Selective IgA Deficiency

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    What Is Selective IgA Deficiency?

    Selective IgA deficiency is an immune system disorder that occurs due to a lack of IgA (immunoglobulin A) immunoproteins. It is the most common primary immune deficiency disorder in both humans and dogs.

    Functions Of An Immune System

    The immune system produces these proteins in response to the presence of antigens such as bacteriaviruses, and toxins. Antibodies recognize and attack antigens by binding to them and remove them from the body.

    The Importance of IGA

    Immunoglobulin A (IgA) is the second most abundant antibody in human blood and is found on the skin, in the respiratory, digestive and reproductive tracts, and in tears. When the immune system fails to produce a sufficient amount of IgA or does not produce it at all, animals have chronic, recurrent respiratory infections, digestive system disorders, dermatitis, and allergies.

    The IgA deficiency in the German Shepherd has been associated with severe infections, such as aspergillosis (almost 100% mortality rate), otitis externaatopic dermatitis, and folliculitis. These infections are generally unresponsive to antibiotic therapy.

    Susceptible Dog Breeds

    Besides the German Shepherd, the disorder is most commonly diagnosed in the Beagle, Shar-Pei, and Irish Setter. Affected dogs are usually smaller than their littermates.

    Signs & Symptoms

    In puppies, the disease manifests as scratching, sneezing, nasal discharge, chronic diarrhea, and frequent urination.


    The IgA deficiency is usually diagnosed through a blood test which may show reduced or absent IgA.

    Video Credits: Osmosis


    1. Olsson et al. – Genome-Wide Analyses Suggest Mechanisms Involving Early B-Cell Development in Canine IgA Deficiency
    2. Tengvall et al. – Genome-Wide Analysis in German Shepherd Dogs Reveals Association of a Locus on CFA 27 with Atopic Dermatitis


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