Detection of frequent neutrophil misclassification by the ProCyte Dx in sick dogs and how to avoid it.

OBJECTIVES: A common and severe error in identifying neutrophils in feline blood samples by the IDEXX ProCyte Dx haematology analyser (ProCyte) has been reported. The hypothesis was that the same or similar error would be identified during analysis of canine blood samples and that white blood cell dot plot evaluation would be critical to detect and avoid erroneous results. MATERIALS AND METHODS: Eighty-six canine blood samples collected for clinical diagnosis of hospital patients were evaluated. Differential leukocyte counts were determined by the ProCyte Dx, ADVIA 2120 and manual methods. ProCyte neutrophil percentage results were considered unacceptable if the result was 15% different than percentage results from both ADVIA 2120 and manual counts. ProCyte WBC dot plots and instrument flags were evaluated for correctness. RESULTS: The ProCyte neutrophil counts were unacceptably lower than the ADVIA 2120 and manual neutrophil counts in 13 samples (15% of 86 samples). Neutrophils misclassified by the instrument were erroneously classified as monocytes and/or lymphocytes. All these samples were from patients with systemic inflammation. The error could be eliminated by rejecting results from samples with incorrect separation of cell clusters in the ProCyte WBC dot plots. CLINICAL SIGNIFICANCE: The ProCyte neutrophil count error with canine blood samples is common, severe and might affect clinical decisions. Operators of the instrument must evaluate white blood cell dot plots for correctness to avoid the error.

Feline Differential Leukocyte Count with ProCyte Dx: Frequency and Severity of a Neutrophil-Lymphocyte Error and How to Avoid It.

BACKGROUND: Erroneous neutrophil and lymphocyte counts from analysis of feline blood samples were transferred directly into the hospital information system from the ProCyte Dx hematology instrument in our after-hours laboratory. Errors usually were not detected by the users. HYPOTHESIS/OBJECTIVES: To quantify the frequency and severity of errors associated with the ProCyte Dx analyzer and to identify methods to avoid the errors. ANIMALS: One-hundred six EDTA blood samples routinely submitted from feline hospital patients were analyzed. METHODS: ProCyte differential leukocyte counts were compared to 2 reference methods: Advia 2120 hematology instrument and manual enumeration. Limits for unacceptable deviation from the reference methods were defined as 18 for % lymphocytes and 23 for % neutrophils. RESULTS: Fourteen of 106 samples had unacceptable errors for both lymphocytes and neutrophils compared to both reference methods. Median % lymphocytes in those 14 samples were 11.2, 15.0, and 53.0% for Advia, manual, and ProCyte, respectively. Median % neutrophils were 85.4, 81.5, and 34.2% for Advia, manual, and ProCyte, respectively. All errors were avoided by rejecting automated ProCyte differential leukocyte results whenever the dot plot appeared clearly incorrect, but only 9 of these 14 samples had a ProCyte WBC distribution error flag. CONCLUSIONS AND CLINICAL IMPORTANCE: Results reported by ProCyte had markedly falsely increased lymphocyte and decreased neutrophil counts in 13% of feline patient samples. Users must reject automated differential leukocyte count results when the WBC dot plot appears overtly incorrect. Rejection based only on ProCyte WBC error flag was insufficient.

Comparison of specific gravity analysis of feline and canine urine, using five refractometers, to pycnometric analysis and total solids by drying.

AIMS: To compare the performance of five refractometers for determination of urine specific gravity in cats and dogs, with reference to weight of total solids and pycnometer analysis. METHODS: Urine samples from 27 cats and 31 dogs submitted for routine urinalysis were included. Urine specific gravity was determined with five refractometers. Four were optical, hand-held refractometers with a temperature compensation method and one was a digital model. Urine was dried to determine the precise weight of total solids. The total solids (g/L) were converted to an estimated specific gravity by division with 2.33. Urine specific gravity of four feline and seven canine samples were analysed with a pycnometer. Limits of agreement analysis was used to evaluate the agreement between specific gravity (analysed as specific gravity minus 1) measured by the refractometers and estimated from dried total solids, or pycnometer results. RESULTS: The five refractometers reported clearly different results from each other. Proportional negative bias was noted for refractometer results compared to estimated specific gravity from total solids and a constant negative bias compared to pycnometer results. The two refractometers designed for cat urine reported similar and lowest specific gravity results with a mean negative bias of 0.007 and 0.008 units compared to estimated specific gravity from total solids, and a mean negative bias of 0.006 units compared to pycnometer results. CONCLUSIONS: Refractometer results did not increase consistently with increasing urine specific gravity compared to reference methods or to other refractometers. Two feline refractometers reported consistently lower specific gravity results than reference methods and other refractometers. CLINICAL RELEVANCE: Because of this imprecision, veterinarians should not use precise cut off values such as 1.030 or 1.035 for evaluation of renal concentrating ability in dogs and cats. Veterinarians should consider the variability of refractometric specific gravity results in their clinical assessment. Two feline refractometers appeared to report falsely low specific gravity results.

Radiographic, biomechanical, and pathologic effects of hemoglobin glutamer-200 in dogs undergoing cemented total hip arthroplasty.

OBJECTIVE: To determine whether use of hemoglobin glutamer-200 (bovine) as a partial blood volume replacement in dogs undergoing cemented total hip replacement caused any deleterious effects on the bone-cement or cement-prosthesis interface, exerted any deleterious effects on body organs, or caused any complications during the anesthetic, immediate recovery, or long-term recovery period. ANIMALS: 9 adult dogs. METHODS: Dogs were anesthetized, and 15% of the blood volume was removed. Simultaneously, lactated Ringer's solution was infused, and 6 dogs were given hemoglobin glutamer (1 g/kg of body weight, IV). Unilateral total hip replacement was performed. Limb use was assessed visually, and force-plate and radiographic evaluations were performed before, and 8 weeks after, surgery. Eight weeks after surgery, dogs were euthanatized, necropsies were performed, and prosthetic component pullout forces were determined. RESULTS: There were no significant differences between treated and control dogs in regard to biomechanical (visual assessment of gait, force-plate analysis, femoral and acetabular component pullout forces) and pathologic evaluations (physical examination, CBC, serum biochemical analyses, necropsy, and histologic evaluations). Radiographic signs of loosening of the femoral component were seen in 4 dogs treated with hemoglobin glutamer. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of hemoglobin glutamer as a blood substitute did not appear to have any deleterious effects in dogs undergoing total hip arthroplasty. The radiographic findings, which were discordant with the biomechanical results, merit further investigation.

Chronic granulocytic leukemia in a dog.

A 4-year-old spayed dog had a recent history of increased WBC count and surgery for pyometra. Two weeks after surgery, WBC count was 57,640 cells/microliter; neutrophilia and immature myelocytic cells were detected. Histologic examination of liver and lymph node biopsy specimens revealed active granulopoiesis. Immature granulocytes that stained with chloroacetate esterase were evident. Bone marrow was excessively cellular and contained numerous granulocytes and blast cells. A diagnosis of chronic granulocytic leukemia was made on the basis of test results. Treatment with hydroxyurea returned the WBC count to reference range within 2 months. Mean survival time for dogs with chronic granulocytic leukemia is approximately 1 year; the dog of this report has remained healthy for more than 2 years. Chronic granulocytic leukemia is a rare neoplastic disease that must be differentiated from leukemoid inflammatory reactions. Although commonly described as a diagnosis determined by exclusion, diagnosis of chronic granulocytic leukemia should be made on the basis of specific criteria.

Diagnosis of microthrombocytosis and immune-mediated thrombocytopenia in dogs with thrombocytopenia: 68 cases (1987-1989).

The mean platelet volume (MPV) was evaluated in 68 dogs with thrombocytopenia attributable to various causes. Platelet size was high or low in some dogs. The most clinically useful observation was that low MPV (microthrombocytosis) was a specific indicator of immune-mediated thrombocytopenia (IMT) in these thrombocytopenic dogs. All but one case of microthrombocytosis (MPV less than 5.4 fl) was found in dogs with IMT. Microthrombocytosis was detected in 17 of 31 dogs with IMT and appeared at the onset of the disease. Macrothrombocytosis (MPV greater than 9.4 fl) indicated active thrombopoiesis, but was not unique to any disease category. Macrothrombocytosis was detected in 18 of 31 dogs with IMT, 3 of 17 dogs with disseminated intravascular coagulation, and 3 of 9 dogs with primary bone-marrow disease.

Natural killer cell activity in untreated and treated dogs with lymphoma.

Natural killer (NK) cell activity and function were determined for 11 untreated and treated dogs with lymphoma. Concurrent chromium release and single cell binding assays, methods used to measure overall cytotoxic activity and that from individual cells, respectively, were performed at effector-to-target cell ratios of 50:1 and 100:1, with incubation periods of 12 and 16 hours. Significant reduction was achieved in overall activity for untreated dogs, using a 16-hour incubation period and an effector-to-target ratio of 100:1 (P less than 0.05). Decreased activity (P less than 0.025) was also achieved for those dogs that were administered combination chemotherapy, consisting of such drugs as cyclophosphamide, vincristine, prednisone, and doxorubicin. There was no significant difference in binding or cytotoxic activity by individual cells in the untreated or treated dogs, compared with the healthy controls. Short- or long-term treatment with glucocorticoids did not influence overall NK cll activity or individual cell cytotoxicity. The overall cytotoxic activity in untreated dogs was reduced, but these dogs had relatively normal numbers of NK cells compared with paracontrols. This suggests that a defect in recycling or the ability to kill targets repetitively, may be involved. A similar defect was found in NK cells of dogs treated aggressively with combination chemotherapy.

Factitious hyperkalemia in dogs with thrombocytosis. The effect of platelets on serum potassium concentration.

To determine the effect of platelet count on the accurate assessment of serum electrolyte concentrations, simultaneous platelet counts and electrolyte determinations were performed on serum and plasma from 40 dogs. Dogs were grouped according to platelet count as follows: thrombocytopenic (less than 150,000/microliters), normal (150,000 to 600,000/microliters), or thrombocytotic (greater than 600,000/microliters). Serum potassium concentration was significantly higher than plasma potassium concentration in normal dogs (mean difference, 0.63 +/- 0.17 mEq/l) and in dogs with thrombocytosis (mean difference, 1.55 +/- 0.73 mEq/l). This difference in potassium concentration between serum and plasma was positively correlated with platelet count (r2 = 0.86). In the blood of dogs with thrombocytosis, the serum-plasma potassium difference was further increased when the time period between blood collection and separation of serum or plasma from cells was lengthened. Differences between serum and plasma concentrations of sodium or chloride were not seen in any platelet group. These results suggest that a portion of the measured serum potassium concentration is released from platelets during the clotting process. In fact, profound elevations in serum potassium concentrations can occur factitiously in dogs with thrombocytosis. Therefore, the actual concentration of potassium in blood is determined more accurately by measuring the plasma concentration rather than the serum concentration of this electrolyte.

Inheritance of associated ocular and skeletal dysplasia in Labrador retrievers.

A breeding colony was established to investigate the inheritance of associated ocular and skeletal dysplasia in Labrador Retrievers; 124 pups were produced. These pups were evaluated for the presence of ocular lesions, including cataracts, vitreous strands, persistent hyaloid remnants, retinal folds, retinal dysplasia, peripapillary hyperreflectivity, and rhegmatogenous retinal detachments, and skeletal abnormality, which was recognized by shorter than normal forelimbs and an abnormal morphologic appearance of the radius and ulna. Analysis of the distribution of lesions in pups indicated that the syndrome is caused by one abnormal gene, which has recessive effects on the skeleton and incompletely dominant effects on the eye. This would suggest that suspect carrier dogs could be identified by test matings with a known homozygote.

Efficacy of clindamycin in the treatment of Staphylococcus aureus osteomyelitis in dogs.

The efficacy of clindamycin in the treatment of experimentally induced, posttraumatic Staphylococcus aureus osteomyelitis was studied in dogs. At the end of the experiment, bacteria could not be isolated from bone marrow of 15 of 16 (93.7%) dogs treated with clindamycin, whereas bacteria could not be isolated from similar specimens obtained from 6 of 13 (46.1%) untreated dogs. None of the 16 dogs treated with clindamycin had histopathologic evidence of osteomyelitis at the end of the experiment. Five of the 13 untreated control dogs had histopathologic evidence of osteomyelitis. The recovery rate was 31% in untreated dogs, whereas 94% of dogs treated with clindamycin recovered from osteomyelitis. Clindamycin, 11 mg/kg of body weight, given orally, q 12 h, for 28 days, was efficacious in the treatment of experimentally induced, posttraumatic S aureus osteomyelitis in dogs.

Automated Blood Cell Counting Systems: A Comparison of the Coulter S-Plus IV, Ortho ELT-8/DS, Ortho ELT-8/WS, Technicon H-1, and Sysmex E-5,000.

Four automated blood cell counting systems were evaluated at the Michigan State University Veterinary Clinical Center (VCC) for their suitability for analyzing various animals' blood in a university teaching hospital laboratory. The instruments were compared to a Coulter Model S-Senior (Coulter Electronics)which had been used for 8 years, and was to be replaced. The instruments were a Coulter Model S-Plus IV, an Ortho ELT-8/ds (Ortho Diagnostics Systems), a Technicon H-1 (Technicon Instruments), and a Sysmex E-5,000 (Toa Medical Electronics). Additionally, an Ortho ELT-8/ws at a private laboratory (Cenvet) was compared to the Coulter S-Senior at the VCC. Based on these evaluations, only the Sysmex E-5,000 was considered unacceptable for the VCC laboratory. Certain advantages and disadvantages of the instruments are described in this article. The comparisons among instruments were not as consistent or repetitive as expected for a controlled experiment but did provide information likely useful to others considering using or purchasing an automated blood cell counting system for a veterinary laboratory.

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.

Adherence of neutrophils from dogs with diabetes mellitus.

Adherence of neutrophils from dogs with type I (insulin-dependent) diabetes mellitus controlled by insulin administration was compared with that from control dogs. Neutrophil adherence in whole blood decreased with increased serum glucose concentration, but was not different from normal cell adherence when isolated cells were examined. The decreased adherence in whole blood was considered to be the result of media factors and not dependent on altered neutrophil function.

Effect of povidone, povidone-iodine, and iodide on locomotion (in vitro) of neutrophils from people, rats, dogs, and rabbits.

The effect of the antiseptic povidone-iodine (P-I) on neutrophil locomotion was tested in vitro. Neutrophil migration into Micropore filters was significantly stimulated by P-I at concentrations between 0.03% and 0.005%. At higher concentrations (greater than or equal to 0.05%), a dose-dependent inhibition of neutrophil migration could be observed which was due to cytotoxic effects of P-I as shown by pyknosis and cell lysis. To analyze these effects, 2 components of P-I (namely, povidone and iodide) were tested separately. In these tests, povidone induced a pronounced stimulation of neutrophil migration at concentrations similar to the stimulatory concentrations of P-I. Inhibition of neutrophil migration or cytotoxic effects of povidone was not observed, even when tested at high concentrations (5.0%). Iodide (as NaI or KI) was cytotoxic and strongly inhibited neutrophil migration when it was tested at concentrations greater than that likely to be present in the inhibitory concentrations of P-I. Stimulatory effects of iodide on neutrophil migration could not be observed when tested over a wide range of noncytotoxic concentrations. Free iodine was not tested, but was considered to be the toxic component by exclusion. The patterns of response were similar for neutrophils from the 4 species tested. Migration of rabbit neutrophils, however, was inconsistently and weakly stimulated by P-I or povidone. These data indicate that the widely used antiseptic P-I, depending on its concentration, can either stimulate or inhibit neutrophil migration.

Mediators of lung injury in mice following systemic activation of complement.

Acute lung injury has been produced in mice by the intravenous injection of cobra venom factor. The marked attenuation of lung injury in C5-deficient mice indicates an absolute requirement for C5 in the development of lung injury. Similar studies carried out in beige mice suggest that leukocytic proteinases play, at best, a limited role in the injury. Neutrophil or platelet depletion resulted in a marked reduction in the extent of lung injury, suggesting that both platelets as well as neutrophils contribute to the injury. Treatment of mice with catalase provided a marked degree of protection from the lung injury, while treatment with superoxide dismutase produced limited protection, which suggests that H2O2 or its derivatives are involved in the induction of acute lung injury. By the use of transmission electron microscopy, areas of lung vascular injury, as manifested by extensive blebbing of endothelial cells, were associated with intravascular aggregates of platelets, neutrophils, and fibrin. Finally, lipoxygenase and thromboxane synthetase inhibitors afforded some protection against cobra venom factor-induced acute lung injury, while cyclooxygenase inhibitors gave variable results. These data suggest that acute lung injury in mice following systemic activation of complement has an absolute requirement for C5, is dependent on a role of both neutrophils as well as platelets, and can be linked to the generation of toxic oxygen products by neutrophils.

Osteochondritis dissecans of the tarsocrural joint in three canine siblings.

Osteochondritis dissecans of the tarsocrural joint was diagnosed in three canine siblings. The lesion, unilateral in one dog and bilateral in two dogs, was on the caudomedial aspect of the trochlea of the talus. Surgical treatment resulted in marked improvement of hindlimb gait.

Tracheal osteochondroma in a dog.

A young female Labrador Retriever-type dog had a 4 1/2-month history of respiratory distress, which eventually became severe, leading to cyanosis. Physical examination suggested an upper airway obstructive lesion, which was confirmed by bronchoscopy and radiography to be a mass in the thoracic portion of the trachea. The mass was removed surgically and, on histologic examination, was found to be an osteochondroma. Six months after surgical extirpation, there was no indication of recurrence of tumor.