Feline lymphoma (145 cases): proliferation indices, cluster of differentiation 3 immunoreactivity, and their association with prognosis in 90 cats.

Paraffin-embedded, formalin-fixed tissue samples from 145 cats with lymphoma were analyzed for cluster of differentiation 3 (CD3, a surface antigen) immunoreactivity, argyrophilic nucleolar organizer region (AgNOR) frequency, and proliferating cell nuclear antigen labeling index (PCNA-LI). This information along with signalment, anatomic site, and feline leukemia virus (FeLV) antigen status was used to determine the potential of these indicators to predict response to therapy, remission, and survival times, and to characterize cats with lymphoma in the era of general availability of FeLV testing and vaccination. Alimentary lymphoma, primarily occurring in older, FeLV-negative cats, was the most common site of involvement. Although the majority of tumors from FeLV-positive cats were CD3-immunoreactive, only one half of CD3-immunoreactive tumors occurred in FeLV-positive cats. Median remission duration and survival times were 126 days and 143 days, respectively, for all cats. Measures of tumor cell proliferation (AgNOR frequency and PCNA-LI) and CD3-immunoreactivity were not predictive of outcome. When all prognostic factors were accounted for by multivariate analysis, response to therapy, FeLV status, and clinical substage were predictive of outcome. FeLV-negative cats that achieved a complete response following induction therapy were likely to have durable (i.e., > 6-month) responses, particularly when doxorubicin was included in the chemotherapy protocol. However, FeLV-positive cats had significantly shorter remission and survival times with available chemotherapeutic protocols.

Treatment of systemic hypertension in cats with amlodipine besylate.

Amlodipine besylate, a calcium channel blocker, was used to treat (mean +/- standard deviation [SD], 127 +/- 68 days) 12 cats with systemic hypertension. Amlodipine was administered orally at a dosage of 0.625 mg per cat (range, 0.08 to 0.23 mg/kg body weight; mean dose +/- SD, 0.17 +/- 0.04 mg/kg body weight) once daily as a single agent. Average indirect systolic blood pressure measurements in the 12 cases decreased significantly from 198 to 155 mmHg during amlodipine treatment. Significant changes in body weight and serum creatinine and potassium concentrations were not detected. Amlodipine appears to be a safe and effective oral treatment for systemic hypertension in cats when used chronically once daily as a single agent.

Frequency of argyrophilic nucleolar organizer regions in fine-needle aspirates and biopsy specimens from mast cell tumors in dogs.

OBJECTIVE: To determine for mast cell tumors in dogs whether frequency of argyrophilic nucleolar organizer regions (AgNOR) determined by examining fine-needle aspirates (FNA) correlated with frequencies determined by examining biopsy specimens or with histologic grade. DESIGN: Case series. ANIMALS: 25 dogs with 32 histologically confirmed tumors. PROCEDURE: Biopsy specimens and FNA were collected from each tumor. Histologic grade and AgNOR frequency were determined. RESULTS: Frequency of AgNOR in FNA was significantly correlated with frequency in biopsy specimens and was significantly associated with histologic grade of the tumor. CLINICAL IMPLICATIONS: Determining AgNOR frequency in FNA of mast cell tumors in dogs is a rapid, minimally invasive means of obtaining information that potentially could be used to help predict biological behavior of the tumor and to guide clinicians and owners in making decisions about further diagnostic tests and treatment.