Type I interferons (IFNs) such as IFN-α, IFN-β, IFN-ε, IFN-κ, and IFN-ω represent
cytokines, which are deeply involved in the regulation and activation of innate and adaptive immune responses. They possess strong
antiviral, antiproliferative, and immunomodulatory activities allowing their use in the
therapy of different
viral diseases,
neoplasms, and immune-mediated disorders, respectively. Initially, treatment strategies were based on nonspecific inducers of type I IFNs, which were soon replaced by different
recombinant proteins. Drugs with type I IFNs as active agents are currently used in the treatment of
hepatitis B and C
virus infection,
lymphoma,
myeloid leukemia,
renal carcinoma,
malignant melanoma, and
multiple sclerosis in humans. In addition, recombinant feline IFN-ω has been approved for the treatment of canine parvovirus, feline leukemia virus, and feline immunodeficiency virus
infections. However, the role of type I IFNs in the pathogenesis of
canine diseases remains largely undetermined so far, even though some share pathogenic mechanisms and clinical features with their human counterparts. This review summarizes the present knowledge of type I IFNs and down-stream targets such as Mx and
2',5'-oligoadenylate synthetase proteins in the pathogenesis of infectious and immune-mediated
canine diseases. Moreover, studies investigating the potential use of type I IFNs in the treatment of canine
lymphomas,
melanomas,
sarcomas, and
carcinomas, canine distemper virus, parvovirus, and
papillomavirus infections as well as immune-mediated
keratoconjunctivitis sicca and
atopic dermatitis are presented. A separate chapter is dedicated to the therapeutic potential of IFN-λ, a
type III IFN, in
canine diseases. However, further future studies are still needed to unravel the exact functions of the different subtypes of type I IFNs and their target genes in healthy and diseased dogs and the full potential action of type I IFNs as treatment strategy.