Canine atopic dermatitis (CAD) is one of the most common and welfare-significant skin conditions in dogs, affecting 10–15% of the canine population. It is a genetically predisposed, chronic inflammatory skin disease mediated by IgE hypersensitivity to environmental allergens. While not curable, evidence-based management achieves excellent quality of life in most affected dogs.
Pathophysiology
CAD involves three interconnected defects:
- Genetic predisposition: West Highland White Terriers, Labrador and Golden Retrievers, Bulldogs, Boxers, and numerous other breeds are overrepresented
- Skin barrier defect: Abnormal ceramide composition and filaggrin expression creates a "leaky" barrier allowing allergen penetration and water loss
- Immune dysregulation: Th2-biased immune response generates IgE antibodies against environmental allergens (house dust mites, storage mites, pollens, moulds)
Clinical Signs and Welfare Impact
- Intense, chronic pruritus (itching) — the primary welfare concern in CAD
- Erythema (redness), particularly affecting face, paws, ears, and flexural skin folds
- Secondary bacterial (Staphylococcus) and yeast (Malassezia) infection exacerbate pruritus and discomfort
- Lichenification (skin thickening) and hyperpigmentation in chronic disease
- Otitis externa (ear inflammation) frequently concurrent
- Sleep disturbance, behavioural changes, and anxiety from chronic itch are important quality-of-life impacts
Diagnosis
CAD is diagnosed clinically by meeting Favrot's criteria (age of onset <3 years, breed predisposition, pruritic response to steroids, etc.) after excluding flea allergy dermatitis and adverse food reaction through treatment trials. Intradermal testing or serological allergen-specific IgE testing identifies specific allergens for immunotherapy.
Treatment Options
Oclacitinib (Apoquel): JAK inhibitor providing rapid pruritus relief (within hours); excellent for acute and chronic management; oral once or twice daily.
Lokivetmab (Cytopoint): Monoclonal antibody targeting IL-31 (the primary itch-mediating cytokine); monthly subcutaneous injection; excellent for dogs with owner compliance challenges.
Ciclosporin (Atopica): Calcineurin inhibitor; slower onset (4–6 weeks) but effective long-term; once daily oral with gradual reduction to alternate-day dosing.
Allergen-specific immunotherapy (ASIT): The only treatment addressing the underlying cause rather than symptoms. Gradual subcutaneous or sublingual exposure to specific allergens desensitises the immune response. Effective in approximately 60–70% of dogs with improvement, though requires 6–12 months to assess efficacy. Most welfare-positive long-term approach.
Integrated Welfare Management
Optimal CAD management combines pharmaceutical control of itch, treatment of secondary infections, regular skin barrier support (specialist shampoos, essential fatty acid supplementation), and allergen-specific immunotherapy. Regular veterinary follow-up every 3–6 months assesses disease control and enables medication adjustment. Client education about the chronic, manageable (not curable) nature of CAD is fundamental to realistic expectations and sustained welfare outcomes.