Platelet function and activation in Cavalier King Charles Spaniels with subclinical chronic valvular heart disease.

OBJECTIVE To assess platelet closure time (CT), mean platelet component (MPC) concentration, and platelet component distribution width (PCDW) in dogs with subclinical chronic valvular heart disease. ANIMALS 89 Cavalier King Charles Spaniels (CKCSs) and 39 control dogs (not CKCSs). PROCEDURES Platelet count, MPC concentration, PCDW, and Hct were measured by use of a hematology analyzer, and CT was measured by use of a platelet function analyzer. Murmur grade and echocardiographic variables (mitral valve regurgitant jet size relative to left atrial area, left atrial-to-aortic diameter ratio, and left ventricular internal dimensions) were recorded. Associations between explanatory variables (sex, age, murmur grade, echocardiographic variables, platelet count, and Hct) and outcomes (CT, MPC concentration, and PCDW) were examined by use of multivariate regression models. RESULTS A model with 5 variables best explained variation in CT (R(2), 0.74), with > 60% of the variance of CT explained by mitral valve regurgitant jet size. The model of best fit to explain variation in MPC concentration included only platelet count (R(2), 0.24). The model of best fit to explain variation in PCDW included platelet count and sex (R(2), 0.25). CONCLUSIONS AND CLINICAL RELEVANCE In this study, a significant effect of mitral valve regurgitant jet size on CT was consistent with platelet dysfunction. However, platelet activation, as assessed on the basis of the MPC concentration and PCDW, was not a feature of subclinical chronic valvular heart disease in CKCSs.

Marked cytoreduction of a lymphocyte-rich mediastinal thymoma with neoadjuvant chemotherapy in a cat.

CASE SUMMARY: A 15-year-old neutered female domestic shorthair cat presented with lethargy and acute-onset dyspnoea. Thoracic computed tomography (CT) revealed a large, cranial mediastinal mass with an estimated volume of 180.7 cm3. Chemotherapy consisting of dexamethasone followed by L-asparaginase, prednisolone, vincristine and doxorubicin was commenced owing to the severity of disease and initial possibility of lymphoma. A diagnosis of lymphocyte-rich thymoma was made based upon histological examination, positive pancytokeratin staining, variable lymphocyte CD3 expression and T cell receptor gamma polyclonality. Thoracic CT performed 35 days after the commencement of chemotherapy showed a marked reduction in the size of the mass, with an estimated volume of 9.4 cm3. A median sternotomy and thymectomy were performed. No clinical signs have recurred 34 months after surgery. CONCLUSIONS AND RELEVANCE: The response to chemotherapy in this case was unusual, and is likely associated with the high non-neoplastic lymphoid component of the mass. The case demonstrates that preoperative chemotherapy can be used to reduce thymoma volume prior to surgery, potentially decreasing anaesthetic risk.