Page 1410 - Small Animal Internal Medicine, 6th Edition

1382 PART XIII Hematology

BOX 86.1
VetBooks.ir Causes of Bicytopenia and Pancytopenia in Dogs and Cats

Chronic leukemias
Decreased cell production
Lymphoma
Bone Marrow Hypoplasia-Aplasia Multiple myeloma
Idiopathic Systemic mast cell disease
Chemicals (e.g., benzene derivatives) Malignant histiocytosis
Estrogen (endogenous or exogenous) Metastatic neoplasms
Drugs (chemotherapeutic agents, antibiotics, Granulomatous disorders
anticonvulsants, colchicine, nonsteroidal Histoplasma capsulatum
antiinflammatories) Mycobacterium spp.
Radiation therapy Storage diseases
Immune-mediated disorders Myelodysplasia
Infectious (parvovirus, FeLV, feline immunodeficiency Increased Cell Destruction and Sequestration
virus, ehrlichiosis, leishmaniasis, and anaplasmosis) Immune-Mediated Disorders
Evans syndrome
Bone Marrow Necrosis Sepsis
Infectious disorders (sepsis, parvovirus) Microangiopathy
Toxins (mycotoxins) DIC
Neoplasms (acute and chronic leukemias, metastatic Hemangiosarcoma
neoplasia)
Other (hypoxia, DIC) Splenomegaly
Congestive splenomegaly
Bone Marrow Fibrosis-Sclerosis Hypersplenism
Myelofibrosis Hemolymphatic neoplasia
Osteosclerosis Other neoplasms
Osteopetrosis Hemophagocytic malignant histiocytosis or histiocytic
sarcomas
Myelophthisis
Neoplasms
Acute leukemias
Note: Entries in boldface are common causes; entries in italics are relatively common causes; entries in regular typeface are uncommon
causes.
DIC, Disseminated intravascular coagulation; FELV, feline leukemia virus.

a cryptorchid) with pancytopenia, which may indicate the cats with bicytopenias or pancytopenias. Infectious diseases
presence of a Sertoli cell tumor or, less frequently, an inter- associated with bicytopenias and pancytopenias commonly
stitial cell tumor or a seminoma with secondary hyperes- diagnosed on serologic or PCR results include monocytic
trogenism. The finding of generalized lymphadenopathy, ehrlichiosis in dogs, anaplasmosis in dogs and cats, Babesia
hepatomegaly or splenomegaly, or intraabdominal or intra- gibsoni infection in dogs (usually in Pitbulls, where there is
thoracic masses may direct the clinician toward a specific combined regenerative anemia and thrombocytopenia),
group of presumptive diagnoses. For example, the finding of leishmaniasis in dogs (and occasionally in cats), systemic
a cranial or midabdominal mass in a dog with regenerative mycoses (i.e., histoplasmosis) in cats (and rarely in dogs),
anemia, thrombocytopenia, and LER is highly suggestive of and feline leukemia virus (FeLV) and feline immunodefi-
splenic hemangiosarcoma. ciency virus infections in cats. If the clinical and hematologic
The presence of diffuse splenomegaly suggests that the features of the case point toward an immune-mediated
spleen may be sequestering or destroying circulating blood disease (e.g., presence of polyarthritis or proteinuria, sphe-
cells or that EMH is occurring in response to a primary BM rocytosis), a direct Coombs test and antinuclear antibody
disorder. Cytologic evaluation of spleen specimens obtained test should be done (see Chapter 71). It is also helpful to
by percutaneous fine-needle aspiration is always indicated in submit fluid obtained from one or more joints for cytologic
dogs and cats with cytopenias and diffuse splenomegaly to evaluation because the presence of suppurative nonseptic
determine whether the enlarged spleen is the cause or con- arthritis suggests an immune pathogenesis or a vector-borne
sequence of the cytopenia (see Chapter 88). disease.
Serologic studies and/or polymerase chain reaction (PCR) Because establishing whether the cytopenia is the result
assays for infectious diseases is usually indicated in dogs and of peripheral cell destruction or a BM disorder is important,