Dermatological Specific Diseases Small Animal Notes

Dermatological specific diseases – small animal

CAT BITE ABSCESS

Cat bite abscesses are common in small animal practice. The abscess forms as a result of a cat bite.

Clinical signs

• Acute onset

• Pyrexia

• Pain

• Fluctant swelling

• Presence of scab and/or puncture marks.

• Inappetance

• Depression

Pathogenesis

• Very common in small animal practice.

• Result from cats a cat bite, usually because of fighting.

• An abscess is a collection of pus formed by tissue destruction in an inflamed area of localised infection. A wall is formed by adjacent healthy cells in an attempt to keep pus from infecting neighbouring structures. However, this barrier can prevent immune cells from attacking bacteria.

• The most common organism found is Staphylococcus spp.

• Abscesses may contain

• Aerobes

• Pasteurella spp.

• Actinomyces spp.

• Nocardia spp.

• Staphylococcus spp.

• Rhodococcus spp.

• Enterobacteriaceae (including Escherichia)

• Streptococcus spp.

• Anaerobes

• Porphyromonas spp.

• Fusobacterium

• Peptostreptococcus spp.

• Clostridium spp.

Diagnosis

• The abscess may be obvious on physical examination.

Treatment

• Draining of the abscess and possibly clipping of the area around the abscess.

• Antibiotic medication

• Amoxicillin-clavulanic acid

• Cephalosporins

• Clindamycin

• Analgesia

• NSAIDS – meloxicam

Prognosis

• Good with treatment.

SURFACE PYODERMA

Surface pyodermas are caused by secondary bacterial colonisation of the skin surface. Infection is confided to the interfollicular epidermal layers of the skin. Surface pyodermas may be

• Acute-moist dermatitis (wet eczema)

• Skin fold dermatitis (intertrigo)

Clinical signs

• Acute moist dermatitis

• Acute onset

• Intesnely pruritic

• Alopecia

• Exudative

• Erythematous

• Skin fold dermatitis

• Present in facial, vulval, lip and tail folds.

• May be chronic in onset.

Pathogenesis

• Acute moist dermatitis is usually a secondary condition to a primary pruritic condition, such as:

• Otitis externa

• Anal gland impaction

• Fleas/other ectoparasites

• Breed disposition

• Skin fold dermatitis is a primary disease caused by skin folds creating an environment permissible for bacterial colonisation.

• Bacteria present is usually Staphylococcus spp.

Diagnosis

• Bacterial culture and susceptibility testing

• Skin biopsies – histopathology and possibly culture.

Treatment

• Acute moist dermatitis

• Treatment of the primary disease.

• Surgical removal of skin folds if possible.

• Treatment of bacterial infection with anti-staphylococcal antibiotic

• Clindamycin

• Amoxycillin-clavulanate

• TMPS (trimethoprim/sulphonamide) – resistance may be an issue.

• Cefalexin

• Quinolones – only if no alternate.

• Topical – fucidic acid/betamethasone (Fuciderm).

• Treatment of inflammation with corticosteroid

• Prednisolone

• Dexamethasone

• Hydrocortisone

Prognosis

• Good.

SUPERFICIAL PYODERMA

A superficial pyoderma secribes cutaneous bacterial infection that involves both the skin and hair follicle epithelium.

Superficial pyodermas include:

• Impetigo

• Superficial bacterial folliculitis

• Pyotraumatic folliculitis

• Mucocutaneous pyoderma

Clinical signs

• Variable pruritus

• Ventral abdomen particularly affected.

• Impetigo:

• Non-follicular pustules

• Epidermal collarettes

• Superficial bacterial folliculitis:

• Most common form

• Pustrules

• Papules

• Associated with follicles

• Patchy alopecia

• Mucocutaneous pyoderma:

• Erythema

• Exudation

• Ulceration

• Crusting of lips and other mucocutaenous junctions

Pathogenesis

• Common organisms seen include

• Staphyloccoccus intermedius

• Staphylococcus aureus

• Staphylococcus pseudointermedius

• Caused by changes to the microenvironment of the skin that lead to conditions permissible to bacterial colonisation.

• May be a primary condition, but this is rare.

• Most pyoderms are due to underlying cutaneous and systemic disorders such as ectoparasite infestation, hypersensitivities, endocrinopathies and keratinisation defects. These pyodermas are commonly recurring.

Diagnosis

• Bacterial culture and sensitivity

• Skin biopsies for histopathology and possibly culture.

Treatment

• Treatment of any underlying cause.

• Systemic anti-staphylococcal antibiotics for a minimum of three weeks.

• Clindamycin

• Amoxycillin-clavulanate

• TMPS (trimethoprim/sulphonamide) – resistance may be an issue.

• Cefalexin

• Quinolones – only if no alternate.

• Topical antibacterial shampoo

• Reduces microbial population, reduces microbial by-products and removes debris and discharge.

• Topical antibacterials

• Chlorhexidine

• Ethyl lactate

• Benzoyl peroxide

• Piroctone olamine

• Selenium sulphide

Prognosis

• Depends on underlying condition.

DEEP PYODERMA

Deep pyoderma is infection that involves the dermis and subcutaneous tissue. Deep pyoderma includes:

• Cellulitis

• Furunculosis

• Acral lick furunculosis

Clinical signs

• Papules

• Pustules

• Alopecia

• Nodules

• Furuncles

• Palpable lumps in the dermis

• Sinuses

• Draining tracts

• Ulcers

• Haemorrhagic bullae.

Pathogenesis

• Furunculosis is caused when follicle infection spreads into the dermis.

• Cellulitis is infection of the follicles and surrounding dermis.

• Both furunculosis and cellulitis are usually secondary conditions.

• Bacteria often involved include:

• Staphylococcus spp.

• Streptococcus spp.

• Pseudomonas spp.

• Pasteurella spp.

• Escherichia coli

Diagnosis

• Bacterial culture and sensitivity testing.

• Cytology from FNA or impression smears.

• Skin biopsies with histopathology and possibly culture.

Treatment

• Treatment of underlying conditions.

• Topical antibacterial shampoo.

• Long courses of systemic antibiotics based on culture and sensitivity for a minimum of 6 weeks.

• Should be anti-staphylococcal

• NOT clindamycin as this is bacteriostatic.

Prognosis

• Long term management may be difficult.

ACRAL LICK GRANULOMA (ACRAL LICK DERMATITIS, LICK GRANULOMA)

Acral lick dermatitis results from an urge to lick the lower cranial portion of a limb, resulting in a thickened, firm oval plaque.

Clinical signs

• Lesion most common on cranial aspect of forelimb.

• Alopecia

• Saliva staining

• Erosion of the skin

• Firm, well-circumscribed, sometimes ulcerated...

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