Regenerative response in dogs naturally and experimentally infected with Babesia rossi.

BACKGROUND: The regenerative response following Babesia rossi infection in dogs is mild, despite severe hemolytic anemia. OBJECTIVE: We aimed to compare the admission absolute reticulocyte count (ARC) and reticulocyte indices in 103 dogs naturally infected with B. rossi with 10 dogs suffering from immune-mediated hemolytic anemia (IMHA) and 14 healthy control dogs. The regenerative response was also evaluated in five dogs experimentally infected with B. rossi. METHODS: This is a retrospective observational study of records generated on the ADVIA 2120 hematology analyzer. RESULTS: The median hematocrits (HCT) of the B. rossi and IMHA groups were significantly lower than the control group (p < .001 for both); however, no differences were seen between the B. rossi and IMHA groups. Compared with the control group, the median ARC was significantly higher in the B. rossi (p = .006) and IMHA (p = .019) groups but significantly lower in the B. rossi group than the IMHA group (p = .041). In the experimentally infected dogs, there was a sudden decrease in the ARC approximately 48 h after the detection of peripheral parasitemia, which was followed by an increase after treatment. Reticulocytes of naturally infected B. rossi dogs were larger, with more variation in cellular volume. The reticulocytes of the experimentally infected dogs decreased in size with decreasing hemoglobin concentrations as the study progressed. CONCLUSIONS: The regenerative response in dogs naturally infected with B. rossi is inadequate, given the severity of the anemia observed, and it might be a result of direct suppressive action by the parasite or host response on the bone marrow.

The dataset for the inflammatory response during experimental infection and treatment of dogs with Babesia rossi.

Babesia rossi causes severe morbidity and mortality in dogs in sub-Saharan Africa. This was an experimental study designed to observe systemic changes caused by Babesia rossi infection within a canine disease model as well as investigate the influence of inoculum dose and treatment on the progression of inflammation and clinical disease. Six healthy male beagle dogs formed the study population, one dog was splenectomised and used to raise the infectious inoculum, three were administered a high B. rossi infectious dose and two a low infectious dose. Clinical examination, complete blood count (CBC) and C-reactive protein (CRP) were determined daily. Cytokines were quantified on stored plasma collected during the study, using a canine specific cytokine magnetic bead panel (Milliplex©). The experiment was terminated, and treatment administered once predetermined experimental or humane endpoints were reached. The data and information provided in the following article is the summary of all data points collected over the course of the eight-day experimental infection.

Oxidative burst and phagocytic activity of phagocytes in canine parvoviral enteritis.

Canine parvoviral enteritis (CPE) is a severe disease characterized by systemic inflammation and immunosuppression. The function of circulating phagocytes (neutrophils and monocytes) in affected dogs has not been fully investigated. We characterized the functional capacity of canine phagocytes in CPE by determining their oxidative burst and phagocytic activities using flow cytometry. Blood was collected from 28 dogs with CPE and 11 healthy, age-matched, control dogs. Oxidative burst activity was assessed by stimulating phagocytes with opsonized Escherichia coli or phorbol 12-myristate 13-acetate (PMA) and measuring the percentage of phagocytes producing reactive oxygen species and the magnitude of this production. Phagocytosis was measured by incubating phagocytes with opsonized E. coli and measuring the percentage of phagocytes containing E. coli and the number of bacteria per cell. Complete blood counts and serum C-reactive protein (CRP) concentrations were also determined. Serum CRP concentration was negatively and positively correlated with segmented and band neutrophil concentrations, respectively. Overall, no differences in phagocyte function were found between dogs with CPE and healthy control dogs. However, infected dogs with neutropenia or circulating band neutrophils had decreased PMA-stimulated oxidative burst activity compared to healthy controls. Additionally, CPE dogs with neutropenia or circulating band neutrophils had decreased PMA- and E. coli-stimulated oxidative burst activity and decreased phagocytosis of E. coli compared to CPE dogs without neutropenia or band neutrophils. We conclude that phagocytes have decreased oxidative burst and phagocytic activity in neutropenic CPE dogs and in CPE dogs with circulating band neutrophils.

Comparison of canine urine specific gravity measurements between various refractometers in a clinical setting.

BACKGROUND: Veterinary facilities might use multiple refractometers and individuals to measure urine specific gravity (USG). Previous comparison studies show conflicting results. Furthermore, the clinical significance of measurement differences and interobserver variabilities has not been assessed. OBJECTIVES: We aimed to determine statistically and clinically significant differences between four refractometers in measuring canine USG and subsequent categorization of urine concentrations and azotemia and determine the variability between different observers performing USG measurements. METHODS: Fifty-nine specimens were included for the USG measurements with four refractometers by different observers. Each refractometer pair was compared using Spearman's rank correlation, Bland-Altman difference plots, and Deming regression analyses. Calculated bias was compared to set performance goals. Interobserver agreement was evaluated, and intraclass correlation coefficients were used to determine differences in the categorization of urine concentrations and azotemia (prerenal or renal). RESULTS: There was excellent correlation (rs  = .99-1.00) between refractometers. All comparisons involving R4 showed significant constant and proportional biases. Mean bias met the clinical performance goals for all refractometers, except for comparisons with R4, where up to 17 results were outside the allowable bias. There was almost perfect agreement (rs  = .999) between observers and excellent agreement (ICC = .96-.99) for the classification of urine concentrations. In azotemic patients (22%), there was perfect agreement (ICC = 1.00) for the categorization of azotemia. CONCLUSIONS: In most cases, three of the refractometers evaluated in this study can be used interchangeably at all USG values, without affecting clinical decision-making. Multiple observers did not significantly affect decision-making.

Neutrophil Myeloperoxidase Index in Dogs With Babesiosis Caused by Babesia rossi.

Babesiosis caused by the virulent tick-borne hemoprotozoan, Babesia rossi, results in a marked systemic inflammatory host response in dogs. Neutrophils form part of the innate immune response and contains myeloperoxidase (MPO) as the predominant component of the neutrophil lysosomal protein in azurophilic granules. The neutrophil myeloperoxidase index (MPXI), determined on the ADVIA hematology analyzer, is a quantitative estimate of intracellular MPO content. Objectives of this study were to: (a) compare MPXI in dogs with babesiosis with healthy control dogs; (b) compare MPXI in dogs that died from babesiosis with dogs that survived and controls; and (c) correlate the MPXI with the previously determined segmented and band neutrophil count and cytokine concentrations in dogs with babesiosis. Data for 140 dogs naturally infected with B. rossi and 20 healthy control dogs were retrospectively evaluated. Neutrophil counts and MPXI were determined on an ADVIA 2120 analyzer. Cytokine concentrations [interleukin (IL)-2, IL-6, IL-8, IL-10, IL-18, granulocyte-macrophage colony stimulating factor (GM-CSF), and monocyte chemo-attractant protein-1 (MCP-1)] were determined using a canine-specific multiplex immunoassay. The mortality rate of the Babesia-infected dogs was 11% (15/140). MPXI was significantly higher in Babesia-infected dogs (P = 0.033), and in Babesia-infected non-survivors (P = 0.011), compared with healthy control dogs. In Babesia-infected dogs a significant positive correlation was found between MPXI and IL-10 (r = 0.211, P = 0.039) and a significant negative correlation was found between MPXI and IL-8 (r = -0.350, P < 0.001). In Babesia-infected non-survivors, significant positive correlations were found between MPXI and IL-2 (r = 0.616, P = 0.033), IL-6 (r = 0.615, P = 0.033), IL-18 (r = 0.613, P = 0.034), GM-CSF (r = 0.630, P = 0.028), and MCP-1 (r = 0.713, P = 0.009). In Babesia-infected survivors, a significant negative correlation was found between MPXI and IL-8 (r = -0.363, P = 0.001). MPXI was correlated with pro-inflammatory cytokines in Babesia-infected dogs that died. The potential of MPXI as a novel marker of inflammation and prognosis in dogs infected with B. rossi, thus warrants further investigation.

Association between computed tomographic thoracic injury scores and blood gas and acid-base balance in dogs with blunt thoracic trauma.

OBJECTIVE: To determine the association between thoracic injuries evaluated by computed tomography (CT) and arterial blood gas and acid-base status in dogs with blunt thoracic trauma caused by motor vehicle accidents. DESIGN: Prospective observational clinical study. SETTING: University teaching hospital. ANIMALS: Thirty-one client owned traumatized dogs and 15 healthy dogs. PROCEDURES: All trauma group dogs underwent a CT scan and simultaneous arterial blood gas analysis within 24 hours, but not before 4 hours, after the traumatic incident within a 45-month enrollment period. MEASUREMENTS AND MAIN RESULTS: Thorax injuries were classified as pulmonary, pleural space, or rib cage and each of these components was scored for severity using a CT composite pulmonary, pleural, and rib score. The trauma group arterial blood gas and acid-base status were evaluated for statistical difference from the control group. The pulmonary-arterial oxygen pressure was significantly lower in the trauma group compared to the control group that was supported by significant differences in the calculated variables of arterial blood oxygenation as well. There was also a significant correlation between the composite lung score and pleural score and the variables of arterial oxygen status. The pulmonary-arterial carbon dioxide pressure was not significantly different to any of the thoracic injury variables indicating normal alveolar ventilation. Acid-base imbalances were generally mild, insignificant, and variable. CONCLUSIONS AND CLINICAL RELEVANCE: Blunt thoracic trauma causes significant pulmonary and pleural injury and the blood oxygen economy is significantly affected by this. The functional measures of arterial blood oxygenation were well correlated with thoracic CT pathology. Alveolar ventilation was mostly spared but a clinically significant ventilation perfusion mismatch was present.

Prevalence of canine Babesia and Ehrlichia co-infection and the predictive value of haematology.

Canine babesiosis and ehrlichiosis are important tick-borne infections in South Africa. Many South African general veterinary practitioners perceive co-infection with Ehrlichia spp. as a common occurrence in dogs with babesiosis. Studies about the prevalence of co-infection in South African dogs are lacking. This retrospective study aimed to determine the prevalence of Ehrlichia co-infection in dogs with babesiosis. Additionally, the predicative value of specific haematological variables for co-infection was evaluated. The study population consisted of 205 dogs diagnosed with canine babesiosis presented to the Onderstepoort Veterinary Academic Hospital (OVAH) in 2006 and between 2011 and 2013. The Babesia-infected dogs were grouped based on presence or absence of an Ehrlichia spp. co-infection. Ehrlichia spp. co-infection was confirmed using polymerase chain reaction. Positive and negative predictive values (PPVs and NPVs) of leukopenia or thrombocytopenia for co-infection were also calculated. The prevalence of Babesiaspp. and Ehrlichia spp. co-infection in this cohort of dogs was 2%. In the babesiosis dogs, the PPV of leukopenia for co-infection with Ehrlichia spp. was 1.3%, and the NPV 97.4%. Similarly, the PPV and NPVs of thrombocytopenia for co-infection were 2.1% and 100%, respectively. Co-infection with Ehrlichia spp. was a rare occurrence in dogs with babesiosis presented to the OVAH. Normal leukocyte or platelet counts confidently ruled out the presence of concurrent ehrlichiosis in this cohort of dogs. However, the diagnosis of Ehrlichia co-infection based on the presence of thrombocytopenia or leukopenia would have been associated with false positive results in more than 97.4% of cases.

A flow cytometric assessment of the lymphocyte immunophenotypes in dogs naturally infected with Babesia rossi.

Immunity to Babesia infection requires both innate and acquired responses, including cell mediated- and humoral responses. The aims of this study were to investigate the variation in selected peripheral blood lymphocyte phenotypes in dogs with virulent babesiosis at presentation and over time after treatment, and to determine whether these were correlated with the severity of clinical signs. Forty-four dogs naturally infected with B. rossi were studied and 5 healthy dogs were included as controls. Blood samples were collected from the jugular vein at admission, prior to any treatment, and at 24h and 48-72h. Leukocytes were incubated with canine specific, fluorochrome conjugated anti-CD3, anti-CD4, anti-CD8, and anti-B cell markers. Babesia-infected dogs were divided into complicated or uncomplicated groups on clinical grounds and in-house laboratory assays. The percentage CD3+ lymphocytes in the complicated group was lower compared to the controls (P=0.014) and uncomplicated group (P=0.007). The percentage CD4+ T lymphocytes in the complicated group was lower compared to the controls (P=0.027) and uncomplicated group (P=0.014). Both the complicated as well as the uncomplicated groups expressed a lower percentage CD8+ T lymphocytes compared to the control group (P<0.001 and P=0.005, respectively). The percentage B lymphocytes was higher in the complicated group at 48-72h. These findings could indicate the presence of a functional immune suppression secondary to increased apoptosis or redistribution of effector lymphocytes and/or a combination of other immune modulatory mechanisms induced by B. rossi infection.

Idiopathic myelofibrosis accompanied by peritoneal extramedullary hematopoiesis presenting as refractory ascites in a dog.

A 2.5-year-old spayed female American Pit Bull Terrier dog presented with a primary complaint of chronic refractory ascites. The dog's CBC displayed a moderate to severe macrocytic, hypochromic, nonregenerative anemia, and a moderate leukopenia as result of a moderate neutropenia and monocytopenia. Microscopic examination of the blood smear showed marked anisocytosis, mild polychromasia, mild acanthocytosis and ovalocytosis, moderate schistocytosis and poikilocytosis, and 4 metarubricytes/100 WBC. Abdominal ultrasonography revealed a homogenous, mild to moderately hyperechoic appearing liver as well as marked amounts of speckled anechoic to slightly hypoechoic peritoneal fluid. Cytology of the ascitic fluid demonstrated a sterile transudate, with evidence of a chronic inflammatory reaction as well as erythroid and myeloid precursor cells, and a few megakaryocytes with occasional micromegakaryocytes. Histologic sections of bone marrow, spleen, and liver were examined, using routine H&E stains, as well as a variety of immunohistochemistry and other special stains. Histopathology of the bone marrow and spleen revealed varying degrees of fibrosis, erythroid, and myeloid hyperplasia, as well as multiple small hyperplastic clusters of megakaryocytes. The megakaryocytes displayed many features of atypia such as increased cytoplasmic basophilia and occasional abnormal chromatin clumping with mitoses. Histopathologic examination of the liver disclosed evidence of mild extramedullary hematopoiesis. This case represents the first report of canine idiopathic myelofibrosis associated with peritoneal extramedullary hematopoiesis, resulting in refractory ascites. Although idiopathic myelofibrosis is a relatively rare condition in dogs, this case demonstrates that ascites caused by peritoneal implants of hematopoietic tissue may be the initial manifestation of myelofibrosis.