Harold Tvedten

Feline platelet counting with prostaglandin E1 on the Sysmex XT-2000iV

BACKGROUND The large size of many feline platelets and the high frequency of platelet aggregation often results in falsely low platelet counts in this species. A combination of optical platelet counting to detect even large platelets and the use of prostaglandin E1 (PGE1) to inhibit platelet clumping may increase the accuracy of feline platelet counting. OBJECTIVE The objective of this study was to compare platelet counts in feline whole blood samples with and without the addition of PGE1 and using different analytical methods in a clinical setting. METHODS Platelet counts were determined in 10 feline patients in a referral veterinary hospital using 2 sample types (EDTA, EDTA with PGE1) and 2 methods of analysis (optical counting [PLT-O] and impedance counting [PLT-I]) on the Sysmex XT 2000 iV analyzer. RESULTS All PGE1-PLT-O samples had platelet counts of >200 x 10(9)/L. Mean platelet count using PGE1-PLT-O (410,256+/-178 x 10(9)/L) was significantly higher (P<.03) compared with PGE1-PLT-I (256+/-113 x 10(9)/L), EDTA-PLT-O (238+/-107 x 10(9)/L), and EDTA-PLT-I (142+/-84 x 10(9)/L) methods. Depending on the method, platelet counts in 2 to 7 of 10 cats were <200 x 10(9)/L when PGE1-PLT-O was not used. A slightly increased platelet count in response to treatment of a feline patient with thrombocytopenia would have been missed without use of PGE1-PLT-O. CONCLUSIONS Using PLT-O analysis on EDTA samples containing PGE1 provides higher, and therefore likely more accurate, feline platelet counts in a clinical setting.

Clinical Pathology of Bovine Neurologic Disease

This article describes the general and specific interpretations of common laboratory tests used to evaluate bovine neurologic disease. Cerebrospinal fluid analysis is emphasized. Comments are made about general conclusions such as hemorrhage, inflammation, infection, and neoplasia as well as specific diseases like thromboembolic meningoencephalitis. Tests in commonly available serum chemistry profiles like total calcium concentration and aspartate aminotransferase activity are described in terms of their usefulness in diseases such as parturient paresis or hepatic encephalopathy. The indications for more specific tests like ionized calcium, blood ammonia concentration, or erythrocyte transketolase are included.

Comparison of a Schmidt and Haensch refractometer and an Atago PAL-USG Cat refractometer for determination of urine specific gravity in dogs and cats.

BACKGROUND The performance of a digital Atago PAL-USG Cat refractometer (Atago) was compared with a Schmidt and Haensch, Goldberg type refractometer (S+H). MATERIALS AND METHODS Specific gravity of 47 canine and feline urine samples was determined with both refractometers and the results were compared with Passing-Bablok and Bland-Altman plots. In addition, the specific gravity of dilutions of 10% glucose, 10% NaCl, and 3% albumin solutions was determined and compared with expected values. RESULTS Both refractometers consistently reported 1.000 with distilled water. The correlation between both refractometers based on Passing-Bablok plots of 47 urine samples was excellent (r = .99), but, in the Bland-Altman plots, there was a significant, proportional, negative error for the Atago readouts. This was also illustrated by the fact that 10 urine samples with an S+H result of > 1.030 were read out between 1.023 and 1.028 by Atago. Schmidt and Haensch results of various glucose solutions matched exactly expected values, but Atago results were lower. Likewise, S+H results with diluted NaCl solutions were closer to expected results than Atago results. In contrast, Atago results with dilutions of 3% albumin were closer to expected results than S+H results. DISCUSSION The Atago refractometer reported lower specific gravity results in urine and standard solutions of glucose and NaCl, which could adversely affect clinical decisions concerning normal renal function based on solute concentrations determined in canine and feline urine samples.

Validation of Advia plateletcrit for assessing platelet mass in dogs, including Cavalier King Charles spaniels.

BACKGROUND Determination of the plateletcrit (PCT) is the most effective way to evaluate platelet mass in dogs, such as Cavalier King Charles spaniel (CKCS) dogs, with macrothrombocytopenia. The IDEXX VetAutoread hematology analyzer, which performs quantitative buffy coat (QBC) analysis, has been validated to determine platelet mass in CKCS dogs. The Advia 2120 reports a PCT, but the validity of this value has not been evaluated for dogs with macrothrombocytopenia. OBJECTIVES The goal of this study was to validate MPV and PCT determined by the Advia 2120 in dogs, including CKCS dogs, comparing values with those obtained from QBC analysis. METHODS Advia PCT was compared with QBC results from 43 CKCS dogs and 15 dogs of other breeds in one study. Advia PCT, platelet count, and MPV were evaluated to identify biologic patterns in 31 clinically healthy CKCS dogs and 66 dogs of 3 other breeds and to generate values used for comparisons. RESULTS Advia PCT agreed well with QBC results in general, but had a negative bias and appeared to underestimate PCT in CKCS dogs with the lowest PCTs. Advia PCT and MPV results followed expected biologic patterns in CKCS dogs and dogs of other breeds with MPVs being highest in dogs with the lowest platelet counts. CONCLUSIONS Advia 2120 PCT and MPV satisfactorily identified changes in platelet mass and size in CKCS dogs, but PCTs were lower than expected, especially in CKCS dogs with the lowest PCTs, when compared with QBC results.

Enumeration of feline platelets in ethylenediamine tetra-acetic acid anticoagulated blood with the ADVIA 2120 system and two manual methods Leucoplate and Thrombo-TIC

A manual method (Thrombo-TIC; Bioanalytic GmbH, Umkirch/Freiburg, Germany) was advertised to disaggregate platelet clumps and to make human platelets spherical to improve platelet enumeration. The current study’s hypothesis was that this method would perform better than current methods for feline blood anticoagulated with ethylenediamine tetra-acetic acid (EDTA), which often contains platelet aggregates. Platelet concentrations (PLTs) were determined in 21 feline blood samples by 3 methods. Thrombo-TIC was compared to the manual method (Leucoplate; Sobioda, Montbonnot-Saint-Martin, France) currently used in the authors’ laboratory along with an ADVIA 2120 (Siemens AG, Eschborn, Germany) optical platelet concentration. Feline blood samples often contained platelet aggregates. ADVIA flagged for platelet aggregates in 11 of the 21 feline blood samples, and examination of blood smear revealed platelet aggregates in 14 of the 21 samples. The hemocytometers displayed more platelet aggregates with the Thrombo-TIC method than with Leucoplate. The method giving the greatest PLT was considered most accurate. The Leucoplate median PLT (238 × 109/1) was greater than Thrombo-TIC (202 × 109/1) or ADVIA (157 × 109/1). Intra-assay precision was determined for the 3 methods using the 21 feline blood samples. Median Thrombo-TIC and Leucoplate precision (7.4% and 7.3% coefficient of variation [CV], respectively) were similar and not much worse than ADVIA (5.9% CV). The Thrombo-TIC method did not appear to perform better than the current manual method (Leucoplate). Leucoplate appeared least affected by platelet aggregation in feline blood. The ADVIA automated PLT appeared to be most negatively affected by platelet aggregation. The Thrombo-TIC method did not appear to prevent platelet aggregation in feline EDTA blood samples and, thus, is not recommended for such use.

Cytologic appearance of retinal cells included in a fine-needle aspirate of a meningioma around the optic nerve of a dog.

A 6-year-old Wirehair Dachshund had a meningioma around the optic nerve that caused exophthalmos. A benign mesenchymal tumor was suspected based on the cytologic pattern of a fine-needle aspirate, and a meningioma was diagnosed by histopathologic examination. In addition to the meningioma cells, the cytologic smears included groups of cells from apparently 4 layers of normal retina. In particular, uniform rod-shaped structures in the cytologic sample could suggest rod-shaped bacteria, but these structures were identified as cylindrical outer segments of photoreceptor rod cells. Other retinal structures recognized included pigmented epithelial layer cells with their uniquely formed pigment granules, the characteristic bi-lobed, cleaved nuclei from the outer nuclear layer, and nerve tissue likely from the outer plexiform layer of the retina.

What is your diagnosis? Discrepancy in platelet counts determined using a Sysmex XT-2000 iV hematology analyzer: Discrepant platelet counts in a dog

A 5-year-old intact female Entlebucher Sennenhund dog had partial anorexia and weakness. She was being treated with levothyroxine (Levaxin 375mg, BID orally; Nycomed AB, Stockholm, Sweden) for hypothyroidism. She had a history of 2 episodes of immune-mediated hemolytic anemia (IMHA) at 8 and 24 months before current signs. Her mucous membranes were too pale to determine capillary refill time. CBC results determined using a Sysmex XT-2000iV hematology analyzer (Sysmex Corporation, Kobe, Japan) included a HCT of 0.14 L/L (reference interval, 0.39–0.59 L/L), WBC count of 15.1 10/L (reference interval, 6–17 10/ L), reticulocyte count of 363 10/L (approximate reference mean, 60 10/L), optical platelet count (PLT-O) of 89 10/ L (reference interval, 150–500 10/L), and impedance platelet count (PLT-I) of 2 10/L (reference interval, 150–500 10/L). The manual platelet count was 16 10/L (reference interval, 150–500 10/L). The dog’s platelet cytogram and histogram were compared with those from a dog with morphologically unremarkable platelets and a count within reference interval (Figure 1), and the Entlebucher Sennenhund’s blood smear was stained with Hemacolor (Merck KgaA, Darmstadt, Germany) and examined (Figure 2).