Parasitic and fungal skin disease Flashcards
(27 cards)
Types of mange seen in small animals
Sarcoptic (Fox mange)
Notoedric mange (Cat mange) - potential imported disease, not in UK
Demodectic (red mange)
Sarcoptic (fox) mange
Intensely pruritic - if untreated, gets more pruritic
Can develop a hypersensitivity component
+ve itch/scratch reflex
Contagious and zoonotic
Dry seborrhoea of the ear margin
Papular lesions
Itch/scratch reflex
Scratch concave aspect of pinna and positive result is that dogs back leg starts to peddle
Not pathognomic to sarcoptic mange
Diagnosis of sarcoptic mange
Clip an area
Spread on liquid paraffin
Scrape off top layer
Find an area with a significant number of papules
Treatment of sarcoptic mange
Selamectin (Stronghold spot on)
Moxidectin (Advocate spot on)
? Use of low dose pred post dx? - can help with the pruritis
Notoedric mange (feline scabies)
Rarely seen in UK
Intensely pruritic (HS component)
Mainly ears/head/neck affected
Excoriation, crusty thickening “grizzled old Tom cat” appearance
Diagnosis of notoedric mange
Tape strips/skin scrapes for dx
Mite has dorsal anus - Sarcops sp have terminal anus
Treatment of notoedric mange
Selamectin spot on (Stronghold)
2% lime sulphur dips
Demodectic manage (red mange)
seen in the UK fairly regularly
Transmitted from bitch to puppies (C. section puppies reared in isolation never get them)
Assumed to be part of the “normal” cutaneous fauna (5% dogs +ve scraping)
Mite proliferation assumed to be related to immune system suppression or defect
Presentation of demodectic mange
Live in hair follicles so cause alopecia and reddish decolouration
Localised
§ Good prognosis
§ Most recover without miticidal treatment
§ May need increased plane of nutrition or some treatment
§ No more than four lesions <2.5cm diameter
Generalised
§ Poor prognosis
§ Very few recover without miticidal treatment
Breed dispositions for demodectic mange
Afghan,
Basenji,
Belgian Tervuren,
Boxer,
Bull Terrier,
Bulldog,
Collie,
Dalmatian,
Doberman,
French Bulldog,
GSH Pointer,
Gt Dane,
Italian Greyhound,
Manchester Terrier,
O.E. Sheepdog,
Pointer,
Rottweiler,
Clinical signs of demodectic mange
Often starts on face and front legs
Erythema, comedomes, and scaling, (seborrhoea oleosa)
Alopecia, follicular casts, papules and pustules, hyperpigmentation, furuculosis, nodules
Pruritic not because of the mites but because of the consequences of infection
Diagnosis of demodectic mange
Clinical signs
Examination of teased hair from within lesions
§ Use paraffin
§ Put under microscope
Microscopy crucial with respect to:
§ Deep skin scrapings
§ Hair plucking
§ Skin squeezings (+/- scotch tape) -
§ Skin biopsies
(Also PCR but not commercially available)
With appropriate clinical signs one mite is suspicious, two mites is a diagnosis
Treatment of localised demodectic mange
No miticidal treatment
Consider topical antiseptic therapy and supplemental treatment (e.g. worming, increased plane of nutrition)
Treatment of generalised demodectic mange
Amitraz (Aludex), sarolaner (Simparica), (ivermectin, milbemycin).
□ Amitraz shampoo
□ Simparica (sarolaner) chewable tablets
Imidacloprid and moxidectin (Advocate spot-on) – applied weekly
Antibiotics, shampoos (chlorhexidine), supplemental treatment, underlying disease
Treat for 1-2 months beyond clinical cure
Cheyletiellosis (Walking dandruff)
C. yasguri (Dogs)
C. blakei (cats)
C. parasitovorax (Rabbits)
Very motile under microscope
Pediculosis (lice)
Linognathus setosus Dogs/Sucking
Trichodectes canis Dogs/Biting
Felicola subrostratus Cats/Biting
Dermatophytosis (ringworm
Variety of keratinophilic fungi which invade hairs and the stratum corneum (Microsporum persicolor)
Zoonoses
Often seen in young animals
(R= commonly recognised reservoir)
Microsporum canis (R: cats)
- well circumscribed alopecia
- ‘cigarette ash’ scale
Trichophyton mentagrophytes (R: rodents)
Microsporum gypseum (R: soil)
Trichophyton erinacei (R: hedgehogs)
Microsporum persicolor (R: rodents)
Diagnosis of ringworm
Wood’s lamp
- M. canis is the only one that fluoresces
- +ve fluorescence 50-70% of the time
- Hair fluorescence is +ve NOT skin scale
McKenzie Toothbrush test
- Long haired cats (in particular) may be asymptomatic carriers of Microsporum canis
- Detect with toothbrush impression culture
Trichogram
Fungal culture
Biopsy
PCR
Treatment of dermatophytosis
Initial:
§ Topical e.g. enilconazole (Imaverol) D/H or chlorhexidine/miconazole (Malaseb) D or lime sulphur C
If necessary:
§ Systemic e.g. itraconazole C/D* 7 days/7days off, or terbinafine
Dermatophytic granulomas and pseudomycetomas
RARE
Persian cats and Yorkshire Terriers
Dermatophylic hyphae spread into dermic/subcutis producing firm dermal or subcut nodules that may ulcerate and discharge
Sx and systemic antifungals
Malassezia infections
Lipophilic yeats that colonise skin in low numbers
Ears/lips/axillae/feet/anal sacs
Common opportunistic pathogens
Proliferate with changes in host defences or local microclimate
Adhere to stratum corneum and secrete enzymes
May get Malassezia HS
Canine breed disposition for Malassezia infections
Basset, WHWT, Am Cocker Spaniel
Feline breed dispositions for Malassezia infections
Sphynx and Devon Rex in particular
