Skin problems: a clinical approach

Ken Robinson

doi:10.22233/9781910443200.27

British Small Animal Veterinary Association , 297 (2015); https://doi.org/10.22233/9781910443200.27

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Skin problems: a clinical approach

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Author: Ken Robinson
From: BSAVA Manual of Canine Practice
Item: Chapter 27, pp 297 - 318
DOI: 10.22233/9781910443200.27
Copyright: © 2015 British Small Animal Veterinary Association
Publication Date: January 2015

Abstract

The main presenting signs of skin disease are: pruritus; alopecia (symmetrical, localized, diffuse, patchy); scaling and crusting; erosions and ulceration; papules, pustules and vesicles; lumps and nodules; and pigmentation disorders. This chapter looks at history, physical examination, diagnostic techniques, pruritic conditions and non-pruritic conditions. Quick Reference Guides: Skin scraping for parasites; Skin cytology; Obtaining a trichogram; Skin biopsy.

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27.1

Examples of dermatological lesions. (a) Papule: a solid elevated lesion, <1 cm diameter (arrowed). (b) Pustule: a circumscribed elevation of the skin, which contains pus (arrowed). (c) Hypopigmentation: (i) <1 cm macule; (ii) >1 cm patch. (d) Scale: an accumulation of loose fragments of the cornified layer of the skin (arrowed). (e) Crusts: accumulation of dried exudate, serum, pus, blood, cells or scales (arrowed). (f) Epidermal collarette: circular arrangement of scale. (g) Alopecia: loss of hair. (h) Comedones: dilated hair follicles filled with cornified cells and sebaceous material (arrowed). (i) Nodule: a circumscribed solid elevation, >1 cm in diameter). (j) Lichenification: thickening and hardening of the skin. Copyright © 2015 British Small Animal Veterinary Association.

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27.1 Examples of dermatological lesions. (a) Papule: a solid elevated lesion, <1 cm diameter (arrowed). (b) Pustule: a circumscribed elevation of the skin, which contains pus (arrowed). (c) Hypopigmentation: (i) <1 cm macule; (ii) >1 cm patch. (d) Scale: an accumulation of loose fragments of the cornified layer of the skin (arrowed). (e) Crusts: accumulation of dried exudate, serum, pus, blood, cells or scales (arrowed). (f) Epidermal collarette: circular arrangement of scale. (g) Alopecia: loss of hair. (h) Comedones: dilated hair follicles filled with cornified cells and sebaceous material (arrowed). (i) Nodule: a circumscribed solid elevation, >1 cm in diameter). (j) Lichenification: thickening and hardening of the skin.

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27.3

An approach to the dog with pruritus. Prior to embarking on using the chart, a thorough clinical history should be taken and a physical examination carried out. Copyright © 2015 British Small Animal Veterinary Association.

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27.3 An approach to the dog with pruritus. Prior to embarking on using the chart, a thorough clinical history should be taken and a physical examination carried out.

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27.4

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27.4 Comma-shaped flea faeces (f), along with white flea eggs (e) are visible in these haircoat combings on an examination table.

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27.5

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27.5 Alopecia, erythema and papules on the eyelids in an early case of atopic dermatitis in a young Staffordshire Bull Terrier.

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27.7

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27.7 Acute moist dermatitis in a cross-bred dog, with an exudative lesion behind the axilla.

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27.8

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27.8 Scaling and crusting lesions on the pinna of a dog with sarcoptic mange.

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27.9

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27.9 Orange Neotrombicula mites are visible on the ventral abdomen of this terrier.

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27.10

An approach to the dog with non-pruritic skin disease. Prior to embarking on using the chart, a thorough clinical history should be taken and physical examination carried out. Copyright © 2015 British Small Animal Veterinary Association.

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27.10 An approach to the dog with non-pruritic skin disease. Prior to embarking on using the chart, a thorough clinical history should be taken and physical examination carried out.

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27.12

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27.12 A middle-aged hypothyroid Dobermann bitch with hair loss, brittle hairs and hyperpigmentation.

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27.13

Colour dilution alopecia. This Dobermann has hair loss in the darker-haired regions but not in the lighter coloured hair regions. Note the clear demarcation between the areas. Copyright © 2015 British Small Animal Veterinary Association.

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27.13 Colour dilution alopecia. This Dobermann has hair loss in the darker-haired regions but not in the lighter coloured hair regions. Note the clear demarcation between the areas.

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27.16

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27.16 American Hairless Terrier. Note the lack of hair on the body that is normal for this breed.

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27.17

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27.17 Patchy alopecia and associated self-trauma on the head of a 12-week-old Pug with localized demodicosis.

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27.18

(a) Dermatophytosis with the usual presentation of alopecia and scaling in a cross-bred dog. (b) Circular lesions (epidermal collarettes) on a terrier with pyoderma. These are commonly mistakenly thought to be due to dermatophyte ‘ringworm lesions’, but nearly always represent a post pustular lesion. Copyright © 2015 British Small Animal Veterinary Association.

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27.18 (a) Dermatophytosis with the usual presentation of alopecia and scaling in a cross-bred dog. (b) Circular lesions (epidermal collarettes) on a terrier with pyoderma. These are commonly mistakenly thought to be due to dermatophyte ‘ringworm lesions’, but nearly always represent a post pustular lesion.

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27.20

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27.20 Follicular casts. Adherent keratin and follicular material on hair shafts (arrowed).

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27.21

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27.21 Cross-bred dog with alopecia, depigmentation, erythema and epidermal thickening of the nasal philtrum due to epitheliotropic lymphoma.

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27.22

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27.22 Crusting and scaling lesions on the eyelids of a young Siberian husky with zinc-responsive dermatosis.

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27.24

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27.24 Pustules and crusting on the paw of a Cocker Spaniel with pemphigus foliaceus.

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27.26

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27.26 A young Shar Pei with mucinosis undergoing excessive skin fold removal. Sticky tenacious fluid can be seen coming from the resection site.

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27.29

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27.29 Vitiligo in a 5-year-old female Rottweiler, showing loss of pigmentation of the nasal planum, eyelids and oral mucosa.

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Demodex canis mites: note the characteristic cigar shape of the adults. j = juvenile. (Original magnification X100)

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Demodex canis mites: note the characteristic cigar shape of the adults. j = juvenile. (Original magnification X100) Demodex canis mites: note the characteristic cigar shape of the adults. j = juvenile. (Original magnification X100)

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Cheyletiella mite from a skin scrape. (Original magnification X200)

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Cheyletiella mite from a skin scrape. (Original magnification X200) Cheyletiella mite from a skin scrape. (Original magnification X200)

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Sarcoptes scabiei mite from a deep skin scrape. (Original magnification X200; examined using potassium hydroxide)

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Sarcoptes scabiei mite from a deep skin scrape. (Original magnification X200; examined using potassium hydroxide) Sarcoptes scabiei mite from a deep skin scrape. (Original magnification X200; examined using potassium hydroxide)

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Cytology sample showing characteristic peanut-shaped Malassezia organisms (arrowed). (Diff-Quik; original magnification X1000, examined under oil emersion)

Cytology sample showing characteristic peanut-shaped Malassezia organisms (arrowed). (Diff-Quik; original magnification X1000, examined under oil emersion) Copyright © 2015 British Small Animal Veterinary Association.

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Cytology sample showing characteristic peanut-shaped Malassezia organisms (arrowed). (Diff-Quik; original magnification X1000, examined under oil emersion) Cytology sample showing characteristic peanut-shaped Malassezia organisms (arrowed). (Diff-Quik; original magnification X1000, examined under oil emersion)

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Cytology sample from a pyoderma lesion showing bacterial cocci (c) and active phagocytosis by neutrophils (n). (Diff-Quik; original magnification X1000, examined under oil emersion)

Cytology sample from a pyoderma lesion showing bacterial cocci (c) and active phagocytosis by neutrophils (n). (Diff-Quik; original magnification X1000, examined under oil emersion) Copyright © 2015 British Small Animal Veterinary Association.

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Cytology sample from a pyoderma lesion showing bacterial cocci (c) and active phagocytosis by neutrophils (n). (Diff-Quik; original magnification X1000, examined under oil emersion) Cytology sample from a pyoderma lesion showing bacterial cocci (c) and active phagocytosis by neutrophils (n). (Diff-Quik; original magnification X1000, examined under oil emersion)

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Mast cells containing granules, including a dividing cell, in a sample from a mastocytoma. (Diff-Quik; original magnification X1000, examined under oil emersion)

Mast cells containing granules, including a dividing cell, in a sample from a mastocytoma. (Diff-Quik; original magnification X1000, examined under oil emersion) Copyright © 2015 British Small Animal Veterinary Association.

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Mast cells containing granules, including a dividing cell, in a sample from a mastocytoma. (Diff-Quik; original magnification X1000, examined under oil emersion) Mast cells containing granules, including a dividing cell, in a sample from a mastocytoma. (Diff-Quik; original magnification X1000, examined under oil emersion)

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Sample from a pustule in a case of pemphigus foliaceous showing epithelial cells (acantholytic (a) cells), that have lost their adhesion to adjacent cells, giving them a rounded appearance. Neutrophils (n) are also present. (Diff-Quik; original magnification X1000, examined under oil emersion)

Sample from a pustule in a case of pemphigus foliaceous showing epithelial cells (acantholytic (a) cells), that have lost their adhesion to adjacent cells, giving them a rounded appearance. Neutrophils (n) are also present. (Diff-Quik; original magnification X1000, examined under oil emersion) Copyright © 2015 British Small Animal Veterinary Association.

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Sample from a pustule in a case of pemphigus foliaceous showing epithelial cells (acantholytic (a) cells), that have lost their adhesion to adjacent cells, giving them a rounded appearance. Neutrophils (n) are also present. (Diff-Quik; original magnification X1000, examined under oil emersion) Sample from a pustule in a case of pemphigus foliaceous showing epithelial cells (acantholytic (a) cells), that have lost their adhesion to adjacent cells, giving them a rounded appearance. Neutrophils (n) are also present. (Diff-Quik; original magnification X1000, examined under oil emersion)

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Anagen hairs, showing rounded bulb ends. (Original magnification X100)

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Anagen hairs, showing rounded bulb ends. (Original magnification X100) Anagen hairs, showing rounded bulb ends. (Original magnification X100)

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Telogen hair showing a tapered end. (Original magnification X200)

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Telogen hair showing a tapered end. (Original magnification X200) Telogen hair showing a tapered end. (Original magnification X200)

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Dermatophytosis: arthroconidia can be seen surrounding the hair shaft (arrowed). (Original magnification X400)

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Dermatophytosis: arthroconidia can be seen surrounding the hair shaft (arrowed). (Original magnification X400) Dermatophytosis: arthroconidia can be seen surrounding the hair shaft (arrowed). (Original magnification X400)

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