Monoblastic leukemia (M5a) with chronic basophilic leukemia in a cat.

A cat was presented with depression and anorexia. The complete blood cell count (CBC) revealed non-regenerative anemia (PCV, 8.5%), marked thrombocytopenia (2,400/µl), and leukocytosis (32,090/µl). In the peripheral blood, proliferation of blast cells (85%; 27,276/µl) and basophils (7.7%; 2,460/µl) was observed. Bone marrow aspirate showed hyperplasia with 8.8% blasts and 90.2% basophils of all nucleated cells. The blast cells were negative for myeloperoxidase staining and positive for alpha-naphthol butyrate esterase staining, indicating the agranular blasts are monoblasts. Thus, acute monoblastic leukemia (M5a) with chronic basophilic leukemia was diagnosed. Basophils accounted for more than 40% of the bone marrow, and we diagnosed secondary basophilic leukemia. Secondary basophilic leukemia should be included in the differential list when abnormal basophil increases are observed in feline bone marrow.

Lymphoma-associated hemophagocytic syndrome in six dogs.

Hemophagocytic syndrome (HPS) is a clinicopathological entity characterized by histiocytic proliferation, with marked hemophagocytosis in the reticuloendothelial organs. HPS caused by lymphoma is termed lymphoma-associated hemophagocytic syndrome (LAHS), and there are few reports on canine and feline LAHS. The objective of this study was to examine the clinical, diagnostic, and clinicopathologic features of LAHS in six dogs. The diagnostic criteria of LAHS consisted of lymphoma, bicytopenia or pancytopenia in the blood, and increased hemophagocytosis in the reticuloendothelial organs. In one dog, an ocular form of lymphoma was recognized. A splenic form was recognized in two dogs, and a hepatosplenic form was recognized in three dogs. Immunophenotyping revealed T-cell origin in five dogs and B-cell origin in one dog by polymerase chain reaction for antigen receptor rearrangement analysis. Nonspecific esterase stain was performed to differentiate between neoplastic lymphocytes and hemophagocytes. All five dogs with T-cell lymphoma were diagnosed with large granular lymphocyte (LGL) lymphoma. In three cases, palliative therapy with glucocorticoids was conducted, while the other three cases received chemotherapy as well. The survival times for the three dogs with glucocorticoids only were 6, 6, and 10 days and were 30, 54, and 68 days for the three treated with anticancer therapy. The median survival time for the dogs was 20 days. This report indicates that canine LAHS is likely to be caused by LGL lymphoma, and it has an aggressive behavior and poor general prognosis, as seen in humans.

Concurrent with T-zone lymphoma and high-grade gastrointestinal cytotoxic T-cell lymphoma in a dog.

A 9-year-old, spayed female Golden Retriever dog was referred to us for lymphocytosis and lymphadenopathy, secondary to suspected chronic lymphocytic leukemia (CLL). The dog had a clinical history of anorexia, vomiting and melena lasting two days. The popliteal lymph node contained small-to-intermediate lymphocytes, which led us to suspect low-grade lymphoma. Thickened lesions in the stomach and small intestine were detected by ultrasonography. Histopathology of the popliteal lymph node and small intestine revealed a simultaneous presence of T-zone lymphoma (TZL) and high-grade gastrointestinal (GI) cytotoxic T-cell lymphoma. Large granular lymphocytes (LGLs) were seen on cytological examination. Polymerase chain reaction (PCR) revealed that both lymphomas originated in the T-cells. The dog died 15 days after diagnosis, despite chemotherapy.

Intestinal gastrointestinal stromal tumor in a cat.

A 12-year-old, 3.6-kg, spayed female domestic shorthaired cat had a 2-month history of anorexia and weight loss. Abdominal ultrasonography and computed tomography revealed an exophytic mass originating from the jejunum with very poor central and poor peripheral contrast enhancement. On day 14, surgical resection of the jejunum and mass with 5-cm margins and an end-to-end anastomosis were performed. Histopathological examination revealed the mass was a transmural, invasive cancer showing exophytic growth and originating from the small intestinal muscle layer. Immunohistochemical analysis of tumor cells revealed diffuse positivity for KIT protein and negativity for desmin and S-100. The mass was diagnosed as a gastrointestinal stromal tumor (GIST). Ultrasonographic findings indicated the tumor probably metastasized to the liver and omentum, as seen in humans and dogs. The owner rejected further treatment at the last visit on day 192. To our knowledge, this is the first report of intestinal tumor and metastasis in feline GIST and its imaging features.

Acute myelomonocytic leukemia (AML-M4) in a dog with the extradural lesion.

A two-year-old dog having presented with neurological signs showed marked leukocytosis and appearance of blast cells in the peripheral blood. Hematological and bone marrow examination showed an increase in blasts having both myeloid and monocytic cells characteristics. The dog was diagnosed with acute myelomonocytic leukemia (AML-M4) on the basis of bone marrow findings. Although the dog was treated with a multi-combination chemotherapy, the neurological abnormalities progressed and the dog was euthanized. Myelographic examination and necropsy revealed the extradural lesion formed by AML-M4 around the cervical spinal cord and this lesion was considered as a cause of the neurological signs.

Differential diagnosis of feline leukemia virus subgroups using pseudotype viruses expressing green fluorescent protein.

Feline leukemia virus (FeLV) is classified into three receptor interference subgroups, A, B and C. In this study, to differentiate FeLV subgroups, we developed a simple assay system using pseudotype viruses expressing green fluorescent protein (GFP). We prepared gfp pseudotype viruses, named gfp(FeLV-A), gfp(FeLV-B) and gfp(FeLV-C) harboring envelopes of FeLV-A, B and C, respectively. The gfp pseudotype viruses completely interfered with the same subgroups of FeLV reference strains on FEA cells (a feline embryonic fibroblast cell line). We also confirmed that the pseudotype viruses could differentiate FeLV subgroups in field isolates. The assay will be useful for differential diagnosis of FeLV subgroups in veterinary diagnostic laboratories in the future.

Low-dose recombinant canine interferon-gamma for treatment of canine atopic dermatitis: an open randomized comparative trial of two doses.

The purpose of this study was to investigate the minimum effective dose of recombinant canine interferon-gamma (rCaIFN-gamma) for the treatment of dogs with atopic dermatitis (AD). Thirty-four dogs with AD from 17 animal hospitals in Japan were administered half or one-fifth of the approved rCaIFN-gamma dose of 10 000 units/kg, three times a week for 4 weeks, followed by once weekly for an additional 4 weeks. Pruritus, excoriation, erythema and alopecia were evaluated and scored by the investigators on weeks 2, 4, 6, 8 and 12. The efficacy rate (number of excellent cases + number of good cases/total number of cases) at week 8 in the 2000 units/kg group was 36.4% for pruritus, 36.4% for excoriation, 45.5% for erythema and 36.4% for alopecia. In contrast, in the 5000 units/kg group, the efficacy rate was 64.3% for pruritus, 57.1% for excoriation, 78.6% for erythema and 78.6% for alopecia. The efficacy rate of the 5000 units/kg group was high for all signs evaluated and comparable to that of the 10 000 units/kg group reported in a previous study. The results of this study showed that 2000 units/kg of rCaIFN-gamma is less effective than 5000 units/kg to treat dogs with AD, and the efficacy of the 5000 units/kg dose is comparable to that of 10 000 units/kg at week 8.

Essential thrombocythemia in a dog.

A two-year old male Welsh Corgi was referred for persistent thrombocytosis and occasional seizure. Hematological findings indicated marked thrombocytosis, eosinophilia, basophilia and moderate anemia. Bone marrow examination revealed marked megakaryocytic hyperplasia with morphologic abnormality. A diagnosis of essential thrombocythemia was made and the treatment was initiated with combination chemotherapy and maintained by prednisolone and busulfan. The dog successfully achieved complete remission on 100 days after initial presentation and has been good in health without chemotherapy since then.

A cat with acute myeloblastic leukemia without maturation (M1) treated with combination chemotherapy.

A 2-year-old domestic shorthair cat was presented to us with decreased activity and anorexia. Hematologic findings revealed a mild non-regenerative anemia, thrombocytopenia, and leukocytosis with an increase in blast cells. Bone marrow aspirates also revealed a marked increase of blasts. The blastic cells were shown to be positive for peroxidase. Acute myeloblastic leukemia without maturation (M1) was diagnosed according to the FAB classification. Chemotherapy was initiated with cyclophosphamide, vincristine, prednisolone, and cytosine arabinoside. The cat responded partially. In total, the cats were given 7 blood transfusions. The cat died 14 weeks after first being presented to us.