A retrospective study in 21 Shiba dogs with chronic enteropathy.

We retrospectively studied the clinical and laboratory features and outcomes of chronic enteropathy in Shiba dogs. Among 99 dogs with chronic enteropathy, 21 Shiba dogs (21%) were included in the study (odds ratio, 7.14). No significant differences were seen in signalment, clinical signs, symptoms or laboratory profiles between the Shiba and non-Shiba groups. Severe histopathological lesions in the duodenum were a common finding in the Shiba group. The median overall duration of survival in the Shiba group was 74 days, while that of the dogs in the non-Shiba group could not be determined because more than half of the cases remained alive at the end of this study. The difference between the groups was statistically significant (P<0.0001). The 6-month and 1-year survival rates for the Shiba group were 46% and 31%, respectively. Conversely, the 6-month, 1-year and 3-year survival rates for the non-Shiba group were 83%, 74% and 67%. The results obtained here demonstrated that the Shiba dog is predisposed to chronic enteropathy and shows severe duodenum lesions and poor outcomes, indicating a breed-specific disease.

Mutations in the fifth immunoglobulin-like domain of kit are common and potentially sensitive to imatinib mesylate in feline mast cell tumours.

The purpose of the current study was to investigate the mutation status of KIT in feline mast cell tumours (MCTs) and to examine the effects of tyrosine kinase inhibition on the phosphorylation of mutant kit in vitro and in clinical cases of cats. Sequence analysis of KIT identified mutations in 42/62 MCTs (67.7%). The vast majority of the mutations were distributed in exons 8 and 9, both of which encode the fifth immunoglobulin-like domain (IgD) of kit. All five types of kit with a mutation in the fifth IgD were then expressed in 293 cells and examined for phosphorylation status. The mutant kit proteins showed ligand-independent phosphorylation. The tyrosine kinase inhibitor imatinib mesylate suppressed the phosphorylation of these mutant kit proteins in transfectant cells. In a clinical study of 10 cats with MCTs, beneficial response to imatinib mesylate was observed in 7/8 cats that had a mutation in the fifth IgD of kit in tumour cells. Mutations in the fifth IgD of kit thus appear to be common and potentially sensitive to imatinib mesylate in feline MCTs. These data provide an in vivo model for paediatric mastocytosis where mutations in the fifth IgD of kit also occur.

Gastrointestinal and hematologic adverse events after administration of vincristine, cyclophosphamide, and doxorubicin in dogs with lymphoma that underwent a combination multidrug chemotherapy protocol.

The present study aimed to objectively evaluate the adverse events after the administration of chemotherapeutic agents used in the University of Wisconsin (UW)-Madison chemotherapy protocol (UW-25) for canine lymphoma, using the Veterinary Co-operative Oncology Group common terminology criteria for adverse events (VCOG-CTCAE). The medical records of 40 dogs with multicentric high-grade lymphoma that underwent UW-25 were reviewed. Gastrointestinal adverse events of grade 2 and above and blood/bone marrow adverse events of all grades were evaluated. Gastrointestinal adverse events occurring at least once during the entire period of UW-25 were observed in 50% (20/40), 17.9% (7/39), and 8.1% (3/37) of the dogs after the administration of vincristine (VCR), cyclophosphamide (CPA), and doxorubicin (DXR), respectively. Blood/bone marrow adverse events occurring at least once during UW-25 were observed in 57.5% (23/40), 41% (16/39), and 8.1% (3/37) of the dogs after the administration of VCR, CPA, and DXR, respectively. The rate of patients that experienced gastrointestinal adverse events was higher after the first administration of VCR than after the first administration of DXR. Findings obtained in this study will be helpful in predicting the adverse events that could occur when dogs with lymphoma are treated with UW-25.

Quantitative analysis of mRNA for 10 different drug resistance factors in dogs with lymphoma.

Expression levels of ABCB1, ABCC1, Lung resistance-associated protein (LRP), ABCG2, p53, p21(waf1), Bcl-2, CD40L, glutathione S-transferase alpha (GSTα), and O6-methylguanine-DNA-methyltransferase (MGMT) genes, and mutation of p53 gene were examined in 23 dogs with multicentric high-grade lymphoma to explore their association with drug resistance of the tumor cells. Dogs were divided into chemotherapy-sensitive (n=13) and -resistant (n=10) groups according to the response to a 6-month modified version of the University of Wisconsin (UW)-Madison chemotherapy protocol (UW-25), and expression levels of these factors and frequency of p53 gene mutation were compared between groups. No significant differences were observed in expression levels of each factor between groups. However, 4 dogs in the chemotherapy-resistant group showed high expression of ABCB1. No significant difference was observed in the frequency of p53 mutation between groups. A possible association of ABCB1 with resistance to UW-25 was shown, but no uniform mechanism associated with drug resistance could be identified in dogs with lymphoma.

Evaluation of prognostic factors and establishment of a prognostic scoring system for canine primary immune-mediated hemolytic anemia.

Clinical courses of primary immune-mediated hemolytic anemia (pIMHA) in dogs are highly variable, however, limited information is available to predict their accurate prognoses. To evaluate the prognostic significance of clinical factors and to propose a scoring system to predict prognoses, the medical records of seventy-one dogs with pIMHA were reviewed. Overall mortality rate of dogs with pIMHA was 39% and most of the dogs died within 3 months from diagnosis. Sex, body weight, seasonality, packed corpuscular volume (PCV), platelet count (PLT), total plasma protein (TP), blood urea nitrogen, albumin, total bilirubin, sodium ion, prothrombin time, and fibrin/fibrinogen degradation products before immunosuppressive treatment can influence on survival time in dogs with pIMHA. A prognostic scoring system using a combination of sex, seasonality, PCV, PLT and TP can be statistically significant for raising the accuracy of prognostic prediction. Using the scoring system for prognostication in dogs with pIMHA may enable veterinarians to predict a prognosis easily and accurately.

Eosinophilia and eosinophilic infiltration into splenic B-cell high-grade lymphoma in a dog.

A 13-year-old mixed-breed dog showing ascites, anorexia and anemia was found to have leukocytosis with marked eosinophilia, splenomegaly and hepatomegaly. The dog died 4 days after initial presentation and was diagnosed with splenic high-grade B-cell lymphoma at necropsy. Remarkable infiltrations of eosinophils were observed in spleen and liver tissues. The eosinophilia and infiltration of eosinophils into the lesions could have been associated with B-cell lymphoma because causes other than lymphoma were excluded. This is the first report of eosinophilia and eosinophilic infiltrations into neoplastic lesions in a dog with high-grade B-cell lymphoma.

Long term survival of primary skeletal muscle lymphoma in a miniature dachshund.

An 8-year-old miniature dachshund presented with a right femoral muscle mass and anorexia. Cytology of the mass revealed a number of small-sized lymphoid cells containing a pleomorphic-shaped dense nucleus and narrow pale cytoplasm. Histopathology indicated that neoplastic lymphoid cells proliferated in skeletal muscles and replaced the muscular architecture. Immunohistochemical and genetic examinations confirmed the diagnosis of primary skeletal muscle lymphoma classified as the pleomorphic small cell type and T-cell low-grade. Although the dog suffered at least three relapses by combination chemotherapy, the dog survived 713 days after the initial presentation.

Antiviral activity of membrane fusion inhibitors that target gp40 of the feline immunodeficiency virus envelope protein.

For the entry of lentivirus into target cells, fusion between its viral membrane and cellular membrane is essential. The present study was conducted to examine the inhibitory effect of modified peptides corresponding to heptad repeats (HR) 1 and 2 of feline immunodeficiency virus (FIV) envelope gp40 on the fusion between the viral and cellular membranes. FIV-N36 and FIV-C35 were synthesized as authentic peptides of the N-terminal HR1 domain and C-terminal HR2 domain of FIV gp40, respectively. FIV-C35EK1, FIV-C35EK2, and FIV-C35EK3 were peptides synthesized by modifying FIV-C35 as the X-EE-XX-KK concept to increase their solubility in water and the stability of their alpha-helicity. FIV-C35 and FIV-C35EK1 inhibited the cell membrane fusion mediated by FIV-infected cells and the replication of FIV. FIV-N36, FIV-C35EK2, and FIV-C35EK3 did not show any apparent inhibitory effect. These results indicated that the newly developed membrane fusion inhibitors could facilitate the development of novel anti-lentiviral chemotherapies.

Prevalence of hematological abnormalities and detection of infected bone marrow cells in asymptomatic cats with feline immunodeficiency virus infection.

Peripheral blood cytopenia such as anemia, leukopenia with neutropenia and thrombocytopenia is frequently observed in cats infected with feline immunodeficiency virus (FIV). Although previous studies report that cytopenia has been observed in FIV-infected symptomatic cats, yet the asymptomatic cats also present cytopenia occasionally. In the present study, hematological and virological analyses in FIV-infected asymptomatic cats were carried out to understand the prevalence and pathogenesis of peripheral blood cytopenia in FIV infection. Hematological abnormalities were detected in 24 of 50 FIV-infected asymptomatic cats (48%) in which no other cause of cytopenia than FIV infection was observed. Anemia only, neutropenia only, thrombocytopenia only, bicytopenia and pancytopenia were observed in 10%, 10%, 6%, 14% and 8%, respectively. Bone marrow (BM) examination was performed in 8 FIV-infected asymptomatic cats with peripheral blood cytopenia. Myeloid dysplasia was observed in 4 cats with neutropenia of which 2 cats with concurrent thrombocytopenia presented morphological abnormalities of megakaryocytes. FIV-infected BM cells in the 8 cats were analyzed by PCR and immunocytochemistry. Lobulated mononuclear cells in BM were infected with FIV in 5 cats with neutropenia of which 2 cats with concurrent thrombocytopenia showed FIV-infected megakaryocytes. Parts of isolated stromal cells from BM were infected with FIV in all the 8 cats. Present results suggest that FIV infection of BM cells can cause peripheral blood cytopenia and myelodysplasia even if the cat is asymptomatic. Such FIV-related hematological abnormalities are supposed to be diagnosed as FIV-myelopathy.

Quantitative analysis of mRNA transcripts of Hox, SHH, PTCH, Wnt, and Fzd genes in canine hematopoietic progenitor cells and various in vitro colonies differentiated from the cells.

Homeobox (Hox), Sonic hedgehog (SHH), and Wingless-type MMTV integration site family (Wnt) are known to modulate the self-renewal and expansion of hematopoietic progenitor/stem cells in humans and mice. Frizzled (Fzd) and Patched1 (PTCH1) represent the receptors of Wnt and SHH, respectively. In this study, the amounts of mRNA transcripts of the genes associated with the self-renewal of hematopoietic stem cells, HoxB3, HoxB4, HoxA10, Wnt5a, Wnt2b, Fzd1, Fzd6, SHH, and PTCH1, were measured in canine unfractionated bone marrow cells, CD34-enriched cells, and various colony-forming units in culture (CFU-C). Partial cDNA sequences of these 9 canine genes were determined in this study. Quantitative real-time polymerase chain reaction was employed to indicate their relative amounts of mRNA transcripts. Amounts of mRNA transcripts of HoxB3, HoxA10, PTCH1, and Wnt5a genes in canine CD34-enriched cell fraction were significantly larger than those in the CD34-depleted cell fraction. Amounts of mRNA transcripts of HoxB3, HoxA10, PTCH1, Wnt5a, and Wnt2b genes in various CFU-C cells were significantly smaller than those in the seeded CD34-enriched cell fraction. These results suggested important roles of the products of these genes in self-renewal, expansion, and survival of hematopoietic progenitor cells in dogs as shown in humans and rodents.

Blood hyaluronic acid as a marker for canine cirrhosis.

Blood hyaluronic acid (HA) concentration was measured in dogs with various liver diseases to determine its relationship with histological fibrosis of the liver. The blood HA concentration significantly increased in dogs with chronic liver diseases compared with extrahepatic diseases and control. Furthermore, the median blood HA concentration in dogs with liver cirrhosis (500 microg/l; range, 151-1970 microg/l) was significantly higher than dogs with non-cirrhotic liver diseases (153 microg/l; range, 15-477 microg/l). In histochemical analysis, HA was distributed primarily in the fibrotic area in dogs with chronic liver diseases. As a conclusion, the blood HA concentration was significantly increased in dogs with chronic liver diseases, especially those with cirrhosis. Measurement of the blood HA levels of dogs with suspected liver disease can be a useful diagnostic aid for canine cirrhosis.

Sensitivity for the detection of a clonally rearranged antigen receptor gene in endoscopically obtained biopsy specimens from canine alimentary lymphoma.

Canine alimentary lymphoma is currently diagnosed on the basis of findings of cytological or histopathological examination. However, it is often difficult to histopathologically distinguish alimentary lymphoma from lymphocytic-plasmacytic enteritis. Recently, the application of polymerase chain reaction for antigen receptor gene rearrangement (PARR) has been reported. In the present study, we assess the sensitivity of PARR analysis in diagnosing canine alimentary lymphoma using endoscopically obtained biopsy specimens from 12 dogs that were histopathologically diagnosed as having lymphoma. The sensitivity of PARR analysis in diagnosing alimentary lymphoma was found to be 66.7%, which was lower than that of other lymphoid malignancies. A combination of histipathological examination and findings of PARR analysis may improve the diagnostic accuracy.

Reticulated platelet levels in whole blood and platelet-rich plasma of dogs with various platelet counts measured by flow cytometry.

Reticulated platelets (RP) are young platelets that contain residual RNA, and measurement of RP has been to assess thrombopoiesis. In the present study, flow cytometric counts of RP were compared using paired specimens elicited from dogs with various platelet counts by different RP collection procedures, the whole blood method (WBM) and platelet rich plasma method (PRPM). The flow cytometric counts of RP for the specimens collected by WBM showed good and stable agreement with those taken by PRPM from the same canine subjects. The result revealed that WBM, as well as PRPM, can be used clinically to determine RP levels in dogs with abnormal platelet counts.

Disseminated histiocytic sarcoma with excessive hemophagocytosis in a cat.

A 10-year-old Japanese domestic cat was presented with anorexia and weight loss. Severe anemia and thrombocytopenia were detected. Abdominal radiography and ultrasonography revealed the presence of multiple masses in the spleen. Cytological analyses of the masses revealed several atypical histiocytic cells and considerable hemophagocytosis. A splenectomy was performed, and the mass was diagnosed as histiocytic sarcoma on the basis of histopathological, cytochemical and immunohistochemical analyses. Further, abnormal hemophagocytosis was observed in the bone marrow. The cat was administered prednisolone and lomustine, and it survived for 107 days after admission. An autopsy revealed the presence of neoplastic histiocytic cells in the bone marrow, liver, pancreatic lymph node and glomeruli. This is the first case of histiocytic sarcoma in a cat to be reported in Japan.

Inhibitory effect of newly developed CXC-chemokine receptor 4 antagonists on the infection with feline immunodeficiency virus.

CXC-chemokine receptor 4 (CXCR4) functions as a receptor for feline immunodeficiency virus (FIV). Although we previously found that a CXCR4 antagonist, T140, inhibited the FIV replication in vitro, it was not effective in cats infected with FIV because of its low stability in feline serum. To resolve this problem, several T140 derivatives have been developed. Here, we examined the efficacy of T140 analogs, TF14016 and TF14013, on the inhibition of FIV infection. These compounds were shown to significantly inhibit the syncytia formation in CXCR4-expressing cells after co-cultivation with FIV-infected cells and the replication of FIV in a feline lymphoid cultured cell line. These results indicated that TF14016 and TF14013 could be useful as antiviral drugs for cats infected with FIV.

Characterization of monocyte-derived dendritic cells from cats infected with feline immunodeficiency virus.

Dendritic cells (DCs) are professional antigen presenting cells (APCs) that possess an extraordinary capacity to stimulate naïve T cells and initiate a primary immune response. To develop a DC-based immunotherapy for feline immunodeficiency virus (FIV) infection, we carried out a study to characterize DCs from FIV-infected cats and compared the observations with those obtained from healthy controls. DCs were derived from adherent peripheral blood mononuclear cells that had been cultivated with recombinant feline interleukin 4, granulocyte macrophage colony-stimulating factor and heat-inactivated autologous plasma. Various parameters, such as cell morphology, surface phenotype, endocytosis and mixed leukocyte reaction (MLR), were analyzed to characterize feline DCs. Monocyte-derived DCs from FIV-infected cats as well as those from healthy controls showed a dendritic appearance and expressed an APC-like phenotype (CD1c(+), CD80(+) and MHC class II(+)). However, the expression level of CD1a was variable in the DCs derived from FIV-infected cats, although this was not the case in the DCs derived from the healthy controls. DCs from the FIV-infected cats retained the ability to take up dextran via the mannose receptor and also showed an apparent MLR, indicating that these cells could be useful in immunotherapy. In this study, monocytes obtained from FIV-infected cats could differentiate into functional DCs, suggesting that they might be used in a DC-based immunotherapy against FIV infection.

Molecular pathogenesis of feline leukemia virus-induced malignancies: insertional mutagenesis.

Feline leukemia virus (FeLV), which is subclassified into three subgroups of A, B and C, is a pathogenic retrovirus in cats. FeLV-A is minimally pathogenic, FeLV-C can cause pure red cell aplasia, and FeLV-B is associated with a variety of pathogenic properties such as lymphoma, leukemia and anemia. FeLV-induced neoplasms are caused, at least in part, by somatically acquired insertional mutagenesis in which the integrated provirus may activate a proto-oncogene or disrupt a tumor suppressor gene. The common integration sites for FeLV have been identified in six loci with feline lymphomas: c-myc, flvi-1, flvi-2 (contains bmi-1), fit-1, pim-1 and flit-1. Oncogenic association of the loci includes that c-myc is known as a proto-oncogene, bmi-1 and pim-1 have been recognized as myc-collaborators, fit-1 appears to be closely linked to myb, and flit-1 insertion is shown to be associated with over-expression of a cellular gene, e.g. ACVRL1. Thus, identification of common integration sites for FeLV is a tenable model to clarify oncogenesis. Recent advances in molecular biology and cytogenetics have developed to rapidly detect numbers of retroviral integration sites by genome-wide large-scale analyses. Especially, polymerase chain reaction (PCR)-based strategies and chromosome analyses with fluorescence in situ hybridization (FISH) will be applicable for studies on FeLV.

Quantitative assessment of minimal residual disease (MRD) in canine lymphoma by using real-time polymerase chain reaction.

Lymphoma is the most common hematopoietic malignancy in dogs. Although a large proportion of dogs with lymphoma can achieve clinical remission by initial chemotherapy, most dogs die as a consequence of tumor relapse. We established a quantitative detection system for minimal residual disease (MRD) in canine lymphoma by using real-time polymerase chain reaction (PCR). A canine T-cell lymphoma-derived cell line, namely, UL-1, was used to examine the specificity and sensitivity of the MRD detecting system. Allele-specific oligonucleotide primers and probes were designed based on the sequence of T-cell receptor gamma chain (TCRgamma) gene fragment of UL-1 cells in conjunction with its downstream sequence, which were obtained from the dog genome database. The real-time PCR system for plasmid DNA containing the TCRgamma gene derived from UL-1 cells and the genomic DNA of UL-1 cells revealed that the system was accurate for 10-100,000 copies per reaction and its sensitivity was 1 cell per 10,000 cells. In order to monitor the kinetics of tumor cell number in canine lymphoma, we quantified the level of MRD in the peripheral blood of 7 dogs with lymphoma under chemotherapy. Since the lymphoma cells from the 7 patients were shown to be B-cell origin from the finding of clonal rearrangement of immunoglobulin heavy chain (IgH) gene, allele-specific oligonucleotide primers and probes were prepared based on the sequence of rearranged IgH gene in each case. The number of peripheral blood tumor cells measured by the real-time PCR was comparable to that estimated by conventional hematological examination in 2 cases of stage V lymphoma. MRD in the peripheral blood was detectable in all 7 cases, even in the complete remission (CR) phase. In the 7 lymphoma dogs, changes in the MRD levels of peripheral blood generally paralleled with the changes in the volumes of lymph nodes. Molecular CR, in which the MRD level was below the detection limit, was not observed in any of these 7 patients under chemotherapy. The MRD level detected by the real-time PCR method described here would be useful for investigating the kinetics of tumor cell growth and its regression in canine lymphoma patients.

Investigation of various methods for the cryopreservation of canine bone marrow-derived CD34(+) cells.

Optimal condition for the cryopreservation of canine CD34(+) cells was explored. Canine bone marrow CD34(+) cells were isolated from 5 healthy dogs by a magnetic- activated cell-sorting system using a monoclonal antibody specific to canine CD34. These cells were cryopreserved by 4 different methods: 2 different cryoprotectant solutions-solutions A (fetal bovine serum containing 10% dimethylsulfoxide (DMSO) and B (physiological saline containing 5% DMSO, 6% hydroxyethyl starch, and 4% bovine serum albumin)-were used in combination with 2 different freezing procedures-in a rate-controlled programmed freezer (PF) and in an ordinary freezing container. The cell viability, cell recovery rates, and colony-forming unit (CFU) recovery rates were examined following cryopreservation for 1 week, 4 weeks, and 6 months. The values of these parameters were significantly higher for the CD34(+) cells that had been frozen in Solution B than for those that had been frozen in Solution A, regardless of the freezing procedure employed. The highest CFU recovery rate following cryopreservation for 6 months corresponded to the cells that had been cryopreserved with Solution B and frozen in a PF. In conclusion, cryopreservation with Solution B in a PF proved to be the most efficient of the 4 cryopreservation procedures investigated in terms of maintaining the quality of canine bone marrow-derived CD34(+) cells. This method will be useful for clinical applications involving the use of canine bone marrow-derived CD34(+) cells.

Vascular and Kupffer imaging of canine liver and spleen using the new contrast agent Sonazoid.

The new ultrasound contrast agent Sonazoid was injected in 5 healthy dogs, and the time course enhancement in liver parenchyma, portal vein, spleen, and renal cortex was evaluated. In liver parenchyma and spleen, sustained enhancement was observed from at least 8 to 15 min after injection with the peak at 45 sec (liver) and 20 sec (spleen), whereas in the portal vein and renal cortex, the time course enhancement dramatically decreased after the peak enhancement at 30 sec and 20 sec, respectively. No adverse effect was observed after Sonazoid injection in all the dogs that we examined. Contrast enhanced ultrasound using Sonazoid is believed to be useful for observing the parenchyma of canine liver and spleen.