Page 1524 - Small Animal Internal Medicine, 6th Edition

1496 PART XIV Infectious Diseases

by immunosuppression. A positive FeLV test result does not is likely to develop as a result of polyneuropathy or lym-
prove disease induced by FeLV. When a clinical syndrome is phoma. Intraocular and nervous system disease in FeLV-
VetBooks.ir diagnosed in a FeLV-seropositive cat, the workup should infected cats can occur from infection with other agents,
including FIPV, Cryptococcus neoformans, or T. gondii.
include diagnostic tests for other potential causes. The
Abortion, stillbirth, or infertility occurs in some FeLV-
opportunistic agents discussed for FIV are also common in
FeLV-infected cats (see Table 96.2). infected queens. Kittens infected in utero that survive to
Bacterial or calicivirus-induced stomatitis occurs in some birth generally develop accelerated FeLV syndromes or die
FeLV-infected cats as a result of immunosuppression. FeLV as part of the kitten mortality complex.
infection can result in vomiting or diarrhea from a form of Some FeLV-seropositive cats present for lameness or
enteritis clinically and histopathologically resembling pan- weakness from suppurative nonseptic polyarthritis attrib-
leukopenia, from alimentary lymphoma, or from secondary uted to immune complex deposition. Multiple cartilaginous
infections attributable to immunosuppression. Icterus in exostoses occur in some cats and may be FeLV related.
FeLV-infected cats can be prehepatic from immune-mediated
destruction of red blood cells induced by FeLV or secondary Diagnosis
infection by M. haemofelis or “Candidatus Mycoplasma hae- A variety of nonspecific hematologic, biochemical, urinaly-
mominutum”; hepatic from hepatic lymphoma, hepatic lipi- sis, and radiographic abnormalities occur in FeLV-infected
dosis, or focal liver necrosis; or posthepatic from alimentary cats. Nonregenerative anemia alone or in combination with
lymphoma. Some FeLV-infected cats with icterus may be decreases in lymphocyte, neutrophil, and platelet counts is
concurrently infected by FIP virus or T. gondii. common. The presence of increased numbers of circulating
Clinical signs of rhinitis or pneumonia occur in some nucleated red blood cells or macrocytosis in association with
FeLV-infected cats as a result of secondary infections. severe nonregenerative anemia occurs frequently; examina-
Dyspnea or dysphagia from mediastinal lymphoma occurs tion of bone marrow often documents a maturation arrest
in some cats. These cats are generally younger than 3 years in the erythroid line (erythrodysplasia). Immune-mediated
and may have decreased cranial chest compliance on palpa- destruction of erythrocytes can be induced by FeLV and
tion, as well as muffled heart and lung sounds if pleural occurs in cats co-infected with hemoplasmas; regenera-
effusion is present. tive anemia, microagglutination or macroagglutination of
Mediastinal, multicentric, and alimentary lymphomas are erythrocytes, and a positive result on the direct Coombs test
the most common neoplasms associated with FeLV; lym- are common in these cats. Neutropenia and thrombocytopenia
phoid hyperplasia also occurs. Alimentary lymphoma most occur from bone marrow suppression or immune-mediated
commonly involves the small intestine, mesenteric lymph destruction. In one study, 37 cats with nonregenerative cyto-
nodes, kidneys, and liver of older cats; however, most cats penias were evaluated for focal FeLV in the bone marrow
with alimentary lymphoma are FeLV-negative. Renal lym- by RT-PCR assay and 2 cats were positive (Stützer et al.,
phoma can involve one or both kidneys, which are usually 2010). FeLV-infected cats with the panleukopenia-like syn-
enlarged and irregularly marginated on physical examina- drome have gastrointestinal tract signs and neutropenia and
tion. For additional discussion, please see Chapter 79. Fibro- are difficult to differentiate from cats with panleukopenia
sarcomas occasionally develop in young cats co-infected virus infection or salmonellosis. However, cats with FeLV-
with FeLV and feline sarcoma virus (see Chapter 81). Lym- induced panleukopenia-like syndrome usually have anemia
phocytic, myelogenous, erythroid, and megakaryocytic leu- and thrombocytopenia, abnormalities rarely associated with
kemia all are reported with FeLV infection; erythroleukemia panleukopenia virus infection. In one study, FeLV-positive
and acute myelomonocytic leukemia are the most common cats with anemia at the time of initial diagnosis had shorter
(see Chapter 80). The history and physical examination find- life span than FeLV-positive cats with normal red blood cells
ings are nonspecific. (Spada et al., 2018).
Renal failure occurs in some FeLV-infected cats from Azotemia, hyperbilirubinemia, bilirubinuria, and in -
renal lymphoma or glomerulonephritis. Affected cats are creased activity of liver enzymes are common biochemical
presented for evaluation of polyuria, polydipsia, weight loss, abnormalities. Proteinuria occurs in some FeLV-infected
and inappetence during the last stages of disease. Urinary cats with glomerulonephritis. Cats with lymphoma have
incontinence from sphincter incompetence or detrusor mass lesions radiographically depending on the organ
hyperactivity occurs in some cats; small-bladder nocturnal system affected. Mediastinal lymphoma can result in pleural
incontinence is reported most frequently. effusion; alimentary lymphoma can cause obstructive intes-
Some FeLV-infected cats are presented for miosis, blepha- tinal patterns.
rospasm, or cloudy eyes from ocular lymphoma. Aqueous Lymphoma can be diagnosed by cytologic or histopatho-
flare, mass lesions, keratic precipitates, lens luxations, and logic evaluation of affected tissues (see Chapters 74 and 79).
glaucoma are often found on ocular examination. FeLV does Because lymphoma can be diagnosed cytologically and
not likely induce uveitis without lymphoma. Neurologic treated with chemotherapy, cats with mediastinal masses,
abnormalities associated with FeLV infection include aniso- lymphadenopathy, renomegaly, hepatomegaly, splenomeg-
coria, ataxia, weakness, tetraparesis, paraparesis, behavioral aly, or intestinal masses should be evaluated cytologically
changes, and urinary incontinence. Nervous system disease before surgical intervention. Malignant lymphocytes are also