Page 1240 - Veterinary Immunology, 10th Edition

validated in domestic species. Affected animals may benefit from
VetBooks.ir high doses of corticosteroids or immunosuppressive therapy.

Immune-mediated bone marrow aplasia is rare in cats and usually
only affects erythrocyte progenitors. It has been recorded in a ferret.

An immune-mediated, vaccine-induced neonatal pancytopenia
does occur in cattle (Chapter 31).

Autoimmune Thrombocytopenia

Autoimmune thrombocytopenia (AITP) due to an immune attack
on platelets has been reported in horses, dogs, and, rarely, cats.
Affected animals usually present with multiple petechiae in the
skin, gingiva, other mucous membranes, and conjunctiva. Epistaxis,
melena, and hematuria may occur. The predominant cause of death

in these dogs is severe gastrointestinal hemorrhage. Antibodies
against platelet antigens cause extravascular destruction of
opsonized platelets in the spleen. As a result, affected animals have

unusually low platelet counts and a prolonged bleeding time. The
disease is commonly observed in association with IMHA and SLE.
The thrombocytopenia occurring in animals with multiple myeloma
or other lymphoid tumors, with ehrlichiosis and leishmaniasis, or
following certain drug treatments may be due to the nonspecific

binding of IgG to platelets. (Drug-induced immune-mediated
thrombocytopenia in humans is associated with quinine and
vancomycin use.) In dogs, the average age of onset is 6 years.

Predisposed breeds include Airedales, Dobermans, Old English
Sheepdogs, Cocker Spaniels, and Poodles. Antibodies to platelets
may be measured by direct immunofluorescence on bone marrow
aspirates looking for positive staining on megakaryocytes.
However, an alternative test is one that measures the release of

factor III from platelets after exposure to autoantibodies. This may
be performed by incubating platelet-rich plasma with a globulin
fraction of the serum under test and estimating the amount of

procoagulant activity released. In about 75% of cases the antibodies
are of the IgG class. Most cases of AITP in cats are probably
secondary to feline leukemia virus infection.
Immunosuppressive doses of a corticosteroid such as
prednisolone are used to treat AITP. Vincristine may also produce a

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