Osteoarthritis is one of the most common chronic musculoskeletal diseases and causes lameness and disability in dogs (Colitti et al., 2012).
It is a complex and multifactorial disease that involves interactions between skin structure, the immune system, and environmental influences (Bensignor, Morgan, and Nuttall 2008). On the one hand, animals suffer from a hereditary predisposition to develop immediate hypersensitivity reactions mediated by IgE antibodies against environmental allergens (Olivry and Hill 2001) and (Fidalgo Álvarez et al. 2007). On the other hand, animals suffer from an alteration in the insulating function of the epidermis, of genetic or acquired origin, based on the mutation of a protein, filaggrin, one of the essential components that constitutes the epidermal barrier and changes in the organization of the lipids of the stratum corneum (Carlott 2005). The dysfunction of the cutaneous barrier would be responsible for an increase in the penetration of allergens via the percutaneous route and also an increase in transepidermal water loss.
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The clinical picture observed is a consequence of a type I hypersensitivity reaction, the first phase of which involves the formation of IgE immunoglobulins to specific allergens and the sensitization of mast cells. This means that upon second and subsequent contact with the allergens, the sensitized cells degranulate vasoactive substances such as histamine, prostaglandins, and leukotrienes, triggering a pruritic inflammatory process (Brazís et al. 1998).
The most characteristic feature is erythema in the facial area (muzzle, periocular region, auricle). and external auditory canal), distal areas of the forelegs and hindlegs (flexed areas of the limbs and interdigital spaces), inguinal, axillary, perianal and abdominal areas, generally without other types of lesions (Fidalgo Álvarez et al. 2007).
Secondary infections (bacterial or Malassezia) and scratching play a fundamental role, since they help keep the inflammatory response active. The chronic nature of the pruritus eventually causes lichenification, hyperpigmentation and hypotrichosis in the most affected areas (Hand et al. 2010). Discover our post about Supplements and vitamins for dogs.
