Skin: atopy

Introduction

• Cause : inherited predisposition to develop hypersensitivity-mediated skin disease against environmental allergens.
• Signs : pruritic skin disease (may be seasonal), recurrent skin and ear infections.
• Diagnosis : suggestive history, compatible clinical signs and exclusion of other pruritic skin diseases.
• Treatment : desensitization or symptomatic management.
• Prognosis : guarded - problems likely to persist lifelong.
  Print off the owner factsheet on Atopy to give to your client.

Diagnosis

Clinical signs

• Diagnosis is clinical and by exclusion of other pruritic skin diseases.
• Fig.1 Atopy peri-orbital
  Facial erythema and pruritus (Fig. 1).
• Fig.2 Atopy extremities
  Pedal erythema and pruritus (Fig. 2).
• Fig.3 Atopy chronic - groin
  Ventral erythema (Fig. 3).
• Fig.4 Pyoderma metatarsus
  Secondary staphylococcal pyoderma (Fig. 4).
• Pinnal erythema.
• Fig.5 Lichenification
  Lichenification of the flexor surface of the tarsal joint and/or the extensor surface of the carpal joint (Fig. 5).
• Chronic or chronically relapsing dermatitis.

• Salivary staining of coat.
• Fig.6 Otitis externa chronic - Cocker Spaniel
  Otitis externa (Fig. 6).
• Hyperhidrosis.
• Conjunctivitis.
• Lichenification (Fig. 5, above).
• Alopecia.

• Rhinitis.
• Asthma.
• Fig.7 Cataract Border Collie 18 months

  Fig.8 Cataract English Springer Spaniel 6 years

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  Cataracts . (Figs. 7-8)

Differential diagnosis

• Flea allergy .
• Sarcoptic mange .
• Bacterial folliculitis .

• Food hypersensitivity .
• Cheyletiellosis .

• Malasseziadermatitis .
• Pediculosis .
• Drug eruption [Skin: toxic epidermal necrolysis].

• Contact hypersensitivity .
• Intestinal parasite hypersensitivity.

Outcomes

Prognosis

• Good if seasonally affected; 90% can be satisfactorily controlled.
• Many develop multiple allergies over succeeding years → increased difficulty in control.
• Cost and time implications for owners of severely affected dogs may lead to requests for euthanasia.

Reasons for treatment failure

• Failure to diagnose concurrent disease, eg flea allergy, food sensitivity.
• Many cases become less responsive to glucocorticoids with the passage of time - frequently due to a failure to manage concurrent disease.
• Inability of client to cope with treatment schedules.