Discordant FeLV p27 immunoassay and PCR test results in 21 cats with hematologic disorders.

CASE SERIES SUMMARY: A total of 1692 medical records from a primary care feline practice and a veterinary referral hospital were evaluated retrospectively to assess discordant feline leukemia virus (FeLV) test results. In total, 73 cats were positive for FeLV using serum in a lateral flow immunoassay (LFI) or laboratory-based ELISA. Of these cats, 21 subsequently tested negative for FeLV proviral DNA by non-quantitative PCR on EDTA whole blood (16/21, 76.2%), bone marrow (4/21, 19%) or both (1/21, 4.7%). The proportional morbidity (an estimate of prevalence in a sample of the total population) for FeLV by LFI/ELISA and PCR assays was 3.1%, consistent with that reported in previous studies for cats in North America. Cats with discordant LFI/ELISA and PCR results had either primary bone marrow disease (18 autoimmune, one neoplastic), a bone marrow insult (hemotrophic mycoplasmosis) or systemic inflammation (pyothorax with a marked neutrophilic leukocytosis). The percentage of cats with a positive LFA/ELISA result and negative PCR assay surviving to discharge was 85.7% (18/21). Of these, 88.9% (16/18) survived 4 months to 6 years. Seven cats (33.3%) were re-tested with LFI or ELISA once primary disease was controlled, and all tested negative. RELEVANCE AND NOVEL INFORMATION: These findings indicate that in cats with bone marrow disease that shares features of progressive FeLV infection, positive LFI and ELISA FeLV test results should be followed up with FeLV proviral DNA PCR testing, particularly in populations where disease prevalence is low.

A Primer for the Evaluation of Bone Marrow.

The traditional role of cytologic and histologic evaluation of bone marrow remains important in understanding diseases and conditions that affect this tissue. It is only through correlation of historical and clinical findings with hematologic, bone marrow, and other ancillary data that an accurate diagnosis can be made. Thus, the clinician is an essential link in helping establish a correct diagnosis. This article is a primer for understanding key features of bone marrow evaluation and provides practical tips for developing the best practices for optimal patient care.

Clinical and clinicopathological features and outcomes of Miniature Dachshunds with bone marrow disorders.

Non-neoplastic bone marrow disorders such as non-regenerative immune-mediated anemia, pure red cell aplasia, and myelodysplastic syndrome are major causes of non-regenerative anemia in dogs. However, there has been no study on the clinical and clinicopathological features of canine non-neoplastic bone marrow disorders in Japan. Hence, we first investigated the breed disposition of non-neoplastic bone marrow disorders that induce anemia as a retrospective study and found that Miniature Dachshund (MD) was a predisposed breed. Based on this finding, we investigated the clinical and clinicopathological features of non-neoplastic bone marrow disorders in MDs as a preliminary retrospective study, and we compared them between immunosuppressive treatment-responsive and -resistant MDs. We found that treatment-resistant MDs showed thrombocytosis and increased frequencies of dysplastic features in the peripheral blood. These results indicate that bone marrow disorders in treatment-resistant MDs might manifest distinct features compared with those in treatment-sensitive MDs, and sensitivity to immunosuppressive treatments could be predicted based on thrombocytosis and dysplastic features in the peripheral blood. Further studies that examine aberrations in the genome are needed to elucidate the pathophysiology of bone marrow disorders in MDs.

Bone Marrow Examination: Why, How, and What to Expect from the Pathologist.

This article describes the indications for sampling of bone marrow, the technical aspects of obtaining marrow core biopsies and aspirates, and the preparation of marrow smears. All aspects are illustrated with clinical cases. The information that can be expected from the pathologist's report of marrow samples is outlined, and the clinical features and prognosis of different types of leukemia are detailed.

Investigation of changes in bone density and chemical composition associated with bone marrow oedema-type appearances in magnetic resonance images of the equine forelimb.

BACKGROUND: The aetiology of bone marrow oedema-like abnormalities (BMOA) seen on magnetic resonance imaging (MRI) is as yet not fully understood. The current study aimed to investigate the potential of projection radiography and Raman microspectroscopy to provide information regarding the underlying physiological changes associated with BMOA in equine bone samples. METHODS: MRI was used to assess 65 limbs from 43 horses. A subset of 13 limbs provided 25 samples, 8 with BMOA present and 17 as controls; these were examined with projection radiography to assess bone mineral density and Raman spectroscopy to assess bone composition. Statistical analysis was conducted using SPSS, the relationship between BMOA and age was tested using binary logistic regression, other outcome measures via unpaired t-tests. RESULTS: Overall BMOA was found to be associated with locally increased bone density (p = 0.011), suggesting increased bone formation; however, no measurable changes relating to bone remodelling were found, and there were no detectable changes in the chemical composition of bone. CONCLUSIONS: BMOA is associated with locally increased bone density, without an associated change in the chemical composition of bone, suggesting this is not linked to BMOA. The presence of increased bone density associated with BMOA does appear to suggest that an increased amount of bone formation is occurring in these regions, but as Raman microspectroscopy data do not demonstrate any significant changes in bone chemical composition associated with BMOA, it would appear that the increased bone volume is due to a greater amount of bone being formed rather than an imbalance in relation to bone remodelling. The study provides a proof of principle for the use of Raman microspectroscopy and projection radiography in in vitro studies of BMOA.

Bone marrow oedema-type signal in the proximal phalanx of Thoroughbred racehorses.

This study focused on 8 Thoroughbred racehorses showing bone marrow oedema-type signal in the proximal sagittal groove of the proximal phalanx, with the aim of understanding its clinical significance. Standing magnetic resonance imaging played an important role in assessing osseous abnormalities that were not radiographically identifiable. Further, a histopathological result from one of the cases showed there was oedema surrounding adipose tissues with increase in density of trabecular scaffolding. This may indicate presence of osseous injury within the area of decreased elasticity due to subchondral bone modeling. This study suggests that detection of osseous abnormality based on bone marrow oedema-type signal, and application of appropriate care following injury would contribute to prevent deterioration of stress-related fractures of the proximal phalanx.

Bone Marrow Aspirate Evaluation.

Important steps in bone marrow aspirate evaluation include determining if bone marrow evaluation is indicated; using appropriate aspirate collection, smear preparation, and staining techniques; and performing a systematic approach for the cytologic evaluation. The cytologic evaluation of bone marrow requires knowledge of the morphology of bone marrow cell types, the proportion of these cell types normally present, and the ability to evaluate overall cellularity of bone marrow. Accurate interpretation of bone marrow cytologic findings depends on evaluation of a current complete blood cell count. These components are the pillars of getting the most useful information in the diagnosis of hematologic disorders.

Canine bone marrow cytological examination, classification and reference values: A retrospective study of 295 cases.

Cytologic assessment of bone marrow with knowledge of the hemogram represents an effective method to investigate hemic tissue and its function. To determine the spectrum and prevalence of canine bone marrow disorders over a 2 year period in a diagnostic laboratory setting achieved through a standard approach to cytologic bone marrow assessment. A retrospective study of bone marrow fine needle aspirates sample preparations, blood smears, hemogram data and case records. Of the 295 bone marrow samples evaluated, 90 (30.5%) were nondiagnostic samples. Of the remaining samples, 25.1% were classified as hyperplasia of which most were granulocytic hyperplasia (58.1% of the total hyperplasia), 19.3% had no cytological abnormalities, 12.9% had malignant hemopathy and 7.8% had hypo-aplastic conditions. Only a small proportion of cases involved dysplasia (1.7%) and metastatic disease was detected in only one case (0.3%). Reference values of nucleated cells and the M/E ratio were calculated for normal and erythroid and granulocytic hyperplastic bone marrow. This study provides the spectrum and the prevalence of canine bone marrow disorders as well as a differential bone marrow cell counting and determination of reference intervals for diseases.

Hematologic findings predictive of bone marrow disease in dogs with multicentric large-cell lymphoma.

BACKGROUND: Evaluation of the bone marrow is needed for complete staging in dogs with multicentric large-cell lymphoma, but is often omitted in clinical practice. OBJECTIVES: The objective was to determine if routine peripheral blood findings, including microscopic evaluation of blood smears, can predict the presence of bone marrow involvement in dogs with lymphoma. METHODS: Hematologic data including evaluation of blood smears and bone marrow aspirates from 107 dogs newly diagnosed with large-cell lymphoma were retrospectively evaluated. Neoplastic lymphocytes were identified based on cell size, nuclear size, chromatin pattern, and the presence of nucleoli. Positive specimens were defined as having ≥ 10% neoplastic lymphocytes. Two groups were established based on the presence or absence of lymphoma in the bone marrow. Variables (positive blood smear, HCT, platelet count, and total and differential WBC counts) were evaluated to determine if they were predictive of bone marrow involvement using univariate and multivariate logistic models. RESULTS: Thrombocytopenia and the presence of > 10% neoplastic lymphocytes on blood smears were identified as significant variables for predicting the presence of bone marrow involvement. When considered independently, either a positive blood smear or thrombocytopenia had low sensitivity (60%) and moderate specificity (89% and 87%, respectively). Sensitivity increased when these variables were evaluated together (80%). CONCLUSIONS: In dogs with multicentric large-cell lymphoma, thrombocytopenia or the presence of neoplastic lymphocytes in circulation is suggestive of bone marrow involvement, but not definitive. Normal peripheral blood findings do not exclude the possibility of lymphoma in the bone marrow.

Idiosyncratic drug toxicity affecting the liver, skin, and bone marrow in dogs and cats.

Idiosyncratic drug toxicity reactions are, by definition, uncommon, but can lead to serious or even fatal organ toxicity. The liver, skin, and peripheral blood cells/bone marrow are common targets. Most of these reactions are the result of reactive metabolites, which may cause local cell or organelle damage, or may be amplified by a systemic immune response. Individual risk may depend on differences in drug biotransformation, levels of oxidative stress, or antigen presentation.

Assessment of bone marrow infiltration diagnosed by flow cytometry in canine large B cell lymphoma: prognostic significance and proposal of a cut-off value.

The aims of this study were to assess the prognostic significance of bone marrow (BM) infiltration in canine large B cell lymphoma (LBCL) and to establish cut-off values for designating the BM as infiltrated by lymphoid blasts. The degree of BM infiltration by large CD21 positive cells in dogs with LBCL was assessed by flow cytometry (FC) and related to time to progression (TTP) and lymphoma-specific survival (LSS). Forty-six dogs were prospectively enrolled, staged and treated with a dose-intense chemotherapeutic protocol. BM infiltration was directly correlated with peripheral blood infiltration (P=0.001), high lactate dehydrogenase activity (P=0.0024) and substage b disease (P<0.001). In the univariate analysis, there was a significant association between BM infiltration diagnosed by FC and both TTP (P=0.001) and LSS (P<0.001). Substage was the only factor associated with TTP in the multivariate analysis (P=0.002), whereas substage (P<0.001) and anaemia (P=0.008) were associated with LSS. A cut-off of 3% BM infiltration had the strongest prognostic value, since it discriminated between dogs with a poorer prognosis (median TTP 69 days; median LSS 155 days) and dogs with a better prognosis (median TTP 149 days; median LSS 322 days). BM analysis is an essential step in the staging of LBCL. The presence of BM infiltration by FC at diagnosis is a negative prognostic indicator in canine LBCL.

Plasmodium coatneyi in rhesus macaques replicates the multisystemic dysfunction of severe malaria in humans.

Severe malaria, a leading cause of mortality among children and nonimmune adults, is a multisystemic disorder characterized by complex clinical syndromes that are mechanistically poorly understood. The interplay of various parasite and host factors is critical in the pathophysiology of severe malaria. However, knowledge regarding the pathophysiological mechanisms and pathways leading to the multisystemic disorders of severe malaria in humans is limited. Here, we systematically investigate infections with Plasmodium coatneyi, a simian malaria parasite that closely mimics the biological characteristics of P. falciparum, and develop baseline data and protocols for studying erythrocyte turnover and severe malaria in greater depth. We show that rhesus macaques (Macaca mulatta) experimentally infected with P. coatneyi develop anemia, coagulopathy, and renal and metabolic dysfunction. The clinical course of acute infections required suppressive antimalaria chemotherapy, fluid support, and whole-blood transfusion, mimicking the standard of care for the management of severe malaria cases in humans. Subsequent infections in the same animals progressed with a mild illness in comparison, suggesting that immunity played a role in reducing the severity of the disease. Our results demonstrate that P. coatneyi infection in rhesus macaques can serve as a highly relevant model to investigate the physiological pathways and molecular mechanisms of malaria pathogenesis in naïve and immune individuals. Together with high-throughput postgenomic technologies, such investigations hold promise for the identification of new clinical interventions and adjunctive therapies.

Comparison of inversion recovery gradient echo with inversion recovery fast spin echo techniques for magnetic resonance imaging detection of navicular bone marrow lesions in horses.

OBJECTIVE: To compare navicular bone marrow lesion (BML) conspicuity in the feet of horses as determined via 2 fat-suppressed MRI techniques, including standard short tau inversion recovery (STIR) and inversion recovery gradient echo (IRGE). SAMPLE: Feet (n = 150) of horses with lameness referable to the distal portion of the digit. PROCEDURES: STIR and IRGE sequences were obtained prospectively in all feet with a standing low-field equine MRI system. Presence of a BML was ascertained by identification of a characteristic combination of marrow alterations in T1-weighted, T2*-weighted, T2-weighted, and STIR images. Signal-to-noise and contrast-to-noise ratios were calculated on STIR and IRGE sequences in 56 feet with a navicular BML. RESULTS: Signal-to-noise and contrast-to-noise ratios of both sequences correlated linearly (r = 0.87 and r = 0.92, respectively) but were significantly higher for STIR images (mean ± SD, 22.6 ± 12.7 and 12.4 ± 11.4, respectively), compared with IRGE images (13.7 ± 8.0 and 5.9 ± 7.2, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that the IRGE sequence revealed BMLs significantly less conspicuously, compared with the standard STIR sequence. The 2 techniques cannot be used interchangeably, and IRGE is therefore not recommended as the sole fat-suppressed sequence for routine equine standing MRI protocols.

Radiotherapy-induced myelosuppression in dogs: 103 cases (2002-2006).

Definitive radiotherapy refers to delivery of large doses, typically 48-62 Gray, of ionizing radiation over several weeks using a daily or alternate-day fractionation schedule. The impact of definitive radiotherapy alone on haematopoiesis in tumour-bearing dogs is unknown. Medical records from 103 dogs receiving definitive (60) Cobalt teletherapy for cancer over a 5-year period were reviewed for signalment, tumour type and location, total radiotherapy dose and fractionation scheme. Complete blood count data were collected before, halfway through, and at the end of radiation treatment, and analysed for changes associated with patient variables. The results demonstrate significant reductions in haematocrit, total white blood cell count, neutrophils, eosinophils, monocytes, lymphocytes and platelets occurred during definitive radiotherapy but remained within laboratory reference intervals. These data are important for anticipation of toxicity associated with combinations of radiotherapy and chemotherapy in dogs but do not support the routine monitoring of haematology parameters during definitive radiotherapy.

Gelatinous marrow transformation and hematopoietic atrophy in a miniature horse stallion.

Gelatinous marrow transformation, or serous atrophy of bone marrow fat, has been noted in livestock, laboratory animals, and wildlife in association with an inadequate plane of nutrition, inanition, or intoxication. This is a report of gelatinous marrow transformation and hematopoietic marrow atrophy in a 5-year-old miniature horse stallion. The horse had oral malformations leading to poor food assimilation and emaciation. A bone marrow biopsy obtained to investigate persistent anemia and leukopenia showed hematopoietic atrophy and replacement of fat with a granular extracellular substance, which stained with alcian blue, consistent with acidic mucopolysaccharide content. Surgical correction of the dental abnormalities resulted in improved food assimilation, weight gain, and resolution of cytopenias. In humans, gelatinous bone marrow transformation and hematopoietic atrophy are commonly associated with malnutrition from anorexia nervosa and other causes. The cause of hematopoietic atrophy is unknown but may relate to a nonsupportive marrow microenvironment and inadequate hematopoietic substrate availability. Similar pathogenic mechanisms were suspected in this horse.

Bone marrow aplasia with pancytopenia and hemorrhage in a Japanese Black calf.

Severe leukopenia was incidentally found in a newborn Japanese Black calf by blood testing during the clinical trial of an iron dextran drug (day 1). At that time, no clinical problems were observed. On day 15, the calf presented with a high rectal temperature and tachypnea. Treatment with antibiotics and non-steroidal anti-inflammatory drugs did not improve clinical signs. Anemia, melena, and prolonged bleeding were also recorded. Necropsy findings revealed subcutaneous petechial hemorrhage and severe bone marrow aplasia. This is the first confirmed case of pancytopenia and hemorrhage associated with bone marrow aplasia in a Japanese Black calf.

Standing magnetic resonance imaging detection of bone marrow oedema-type signal pattern associated with subcarpal pain in 8 racehorses: a prospective study.

REASON FOR PERFORMING STUDY: The proximal metacarpal region is a common site of origin of lameness in the performance horse. A number of disease entities are recognised as causes of proximal metacarpal lameness but a definitive diagnosis is often elusive. Magnetic resonance imaging (MRI) is hypothesised to offer advantages over traditional imaging modalities in the investigation of proximal metacarpal pain. OBJECTIVE: To describe clinical and imaging features of cases of lameness in racehorses arising from the proximal metacarpal region in which standing MRI identified 'bone marrow oedema-type' (BMO-type) signal patterns. METHODS: Records for all horses undergoing standing MRI of the proximal metacarpus/distal carpus from September 2006 to December 2008 were reviewed. Cases underwent a standardised protocol for diagnostic analgesia, radiography and ultrasonography of the proximal metacarpus and distal carpus. Cases with proximal metacarpal lameness displaying a characteristic BMO-type signal pattern on MRI were identified and outcomes analysed. RESULTS: Eight cases were identified with characteristic MRI findings of extensive hyperintensity on T2* gradient echo and short tau inversion fast spin echo sequences and corresponding hypointensity on T1 gradient echo images within the palmaroproximal aspect of the third metacarpal bone. Follow-up information was available for all cases; at the time of writing 7/8 had returned to full work and were free from lameness. CONCLUSIONS: The BMO-type signal patterns visible on MR images in these cases may signal the existence of a previously under-diagnosed pathological process associated with proximal metacarpal lameness in racehorses. This finding is postulated to be associated with a stress reaction and possible prodromal stress fracture of the palmaroproximal metacarpus not appreciable radiographically or ultrasonographically. POTENTIAL RELEVANCE: MRI of the proximal metacarpal region permits detection of pathological processes, which may elude conventional imaging and, therefore, has important therapeutic and prognostic implications in these cases.