successful management)
- always do cytology
- id all predisposing, primary, perpetuating factors
- appropriate medical management –> removal of all etiological factors
Surgical Management of Skin Fold Pyoderma
Episioplasty:
- dog placed in perineal stand
- estimate the amount of skin to be removed
- resect an elliptical portion of skin around vulva
- resolution of UTIs in 84-100%
Indications for total ear canal ablation
- end-stage otitis externa
- ear canal neoplasia (ceruminous gland carcinoma)
- cholesteatoma
TECA-BO Surgery
- total ear canal ablation - bullus osteotomy
- want to stick to the cartilage all the way down the ear canal to minimize damage to surrounding tissues
- highly effective but complications commons
TECA-BO Complications
- Facial Nerve Paralysis (cats > dogs) (treatment w/ corneal protectants necessary d/t loss of ability to blink)
- Horner’s Syndrome (mainly cats) (ptosis, miosis, enophthalmus)
- Vestibular syndrome (occurs in 3-8% of dogs) (less common but high impact on QOL)
- Post-op Fistula Formation (incomplete removal of secretory epithelium)
Outcomes of Traction-Avulsion for treatment of nasopharyngeal polyps in cats
- 50% success rate
- when treated w/ pred post traction – recurrence after traction only: 11% for nasopharyngeal, 50% of aural
- ventral bulla osteotomy may reduce recurrence rate
T/F: the treatment of choice for any primary ear canal neoplasia is a total ear canal ablation.
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