Dermatology Flashcards
Outline the common clinical signs associated with ectoparasitic disease.
- Puritis
- Alopecia
- Erosions
- Crust
- Scale
- Secondary infection
- Chronic changes
Outline the 4 cutaneous reaction patterns of cats.
- Head and neck pruritus
- Symmetrical alopecia
- Eosinophilic granuloma complex (EGC)
- Miliary dermatitis
Outline the common clinical signs associated with fleas.
Puritis (variable)
Dogs - caudal/dorsal part of body.
Cats - 4 cutaneous reaction patterns
Rabbits - pinna affected with dorsum/rump
Name the surface mites of cattle and whether they are common or rare.
Chorioptes bovis (common)
Psoroptes (rare)
Name the surface mites of sheep and whether they are common or rare.
Psoroptes ovis - sheep scab
Chorioptes bovis - scrotal scab
Name the surface mites of the horse and whether they are common or rare.
Chorioptes equi (common)
Psoroptes
Neotrombicila (harvest mite)
Outline where Chorioptes equi are commonly found.
Leg/tail mange especially with horses that are feathered.
Name the surface mites of dogs and cats and their common clinical signs.
Otodectes - dark dry exudate
Cheyletiella (fur mite) - truncal scale
Neotrombicula (harvest mite) - head/limbs.
Name the surface mites of rabbits and their clinical signs.
Cheyletiella (fur mite) - common, causes truncal scale.
Leporacus gibbus (fur mite) - asymptomatic, brown mite dust
Psoroptes cuniculi (ear mite) - very painly flackey adherent otic crust.
Name the burrowing mites of Dogs and whether their clinical signs.
Sarcoptes scabiei - sarcoptic mange- very puritic, crust on pinnal margins/hocks/elbows, positive pinnal/pedal reflex. Zoonotic
Name the burrowing mites of the guinea pig and their clinical signs
Trixacarus - extremely puritic, can cause seizures and death. Zoonotic
Name the burrowing mites of birds and their common clinical signs.
Cnemidocoptes - scaley beak and scaley leg
Outline the species impacted by demodex
Dog, hamster, occasionally cat.
Outline the common clinical signs associated with demodex.
- Folliculitis - pustules, papules, comedones, casts
- Alopecia
- Inflammation
- Puritis
- Furunculosis/deep pyoderma
Outline the main tick species in the UK.
Ixodes spp.
Outline the causes of blowfly strike
Cutaneous myiasis
Outline the clinical signs seen with an infestation of Culicoides spp.
Hypersensitivity- sweet itch in horses - puritis along crest of neck, tail base and face.
They also are vecrotrs for BTV in sheep and cattle.
Outline the causative agent of poultry red mite.
Dermanyssus gallinae
What are the clinical signs associated with Dermanyssus gallinae
Irritation, feather loss and debilitation.
Outline what is meant by the term surface pyoderma.
Give examples.
Where bacteria multiply on skin surface only
- Canine intertrigo (skin fold pyoderma)
- Acute moist dermatitis (hotspots)
- Bacterial overgrowth syndrome - bacterial multiplication with no/minimal inflammation- often highlly puritic
Outline what is meant by the term superficial pyoderma.
Give examples.
Infection within the epidermis or hair follicle
Evidenced by papules, pustules, crust, sclae and alopecia. Primarily neurtophilic inflammation.
Examples:
* Bacterial folliculitis
* Impetigo - interfollicular infection of epidermis.
* Exfoliative superficial pyoderma - infection between layers of stratum corneum.
* Dermatophilosis
* Fleece rot - pseudomonas
* Greasy pig disease - staph hyicus
Outline what is meant by the term deep pyoderma.
Infection outside the epidermis due to:
* Rupture of hair follicle wall (furunculosis)
* Penetrating wounds
* Haematogenous spread
Associated with thickening of skin
Give examples of deep pyoderma
- Furunculosis
- Absecess
- Cellulitis
Outline a treatment for a rabbit abcess.
Surgically remove and give antibiotics - Trimethroprim-Sufadiazine
Can’t lance! As rabbits have caseous pus.
Outline what is meant by the term bacterial granulomatous dermatitis.
Give examples.
Caused by traumatic implantation of saprophytic organisms.
- Mycobacterial (pyo)granulomas
- Non-filamentous bacterial graulomas
- Filamentous bacterial granulomas.
Identify causative agents of non-filamentous bacterial granulomas.
Staphylococci, Streptococci, Actinobacillus
Lesions contain small yellow granules.
Identify causative agents of filamentous bacterial granulomas.
Nocardia, Actinomyces
Nodular masses which may involve bone.
What are: Skin lesions secondary to systemic bacterial infections /
infections with toxin-producing bacteria
Give examples.
- Systemic bacterial infections - vascular damage of the skin leading to necrosis.
For example erysipelas
Or
- Infection with a toxin-producting bacteria (Rare)
What diagnostic tools could you use to investigate bacterial skin disease?
Cytology
Culture (and sensitivity)
Histopathology
Identify this skin disease.
Acute moist dermatitis
Surface pyoderma
Identify this skin disease.
Bacterial folliculitis
Superficial pyoderma
Identify this skin disease.
Bacterial folliculitis
Superficial pyoderma
Identify this skin disease
Canine deep pyoderma with furunculosis
Identify common presentations of dermataphytosis.
- Folliculitis - well demarcated allopecia
- Adherent scale
- Crust
- Asymmetric at outset
Identify uncommon presentations of dermataphytosis.
- Furunculosis
- Fungal kerion - a nodular inflammatory mass due to inoculation of fungus into dermis.
- Pseudomycetoma
- Onychomycosis - claw disease
Identify common diagnostic methods for M.Canis
- Dicrect examination
- Wood’s lamp
- Fungal culture
- Fungal PCR
- Histopathology
Identify common clinical signs of malassezia.
- Erythema, grease, scale, crust → chronic changes (lichenification, hyperpigmentation)
- Often malodourous
- Focal/multifocal/generalised
- Diffuse/well-demarcated
- Commonly affected areas ears, lips, muzzle, interdigital skin, flexor surfaces/medial aspects of limbs, ventral neck/body, axillae, perineum
Identify diagnostic methods for malassezia
- Cytology
- Acetate tape strip
- Impression smear
- x100 oil immersion
- Response to therapy
Identify the condition and the casuative agent.
Onychomycosis
Dermataphytosis
Identify the condition and the casuative agent.
Fungal kerion
Dermataphytosis
Identify the causative agent.
Malassezia
List common viral skin diseases.
- Papilloma virus - BPV, EPV and CPV
- Pox viruses - cow pox, horse pox, myxomatosis
- Parapoxviruses - CPD (Orf)
- Pestivirus
Outline common apperances of viral diseases
Macules, papules, vesicles, crusts, pustules
Outline diagnostic techniques for viral disease.
PCR
Histopathology
ELISA
Ouline the main protozoal skin disease and diagnostic methods.
Leishmaniasis- wide range of skin and systemic signs
Aspirates, PCR and biopsy.
Outline the common causes of allergic skin disease.
- Enviromental allergens
- Foods
- Ectoparasites
- Contact allergens
- Micro-organisms
- Drugs
What is the immunological basis for drug reactions?
Type 1 hypersensitivity mostly.
Drug reactions may be any type.
Outline how type 1 hypersensitivity causes puritis.
Mast cell mediators, cytokines, IL-31 bind to nerve endings causing puritis.
Outline the clinical features of enviromental atopic dermatitis.
Dogs
- Age of onset 0.5 to 3 years old
- Chronic relapsing puritic dermatitis
- Responsive to glucocorticoids
- Initially erthema/papules before self induced alopecia (chronic changes)
Outline the clinical features of food-induced atopic dermatitis.
Dogs
- Age of onset any, however, 50% of cases in dogs happen under 1 year old.
- Variable response to glucocorticoids
- May have GI signs
- May have increased malassezia
- Non-seasonal
Describe feline atopic skin syndrome (FASS)
- Inflammatory/puritic skin, liekly associated with IgE
- 0.5-5 years onset.
- Seasonal or non seasonal
- Presents with one or more of the four cutaneous reaction patterns
Describe feline food allergy (FFA)
- Any age
- Non-seasonal
- May have GI signs, conjunctivitis and respiratory signs.
- Presensts with one or more of the four cutaneous reation patterns.
Describe equine atopic dermatitis
- Age of onset commonly 1.5-6 years old
- Seasonal or non-seasonal
- Often co-exists with insect bite hypersensitivity
Outline the clinical signs of equine atopic dermatitis
- Pruritus +/or urticaria (odematous nodules/wheels)
- Sometimes nodules (eosinophilic granulomas)
- Lesion distribution poorly-defined generalised/localised lesions
Outline the two types of contact dermatitis and their physiological causes.
Contact irritant dermatitis
* Due to irritant nature of substance (not hypersensitivity).
* Will affect multiple animals - i.e. the chemicals used to clean the floor.
Contact hypersensitivity
* Type IV hypersenstivity
Describe contact hypersensitivity.
Sensitisation occurs over a prolonged period to plants, topical drugs, shampoos and other materials. Then causes a sensitivity reaction.
Explain why pemphigus foliaceus appears like this:
Pustules rapidly develop into crusts leaving erosions.
Antibodies attack keratinocytes causing this auto-immune reaction.
Explain why facial cutaneous lupus erythematosus appears like this.
T-cells attack the epithelium causing ulceration and depigmentation.
Explain why vitiligo appears like this.
Antibodies and T-cells attack melanocytes. As there are fewer melanocytes, there is less inflammation and virtually no crusting.
List the targets in auto-immune skin disease.
- Isthmus of hair follicle
- Hair bulb
- Sebaceous glands
- Dermal blood vessels
- Collagen VII
Outline why sebaceous adenitis appears like this.
T-cells attack and destroy sebaceuos gland. As a result, no oil is produced so the hair cant slide out.
Outline how auto-immune vasculitis is caused.
Antibodys attack immune complexes lodged in the vascular wall. This causes death of the blood vessel, preventing oxygen sypply to an area. As a result, tissue necrosis.
Outline what happens in panniculitis.
Soft-fluctuating nodules rupture do to an unknown immunological attack.
Outline diagnostic methods for autoimmune dieases.
Conformational
* Cytology
* Biopsy of typical lesions
* Routine bloods
Exclusion
* History taking - speed of onset, first lesions
* Skin scrapes
* Cultures
* Test treatment
Outline interface dermatitis
Inflammation at interface between dermis and epidermis.
Associated with immune-mediated disease
On histopathology you examine this.
What is your diagnosis, why?
Vasculitis.
Basophilic inflammatory cells surround blood vessel.
Interperate this histology section
Nodular (granulomatous) dermatitis.
Caused by fungus
What condition does this diagram represent?
Intraepidermal vesicular/pustular dematitis.
What condition does this diagram represent?
Panniculitis - inflammation of subcutaneous adipose tissue.
Multiple causes:
* Infectious agents
* Vasculitis
* Foreign body
* Pancreatic disease
* Trauma
What does this histological section indicate.
Atrophic dermatosis
What is a papule?
A small solid elevation of skin (often erythematous).
Less than 1 cm in diameter
What is a pustule?
A small (less than a centimetre) skin elevation filled with puss.
What are common causes of pustules and papules?
- Infections
- Ectoparasites
- Hypersensitivities
- Auto-immune diesase
Identify this lesion.
Papule
Identify this lesion.
Pustule
What are scale?
Rafts of immature keratinocytes which accumulate at the skin surface.
Caused by increased or disrupted epidermal turnover.
What is crust?
When exudates dry on the skin surface.
Identify which of the following are primary or secondary lesions:
Pustules, papules, scale, crust.
Primary
Pustules, Papules,
Secondary
scale, crust.
Outline common causes of scale and crust.
- Infection
- Parasites
Identify this lesion
Crust
Identify this lesion.
Scale
List the major causes of alopecia
- Congenital
- Hair follicle inflammation
- Hair cycle abnormality
- Hair morphological abnormalities
List the major dermatological causes of skin lumps.
9
- Abscess/cellulitis
- Furunculosis
- Bacterial granulomas
- Deep fungal granuloma
- Urticaria
- Seroma
- Haematoma
- Neoplasm
- Cysts
What are the differences between emolients and moisturisers?
Emollients: soften, sooth, lubricate and trap water in (vaseline).
Moisturisers increase the water content of the stratum corneum.
What do antiseborrhoeic agents do?
Reduce epithelial turnover
Restore normal epidermal keratinisation.
How does oclacitinib work?
Blocks the JAK-1 pathway
How does lokivetmab work?
Monoclonal antibody targets IL-31. Good antipruritic, but little anti-inflammatory action
How does ciclosporin work?
Inhibits the activation of T-lymphocytes on antigenic stimulation by impairing the production of IL-2 and other T-cell derived cytokines
Outline what neonicotinoids target
Give an example of a drug in this class.
These are nACh receptor agonists that target fleas and lice.
Imidacloprid - Dogs, cats and rabbits
Outline how organophosphates work, their targets and give an example.
Inactivates AChE.
Flys, ticks, keys, lice and scab.
Diazinon - sheep
Outline how phenylpyrazoles work, their targets and give an example.
Blocks GABA gated chloride channels in the CNS of targets.
Fleas and Ticks
Fipronil
NOT for use in RABBITS
Outline how isoxazolines work, their targets and give an example.
They bind to GABA and glutamate gated chloride channels in the CNS of targets.
Fleas, ticks, Demodex, Sarcoptic mange.
Fluralaner, afoxolaner and sarolaner
Dogs, cats and chickens!
Outline how macrolytic lactones work, their targets and examples of drugs.
GABA agonist (flaccid paralysis)
Mites and Lice
Ivermectin
Doramectin
Eprinomectin
Selamectin
SA, LA and Exotics
Outline how pyrethroids work, their targets and an example of a drug in this class.
Pyrethroids prevent the closure of the para-sodium channel blocking synaptic transmission causing flaccid paralysis.
Flys, ticks and lice.
Cypermethrin, permethrin
