Adapted technique for demonstrating argyrophilic nucleolar organizer regions in the cytologic samples of canine mast cell tumors.

INTRODUCTION: Argyrophilic nucleolar organizer regions (AgNORs) are nonhistone argyrophilic nucleolar proteins associated with ribosomal genes found in the nucleolar organizer region that reflect cell proliferation and have an affinity for silver. AgNOR staining may be useful to evaluate prognosis in several neoplasms because higher AgNOR counts are related to higher grade tumors, metastases, and shorter survival times. OBJECTIVE: We aimed to report on a quick and practical technique to identify AgNORs adapted for use in routine cytology. MATERIALS AND METHODS: The cytopathologic diagnosis of mast cell tumor (MCT) in samples collected by fine-needle aspiration (FNA) was determined. Next, slides were impregnated with a solution containing silver nitrate; the main modification of our technique included incubation of these slides at a controlled temperature of 25 °C. Some slides were previously stained with Diff-Quik and others were only fixed with methanol. The slides were analyzed under a microscope, and the number of blackened intranuclear points (AgNORs) was counted. RESULTS: Slides prestained with Diff-Quik were easily counted compared with slides only fixed in methanol. Technical issues encountered with the methanol-fixed slides included insufficient cellularity, background precipitation, and an absence of silver impregnation. CONCLUSIONS: The technique reported in this study showed satisfactory results for AgNOR counting in cytologic smears from MCT, such as good impregnation and the elimination of background interferents. Further evaluation of this method comparing AgNOR counts with histologic examinations, tumor grades, other prognostic markers, and survival times are needed to fully evaluate the benefit of this technique.

Amikacin prevents platelet aggregation in feline venous blood samples.

INTRODUCTION: Physiologically, feline platelets are more reactive and prone to aggregation, which interferes with platelet counts using automated counters and manual methods. The use of aminoglycoside amikacin in association with EDTA has proven to be efficient in preventing platelet aggregates in cases of pseudo thrombocytopenia (PTP) in people. OBJECTIVES: This study evaluated the efficacy of amikacin in preventing platelet aggregation in EDTA-containing feline blood samples and investigated the possible effects on hematologic measurands. MATERIALS AND METHODS: Blood samples (1.0 mL) collected from 100 healthy cats were stored in two EDTA tubes: 0.5 mL in a microtube containing 10 µL of 250 mg/mL amikacin (EDTA-AMK group) and 0.5 mL in a microtube containing only K2 EDTA 10% (EDTA group). A CBC was executed with an automated impedance blood analyzer, and a microscopic examination of the blood smears was performed. RESULTS: Platelet clumps were observed in 56% of samples from the EDTA group and 5% of samples from the EDTA-AMK group. Platelet counts (PLT), plateletcrit (PCT), and WBC counts were significantly higher (P < .001) in the EDTA-AMK group compared withi the EDTA group. CONCLUSIONS: Amikacin prevents platelet aggregation in feline venous blood samples and does not cause clinically relevant changes in other hematologic measurands. To our knowledge, this is the first report showing the use of amikacin in preventing platelet aggregation in feline blood samples. Based on this study, amikacin could be added to EDTA collection tubes for complete blood counts in cats.