Breed Distribution and Clinical Characteristics of B Cell Chronic Lymphocytic Leukemia in Dogs.

BACKGROUND: B-cell chronic lymphocytic leukemia (B-CLL) is the most common hematopoietic malignancy in humans in the developed world and the primary risk factor is genetic. Dogs also develop B-CLL, but there is no systematic description of the disease in dogs. Understanding the epidemiology of B-CLL in dogs may help practitioners recognize the disease and position the dog as a model for future genetic studies. OBJECTIVES: To describe B-CLL presentation in dogs, its clinicopathologic findings, and breed predisposition. ANIMALS: Four hundred and ninety-one dogs with B-CLL and 5,673 control dogs with suspicion of a lymphoproliferative disorder (LPD). METHODS: Retrospective cross-sectional study of dogs for which samples were submitted to the Colorado State University Clinical Immunology Laboratory for immunophenotyping between 2010 and 2014. To assess breed predilection, dogs with B-CLL were compared to those with suspicion of other LPDs using logistic regression. RESULTS: The median age was 11 years with no sex predilection. Half of the dogs presented with peripheral lymphadenopathy or splenomegaly and 26% had anemia. Eleven small-breed dogs had significantly increased odds of B-CLL. In addition, English Bulldogs had an increased risk and a unique presentation: these dogs were diagnosed at a median of 6 years and expressed lower class II MHC and CD25. CONCLUSIONS: B-cell chronic lymphocytic leukemia is overrepresented in small-breed dogs. Future genetic studies of these breeds may identify genetic risk factors. The unique presentation of English Bulldogs provides evidence of multiple forms of this disease. Additional studies are necessary to determine whether presenting signs are associated with survival.

Exercise-induced pulmonary haemorrhage impairs racing performance in Thoroughbred racehorses.

REASONS FOR PERFORMING STUDY: Exercise-induced pulmonary haemorrhage (EIPH) occurs commonly in Thoroughbred racehorses worldwide. While EIPH is believed to be an important cause of impaired performance in these horses, there is limited evidence from sufficiently powered studies to evaluate this association. OBJECTIVES: To evaluate whether EIPH is associated with finishing position, distance finished behind race winners and differences in race earning among Thoroughbred horses racing in South Africa. STUDY DESIGN: Prospective cross-sectional study. METHODS: One thousand Thoroughbred horses racing in South Africa were enrolled prior to a single race and underwent tracheobronchoscopic examination within 2 h of racing. Three observers, blinded to the horses' identity and race performance, independently evaluated EIPH occurrence and severity using video recordings of the examination. Data were analysed using multivariable logistic and linear regression while controlling for important horse and race factors as potential confounding variables. RESULTS: Overall, 68% of horses had evidence of EIPH (grade ≥1). Horses without evidence of EIPH (severity grade 0), when compared with horses with any evidence of EIPH (grade ≥1), were >2 times more likely to win races (odds ratio = 2.3; 95% confidence interval 1.4-3.7; P = 0.001), finished an average of one length ahead of horses with EIPH (P = 0.03), and were 2.5 times more likely to be in the highest decile in race earnings (odds ratio = 2.5, 95% CI 1.5-4.1, P<0.001). However, no association was identified regarding finishing in the top 3 positions or earning money when analysed as a continuous variable or analysed as any winnings vs. none. CONCLUSIONS: Exercise-induced pulmonary haemorrhage was associated with impaired performance in Thoroughbred racehorses not medicated with furosemide and not using nasal dilator strips. These findings provide strong corroboration of previous research indicating that the occurrence of EIPH has a major impact on the ability of Thoroughbred racehorses to compete successfully as elite athletes.

Canine T-zone lymphoma: unique immunophenotypic features, outcome, and population characteristics.

BACKGROUND: Canine T-cell lymphoma (TCL) is clinically and histologically heterogeneous with some forms, such as T-zone lymphoma (TZL), having an indolent course. Immunophenotyping is an important tool in the classification of TCL in people, and can be equally useful in dogs. HYPOTHESIS/OBJECTIVES: We hypothesized that loss of expression of the CD45 antigen is a specific diagnostic feature of TZL. ANIMALS: Twenty dogs with concurrent histology and immunophenotyping by flow cytometry were studied in depth. An additional 494 dogs diagnosed by immunophenotyping were used to characterize the population of dogs with this disease. METHODS: Lymph node biopsies from 35 dogs with TCL were classified by 2 pathologists using WHO criteria. Twenty lymph nodes were from dogs with CD45- TCL and 15 were from CD45+ TCL. The pathologists were blinded to the flow cytometry findings. Outcome information was sought for the 20 dogs with CD45- lymphoma, and population characteristics of the additional 494 dogs were described. RESULTS: All 20 CD45- cases were classified as TZL. The 15 CD45+ cases were classified as aggressive TCL and are described in an accompanying paper. TZL cases had a median survival of 637 days. Examination of 494 additional dogs diagnosed with TZL by immunophenotyping demonstrated that 40% of cases are in Golden Retrievers, are diagnosed at a median age of 10 years, and the majority have lymphadenopathy and lymphocytosis. CONCLUSIONS: TZL has unique immunophenotypic features that can be used for diagnosis.

Flow cytometric characterization and clinical outcome of CD4+ T-cell lymphoma in dogs: 67 cases.

BACKGROUND: Canine T-cell lymphoma (TCL) is conventionally considered an aggressive disease, but some forms are histologically and clinically indolent. CD4 TCL is reported to be the most common subtype of TCL. We assessed flow cytometric characteristics, histologic features when available, and clinical outcomes of CD4+ TCL to determine if flow cytometry can be used to subclassify this group of lymphomas. OBJECTIVE: To test the hypothesis that canine CD4+ T-cell lymphoma (TCL) is a homogeneous group of lymphomas with an aggressive clinical course. ANIMALS: Sixty-seven dogs diagnosed with CD4+ TCL by flow cytometry and treated at 1 of 3 oncology referral clinics. METHODS: Retrospective multivariable analysis of outcome in canine CD4+ TCL including patient characteristics, treatment, and flow cytometric features. RESULTS: The majority of CD4+ TCL were CD45+, expressed low class II MHC, and exhibited an aggressive clinical course independent of treatment regimen (median survival, 159 days). Histologically, CD4+ TCL were classified as lymphoblastic or peripheral T cell. Size of the neoplastic lymphocytes had a modest effect on both PFI and survival in this group. A small number of CD4+ TCL were CD45- and class II MHC high, and exhibited an apparently more indolent clinical course (median survival not yet reached). CONCLUSIONS AND CLINICAL IMPORTANCE: Although the majority of CD4+ TCL in dogs had uniform clinical and flow cytometric features and an aggressive clinical course, a subset had a unique immunophenotype that predicts significantly longer survival. This finding strengthens the utility of flow cytometry to aid in the stratification of canine lymphoma.