Parasitic and fungal skin disease

Question 1

Types of mange seen in small animals

Answer 1

Sarcoptic (Fox mange)

Notoedric mange (Cat mange) - potential imported disease, not in UK

Demodectic (red mange)

Question 2

Sarcoptic (fox) mange

Answer 2

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

Question 3

Itch/scratch reflex

Answer 3

Scratch concave aspect of pinna and positive result is that dogs back leg starts to peddle

Not pathognomic to sarcoptic mange

Question 4

Diagnosis of sarcoptic mange

Answer 4

Clip an area

Spread on liquid paraffin

Scrape off top layer

Find an area with a significant number of papules

Question 5

Treatment of sarcoptic mange

Answer 5

Selamectin (Stronghold spot on)

Moxidectin (Advocate spot on)

? Use of low dose pred post dx? - can help with the pruritis

Question 6

Notoedric mange (feline scabies)

Answer 6

Rarely seen in UK

Intensely pruritic (HS component)

Mainly ears/head/neck affected

Excoriation, crusty thickening “grizzled old Tom cat” appearance

Question 7

Diagnosis of notoedric mange

Answer 7

Tape strips/skin scrapes for dx

Mite has dorsal anus - Sarcops sp have terminal anus

Question 8

Treatment of notoedric mange

Answer 8

Selamectin spot on (Stronghold)

2% lime sulphur dips

Question 9

Demodectic manage (red mange)

Answer 9

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

Question 10

Presentation of demodectic mange

Answer 10

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

Question 11

Breed dispositions for demodectic mange

Answer 11

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,

Question 12

Clinical signs of demodectic mange

Answer 12

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

Question 13

Diagnosis of demodectic mange

Answer 13

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

Question 14

Treatment of localised demodectic mange

Answer 14

No miticidal treatment

Consider topical antiseptic therapy and supplemental treatment (e.g. worming, increased plane of nutrition)

Question 15

Treatment of generalised demodectic mange

Answer 15

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

Question 16

Cheyletiellosis (Walking dandruff)

Answer 16

C. yasguri (Dogs)

C. blakei (cats)

C. parasitovorax (Rabbits)

Very motile under microscope

Question 17

Pediculosis (lice)

Answer 17

Linognathus setosus Dogs/Sucking

Trichodectes canis Dogs/Biting

Felicola subrostratus Cats/Biting

Question 18

Dermatophytosis (ringworm

Answer 18

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)

Question 19

Diagnosis of ringworm

Answer 19

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

Question 20

Treatment of dermatophytosis

Answer 20

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

Question 21

Dermatophytic granulomas and pseudomycetomas

Answer 21

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

Question 22

Malassezia infections

Answer 22

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

Question 23

Canine breed disposition for Malassezia infections

Answer 23

Basset, WHWT, Am Cocker Spaniel

Question 24

Feline breed dispositions for Malassezia infections

Answer 24

Sphynx and Devon Rex in particular

Question 25

Clinical signs of Malassezia infections

Answer 25

Erythema

Pruritis

Alopecia

‘greasy’ exudate

Nail bed staining

Question 26

Clinical signs of chronic Malassezia infections

Answer 26

Hyperpigmentation

Lichenification

Malodour

Question 27

Treatment of Malassezia infections

Answer 27

Identify and treat underlying cause

2x weekly shampoo: 2% miconazole/2% chlorhexidine (Malaseb) or 3-4% chlorhexidine

Itraconazole or terbinafine systemically