This article briefly reviews the concepts of immunodeficiency and
immunomodulation as they relate to selected
skin diseases in the dog and cat. Immunodeficiency states are uncommon and may be associated with a subnormal or down-regulated immune system, including humoral deficiencies, such as
IgA, and abnormal lymphocyte or neutrophil function. Establishing a causal relationship between a
skin disease and presumed immunodeficient state has been difficult due to the rarity of such conditions, and the limited nature of the techniques used to characterise the immune system response.
Severe combined immunodeficiency in dogs is a well characterised primary immunodeficiency state involving lymphocytes;
retrovirus infection in cats may lead to an acquired immunodeficient state with some association with certain dermatological conditions although it remains unclear that
infection is causally linked with disease.
Immunomodulation usually implies stimulating the immune system along a beneficial pathway. Such a therapeutic approach may involve a wide variety of agents, for example
intravenous immunoglobulin. There are few randomised controlled trials with veterinary patients that unequivocally demonstrate beneficial responses to
immunomodulatory agents.
Interferons are
cytokines of major interest in human and veterinary medicine for their
antiviral, anti-tumour and immunomodulatory effects. The advent of veterinary-licensed products containing recombinant
interferon may enable demonstration of the efficacy of
interferons for conditions such as canine
papillomatosis and feline
eosinophilic granuloma complex. Canine
pyoderma has been treated with a number of presumed
immunomodulatory agents with limited success. With more detailed knowledge of the pathogenesis of
pyoderma it may be possible to develop efficacious
immunomodulators.