Evaluation of a point-of-care hematology analyzer for use in dogs and cats receiving chemotherapeutic treatment

OBJECTIVE: To compare WBC, neutrophil, and platelet counts and Hct values obtained with a point-of-care hematology analyzer with values obtained by a reference method for dogs and cats receiving chemotherapy. DESIGN: Cross-sectional study. ANIMALS:105 dogs and 25 cats undergoing chemotherapy. PROCEDURES:Blood samples were analyzed with a point-of-care hematology analyzer and with an impedance- and laser-based analyzer with manual differential WBC counts. Results for WBC, neutrophil, and platelet counts and Hct were compared. Sensitivity and specificity of the point-of-care analyzer to detect leukopenia, neutropenia, and anemia were calculated. RESULTS: 554 canine and 96 feline blood samples were evaluated. Correlation coefficients for dogs and cats, respectively, were 0.92 and 0.95 for total WBC count, 0.91 and 0.88 for neutrophil count, 0.95 and 0.92 for Hct, and 0.93 and 0.71 for platelet count. Sensitivity and specificity, respectively, of the point-of-care analyzer to detect leukopenia were 100% and 75% for dogs and 100% and 68% for cats; to detect neutropenia were 80% and 97% for dogs and 100% and 80% for cats; to detect anemia were 100% and 80% for dogs and 100% and 66% for cats; and to detect thrombocytopenia were 86% and 95% for dogs and 50% and 87% for cats. CONCLUSIONS AND CLINICAL RELEVANCE:The point-of-care analyzer was reliable for monitoring CBCs of dogs and cats receiving chemotherapy. It had good to excellent correlation for WBC and neutrophil counts and Hct and accurately detected leukopenia, neutropenia, and anemia. Sensitivity of the analyzer for detecting thrombocytopenia was lower but acceptable.     

Role of platelet activating factor in development of thrombocytopenia and neutropenia in dogs with endotoxemia

OBJECTIVE: To determine the role of platelet activating factor (PAF) in lipopolysaccharide (LPS)-induced thrombocytopenia and neutropenia in dogs. ANIMALS: 42 dogs. PROCEDURES: Blood samples were obtained from dogs given LPS (40 microg/kg of body weight; n = 16), PAF (1 microg/kg; 6), PAF (5 microg/kg/h for 90 minutes; 4), or physiologic saline (0.9% NaCl) solution (0.1 ml/kg/h for 90 minutes; 3) IV to monitor changes in blood cell counts, using automated counters and blood smears stained with Giemsa. Blood samples were also obtained from dogs given LPS (40 microg/kg) that had (n = 5) or had not (6) been treated beforehand with TCV-309, a potent PAF antagonist. Concentration of PAF in blood was determined by use of 125I-radioimmunoassay in dogs given LPS at 1 mg/kg (n = 3) and 40 microg/kg (9). RESULTS: Thrombocytopenia and neutropenia were found in all dogs except those given saline solution. The LPS-induced thrombocytopenia was significantly suppressed by prior treatment with TCV-309. The PAF concentrations increased markedly 1 hour after injection of 1 mg/kg of LPS and increased slightly but significantly 10 minutes after injection of 40 microg/kg of LPS. CONCLUSION AND CLINICAL RELEVANCE: PAF plays an important role in the development of LPS-induced thrombocytopenia and neutropenia in dogs. Control of PAF production, PAF-induced effects, or both may be important in the treatment of dogs with gram-negative bacterial infections and associated thrombocytopenia and neutropenia.     

Plateletcrit is superior to platelet count for assessing platelet status in Cavalier King Charles Spaniels

Background: Many Cavalier King Charles Spaniel (CKCS) dogs are affected by an autosomal recessive dysplasia of platelets resulting in fewer but larger platelets. The IDEXX Vet Autoread (QBC) hematology analyzer directly measures the relative volume of platelets in a blood sample (plateletcrit). We hypothesized that CKCS both with and without hereditary macrothrombocytosis would have a normal plateletcrit and that the QBC results would better identify the total circulating volume of platelets in CKSC than methods directly enumerating platelet numbers.
Objectives: The major purpose of this study was to compare the QBC platelet results with platelet counts from other automated and manual methods for evaluating platelet status in CKCS dogs.
Methods: Platelet counts were determined in fresh EDTA blood from 27 adult CKCS dogs using the QBC, Sysmex XT-2000iV (optical and impedance), CELL-DYN 3500, blood smear estimate, and manual methods. Sysmex optical platelet counts were reanalyzed following gating to determine the number and percentage of normal- and large-sized platelets in each blood sample.
Results: None of the 27 CKCS dogs had thrombocytopenia (defined as <164 × 10⁹ platelets/L) based on the QBC platelet count. Fourteen (52%) to 18 (66%) of the dogs had thrombocytopenia with other methods. The percentage of large platelets, as determined by regating the Sysmex optical platelet counts, ranged from 1% to 75%, in a gradual continuum.
Conclusions: The QBC may be the best analyzer for assessing clinically relevant thrombocytopenia in CKCS dogs, because its platelet count is based on the plateletcrit, a measurement of platelet mass.     

Comparison of manual and automated methods for determining platelet counts in dogs with macrothrombocytopenia.

Platelet counts were performed in 43 Cavalier King Charles Spaniels (CKCS, a breed predisposed to macrothrombocytopenia) and in 10 control dogs using 3 automated systems and 3 manual methods (erythrocyte-lysing agents + counting chamber or evaluation of blood smear). Good correlations were found between platelet counts using all methods (all P < 0.0001; R2 = 0.71-0.85). Best correlations were found between the manual methods. Significantly larger platelets were found in CKCS with platelet count < or = 100,000/microl when compared with control dogs and CKCS with platelet count > 100,000/microl (both P < 0.0001). All platelet counts--except when made with the 2 counting chamber methods--were underestimated at platelet counts < or = 100,000/microl.     

Prevalence of low automated platelet counts in cats: comparison with prevalence of thrombocytopenia based on blood smear estimation

Abstract: True thrombocytopenia is uncommon in cats; however, low platelet counts frequently are found using automated cell counters. Although this discrepancy is a well known problem, the prevalence of low automated platelet counts in feline blood samples has not been documented. We retrospectively compared the prevalence of low automated platelet counts with low blood smear-estimated platelet counts in feline blood samples. Results of blood sample analysis from 359 cats during a 1-year period at the University of Glasgow Veterinary Haematology Laboratory were examined. Smear estimates of platelet number were done in those cases in which records did not indicate adequate platelet numbers. Platelet counts obtained with an impedance counter (Minos Vet, Abx Hematologie) were <200×10⁹ cells/L in 256 samples (71%) and <50×10⁹ cells/L in 43 samples (12%). However, based on estimation of platelet numbers from blood smears, only 11 samples (3.1%) had platelet counts of <200×10⁹ cells/L and 9 samples (2.5%) had counts of <50×10⁹ cells/L. Four cats with thrombocytopenia estimated by blood smear evaluation had clinical signs of a bleeding disorder. Disorders associated with thrombocytopenia included neoplasia, cytotoxic chemotherapy, and infectious diseases. There was no evidence that delay due to mailing of samples was associated with lower automated platelet counts than would have been obtained on the day of sampling. The high prevalence of apparent thrombocytopenia in automated platelet counts was attributed to a combination of platelet aggregation and the impedance method of cell differentiation by size. Vigilance and careful examination of blood smears is required to identify the few cats with true thrombocytopenia.     

The efficacy and adverse event profile of dexamethasone,melphalan, actinomycin D,and cytosine arabinoside (DMAC) chemotherapy in relapsed canine lymphoma

In this retrospective study, a chemotherapy protocol using dexamethasone, melphalan, actinomycin D, and cytosine arabinoside (DMAC) was evaluated for efficacy and adverse event profile as a first line rescue protocol in 86 client-owned dogs previously treated with a CHOP-based protocol. Forty-three dogs (43%) achieved remission (16% complete remission, 27% partial remission), and 57% were non-responders. The median overall progression-free survival (PFS) was 24 days. Adverse events included thrombocytopenia in 41% of dogs, neutropenia in 17% of dogs, and gastrointestinal toxicity in 13% of dogs. Overall, 16% (13/79) dogs experienced grade III to IV thrombocytopenia, 8% (6/74) dogs grade III to IV neutropenia and 1% (1/79) dogs grade III to IV gastrointestinal toxicity. The efficacy of the DMAC protocol is similar to that of other rescue protocols in dogs with relapsed lymphoma but is associated with shorter PFS. The main toxicity is thrombocytopenia, which may limit treatment.     

Platelet size,platelet surface-associated IgG,and reticulated platelets in dogs with immune-mediated thrombocytopenia

Abstract: Immune-mediated thrombocytopenia (IMT) is a disorder in which bound IgG on the surface of platelets results in platelet removal and alterations in mean platelet volume. Using flow cytometry, alterations in platelet size, platelet surface-associated IgG (PSAIgG), and numbers of reticulated platelets were determined in 13 dogs with primary IMT and 4 dogs with secondary IMT induced by experimental infection with Babesia gibsoni . Effects of sample age on platelet parameters also were determined, using samples from 20 dogs with normal platelet counts analyzed within 4 hours and after 24, 48, and 72 hours of storage in EDTA. No significant changes in platelet count, platelet size, or reticulated platelet percentage were observed in samples assayed within 4 and 24 hours of blood collection; whereas PSAIgG values increased 3 to 7 fold in samples stored for 24–72 hours. Using reference values for freshly collected or 24-hour-old samples, 10 of 13 (77%) dogs with primary IMT and all B gibsoni-inf ected dogs had increased PSAIgG levels. In 12 (75%) of the 16 dogs with thrombocytopenia the percentage of reticulated platelets was increased; however, absolute numbers of reticulated platelets were within reference values. Moreover, PSAIgG level and the percentage of reticulated platelets were not always increased concurrently in dogs with primary and secondary IMT. Platelet microparticles were detected in all B gibsoni-infected dogs, 8 of 13 (62%) dogs with primary IMT, and transiently in a dog that responded to immunosuppressive treatment. The results of this study indicate that sample age and time of sampling during disease affect interpretation of platelet parameters in dogs with IMT.     

Validation of the Sysmex XT‐2000iV hematology system for dogs,cats, and horses. I. Erythrocytes,platelets, and total leukocyte counts

Background: The Sysmex XT‐2000iV is a laser‐based, flow cytometric hematology system that has been introduced for use in large and referral veterinary laboratories. Objective: The purpose of this study was to validate the Sysmex XT‐2000iV for counting erythrocytes, reticulocytes, platelets, and total leukocytes in blood from ill dogs, cats, and horses. Methods: Blood samples from diseased animals (133 dogs, 65 cats, and 73 horses) were analyzed with the Sysmex XT‐2000iV and the CELL‐DYN 3500. Manual reticulocyte counts were done on an additional 98 canine and 14 feline samples and manual platelet counts were done on an additional 73 feline and 55 canine samples, and compared with automated Sysmex results. Results: Hemoglobin concentration, RBC counts, and total WBC counts on the Sysmex were highly correlated with those from the CELL‐DYN (r≥0.98). Systematic differences occurred for MCV and HCT. MCHC was poorly correlated in all species (r=0.33–0.67). The Sysmex impedance platelet count in dogs was highly correlated with both the impedance count from the CELL‐DYN (r=0.99) and the optical platelet count from the Sysmex (r=0.98). The Sysmex optical platelet count included large platelets, such that in samples from cats, the results agreed better with manual platelet counts than with impedance platelet counts on the Sysmex. Canine reticulocyte counts on the Sysmex correlated well (r=0.90) with manual reticulocyte counts. Feline reticulocyte counts on the Sysmex correlated well with aggregate (r=0.86) but not punctate (r=0.50) reticulocyte counts. Conclusion: The Sysmex XT‐2000iV performed as well as the CELL‐DYN on blood samples from dogs, cats, and horses with a variety of hematologic abnormalities. In addition, the Sysmex detected large platelets and provided accurate reticulocyte counts.     

Hematological changes during the course of canine babesiosis caused by large Babesia in domestic dogs in Warsaw (Poland)

In the presented study we evaluated the hematological changes in samples of blood obtained from 248 dogs naturally infected with large Babesia. The evaluation included red blood cell count, hemoglobin concentration, hematocrit, mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), leucocyte counts, thrombocyte counts, mean platelet volume (MPV), morphology of erythrocytes and leucogram. The most common disorders in affected dogs were thrombocytopenia and anisocytosis. The count of erythrocytes below reference values was detected in 26.2% of dogs and 31.4% of affected animals presented hematocrit below the reference values. Hemoglobin concentration below the reference values was noted in 29% of dogs, an increase of MCHC above normal values was detected in 21% of examinated dogs and MCV below normal values was recognized in 2% of dogs. 60.5% of dogs presented anisocytosis, 25% poikilocytosis, 23.8% polychromasia, 19.7% hypochromia and 4.4% erythroblastosis. Thrombocytopenia was detected in 99.5% of dogs, but only 15.3% of examined animals showed increase of MPV, which suggests a response of the bone marrow. 36.3% of dogs had neutropenia, and 21.8% presented a left shift, 14.9% had the lymphocytosis and 7.2% lymphopenia.     

Clinical evaluation of the CA530-VET hematology analyzer for use in veterinary practice

BACKGROUND: The CA530-VET is a completely automated impedance cell hematology analyzer, which yields a 16-parameter blood count including a 3-part leukocyte differential. OBJECTIVES: The aim of this study was to examine the operational potential of the CA530-VET and its value for use in veterinary practice. METHODS: The analyzer was tested for blood carry-over, precision, and accuracy. Comparison methods included the CELL-DYN 3500, microhematocrit centrifugation, manual platelet (PLT) counting for feline and equine species, and a 100-cell manual WBC differential. Blood samples for comparison of the methods were obtained from 242 dogs, 166 cats, and 144 horses. RESULTS: The carry-over ratio (K) was 0.28% for RBC, 0.59% for PLT, 0.32% for WBC, and 0.18% for hemoglobin (HGB) concentration. Coefficients of variation (CVs) for within-batch precision and duplicate measurement of blood samples were clearly within the required limits, except for duplicate platelet counts in cats (8.7%) and horses (9.5%). The WBC count was in excellent agreement for dogs and horses and RBC count was in excellent agreement for horses. The accuracy of feline WBC counts was not acceptable, with the exception of values at the high end of the range. RBC counts in dogs and cats, and HGB concentration and MCV in all 3 species were sufficiently accurate. The CA530-VET HCT results were in excellent agreement with microhematocrit results in horses but exceeded the maximum allowed inaccuracy for cats and dogs. In all species, PLT counts established mechanically and manually were not in adequate agreement. Large differences were found between the CA530-VET and the manual differential percentage for lymphocytes and "mid-sized cells" (monocytes and basophilic granulocytes). CONCLUSIONS: The CA530-VET can be considered useful for routine canine, feline, and equine blood cell analyses. It should not be considered accurate, however, for PLT counts, feline total WBC counts in the subnormal and normal range, and leukocyte differentials, except for granulocytes.     

Comparison of platelet count recovery with use of vincristine and prednisone or prednisone alone for treatment for severe immune-mediated thrombocytopenia in dogs

OBJECTIVE: To evaluate the effect of prednisone alone, compared with a combination of prednisone and vincristine, on platelet counts in bleeding dogs with severe primary immune-mediated thrombocytopenia (IMT). DESIGN: Prospective case study. ANIMALS: 24 dogs with severe primary IMT PROCEDURE: All dogs received immunosuppressive doses of prednisone (1.5 to 2 mg/kg [0.7 to 0.9 mg/lb] of body weight, PO, q 12 h). In addition, 12 dogs received a single dose of vincristine (0.02 mg/kg [0.01 mg/lb], IV). Platelet count, transfusion requirement, and outcome were monitored. A response was defined as an increase in platelet count to > or = 40,000/microl. Dogs in the prednisone group that failed to respond received 1 dose of vincristine on day 7. RESULTS: Dogs that received prednisone and vincristine had a significantly faster increase in platelet count to > or = 40,000 platelets/microl than dogs that received prednisone alone (mean +/- SD, 4.9 +/- 1.1 vs 6.8 +/- 4.5 days, respectively). A similarly rapid response was observed in dogs that received vincristine on day 7 after treatment with prednisone alone failed. Furthermore, duration of hospitalization was reduced in the vincristine group, compared with the prednisone group (5.4 +/- 0.3 vs 7.3 +/- 0.5 days, respectively). No adverse effects attributable to vincristine were observed in any dog. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of combined vincristine and prednisone is associated with more rapid increase in platelet numbers and shortened duration of hospitalization in dogs with IMT, compared with use of prednisone alone. Early use of vincristine seems warranted in dogs with severe primary IMT.     

Hematopathology in dogs experimentally infected with a Swedish granulocytic Ehrlichia species

Seven, adult, female beagles were inoculated with a Swedish granulocytic Ehrlichia organism closely related to Ehrlichia equi and E. phagocytophila. Blood and bone marrow changes were evaluated throughout the acute phase of infection. All dogs developed moderate to severe thrombocytopenia during the parasitemic period. The mean platelet volume and platelet distribution width increased, and large platelets were seen on blood smears when platelet numbers were low. In bone marrow, absolute numbers of megakaryocytes and immature megakaryocytes were increased. These results suggested the thrombocytopenia was caused by increased platelet destruction. The dogs also developed mild, normocytic, normochromic anemia, with simultaneous decreases in serum iron concentration and total iron-binding capacity that resembled the anemia of inflammation. In bone marrow, there was a slight increase in immature erythroid cells and no erythroid hypoplasia; iron stores were normal to increased. Myeloid hyperplasia was seen in all infected dogs, despite neutropenia in peripheral blood. Lymphopenia occurred early in the parasitemic period, but lymphocytes responded strongly and numbers increased above baseline levels by the end of parasitemia. Blast-transformed lymphocytes (5% to 20%) were seen in peripheral blood for a few days. Experimentally-induced canine granulocytic ehrlichiosis caused cytopenias of short duration, coincident with the appearance of ehrlichial inclusions in neutrophils.     

Evaluation of methods of platelet counting in the cat

Platelet counts were performed in 50 cats presented for diagnostic investigation. For each cat, counts were obtained using a manual haemocytometer method and compared with counts obtained by estimation from a stained blood smear, a QBC VetAutoread analyser, a Zynocyte VS/2000 analyser, impedance automated counts on a Baker System using both EDTA and citrated anticoagulated blood, and use of a Zynostain modified counting chamber kit. None of the methods gave high correlation with the haemocytometer counts. The blood smear estimation of platelet counts had the highest correlation (r = 0.776) and was the only method to have reasonable values for both sensitivity and specificity. With the impedance automated counts, citrated anticoagulated blood had marginally higher correlation than EDTA anticoagulated blood, and the time between blood sampling and platelet count determination had no effect on the count obtained. When in-house analyser or impedance automated platelet counts are abnormal or not consistent with clinical findings, the authors recommend that a manual platelet count using either haemocytometry or examination of a blood smear is performed.     

Efficacy and toxicity of BOPP and LOPP chemotherapy for the treatment of relapsed canine lymphoma*

Mechlorethamine (Mustargen^®, Oncovin^® (vincristine), procarbazine and prednisone (MOPP) chemotherapy is useful for relapsed canine lymphoma. This study evaluates the efficacy of MOPP after substitution of CCNU (lomustine, LOPP protocol) or BCNU (carmustine, BOPP protocol) for mechlorethamine in 60 dogs with relapsed lymphoma. Seven of 14 (50%) dogs treated with BOPP responded, for a median of 129.5 days for complete responders (range 9–354 days) and a median of 140 days for partial responders (range 4–276 days). Twenty‐three of 44 (52%) dogs treated with LOPP responded for a median of 112 days for complete responders (range 48–250 days) and a median of 84.5 days for partial responders (range 69–290 days). Two dogs receiving a combination of LOPP and BOPP partially responded for 28 and 163 days, respectively. With BOPP chemotherapy, nine dogs (20.5%) and seven dogs (50%) had one or more episodes of Grade II or higher neutropenia and thrombocytopenia, respectively. Seven dogs (50%) had one or more episodes of Grade II or higher gastrointestinal toxicity. While receiving LOPP chemotherapy, 28 dogs (63.6%) and 17 dogs (38.6%) had one or more episodes of Grade II or higher neutropenia and thrombocytopenia, respectively. Seventeen dogs (38.6%) had one or more episodes of Grade II or higher gastrointestinal toxicity. Overall, there were 17 non‐fatal treatment‐related episodes of sepsis requiring hospitalization. Eight dogs (13%) died or were euthanized because of treatment‐related sepsis and/or chemotherapy‐related complications. Severe haematologic toxicity, coupled with the improved response duration observed in dogs receiving reduced doses during B/L‐OPP rescue, underscores the need for protocol optimization.     

Ehrlichiosis in anemic, thrombocytopenic, or tick-infested dogs from a hospital population in South Brazil

Ehrlichia canis has a worldwide distribution, but clinical manifestations may vary geographically. We selected 129 dogs to determine prevalence of ehrlichiosis in dogs with anemia, thrombocytopenia, or ticks presented to a Veterinary Teaching Hospital in South Brazil. Of the 129 dogs, 68 carried the brown dog tick (Rhipicephalus sanguineus), 61 had thrombocytopenia (platelet count <150,000/microl), and 19 had anemia (PCV < 22%). Twenty dogs fulfilled more than one inclusion criteria. Ehrlichiosis was diagnosed by positive amplification of ehrlichial DNA by PCR using primers ECC and ECB that amplify a sequence of the 16S rRNA gene. Presence of E. canis was confirmed by cleavage of the amplified DNA using endonucleases HaeIII and AvaI. Fourteen of 68 (21%) dogs with ticks had ehrlichiosis, whereas 12 of 61 (20%) dogs presented with thrombocytopenia and 4 of 19 (21%) anemic dogs had ehrlichiosis. Similar results were obtained in dogs with thrombocytopenia and anemia (one of eight positive) and in dogs with thrombocytopenia and ticks (two of seven positive). All four dogs with anemia and ticks, and the dog that fulfilled all inclusion criteria yield no amplification of ehrlichial DNA by PCR. Based on our results, one in each five dogs infested by the brown dog tick, with anemia or thrombocytopenia had ehrlichosis. Contrary to widespread believe, ehrlichiosis was not the main cause for thrombocytopenia in our region.     

Evaluation of platelet activation in canine immune-mediated haemolytic anaemia

Objectives : To establish whether heightened platelet activation is a common feature of canine immune-mediated haemolytic anaemia, and to evaluate the hypothesis that platelet activation plays a role in the pathogenesis of thromboembolism. Methods : Using whole-blood flow-cytometric analysis, the proportion of activated platelets and platelet-leucocyte aggregates in blood samples from 14 dogs with immune-mediated haemolytic anaemia and 14 healthy dogs was calculated. General linear models with binomial errors were used to compare groups. Results from the immune-mediated haemolytic anaemia-affected dogs were then correlated with established risk factors for thromboembolism in canine immune-mediated haemolytic anaemia, D-dimer concentration and antithrombin activity. Results : There was a strong correlation between platelet activation and severe thrombocytopenia, with heightened platelet activation being observed predominantly in severely thrombocytopenic dogs. Clinical Significance : Dogs with immune-mediated haemolytic anaemia, particularly those with concurrent severe thrombocytopenia, are likely to have heightened platelet activation, which may play a role in the pathogenesis of thromboembolism.     

Canine distemper virus-induced thrombocytopenia

Effects of canine distemper virus (CDV) infection on circulating platelet values were studied in gnotobiotic dogs inoculated with R252-CDV. Thrombocytopenia (less than 200,000 platelets/microliter) was present on postinoculation day (PID) 5 and persisted through PID 15. Peak thrombocytopenia occurred on PID 10 (less than 85,000 platelets/microliter). Thrombocytopenia was accompanied by lymphopenia, neutropenia, and monocytopenia. Platelet membrane-bound CDV antigen and IgG were present from PID 7 onward; neither the third component of complement nor IgM was detected on platelets from CDV-inoculated dogs. The mean number of megakaryocytes per unit of bone marrow surface area was unchanged. Megakaryocyte infection was present in dogs euthanatized on PID 4 (0.33%), increased slightly in dogs euthanatized on PID 8 (3%), and increased sharply in dogs euthanatized on PID 9 and 10 to 17.8% and 8.3%, respectively. Phagocytosis of platelets by stellate reticuloendothelial (Kupffer's) cells in the liver was prominent in dogs euthanatized from PID 5 onward. Seemingly, CDV-induced thrombocytopenia was mediated by virus-antibody immune complexes on platelet membranes. Decreased platelet production after PID 8 resulting from direct viral infection of megakaryocytes was a likely contributing factor and occurred against a background of profound virus-induced dysfunctions of all hematopoietic cellular elements.     

Validation of the Sysmex XT‐2000iV hematology system for dogs,cats, and horses. II. Differential leukocyte counts

Background: The Sysmex XT‐2000iV is a laser‐based, flow cytometric hematology system that stains nucleic acids in leukocytes with a fluorescent dye. A 4‐part differential is obtained using side fluorescence light and laser side scatter. Objective: The purpose of this study was to validate the Sysmex XT‐2000iV for determining differential leukocyte counts in blood from ill dogs, cats, and horses. Methods: Blood samples from diseased animals (133 dogs, 65 cats, and 73 horses) were analyzed with the Sysmex XT‐2000iV (Auto‐diff) and the CELL‐DYN 3500. Manual differentials were obtained by counting 100 leukocytes in Wright‐stained blood smears. Results: Leukocyte populations in the Sysmex DIFF scattergram were usually well separated in equine samples, but were not as well separated in canine and feline samples. Correlation among the Sysmex XT‐2000iV, CELL‐DYN 3500, and manual counts was excellent for neutrophil counts (r ≥.97) and good for lymphocyte counts (r ≥.87) for all three species. Systematic differences between the 3 methods were seen for lymphocyte and monocyte counts. The Sysmex reported incomplete differential counts on 18% of feline, 13% of canine, and 3% of equine samples, often when a marked left shift (>10% bands) and/or toxic neutrophils were present. Eosinophils were readily identified in cytograms from all 3 species. Neither the Sysmex nor the CELL‐DYN detected basophils in the 7 dogs and 5 cats with basophilia. Conclusions: The Sysmex XT‐2000iV automated differential leukocyte count performed well with most samples from diseased dogs, cats, and horses. Basophils were not detected. Immature neutrophils or prominent toxic changes often induced errors in samples from cats and dogs.     

Fluorophotometric determination of aqueous humor flow rate in clinically normal dogs

OBJECTIVE: To determine aqueous humor flow rate in clinically normal dogs, using fluorophotometry. ANIMALS: 20 clinically normal Beagles. PROCEDURE: A study was performed on 5 dogs to establish an optimal protocol for fluorophotometric determination of aqueous humor flow rate. This protocol then was used to measure aqueous humor flow rate in 15 dogs. Corneas were loaded with fluorescein by topical application, and corneal and aqueous humor fluorescein concentrations were measured 5, 6.5, and 8 hours after application. Concentration-versus-time plots were generated, and slopes and ratios of the fluorescein concentration in the cornea and aqueous humor from these graphs were used to calculate flow rates. Calculations were performed by use of automated software provided with the fluorophotometer and by manual computation, and the 2 calculation methods were compared. RESULTS: The protocol established for the 5 dogs resulted in semilogarithmic and parallel decay of corneal and aqueous humor concentrations. Manually calculated mean +/- SD aqueous humor flow rates for left, right, and both eyes were 5.58 +/- 2.42, 4.86 +/- 2.49, and 5.22 +/- 1.87 microl/min, respectively, whereas corresponding flow rates calculated by use of the automated software were 4.54 +/- 3.08, 4.54 +/- 3.10, and 4.54 +/- 2.57 microl/min, respectively. Values for the left eye were significantly different between the 2 computation methods. CONCLUSIONS AND CLINICAL RELEVANCE: Aqueous humor flow rates can be determined in dogs, using fluorophotometry. This technique can be used to assess pathologic states and medical and surgical treatments that alter aqueous humor dynamics.     

Serial haematology results in transfused and non-transfused dogs naturally infected with Babesia rossi

This prospective longitudinal study investigated the progression of haematological changes in 32 transfused and 54 non-transfused dogs naturally infected with Babesia rossi over the 1st 6 days following diagnosis and treatment. The effect of patient age on the results of complete blood counts was determined. Haematology data were analysed at presentation and at 24 hours, 3 days and 6 days after presentation. Dogs were treated with diminazene aceturate at diagnosis and a blood transfusion was given if deemed clinically required. Mildly to moderately regenerative normocytic normochromic anaemia was observed in all dogs throughout the study period. Transfused dogs more often had an inflammatory leukogram at presentation and at 24 hours, than dogs that were not transfused. In dogs with a left shift, a concurrent normal or decreased segmented neutrophil count was found more commonly than neutrophilia. Severe thrombocytopenia that resolved within a week was common. Blood transfusion alleviated the anaemia, but had no significant effect on white blood cell or platelet responses. Blood cell responses were not significantly influenced by age. In conclusion, the red blood cell and white blood cell responses were less than expected in dogs with babesiosis, given the degree of anaemia and inflammation present. The magnitude of thrombocytopenia and rapid return of the platelet count to normal suggested a possible immune-mediated mechanism for the thrombocytopenia.