Hematology without the numbers: in-clinic blood film evaluation

A rapid manual technique does not have adequate sensitivity and specificity to reliably discriminate between neutropenic and non-neutropenic dogs prior to administration of chemotherapy

OBJECTIVES

To develop and determine the accuracy of a rapid manual technique for the detection of pre-treatment neutropenia (<1.50 × 109/L) in dogs receiving chemotherapy.

MATERIALS AND METHODS

Twenty canine blood smears with known neutrophil counts between 1.00 × 109/L and 3.00 × 109/L were reviewed by two internal medicine clinicians and linear regressions performed to determine a cut-off value for a manual neutrophil count equating to >1.50 × 109/L. Consecutive blood samples from dogs undergoing chemotherapy were processed through an automated haematology analyser (VetScan HM5, Abaxis), and prospective blinded manual review by the same two observers assessed whether the manual technique could accurately detect dogs with neutropenia.

RESULTS

Linear regression analysis found a cut-off of >26 neutrophils per 10 low power fields at the monolayer to be equivalent to a neutrophil count of >1.5 × 109/L. A total of 183 blood samples from 43 dogs were reviewed. Automated techniques detected neutropenia in 16 of 183 (9%) blood samples. Using the manual cut-off technique, 13 of 16 (81%) and 11 of 16 (69%) of neutropenic samples were correctly identified by observer 1 and observer 2, respectively. Twenty-three of 167 non-neutropenic dogs (14%) were incorrectly classified as neutropenic by observer 1, and 27 (16%) by observer 2. Inter-observer agreement was 92%. Sensitivity was 81% (95% confidence interval 54% to 96%) for observer 1 and 69% (95% confidence interval 41% to 89%) for observer 2. Specificity was 86% (95% confidence interval 80% to 91%) for observer 1 and 84% (95% confidence interval 77% to 89%) for observer 2.

CLINICAL SIGNIFICANCE

Manual estimation resulted in up to five of 16 (31%) neutropenic samples being incorrectly classified. A full automated differential cell count remains preferable.

Evaluation of canine and feline leukocyte differential counts obtained with the scil vCell 5 compared to the Advia 2120 hematology analyzer and a manual method

The vCell 5 (scil Animal Care), a point-of-care hematology analyzer (POCA), was recently introduced to veterinary laboratories. This laser- and impedance-based analyzer is capable of providing a CBC with 5-part WBC differential count (Diff) along with WBC cytograms and flags serving as interpretation aids for numerical results. We compared the scil POCA-Diff to reference methods (i.e., manual differential count, Advia 2120 hematology analyzer [Siemens]) for canine and feline blood samples and considered WBC cytograms and flags. Total observed error (TEo), calculated from CV and bias%, was compared to total allowable error (TEa). Data were analyzed before and after a review process (exclusion of flagged and samples with invalid cytograms). For both species, correlation was good-to-excellent (rs = 0.81-0.97) between both analyzers for all variables, except for feline monocytes (rs = 0.21-0.63) and canine monocyte% (rs = 0.50). Smallest biases were seen for neutrophils (dog: -5.7 to 0.8%; cat: 1.5-9.4%) with both reference methods. Quality requirements (TEo < TEa) were fulfilled for canine and feline neutrophils (TEo = 5.3-10.6%, TEa = 15%) and eosinophils (TEo = 67.1-83%, TEa = (90)-50%) considering at least one reference method. Our review process led to mildly higher rs-values for most variables. Although not completely satisfactory, the scil POCA provides reliable results in compliance with ASVCP quality goals for canine and feline neutrophils and eosinophils. Analyzer flag and cytogram analysis served as useful tools for QA, indicating the necessity for manual review of blood smears, and contributed to improvement of scil POCA performance.

Red blood cells morphology and morphometry in adult, senior, and geriatricians dogs by optical and scanning electron microscopy

Red blood cells (RBC) morphologic evaluation through microscopy optical (OM) and SEM, provides information to forecast, evaluate, and monitor the functioning of many organs. Factors, such aging and diseases affect RBC morphology in both, human and animals. SEM is useful to evaluate RBC morphology, although its use in diagnosis and evaluation in dogs is limited, due to the availability and cost. The aim of this research was to assess the normal RBC morphology in adult, senior and geriatrician dogs, clinically healthy by OM and SEM. In addition to evaluating the age effect, sex, body size, and their interaction on erythrocyte morphometry. To carry out the research 152 blood samples were evaluated from dogs of different sexes and body sizes (small, medium, and large). Three groups were made based on dogs age: group I adults (1-7.9 years old), group II senior (8-11.9 years old), and group III geriatricians (>12 years old). Erythrocyte parameters were evaluated by OM (diameter, height, and axial ratio). Per each dog, the parameters of 20 erythrocytes were measured. A total of 2,600 cells were scanned with the AmScope™ Software scale. In addition, the RBC morphology was evaluated by SEM. Statistical analyses used analysis of variance and a general linear model, which allows the comparison of multiple factors at two or more levels (p < 0.05). The results of this study showed that diameter and height were lower in adult dogs than in senior and geriatrician dogs (p < 0.05). Whereas, sex, body size, and the interaction did not show a significant effect (p > 0.05). Additionally, some images of anisocytosis, polychromasia, and poikilocytosis (echinocytes, acanthocytes, codocytes, spherocytes, stomatocytes, dacryocytes quatrefoil, and elliptocytes) were obtained by OM and SEM. Our study provides information about the morphological and morphometry alterations of adult, senior, and geriatrician dogs RBC. This work contributes to future investigations and the diagnosing diseases, where it is necessary to evaluate the morphology of RBC.

Emergence of Babesia conradae infection in coyote-hunting Greyhounds in Oklahoma, USA

BACKGROUND

Babesia species are intraerythrocytic Apicomplexan parasites that infect a wide range of vertebrate hosts. These pathogens are typically transmitted either by tick vectors or by direct blood-to-blood contact, and may cause life-threatening clinical disease, such as thrombocytopenia, hemolytic anemia and acute renal failure, in canine hosts. While Babesia vogeli and Babesia gibsoni infections have both been reported in Oklahoma, reports of Babesia conradae infections have been limited to California.

METHODS

Four separate kennels of coyote-hunting dogs were identified in Oklahoma after the kennels had consulted with Oklahoma State University Boren Veterinary Medical Teaching Hospital (antemortem cases) or the Oklahoma Animal Disease Diagnostic Lab (postmortem cases). Upon owner consent, every accessible dog from each of the four kennels was briefly examined for ectoparasites, particularly ticks, and whole blood samples were collected in EDTA tubes. Clinically ill dogs were examined by a practicing veterinarian, and clinical signs included anorexia, vomiting, lethargy, fever and anemia. DNA was extracted from each blood sample, and a nested PCR was performed using general apicomplexan primers for the partial 18S rRNA gene. PCR products were electrophoresed in agarose matrix, and appropriately sized amplicons were sequenced. Sequences were compared to reference 18S rRNA gene sequences available in GenBank, and samples with > 98% homology to B. conradae (GenBank: AF158702) were considered positive. Babesia conradae-positive dogs were then treated with atovaquone (13.5 mg/kg three times per day) and azithromycin (10 mg/kg once daily) for 10 days and retested at 30 and 60 days post-treatment by PCR.

RESULTS

Of 40 dogs tested, 15 (37.5%) were positive for B. conradae with 98-99% sequence homology to B. conradae from California. All positive cases were coyote-hunting Greyhounds. Ectoparasites were not identified on any of the dogs at the time of blood collection. Treatment of clinically ill dogs with atovaquone and azithromycin resulted in complete clinical recovery in all treated dogs with negative follow-up PCR at 30 and 60 days post-treatment.

CONCLUSIONS

Collectively, this study (i) documents the occurrence of B. conradae in Oklahoma, (ii) highlights this pathogen as a differential to be considered when clinical signs are present, (iii) supports the use of atovaquone and azithromycin as effective treatment in these cases and (iv) demonstrates chronic subclinical carrier dogs serving as potential reservoirs of B. conradae infection to naïve dogs.

A probe-based droplet digital polymerase chain reaction assay for early detection of feline acute cytauxzoonosis

Cytauxzoonosis is a tick-borne disease of domestic cats with high mortality and narrow therapeutic window, particularly in the southcentral and southeastern United States. The causative agent is the apicomplexan protozoal parasite Cytauxzoon felis and is primarily transmitted by Amblyomma americanum, the lone star tick. Currently there is no vaccine available to prevent cytauxzoonosis and treatment is often ineffective if not initiated early enough in the course of disease. Early diagnosis and therapeutic intervention are therefore crucial for the survival of infected cats. Several methods are available for diagnosis of cytauxzoonosis, with PCR being the most sensitive. However, current PCR assays, which employ double-stranded DNA intercalating dyes to detect C. felis infection, have inherent limitations such as the potential for false positive detection of non-specific amplification products and inability to provide absolute quantification of parasite load. The objective of this study was to develop a probe-based droplet digital PCR (ddPCR) assay capable of detection and quantification of C. felis load over time and during treatment. The C. felis ddPCR assay was able to (i) reliably detect and quantify C. felis DNA in clinical blood samples from cats with acute cytauxzoonosis and (ii) monitor clinical parasite load in response to anti-protozoal treatment through absolute quantification of C. felis DNA over time. When tested on blood samples from cats with experimental C. felis infection, the assay was able to detect infection in cats as early as 24 h prior to the development of clinical signs. In addition, we demonstrate that this probe-based design can be utilized in traditional real-time PCR systems, with similar detection capabilities as compared to ddPCR. The C. felis probe-based ddPCR was also able to detect infection in samples with lower parasite loads when compared to existing nested PCR assays, although these results were not significant due to small sample size. To the author's knowledge, this is the first reported probe-based ddPCR assay to detect Cytauxzoon felis infection in domestic cats.

Estimation of white blood cell and platelet counts in ovine blood smears, and a comparison with the ADVIA 120 hematology analyzer

BACKGROUND

Manual evaluation of blood cell counts on stained blood films is a common procedure in resource-limited laboratories of farm animal clinics. Moreover, settings for sheep blood cell counts are not provided on most veterinary hematology analyzers.

OBJECTIVES

We aimed to (a) compare the results of white blood cell (WBC) counts evaluated microscopically on ovine blood smears with those obtained by the ADVIA 120 hematology analyzer and validate appropriate correction factors for the manual technique; and (b) assess the two suggested factors to calculate platelet counts on blood smears in sheep.

METHODS

The blood samples of 57 sheep were used to generate a regression equation between the average WBC count per field and the WBC count determined using the ADVIA 120 analyzer. Thirty-one new ovine samples were used to assess the agreement between the calculated WBC counts based on a generated equation and those obtained by the analyzer using the Passing-Bablok test and Bland-Altman plots. Similarly, agreements between platelet counts using two different factors for platelet calculation were assessed using the Bland-Altman plot.

RESULTS

The average bias of calculated WBC counts was 0.4%, with precision and accuracy being over 95%. Regarding calculated platelet counts, Bland-Altman plots revealed a bias of 26.4% and 1.4% when the average number of platelets per field was multiplied by 15 000 and 20 000, respectively.

CONCLUSIONS

Microscopic WBC counting in ovine blood is a reliable alternative to automated analyses using the generated equation. A better agreement between the two methods was observed when a factor of 20 000 was used to calculate platelet counts in ovine blood smears.

Intra- and inter-rater agreement for the detection of band neutrophils and toxic change in horses

BACKGROUND

The detection of band neutrophils and toxic change via microscopic blood smear review is vitally important, as their presence indicates systemic inflammation. However, in-clinic evaluation of WBC morphology is often limited.

OBJECTIVE

We aimed to determine the agreement between expert raters in the detection of bands and toxic change.

METHODS

Three board-certified clinical pathologists each evaluated 109 blood smears from horses with acute disease, and 19 control smears from healthy horses. The pathologists determined if bands were present, and if so, the percentage of bands present. They also determined if toxic change was present, and if so, the grade of toxic change. Intra-rater agreement was evaluated using 12 duplicate blood smears. Agreement on the presence of bands between pathologists and an in-clinic hematology analyzer was evaluated.

RESULTS

Intra-rater agreement was substantial to almost perfect. Agreement between pathologists for the detection of bands was moderate, but when pathologists agreed bands were present, there was excellent agreement on the percentage of bands and mature neutrophils. Agreement between pathologists for the detection of high-grade, clinically relevant toxic change was fair. When pathologists agreed high-grade toxic change was present, there was fair agreement on Döhle bodies and cytoplasmic basophilia and poor agreement on cytoplasmic vacuolation. Agreement between individual pathologists and the in-clinic hematology analyzer for the indication of bands was fair to moderate.

CONCLUSIONS

Consistent identification of bands and toxic change is challenging, even for highly trained personnel. It is, thus,not surprising that in-clinic blood smear evaluation of WBC morphology by non-experts could be inadequate.

Heinz body-related interference with leukocyte and erythrocyte variables obtained by an automated hematology analyzer in cats

Heinz bodies (HBs) are known to interfere with automated hematology in cats, particularly with the white blood cell (WBC) count. We evaluated the influence of feline HBs on the complete blood count (CBC) results obtained using a flow cytometry-based analyzer. We retrospectively selected cats with circulating HBs and reviewed the results of their CBCs, including red blood cell (RBC) indices, basophil/lobularity (Baso) WBC count (WBCB), peroxidase (Perox) WBC count (WBCP), and cytograms. Based on the presence or absence of HB-related artifacts in their Baso cytogram, cats were grouped into Baso-HBs and HBs groups, respectively, for comparison. The WBCB and WBCP were compared to manual counts of WBCs carried out on blood smears at 400× (MC-WBC). We included 32 cats in our study: 9 of 32 were in the Baso-HBs group, and 23 of 32 were in the HBs group. Baso-HBs cats had a significantly increased HB percentage (p < 0.001), WBCB (p < 0.001), difference between WBCB and WBCP (p < 0.001), lymphocyte count (p < 0.001), mean corpuscular hemoglobin concentration (p < 0.001), and difference between calculated and measured erythrocyte hemoglobin concentrations (p < 0.001) compared to HBs cats. In Baso-HBs cats, the WBCB was significantly higher than the WBCP (p = 0.02); no significant difference was detected between the WBCP and the MC-WBC (p = 0.88). Evaluation of automated CBC results raised the suspicion of HB-related interference when using a hematology analyzer in cats; hence, blood smear examination remains essential in routine practice.

Smudge cell percentage as a surrogate marker for ZAP-70 expression in patients with chronic lymphocytic leukemia

BACKGROUND

This study aimed to evaluate the prognostic value of smudge cell percentage as a surrogate marker for zeta-chain-associated protein kinase 70 (ZAP-70) expression in chronic lymphocytic leukemia (CLL) patients.

METHODS

Sixty three newly diagnosed CLL patients were investigated at the Hematology Department of the Medical Research Institute of Alexandria University with complete blood count, lactate dehydrogenase, β2 microglobulin levels, ZAP-70 expression, and estimation of the percentage of smudge cells.

RESULTS

The percentage of smudge cells ranged from 2 to 58% with a mean of 24.03±13.98%. Higher percentages of smudge cells (>30%) were statistically significantly associated with markers of better prognosis (negative ZAP-70, early-stage disease according to the Binet and Rai staging systems, as well as low and intermediate risk CLL prognostic index). The percentage of smudge cells showed significantly negative correlation with the ZAP-70 expression and higher area under the curve for prediction of ZAP-70 positivity with better survival for 36 months in patients with >30% smudge cells.

CONCLUSION

The percentage of smudge cells at presentation of newly diagnosed CLL patients could be used as a surrogate marker for ZAP-70 expression and an additional prognostic marker for disease progression.

Species determination using the red blood cells morphometry in domestic animals

AIM

This investigation is placed in the context of continuity of a preliminary study already published; it was conducted in cattle, sheep, goats, horses, and dogs; the main aim is to reveal and develop criteria for the animal species determination based on the morphometric parameters of red blood cells.

MATERIALS AND METHODS

Blood samples were taken from the jugular vein; and the smears were confectioned on slides immediately after the blood collection and stained according to the May-Gründwald Giemsa method. For the morphometric study, three parameters were considered which are: The diameter, the circumference, and the surface of erythrocytes; and measurements were achieved using the OPTIKATM Vision Pro software. Statistical analysis was performed by both analysis of variances and Student's t analytical tests.

RESULTS

The recorded data showed that the three morphometric parameters of red blood cells are higher in dogs followed, respectively, by those of horses, cattle, and sheep, whereas, the goats have the lowest ones. In addition, the obtained results allowed us to propose new reference values for the circumference and the surface of erythrocyte in considered species.

CONCLUSION

This investigation permit concluding that from a drop of blood it is possible to characterize the different animal species, taking into account the diameter, the circumference, and the surface of erythrocytes.

Hematology of dugongs (Dugong dugon) in southern Queensland

BACKGROUND

Little is known of the hematology of the dugong (Dugong dugon), a secretive and endangered coastal marine mammal.

OBJECTIVES

This paper reports hematologic reference intervals (RI) for dugongs and characterizes morphologic, cytochemical, and ultrastructural features of dugong leukocytes.

METHODS

Blood was collected from live, apparently healthy dugongs and analyzed using Cell-Dyn 3700 or Sysmex XT-2000iV hematology analyzers. Blood films were subjected to a series of cytochemical stains, and leukocyte structure was examined using transmission electron microscopy.

RESULTS

Reference intervals were established for 14 hematologic variables, total solids, and fibrinogen for 92 dugongs. Significant differences in some variables were found for animal size class, sex, and pregnancy status, and between analyzers. Subadults had higher leukocyte and lymphocyte counts than adults. Males had higher total solids and fibrinogen than females. Pregnant females had higher HCT, MCV, and circulating nucleated RBC, and lower platelet counts than nonpregnant females. Lymphocytes were usually the predominant circulating leukocyte. Heterophil cytoplasmic granules were abundant, fine, round to ovoid, and intensely eosinophilic, and round to ovoid or rod-shaped, and variably electron dense in electron microscopy. Eosinophils contained larger round eosinophilic to orange cytoplasmic granules, which ultrastructurally were bicompartmental with a round eccentric electron-dense core. Cytochemical staining of dugong heterophils suggests biochemical similarity to those of manatees and elephants, and for eosinophils, similarity to those of elephants, ruminants, and equids.

CONCLUSIONS

Generation of hematologic RI and characterization of leukocyte morphology improves evaluation of dugong health across this population and serves as a reference for other populations outside southern Queensland.

Canine vector-borne infections in Mauritius

Background

Canine vector-borne diseases have a worldwide distribution, but to the best of our knowledge, no research has been carried out to evaluate their presence on the Indian Ocean island of Mauritius. An investigation into canine vector-borne infections was conducted in dogs (n = 78) resident at an animal shelter in Port Louis, Mauritius using a combination of traditional microscopy and serological methods.

Methods

Ticks were manually collected from the stray dog population for identification as well as for quantifying tick burdens. Blood was also collected from each dog via either the jugular vein or the cephalic vein, and was stored in EDTA tubes. The stored blood was then used to measure PCV values, make blood smears for the identification of parasites, and used for serological testing of vector-borne disease.

Results

A total of 178 ticks were collected from 52 dogs and identified as Rhipicephalus sanguineus (175/178) or Amblyomma variegatum (3/178). Twenty-six (33%; 95% CI 23, 45) dogs were seropositive for Ehrlichia spp., and 12 (15%; 95% CI 8, 25) for Anaplasma spp., Dirofilaria antigen was detected in 14 (18%; 95% CI 10, 28), and nine (12%; 95% CI 5, 21) dogs had Hepatozoon canis gamonts observed in blood films during microscopic examination. Eleven (14%; 95% CI 7, 24) dogs were co-infected with two pathogens. Borrelia burgdorferi antibodies were not detected in any dogs.

Conclusions

Infection with these pathogens had no significant effect on the packed cell volume (PCV), but high tick burdens were significantly associated with the presence of a tick-borne pathogen. This is the first study of its kind on the dog population in Mauritius and demonstrates the presence of previously undocumented canine vector-borne infections on the island. The relatively high proportion of infected dogs within the study should alert clinicians to the presence of canine vector-borne diseases on the island of Mauritius.

Health assessment of free-ranging endangered Australian sea lion (Neophoca cinerea) pups: effect of haematophagous parasites on haematological parameters

Evaluation of the health status of free-ranging populations is important for understanding the impact of disease on individuals and on population demography and viability. In this study, haematological reference intervals were developed for free-ranging endangered Australian sea lion (Neophoca cinerea) pups within the context of endemic hookworm (Uncinaria sanguinis) infection and the effects of pathogen, host, and environment factors on the variability of haematological parameters were investigated. Uncinaria sanguinis was identified as an important agent of disease, with infection causing regenerative anaemia, hypoproteinaemia, and a predominantly lymphocytic-eosinophilic systemic inflammatory response. Conversely, the effects of sucking lice (Antarctophthirus microchir) were less apparent and infestation in pups appears unlikely to cause clinical impact. Overall, the effects of U. sanguinis, A. microchir, host factors (standard length, body condition, pup sex, moult status, and presence of lesions), and environment factors (capture-type and year of sampling) accounted for 26-65% of the total variance observed in haematological parameters. Importantly, this study demonstrated that anaemia in neonatal Australian sea lion pups is not solely a benign physiological response to host-environment changes, but largely reflects a significant pathological process. This impact of hookworm infection on pup health has potential implications for the development of foraging and diving behaviour, which would subsequently influence the independent survival of juveniles following weaning. The haematological reference intervals developed in this study can facilitate long-term health surveillance, which is critical for the early recognition of changes in disease impact and to inform conservation management.

Retrospective and Prospective Investigations about "Quatrefoil" Erythrocytes in Canine Blood Smears

The presence of unusual two RBCs patterns (so-called “quatrefoil RBCs,” qRBCs) on canine blood smears at Optical Microscope (OM) was seen during routine evaluation of CBCs. Two consecutive retrospective investigations were arranged including about 7,000 CBCs and clinical records and laboratory data from dogs showing qRBCs. Few samples with qRBCs were prepared for Scanning Electron Microscope (SEM). qRBCs were found in 6.89% (139 of 2016) and 8.47% (133 of 1569) of dogs and in 3.89% (154 of 3,958) and 4.47% (138 of 3,081) of CBCs (some dogs were tested more than once). Statistical analysis was significant for age groups (Chi squared, P < 0.0001), decreased total leukocyte and neutrophil counts (ANOVA, P < 0.0001), RBCs anisocytosis, polychromasia, and Howell-Jolly bodies (ANOVA, P < 0.018, <0.005, and <0.003, respectively). qRBCs were distributed in the area of feathered edge and at the smear side of body-feathered edge area in blood films. SEM ruled out the possibility of an optical illusion or an accidental overlap. qRBCs are associated with ageing of dogs, total leukocyte and neutrophil counts, and RBC anisocytosis, polychromasia, and Howell-Jolly bodies. Few hypotheses were discussed to explain the origin and meaning of this RBC arrangement.

Blood Collection from Mice and Hematological Analyses on Mouse Blood

Basic phenotyping of inbred mouse strains and genetically modified mouse models usually includes the determination of blood-based parameters as a diagnostic screen for genotype effects on metabolism and organ function. A broad range of analytes, including hematological parameters, can be reliably determined in mouse blood, if appropriate samples are available. Here we describe recommended techniques for blood collection from mice and the considerations that have to be taken into account to get adequate samples for hematological investigations. Furthermore, we describe established methods used in the German Mouse Clinic (GMC) to determine hematological parameters in the mouse. Curr. Protoc. Mouse Biol. 3:101-119 © 2013 by John Wiley & Sons, Inc.