Dermatology
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| Dermatologic history 1 | Initial lesions (age/characteristics)
Progression of lesions
Pruritis
Seasonality/periodicity
Familial history
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| Dermatologic history 2 | Geographic location/Travel
Environmental exposure
Use of animal
Other animals in environment affected?
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| Dermatologic history 3 | Zoonoses (Owners or children)
Previous therapy (esp. AB's and steroids)
Previous skin disease (new dz or recurrence)
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| Physical exam | General exam
Skin
Lymph nodes
Genitals
Ears
Eyes
Mouth
Mucocutaneous jxns
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| Physical exam of the skin | visualize gross and subgross pathology
Lighting
Types of skin lesions (papule, macule, etc)
Distribution of skin lesions
Configuration of skin lesions (clumped, singular, etc)
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| Macule | - circumscribed change in skin *color* without elevation or depression of the surface
- only a change in color!
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| Patch | a large macule
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| Papule | - circumscribed solid elevation of the skin
- imply involvement of the epidermis and the underlying dermis
- The most common skin lesion
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| Plaque | - a large, usually flat-topped circumscribed elevation of the skin
- often evolve from papules (papules raise up and join to become a plaque)
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| nodule | - large papule or solid deep-seated mass in either the dermal or subcutaneous tissue
- visible elevation of the skin is usually present
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| Dermal nodule | skin and fixed nodule move over underlying tissue
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| Subcutaneous nodule | skin moves over nodule and underlying tissue but the nodule itself doesn't move
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| Wheals | - well circumscribed flat-topped firm elevation of the skin with a well demarcated palpable margin
- produced from dermal edema (should pit)
- AKA hives
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| Urticaria | - syndrome characterized by lots of wheals/hives on an animal (due to a number of diff etiologies)
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| Vesicle | - fluid filled circumscribed elevation of the epidermis
- very fragile and rupture easily
- AKA blisters
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| Bulla | - large (>1cm) vesicle
- can form in the epidermis, btw the epidermis and dermis, or within the dermis
- fragile: the more superficial, the more fragile
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| Pustule | - pus filled circumscribed elevation of the epidermis
- vesicle that contains pus
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| Erosion | - superficial denudation of the skin confined to the epidermis
- erosions DO NOT damage or breach the dermal-epidermal junction (basement membrane zone)
- erosions DO NOT bleed but MAY exude serum
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| Ulcers | - defect of the skin extending through the dermal-epidermal jxn (basement membrane zone)
- ulcers bleed
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| Excoriation | - a lesion produced by self-trauma
- can be either erosions or ulcers
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| Scale | - accumulated fragments of dead, cornified epidermal cells (stratum corneum)
- results from altered keratinization or cornification
- AKA dandruff
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| Crust | - accumulated fragments of dead, cornified epidermal cells (scales) PLUS dried residue of serum, blood, or pus
- crusts imply inflammation
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| Lichenification | - skin thickening +/- hyperpigmentation with increased prominence of the normal surface
- CHRONIC DZ +/- self trauma
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| Pruritus | - sensation that elicits the desire to scratch
- most common CS in dogs or cats
- secondary skin and personality changes
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| Skin changes secondary to pruritus | erythema
excoriations
alopecia
lichenification
pigmentary changes
secondary infection (bacteria or yeast)
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| Alopecia | - absence of hair from areas of the body where hair normally is expected to be present
- begins subtly and slowly progresses until O recognition
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| Four stages of the mammalian hair cycle | Anagen
Catagen
Telogen
Exogen
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| Anagen Stage | mitotically active hair growth phase (so active, anywhere else in the body would be considered neoplastic= reason lose hair with chemo)
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| Catagen Stage | involutional (slowing down of growth stage)
no growth
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| Telogen Stage | Long transitional resting phase
no active metabolism
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| Exogen Stage | Brief phase
Telogen hair is shed and pushed out by new anagen hair
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| Factors that can alter the hair cycle | - endocrine disease (hormonal imbalance)
- Vascular sustenance (hair follicle goes before skin)
- inflammation near or in hair bulb
- Metabolic abnormalities
- Dysplasia (genetically pre-programmed)
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| Classification of alopecia | - traumatic vs nontraumatic (pruritus)
- congenital vs acquired
- cicatricial (scarring) vs noncicatricial
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| Diagnosis of alopecia | - History
- Visual examination
- Trichogram (hair plucked)
- Skin biopsy
- Cytology (for infectious etiology)
- other lab procedures depending on differentials
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| Dx of Drug Rxns | - previous experience (if occurred once, will prolly happen again)
- Rule out other differentials
- Timing
Response to taking drug away (de-challenge)
Skin Bx (EM, TEN)
Re-challenge (not recommended)
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| Common initiators of drug rxns in many species | Trimethoprim-Sulfa
Penicillins
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| Common initiators of drug rxns in horses | phenylbutazone
acepromazine
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| Prognosis of most drug rxn | most self limiting after drug withdrawal
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| prognosis of erythema multiforme | potentially life threatening
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| prognosis of Toxic Epidermal Necrolysis | always life threatening
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| Management of drug rxns | withdraw suspected drug(s)
supportive therapy
immunosuppressive therapy
avoid suspect drug and all related drugs forever (and any related foods)
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| Dx of Drug Rxns | previous experience
Rule out other differentials
Timing
Response to taking drug away (de-challenge)
Skin Bx (EM, TEN)
Re-challenge (not recommended)
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| Common initiators of drug rxns in many species | Trimethoprim-Sulfa
Penicillins
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| Common initiators of drug rxns in horses | phenylbutazone
acepromazine
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| Prognosis of most drug rxn | most self limiting after drug withdrawal
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| prognosis of erythema multiforme | potentially life threatening
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| prognosis of Toxic Epidermal Necrolysis | always life threatening
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| Management of drug rxns | withdraw suspected drug(s)
supportive therapy
immunosuppressive therapy
avoid suspect drug and all related drugs forever (and any related foods)
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| Dx of Drug Rxns | previous experience
Rule out other differentials
Timing
Response to taking drug away (de-challenge)
Skin Bx (EM, TEN)
Re-challenge (not recommended)
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| Common initiators of drug rxns in many species | Trimethoprim-Sulfa
Penicillins
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| Common initiators of drug rxns in horses | phenylbutazone
acepromazine
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| Prognosis of most drug rxn | most self limiting after drug withdrawal
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| prognosis of erythema multiforme | potentially life threatening
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| prognosis of Toxic Epidermal Necrolysis | always life threatening
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| Management of drug rxns | withdraw suspected drug(s)
supportive therapy
immunosuppressive therapy
avoid suspect drug and all related drugs forever (and any related foods)
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| What is a macular-papular rash? An example? | raised region that's caused a change in color (for ex. erythema)
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| What is the most common derm sign you see? | papular
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| When would you do a skin scraping? | Parasites, bacteria, yeast
Superficial = scabies (chorioptes, notoedres, cheyletiella
Deep = demodex
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| How do you do a skin scraping for parasites? | You use a spatula with oil and scrape perpendicular and in the direction of the hair. (Trying to get a sampling of the keratinocytes)
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| How do you prep a slide from a skin scraping for cytology? | - smear material on DRY slid
- heat fix (if oily)
- rapid stain (Diff Qwik)
- scan with 4x then work up to 100x
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| What type of infections do skin scrapings help identify? | - Malassezia (yeast)
- Staphylococcus sp (in K9 usually S. intermedius)
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| How do you do an acetate tape preparation? | - press on lesions
- stick side down on slide
- keep dry for cytology, mineral oil for parasites, or stain for bac/yeast
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| When would you use an acetate tape prep? | - for areas that are too sensitive for a skin scraping
- to see surface mites, bacteria and yeast
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| How do you look at an exudate/pustule for cytology? | - collect material with cotton swab (remove the pustule roof)
- smear on a dry microscope
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| What is a Tzanck preparation? | - when take off the vesicle/pustule roof and swab the surface to look for inflammatory cells, cocci, acantholytic cells (Pemphigus foliaceus)
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| What are exudate/pustule smears and cytology good for? | - bacterial infxn
- systemic fungal infxns
- otitis externa
- anal saculitis
- pemphigus foliaceus (auto immune skin dz)
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| What is an acantholytic cell? | - An immature keratinocyte that has lost its attachment to its neighbor so they round out and pop off into the pustule.
- See with Pemphigus foliaceus or other severe inflam dz with cytokines that disrupt the keratinocytes.
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| How do you do a hair pluck? | -pluck hair with hemostat
- place in mineral oil on microscope slide
- cover with cover slip
- examine 10-40x
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| When would you use a hair pluck test? | Useful in determining:
- pruritus (broken hair ends)
- demodicosis/lice/Cheyletiella
- color dilution alopecia (see how the melanin clumps and swells then hair fx)
- dermatophytes
- lice
- follicular casting (sebum clumping the hair shafts toge
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| What is a characteristic feature of sebaceous adenitis? | follicular casting
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| When is it useful to do aspirates? | - nodular lesions
- neoplasia
- bac infxns
- fungal infxns
- sterile granulomatous dz
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| How does a woods lamp work? | - some strains of dermatophytes fluroesce when exposed to UV light due to a TRYPTOPHAN metabolite produced only ON THE ANIMAL
- make sure to sample fluorescing hair to confirm
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| Which species of dermatophytes fluroesce in vet med? | Microsporum canis (but only 40-60% fluroesce) (Most body fluids, keratin, topical meds fluoresce white)
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| When is a bacterial culture indicated? | When there is no initial response to "staphylocidal" abx (usually not done at first presentation)
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| How do you do a bacterial culture? | Culture from the edge of the collarette, exudate from draining tract, ear canal, macerated tissue sample
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| What is diascopy? | Using 2 glass slides to apply pressure on skin and determine if erythema or hemorrhage. If there is blanching, then it is erythema (dilatation). No blanching, then hemorrhage.
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| When would it be good to do a skin bx? | - may give a definitive dx
- r/o other dz
- give a prognosis about future hair growth
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| How do you do a skin bx? | - areas unaffected by self-trauma
- multiple sites (representative sample)
- cassette diff lesions if suspect diff dzs
- wedge bx or punch bx
- do not prep this area otherwise remove stratum corneum
- mark area of interest, inject lidocaine
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| What is the adv of wedge bx? | - better for deep lesions
- less traumatic for fragile lesions
- takes more material
- but takes longer to do and usually need general anesthesia
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| What is the adv of a punch bx? | - fast, easy
- take less sutures
- only needs local anesthetic
- problem is get a smaller sample and may not be enough for the pathologist
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| What are the 3 common therapeutic trials? | - response to appropriate abx
- response to acarcidal therapy
- response to elimination diet trials
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| What is the neural pathway to the skin? | - myelinated branches come out of the SC and supply dermatomes in 2 ways: free nerve endings and specialized corpuscular receptors
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| What are free nerve endings impt for? | touch, temperature, pain, pruritis
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| What are 2 examples of specialized corpuscular receptors? Associated with what? | - pacinian corpuscles (thumb print), merkel's discs
- associated with pressure and balance
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| What is the perception of itch? | - itch sensation carried centrally from free nerve endings via nonmyelinated, slow C fibers and myelinated, fast Adelta fibers
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| T or F. Pruritus mimics pain. | T
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| 3 theories on pain and pruritus pathways. | 1. SPECIFICITY THEORY- diff types of nociceptors transmit pain and itch
2. PATTERN THEORY - spatiotemoral pattern of nerual activity permits distinction
3. CENTRAL PROCESSING THEORY - overlapping popln, central processing differences(cortex sorts it out
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| Are itch and inflammaiton synonymous? | NO! Pruritus is a common sequelae of inflammation and frequent inducer of inflammation.
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| T or F. Scratching neural stimuli can amplify the perpetuation of the sensation to itch. | T. More damage to the epithelial barrier can cause positive feedback, more inflammation thus more inflam mediators, and infxn all which make the itch worsen.
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| Give an example of the pharmacological mediators of pruritus. | opioid peptides, prostaglandins (PGE1), histamine (less so in animals than humans), neuropeptides (substance P), proteases (trypsin)
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| Would you use opioids in trying to manage pruritus? | NO. bc opioid mediators are pruritogenic.
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| What is capcaisin used for? | It is used for pruritus, as a Substance P depletor.
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| What is atopic dermatitis? | Environmental allergies.
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| How do bac/fungal infxns make pruritus worse? | They have endopeptidases which are mediators that increase pruritus
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| When you see an epidermal collarette, what should your top ddx be? | 95% of them are a bacteria (Staph) infxn (Dr White thinks the most impt thing in vet school)
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| How do arthropods make pruritus worse? | - Release mediators via saliva, venom, body fluids, hairs, or just physical presence can illicit pruritus.
- endopeptidases & proteinases
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| What environmental or local factors can exacerbate pruritus? | dry temp, low humidity
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| What is the threshold phenomenon? | A certain amt of pruritus is tolerated, but then there is a threshold to which beyond it you see clinical signs of pruritus
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| What is the summation effect wrt pruritus? | multiple pruritic mediators combine to push the individual over the pruritus threshold.
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| Where does most of the mitotic activity of the hair occur? | in the bulb of the anagen follicle
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| How long does hair regrowth take? | - 2-3mo assuming tx successfully underlying cause and not on antimitotics and steroids
- K9 growth is 0.7mm/day
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| What are 2 categories of drug rxn pathogenesis? | - nonimmunologic mechanism, either related or not to the pharmacologic action
- immunologic mechanism
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| What are the characteristics of non-immunologic mechanisms related to pharmacologic action. | - predictable
- dose dependent
- related not just to drug but also any drug produced by its metabolism
- alopecia, purpura (bleeding into skin), poor wound healing, infxn
(usually in the corticosteroids)
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| What are the immunologic mechanisms of drug rxns. | - not predictable and more dramatic
- relatively dose independent
- use in 21 animals and only 1 has the rxn
- abn prodn of IgE, IgA, IgG, IgM (hypersensitivity)
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| What are clinical features of adverse drug rxns? | - they can mimic anything
- maculopapular rash, urticaria, angioedema, erytroderma, exfoliative dermatitis, hair loss, pruritus, purpura, altered pigmentation, erosions, ulcers, target lesions
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| In general, what are Erythema Multiforme and Toxic Epidermal Necrosis? | NOT DZ!
- syndromes caused by cell-mediated attack on the epidermis
- commonly inititated by drugs but also by neoplasia, infxn, idiopathic
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| What are the clinical signs of Erythema Multiforme? | - erythematous macules and papules, target lesions, erosions, ulcers, collarettes
- anywhere on body; usually on the trunk, ears, face, mucocutaneous jxns
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| What are the clinical signs of Toxic Epidermal Necrolysis? | - macular erythema --> confluent erythema, ulceration, pain (looks like burns)
- face, trunk, mucocutaneous jxns, pawpads
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| Common adverse drug rxn patterns. (10) | - urticaria
- maculopapular eruptions
- injxn site drug rxn, usually ischemic(rabies)
- erythroderma
- exfoliative dermatitis
- purpura
- fixed drug eruption
- vesiculobullous rxn
- lichenoid drug eruptions
- superficial suppurative necrolytic d
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| what is erythroderma? | Bright red skin.
- drug rxn caused
- may not be associated with pruritus
- common with LSA
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| What is a fixed drug rxn? | Drug only occurs in the same area. Commonly seen in the scrotum.
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| How are lichenificaition and lichenoid drug eruptions different? | - Lichenification is common. A gross term used to describe thickening and color change.
- Lichenoid drug rxn far less common. Small, hyperpigmented, thickened, well circumscribed.
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| What is superficial suppurative necrolytic dermatitis? | Sterile pustular erythroderma of mini schnauzers. Get very sick. Temporal relationship with shampoos. Usually die within 24-48hr. Imppressive immunosuppression can help.
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| How do you dx drug rxns? | - previous experience
- r/o alternatives
- timing (1-2 wks)
- response to de-challenge (take drug away)
- skin bx (EM, TEN)
- Re-challenge (don't recommend reexposing animal to the drug)
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| What are the 2 vet species of Dermatophytes? | - Microsporum
- Trichophyton
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| What are the Equine dermatophytes? | - Trichophyton equinum, T. mentagrophytes, T. verrucosum, Microsporum equinum
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| What are the small animal dermatophytes? | - Microsporum canis, M.gypseum, Trychophyton mentagrophytes
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| Which dermatophyte is geophilic? | M. gypseum (lives in the soil, so ubiquitous)
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| Which dermatophyte is anthrophilic? | Epidermophyton species
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| Which dermatophyte is zoophilic? | - M. canis most impt (normal reservoir is the cat).
- T. mentagrophytes (rodent reservoir)
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| Different between ectothrix and endothrix dermatophytes? | - Ectothrix- spores coat outside of hair shaft (most of the animal spp)
- Endothrix- spores aon the inside of hair shaft (human spp)
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| Do dermatophytes normally penetrate into deep tissue? | No not normally. If there is evidence of it, maybe review drug hx or the overall health of the pt.
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| Which breed of cats are predisposed to dermatophytosis? | Persian cats
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| How are dermatophytes transmitted? | animal to animal, fomites, soil to animal, animal to humans
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| Dermatophytosis risk factors. | - young age
- stress
- poor nutrition
- debilitating dz
- compromised immune system
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| Why do dermatophytes no invade the nasal planum? | Because there are no hair follicles on the nose.
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| What is the pathogenesis of dermatophytes? | - they invade the hair or stratum corneum and move downward to avoid shedding
- invade hair shafts
- disrupt keratinization
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| What are the clinical signs of dermatophytosis? | - alopecia: centrifugal pattern (ring)
- crusts, erythema, papules
- +/- puriritus & inflammation
- claw, hooves- weaken and split
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| Characteristics of Dermatophytes in cats. | - M.canis most casts
- ears, legs, face
- usually mild erythema
- partial alopecia, scaling, crusting, miliary dermatitis (very pleomorphic)
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| Characteristics of dermatophytes in dogs. | - localized patterns: face, feet, tail
- circular alopecia with scale, crusts, folicular pustules/papules at margin
- sometimes just face involved(T.mentag when stuck face down rodent hole)
- kerions - tumor-like deeper fungal infxn
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| When would you see onychomycosis? | Deep fungal infxn of the claw seen in dogs with dermatophytosis. Usually just 1 claw is involved.
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| Can you dx dermatophytosis just on appearance of skin lesions? | No. Looks like other things. Culture it to prove it.
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| Characteristics of dermatophytes in horses. | - usually circular alopecia & crusts
- usually in areas of tack
- may be urticarial
- occassionally affects only the coronary band
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| How do you dx dermatophytosis? | Fungal culture is the best. Can also do Woods lamp (50%), bx (70%), or microscopic examination of hairs.
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| How do you do a fungal dermatophyte culture? | - Dermatophyte Test Media (DTM): turns red during early fungal growth of dermatophyte
- Sab-Duet: DTM + Sabouraud's: can ID specific fungal colonies
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| What are the 3 indications of a positive DTM result? | - fluffy, white colonies
- colony growth in first 3 weeks
- medium turns red in first 48hr
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| How can you speciate the dermatophytes? | - use acetate tape and lactophenyl blue dye
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| Will dermatophytes self cure? | Yes, but it takes several weeks. It is best to tx to eliminate zoonosis.
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| How do you tx for dermatophytes? | - systemic therapy decreases duration and severity but still contagious
- need topicals too
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| What are drugs for systemic tx of dermatophytes? | - ketoconazole, fluconazole, (itraconazole the best but most $$$), terbinafine, griseofulvin (horses), lufenuron (but not used anymore for it)
***GIVE WITH FOOD****
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| WHat are drugs for topical tx of dermatophytes? | - LIME-SULFER (the best), ketoconazole or enilconazole, chlorohexidine
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| How do you know when dermatophyte tx is successful? | Serial cultures q 1-2weeks for 3 consecutive negative cultures.
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| How do you tx the environment for dermatophytes? | - isolate the affected animals
- clean surfaces and discard any objects that aren't disinfected (like carpet/beds/etc)
- only straight bleach works to kill all spores
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| Do they recommend the Microsporum vaccine? | No. It just reduces the size of the lesion but not reinfection or prevention of carrier state. Does work in large animals.
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| What are the advantages of topical therapy? | - dec need for systemic therapy
- palliative therapy while making a definitive dx
- additional features: dec pruritus, dec microbial counts, can be keratoplastic or keratolytic (help remove debris from body and help with normal cell turnover)
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| What are the disadvantages of topical therapy? | - owner compliance (not practical for O, cosmetically not appealing to O)
- patient's temperament (pt too aggressive, painful)
- pot'l irritation or contact dermatitis (so chance or rxn)
- can be absorbed percutaneously or ingested via grooming
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| What are the agents of topical therapy? | - antibacterial
- antifungal
- antiparasitic
- antiseborrheic
- antipuriritic
- moisturizing agents
- sunscreens
- deterrents
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| What are the vehicles of topical therapy? | - shampoos
- pledgets/towelletes
- soaks/dressings
- dips/rinses
- powders
- lotions
- creams
- ointments
- gels
- sprays
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| When are topical therapies used? | - Usually for adjunct therapy to systemic therapy for allergies, infections and seborrheic conditions.
- alone might be with dermatophytes and use lime-sulfer as main therapy
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| How do you pick your active ingredient of topical therapy? | - definitive dx
- desired effect
- current condition of skin
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| Define keratoplastic. | Normalizes epidermal cell turnover.
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| Define keratolytic. | Decreases keratinocyte adhesion.
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| Examples of antibacterial topical agents. | Benzoyl peroxide, ethyl lactate, chlorhexidine, sulfer/salicylic acid, Mupirocin (Bactoderm), Triclosan, Silver Sulfadiazine
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| What is the most common bac in superficial pyoderma? | Staph pseudintermedius
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| What is the most common bac in otitis externa? | Staph. pseudintermedius (sometimes Pseudomonas)
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| Examples of antifungal agents. | Azoles (ketoconazole, clotrimazole, miconazole, fluconazole), chlorhexidine (Ketochlor shampoo), Lime-sulfer
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| Antiseborrheic agent examples. | Sulfer/salicylic acid (dry; keratolytic & plastic), benzoyl peroxide (oily; lytic), tar (toxic in cats)
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| What is seborrhea. | Xs scaling and crusting. Both a dry form and a oily form.
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| Antiparasitic agent examples. | Amitraz (demodex, not fleas), Promeris (demodex, fleas)
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| Antipruritic/antiinflammatory agent examples. | - rarely used alone
- colloidal oatmeal, topical corticosteroids, topical anesthetics (pramoxine, lidocaine), antihistamines (mildly work), tar (not in cats), sulfer
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| Moisturizing agent examples. | - emollient oils (dec water loss, HyLyt bath oil)
- humectants (promote water retension, propylene glycol, glycerin)
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| Sunscreen agent examples. | - chemical (absorb UV light; water babies)
- Physical (reflect light, ZnOxide)
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| Deterrent agent example. | - unpleasant taste (bitter apple, hot pepper)
- anesthetize area (lidocaine, benzocaine; Capsaicin)
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| 4 main effects of corticosteroids. | - anti-inflammatory
- immunosuppressive
- antimitotic (affect epithelial cell turnover)
*diff effects vary on the dose given (usually a range; also vary on species)
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| What are the antiinflammatory effects of corticosteroids? | - higher neutrophil count (can't migrate into tissues)
- dec eos, basos, monocytes & macrophages
- affects arachidonic acid cascade (makes more lipocortin -> dec PLA -> dec Pg and Lt prodn)
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| What are the immunosuppressive effects of corticosteroids? | - affect cell mediated immunity bc toxic to lymphocytes
- affect humoral immunity bc can't produce antibodies (toxic to B lymphos) or cytokines (toxic to macrophages)
- interferes with antigen presention by mononuclear cells
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| Dermatologic uses for corticosteroids? | - pruritus
- inflammation of skin/ear canals
- allergic/hypersensitivity rxns (esp type 1 hypersensitivity)
- immune mediated/auto immune skin dz
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| General adverse effects of corticosteroids. | - PU/PD/PP
- behavioral changes (aggitation, slugish)
- muscle/connective tissue weakness/atrophy (protein catabolism)
- infxns (easier to get, harder to find/dx)
- adrenal suppression
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| Corticosteroid adverse effects on the skin. | - epidermal atrophy (thin epidermis, less collagen)
- bruising (collagen weakens, fragile vessels)
- hyperpigmentation (inc MSH)
- comedones (keratin/sebaceous material)
- increased telogen follicles (alopecia; no anagen)
- poor wound healing
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| Adverse corticosteroid effects in dogs. | - PP, PU/PD
- abdo enlargement
- urinary incontinence
- hepatopathy, pancreatitis, DM
- skin changes (Calcinosis cutis)
- muscle weakness (swayed back)
- hypertension
- alopecia +/- Calcinosis cutis
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| What is calcinosis cutis? | Dystrophic calcification of the skin. See in dogs with corticosteroid adverse side effects. Usually erythematous papules coalesce and form gritty plaques/ulcerations/crusts.
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| What are the adverse effects of corticosteroids in cats? | - most resistant to SE
- PP, PU/PD
- DM
- CHF (inc blood vol will make cardiac dz worse)
- "ear tipping" (dec/weakened collagen)
- acquired skin fragility (so thin, will rip right off)
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| What are the adverse effects of corticosteroids in horses? | - more resistant than dogs
- CONTRAINDICATED in LAMINITIS cases
- risk for laminitis follows drug strength
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| Give an example of a short, intermediate, long acting corticosteroid. | - short- hydrocortisone, cortisone (least potent)
- int- pred, prednisilone, methylpred (medium potency)
- long- dexamethasone (more potent)
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| Methods of corticosteroid delivery? | - oral (best)
- parenteral
- intralesional (aka parenteral)
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| Why use prednisolone in cats/horses? | - Cats cant convert all the pred into prednisolone
- prednisolone is more bioavailable in horse gut than pred
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| Immunosuppressive corticosteroid doses are ______________ the anti-inflammatory doses. | double
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| What does pyoderma mean? | pus-producing bacterial infxn of the skin
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| 2 reasons for frequency of K9 pyoderma | 1. stratum corneum less efficient at protecting against bac invasion
2. lack of ostial plug at entrance of K9 hair follicle
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| Most common K9 skin pathogen for pyoderma. What are secondary gram neg invaders? | Staph pseudintermedius.
Proteus, Pseudomonas, E.coli
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| What are 4 general perdisposing factors for K9 pyoderma? | - PRURITUS
- ENDOCRINOPATHY
- inflammation
- dz of hair follicle
- poor grooming
- disorders of cornification
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| What are the 3 classifications of pyodermas? | surface - superficial - deep
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| what are the 3 categories of surface pyoderma? | - acute moist dermatitis ('hot spot')
- intertrigo (skin fold pyoderma)
- mucocutaneous pyoderma (around lips/nasal planum)
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| What are the 3 categories of superficial pyoderma? | - impetigo (pustules not associated with hair follicle; ventral abdomen)
- superficial folliculitis (usually due to allergies)
- superficial spreading pyoderma (bac splitting right thru stratum corneum and see epidermal collarettes)
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| What can you rule down to if your dog has papular folliculitis? | pyoderma, dermophyte, demodex
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|
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| Most of the time, what do epidermal collarettes indicate? | pyoderma
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| What are the 2 categories of deep pyoderma? | - deep folliculitis/furunculosis (folliculitis that has damaged the walls of hair follicle that it has blown up) both local/generalized
- cellulitis (infxn along in the dermis and SQ tissue planes)
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| What is a common word for furunculosis? | boil
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| What is K9 acne? | Localied deep folliculitis (deep pyoderma) that don't respond to only topical therapy (have to use systemic abx therapy)
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|
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| what are the initial management of pyodermas? | - investigate for predisposing factors
- systemic abx (bacteriocidal if deep infxn/immunodeficiency)
- antibacterial shampoo (etiderm; ethyl lactate)
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| 3 common dz for pyoderma and recurrent pyodermas | - non-parasitic allergic dz (atopy)
- allergic parasitic dz (FAD)
- demodicosis
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| 3 principles of effective abx therapy | - choose proper abx
- establish effective dose
- maintain therapy long enough (at least 4 weeks)
- reevaluate lesions & pruritus
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|
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| What are the first line of abx used for pyoderma? | - vephalosporins, lincomycin, clavamox (amoxi/clavulanate)
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|
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| What do you do if you suspect the pyoderma is MRS & MDRS? | - CULTURE AND SENSITIVITY
- Give one of the following: TMS, doxycycline, chloramphenicol (aplastic anemia in people), amikacin (renal monitoring)
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| Pyoderma tx failure | - **failure to dx & tx UNDERLYING dz**
- wrong abx choice/dose
- poor O compliance
- incorrect diagnosis
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| What is the most common flea? | Ctenocephalides felis felis
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|
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| What is the average life cycle of the flea? | 21 days (range 21-190 depending on environmental temperatures)
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|
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| How many hr does it take for the flea to lay eggs? | 24-36h post first blood meal
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|
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| Do flea larva develop on or off the host? | off the host
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|
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| Which stage of the flea is highly susceptible to heat and dryness? | the larval stages
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|
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| Which is the most difficult flea stage to kill? | the pupae (cocoon)
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|
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| When do adults expupate? | In response to heat, CO2, vibrations or physical pressure.
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|
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| T or F. The flea is a permanent ectoparasite. | T. It will stay on the host until removed.
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|
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| Which flea stage triggers FAD? | the adult flea.
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|
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| what is the pathogenesis of FAD? | hypersensitive to flea saliva
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|
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| What is the classic clinical sign of FAD in the dog? | Pruritus "behind the belt". But may or may not have a flea on them.
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|
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| What are the 4 stages of immunologic response to a flea bite? | - type 1 hypersensitivity (min-1hr)
- late phase IgE response (2-4hr)
- Cutaneous basophil hypersensitivity (12-24hr)
- type IV hypersensitivity (24-28hr)
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|
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| Which K9 conditions predispose a dog to FAD? | Atopic dermatitis
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|
||||
| 4 steps of dx FAD | - signalment
- pt hx (behind the belt?; flea control; bathing; boarding/new pet?)
- fleas, flea dirt
- PE
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|
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| Where do you find FAD lesions on dogs? What types of lesions? | - behind the belt (caudal half of body)
- Papules -> crusts (scaling, excoriation, alopecia, dull hair coat, hot spots <pyotraumatic dermatitis>)
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| Where do you find FAD lesions on cats? What types of lesions? | - lesions can occur anywhere
- miliary dermatitis (small pinpoint papules), excoriation, alopecia, eosinophilic skin dz
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|
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| What is the specific name for hot spot? | pyotraumatic dermatitis
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|
||||
| With FAD, what tests would you use? | cbc- regenerative anemia. eosinophilia
tissue bx- r/o other dz
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|
||||
| What is the specific therapy for FAD? | - nothing specific... have to tailor to pt
- overall goal is to kill adults as fast as you can
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|
||||
| 3 objectives to managing FAD | - complete flea eradication in the environment (wash blankets, vacuum, professional service)
- provide symptom relief (allergy, secondary infxn) using corticosteroids
- tx and prevent infestations on pt
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|
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| What are the 2 categories of flea control? | - adulticides
- insect growth regulators
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|
||||
| What are the 2 types of insect growth regulators? | - juvenile hormone analogues (JHA)
- insect development inhibitors (IDI)
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|
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| How do JHAs work? Medication example. | - contain a synthetic hormone that prevents flea larva to molt to a pupa
- S-methoprene (Frontline plus), Vectra 3D
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|
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| How do IDIs work? Medication example. | - cause malformation of chitin cuticle preventing flea from emerging from pupa
- lufenuron (program, sentinel)
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|
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| What are the topical flea meds we discussed? | - Imidacloprid, Fipronil, Selamectin, Pyrethrins, Dinotefuran, Metaflumizone, Nitenpyram, Spinosad (IFSPDMNS)
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|
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| Why can you put a spot on in one place and have it work all over? | It distributes via translocation in the body oils.
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|
||||
| What does imidacloprid tx? | flea adulticide & larvacide
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|
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| What does fipronil tx? | fleas & ticks (disrupts Cl channels)
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|
||||
| What does Selamectin tx? | adults, larvae & eggs (inc GABA permeability = paralysis)
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|
||||
| What does dinotefuran tx? | fleas (all 4 life stages), ticks, mosquitoes
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|
||||
| What does Metaflumizone tx? | fleas and ticks and poss demodex (Na channel blocker) << dont rx it bc pemphigus foliaceous rxn at application site>>
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|
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| Name the oral flea meds | Nitenpyram, spinosad
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|
||||
| What does nitenpyram tx? | Adulticide only
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|
||||
| What is the gold standard for tx FAD? | Nitenpyram (capstar)
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|
||||
| What does spinosad tx? | fleas (don't give with ivermectin)
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|
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