The function of the immune system is the detection and destruction of invading microorganisms and abnormal cells. Because of the great diversity of microbial invaders, the immune system is a complex mixture of protective mechanisms. These may be simply classified as innate immunity Innate Immunity in Animals Innate immunity is one of two main immunologic strategies found in animals, the other being adaptive immunity. Major functions of the innate immune subsystem include anatomic defenses against... read more and adaptive immunity Adaptive Immunity in Animals Innate immune responses, although critical to the defense of the body, cannot guarantee protection. They lack the flexibility to respond optimally to a diverse set of microorganisms, and they... read more . Immediate protection within the first few hours and days of microbial invasion is the responsibility of the “hardwired” innate immune system. Longer-term protection is the responsibility of the adaptive immune system.
In general, immune system disease takes three forms:
insufficient immune function causing immunodeficiencies Immunodeficiency Diseases in Animals Immunodeficiency diseases manifest clinically as a predisposition to infections. They are usually recognized when an animal makes multiple visits to a veterinarian for infections that would... read more , manifested as increased susceptibility to infections
excessive immune function Excessive Immune Function in Animals There are three different ways by which excessive immune function can cause disease or death. These include excessive inflammatory responses, allergic diseases, and autoimmune diseases. Although... read more , resulting in inappropriate cell and tissue damage or hypersensitivities Hypersensitivity Diseases in Animals Inappropriate or excessive activity of the adaptive immune system can lead to damaging immune responses collectively called hypersensitivities. In general, inappropriate innate immune responses... read more
autoimmune diseases Autoimmune Diseases Inappropriate or excessive activity of the adaptive immune system can lead to damaging immune responses collectively called hypersensitivities. In general, inappropriate innate immune responses... read more , in which the immune system directly attacks normal body cells and organs.
Some inflammation and limited tissue destruction are features of the normal innate and adaptive immune responses. Clinical disease occurs when this inflammation is excessive, in the wrong place, or directed against the wrong target.
For More Information
Viviano KR. Glucocorticoids, cyclosporine, azathioprine, chlorambucil, and mycophenolate in dogs and cats: clinical uses, pharmacology, and side effects. Vet Clin North Am Small Anim Pract. 2022;52(3):797-817. doi:10.1016/j.cvsm.2022.01.009
Beasley MJ, Shores A. Perspectives on pharmacologic strategies in the management of meningoencephalomyelitis of unknown origin in dogs. Front Vet Sci. 2023;10:1167002. doi:10.3389/fvets.2023.1167002
Hernandez-Bures A, Bidot WA, Griffin CE, Rosenkrantz WS. The use of oclacitinib compared to azathioprine in the management of canine pemphigus foliaceus: a retrospective analysis. Vet Dermatol. 2023 Sep 12. Epub ahead of print. doi:10.1111/vde.13203