Introduction to dermatology 2 Flashcards
What are the 3 key facts you should known at the end of the dermatology consult?
- Age of onset
- The presence or absence of primary pruritus
- The distribution and type of the lesions
What are the 5 major dermatological presenting signs?
- Pruritus
- Alopecia
- Crusting
- Scale
- Nodules
Give some examples of parasites that cause pruritic disease in cats
Cheyletiella blakei Felicola subrostratus Sarcoptes scabei Fleas Notoedres cati Demodex gatoi
What are the 2 most common infections in cats that cause puritis?
- Superficial bacterial pyoderma
- Malassezia dermatitis
How would you diagnose surface ectoparasites?
- Consider where they are found on the skin
- Coat brushings
- Flea comb wet paper test
- Sellotape impression
How would you diagnose shallow and surface mites living in the epidermis?
Superficial skin scrapes
Give some examples of surface parasites
Fleas, lice, ticks, harvest mites, Cheyletiella and Demodex gatoi
Give some examples of shallow and surface mites living in the epidermis
Cheyletiella
Demodex gatoi
Sarcoptes scabei
Notoedres cati
How would you diagnose mites living deep in the skin?
- Deep skin scrapes
- Hair plucks
- Biopsy
Describe the clinical features of Demodex gatoi in cats
- Contagious
- Pruritic
- Head, neck and truncal barbered alopecia ± excoriation
How can Demodex gatoi be diagnosed?
- Skin scrapes – very poor sensitivity
- Tape cytology often more useful
- Faecal floatation has been used successfully
How can Demodex gatoi be treated?
Selamectin
Fluralaner
Acetate tape samples are suitable for which parasites?
Cheyletiella spp and Demodex gatoi
Describe the features of a Notoedres cati infection
- Rare in the UK
- Zoonotic
- The disease affects the head and ears and as the disease becomes more chronic the rest of the body
Which part of the body is not affected by Notoedres cati, even in chronic cases?
Plantar/palmar feet are not affected
How is Notoedres cati differentiated from Sarcoptes scabei?
Smaller size
Dorsal not terminal anus
How is Notoedres cati diagnosed?
Skin scrape
Describe the steps in carrying out a superficial skin scrape
- Clip the hair
- Place liquid paraffin on the target area
- Scrape with a blunted blade
- Transfer to a slide prepared with a small amount of liquid paraffin on it
- Place a cover slip
- Observe at low power
What are some of the common causes of alopecia in cats?
- Demodex cati
- Superficial bacterial pyoderma
- Dermatophytosis
- Allergies
- Neoplasia
Dermatophytosis is also known as?
Ringworm
Where are localised lesions due to Demodex cati seen?
- Eyelids
- Head
- Neck
- Ear
What are the major causes of Demodex cati?
Immunosuppression
- FIV/FeLV
- Diabetes mellitus
- Squamous cell carcinoma
What are the main signs of Demodex cati?
- Comedones
- Alopecia
- Erythema
- Crust and scale
- Pruritis
How can Demodex cati be treated?
Isoxazolines - Flurolaner, Selamectin
How is Demodex cati diagnosed?
Deep skin scrapes
Describe the steps taken when carrying out a deep skin scrape
- Same as superficial skin scraping but there should be a capillary ooze
- The skin should be squeezed and rolled between the fingers to maximize the yield of follicular material.
- These scrapes often hurt – ensure suitable analgesic and chemical restraint
In which cases can a direct impression smear cytology sample be carried out?
- Rupture pus filled lesion or lift crust
- Pustule / papule / bulla / epidermal collarette
Which cells are common to see in cats during all kinds of inflammation?
Eosinophils
If macrophages or RBCs are seen when analysing cytology, what does this mean?
That the dermis is involved i.e. a deep pyoderma
Describe the features of paraneoplastic alopecia in cats
- Rare, unknown pathophysiology
- Usually older cats >10yo
- Underlying tumour of the pancreas, bile duct
What are the clinical signs of paraneoplastic alopecia in cats?
- Alopecia and thin, shiny skin +/- Malassezia
- Ventral body, neck, chin, body, inner legs, feet, nasal planum and footpads
How is paraneoplastic alopecia in cats diagnosed?
Skin biopsy
Describe how a skin biopsy is carried out
- place the punch firmly onto the skin and twist 180 degrees
- lift the biopsy from the dermis delicately to avoid damage
- place the biopsy dermis down to stop it from curling
What are the common causes of scale and grease in cats?
- Cheyletiella blakei
- Felicola subrostratus
- Notoedres cati
- Neoplasia
- Keratinisation disorders
- Infections
Give 2 examples of keratinisation disorders
- Chin acne
- Idiopathic facial dermatitis
Which neoplastic disease causes scale and grease?
Thymoma-induced exfoliative dermatitis
What are the signs of thymoma-induced exfoliative dermatitis
- Middle to older age
- Diffuse, non-pruritic erythema and exfoliation (large 1+ cm flakes if skin)
+/- alopecia - Concurrent signs from respiratory compromise
How is thymoma-induced exfoliative dermatitis diagnosed?
Biopsy
Chest radiograph
How is thymoma-induced exfoliative dermatitis treated?
- Immunomodulatory drugs (e.g. prednisolone & ciclosporin) have been used with some success
- Surgery is reported to be curative, but some have reported needing immunosuppression after thymoma removal
Idiopathic facial dermatitis affects which cat breed?
Persians
Describe the signs of Idiopathic facial dermatitis
Tightly adherent, greasy black scales, lead to ulceration and soreness which is very pruritic
What is seen on cytology of Idiopathic facial dermatitis?
- Cytology shows yeast and secondary infection over the area
- Malassezia dermatitis
How is Idiopathic facial dermatitis treated?
- Anti-yeast therapy
- Keratolytic shampoos
- Ciclosporin ± prednisolone
Describe the features and signs of feline acne
- Common keratinization disorder of cats
- May be asymptomatic
- Dark, waxy scales and comedones
- Largely clinical diagnosis
- Secondary Malassezia, superficial and deep pyoderma (leading to pruritus ± pain)
How can feline acne be treated?
- topical antiseptics +/- antimicrobials
- anti-keratinolytics
- Routine hygiene may be useful in prevention
Which 3 species of cat are predisposed to Malassezia dermatitis?
- Devon rex
- Sphinx
- Persian
Malassezia dermatitis is a secondary disease in which conditions?
- Thymoma-induced exfoliative dermatitis
- Paraneoplastic alopecia
- FIV or FeLV
- Feline allergy
What is the test of choice for Malassezia?
Tape cytology
Describe how tape cytology is carried out
- Press tape onto the skin
- Apply firmly and peel away
- Good for places with little exudate or a wriggly patient
- Label slide
- Stain and dry
- Examine within 60 minutes
What are some of the causes of crusts in cats?
- Superficial bacterial pyoderma
- Allergy
- Herpes virus
- Calicivirus
- Pox virus
- Immune mediated disease
When does cow pox infection occur in cats, and which cats are affected most commonly?
- Hunting cats, rural, males
- End of summer/autumn
- Zoonotic
Describe how the cowpox virus infects cats and its timeline of infection
- Virus is inoculated by a bite or scratch from the prey - replicates locally in the epidermis , forms a crusted ulcerated area with central ulceration and a distinctive crater-edge in some
- Viral replication results in secondary papular crusting eruption after 7-14 days
- Spontaneous recovery occurs in around 4-5 weeks in most
Generalised cowpox infections may be fatal in…?
Young kittens and in cats treated with corticosteroids
Cowpox infections are diagnosed by?
PCR and/or biopsy
Cowpox infections are treated by?
- Specific treatments not available
- Steroids or immunosuppressants must not be used
- Supportive therapy e.g. fluids, appetite stimulation, tube feeding
What are the signs of a feline calicivirus infection?
Usually URTI - ulcers and vesicles on mucous membrane, lips and nose
What are the signs of a feline herpes virus infection?
- May not have active or historical URTI signs
- Usually adults
Facial lesions make a mask: eyelids, muzzle and nose +/- elsewhere on body
How are URT viruses treated?
- Fluids, and nutritional support
- Appetite stimulants e.g. mirtazapine
- Topical ocular medications are often needed in FHV-1 to treat pain and ulceration
What are the signs of mosquito bite hypersensitivity?
- Nose, ears and feet affected
- Papules rapidly developing into small crusts
- May be alopecia, depigmentation and ulcerations
- Hypersensitivity to mosquito saliva
- Peripheral lymphadenomegaly
Name the auto immune skin disease in cats that affects the head and ears initially, and may then spread to the nipples and feet ? What is the main sign of it?
Feline pemphigus foliaceus
Main sign is dramatic crusting
Give some examples of nodular disease in cats
- Neoplasia
- Mycobacterial infections
- Fungal infections
Considerable care is needed in cats with recurrent ‘abscess’ like lesions as these may represent …?
Mycobacterial disease
What needs to be considered if mycobacterial disease is suspected?
- Wear protective clothing
- Submissions to the lab need extra precautions
- When M. bovis is suspected or confirmed in a cat or dog post-mortem or confirmed in a living patient, the disease is notifiable.
- However, the suspicion of infection in a living animal is not.
- Notification should be to APHA England
Describe how an indirect smear would be carried out
- Roll swabs (gently) to avoid cell damage
- Used for sinus tracts, folded areas and ear sampling
- Pick off any lumps!
- Stain as for haematology
- For very greasy or waxy lesions use just the aqueous (red & blue) haem stains, but if possible use all three
Which types of inflammation is seen with mycobacteria?
Pyogranulomatous inflammation
What are the clinical signs of plasma cell pododermatitis?
- Soft, swollen pads with scaling
- Ulceration centrally in some
- Some cats have gingivitis-stomatitis or nasal lesions
- May be associated with glomerulopathy and/ or FIV
- Unknown aetiology
How is plasma cell pododermatitis treated?
- Spontaneous regression
- Prolapsed material needs surgical repair
- Immune-modulation: steroids, ciclosporin
