Despite haemolytic anaemia being the main consequence of Babesia rossi infection in dogs, the bone marrow response has been reported to be mild in the face of severe anaemia. A similar finding has been described in falciparum malaria and has been ascribed to either a decreased production of erythroid precursors or an inability of erythroid precursors to respond to hormonal stimulus. Recently, more information has become available on the use of various reticulocyte indices in an attempt to describe and explain the underlying pathogenesis of various anaemias as their release describes the recent functional state of the bone marrow. The objective of this study was to compare the admission absolute reticulocyte count (ARC) and reticulocyte indices in dogs naturally infected with B. rossi with dogs suffering from immune-mediated haemolytic anaemia (IMHA), unrelated to babesiosis, as well as healthy control dogs. The ARC and reticulocyte indices were also evaluated in five experimentally B. rossi infected dogs throughout the disease course. This was a retrospective observational study looking at the records generated on a haematology analyser, the ADVIA 2120 (Siemens, Munich, Germany). The haematocrit (HCT), ARC and other reticulocyte indices for 103 dogs, naturally infected with B. rossi was compared to 16 dogs with IMHA and 14 control dogs. The experimentally infected dogs consisted of five purpose-bred beagles that were infected with high and low dose B. rossi parasite inoculum. Differences between groups were assessed using the Mann-Whitney U test, whereas the Friedman’s ANOVA was used to assess the change over time during the disease course in the experimentally infected dogs. The Wilcoxon Signed Ranks test was then used to determine the differences within the experimentally infected groups. The median (IQR) HCT for the Babesia (0.16 L/L; 0.12 – 0.27; P < 0.001) and IMHA (0.15 L/L; 0.12 – 0.17; P < 0.001) groups were significantly lower than the control group (0.52 L/L; 0.45 – 0.57). For the Babesia and IMHA groups the HCT did not differ significantly. Compared to the control group (42.1 x109/L; 33.8 – 62.6), the median (IQR) ARC was significantly higher in the Babesia (82.1 x109/L; 48.6 – 174.9; P = 0.006) and IMHA (256.7 x109/L; 79.0 – 436.9; P = 0.004) groups. The ARC was significantly lower in the Babesia group compared to the IMHA group (P = 0.011), despite no significant difference for HCT between groups. On day four of the experimentally infected group, approximately 24 – 48 hours after a peripheral parasitaemia was observed, there was a sudden decrease in the ARC to less than its value on day one, which was inappropriate for the degree of anaemia observed. The reticulocytes of B. rossi naturally infected dogs were larger and more hypochromic with a greater difference in cellular haemoglobin (CH) between reticulocytes and mature erythrocytes compared to the control group, whereas the reticulocytes of the experimentally infected dogs were smaller and more hypochromic than day one of infection. All reticulocyte indices demonstrated significant differences on day four compared to day one of the experimental study. The changes noted in the reticulocyte indices are postulated to be a contribution of anaemia of inflammation (AID), shift reticulocytosis and iron-restricted erythropoiesis. This study concludes that the regenerative response in dogs naturally infected with B. rossi is inappropriate, despite the severity of anaemia observed, compared to dogs with IMHA. Furthermore, the findings of the experimentally group may indicate a possible direct suppressive action of the Babesia parasite on the bone marrow during the time of parasitaemia, resulting in insufficient erythropoiesis. Similar findings have been reported in falciparum malaria and other factors will require further investigation. / Dissertation (MSc)--University of Pretoria, 2020. / Companion Animal Clinical Studies / MSc / Unrestricted

Abnormal carbohydrate metabolism is a commonly encountered feature of malaria in people, and similar derangements have been detected in veterinary patients with canine babesiosis. Glucose, the major metabolic fuel source, is a key resource in critically ill patients as they mount an immunological response to infection and inflammation. The ability of the individual to effectively mobilise, distribute and utilise glucose is a major determinant of morbidity and mortality. Hypoglycaemia has been identified as a life threatening metabolic complication in almost 20% of severely ill dogs suffering from babesiosis due to Babesia rossi infection. Insulin and glucagon are the primary hormones involved in glucose homeostasis. Insulin lowers blood glucose concentration by facilitating cellular uptake and utilisation of glucose. Hyperinsulinaemia as a result of inappropriate insulin secretion may precipitate hypoglycaemia, and has been identif ed as a cause of hypoglycaemia in human and murine malaria. A similar phenomenon may exist in canine babesiosis. This prospective, cross-sectional, observational study, including 94 dogs with naturally acquired virulent babesiosis, sought to investigate and characterise the relationship between blood glucose concentrations and insulin concentrations in cases of canine babesiosis. Pre-treatment jugular blood samples were collected for simultaneous determination of plasma glucose and insulin concentrations. Animals were retrospectively divided into three groups: hypoglycaemic (plasma glucose concentration < 3.3 mmol/L; n=16), normoglycaemic (3.3-5.5 mmol/L; n=62), and hyperglycaemic (> 5.5 mmol/L; n=16). The median plasma insulin concentrations (IQR in parentheses) for the hypoglycaemic, normoglycaemic and hyperglycaemic groups were 10.7 pmol/L (10.7-18.8 pmol/L), 10.7 pmol/L (10.7-29.53 pmol/L; i.e below the detection limit of the assay), and 21.7 pmol/L (10.7-45.74 pmol/L), respectively. Statistical analysis revealed no significant difference in insulin concentration between the three groups. These results suggest that insulin secretion was appropriately suppressed in these dogs. Only two dogs had elevated insulin concentrations, one of which was hypoglycaemic. The median time since last meal (available for 87 dogs) was 24 hours (IQR 2-4 days), constituting a significant period of illness-induced starvation. We conclude that hyperinsulinaemia is not a cause of hypoglycaemia in virulent canine babesiosis. It is speculated that prolonged fasting due to disease-induced anorexia, in addition to increased glucose consumption, depletion of hepatic glycogen stores, and hepatic dysfunction with impaired gluconeogenesis, may play important roles in the pathophysiology of hypoglycaemia in canine babesiosis. / Dissertation (MMedVet)--University of Pretoria, 2010. / Companion Animal Clinical Studies / unrestricted

Acute phase proteins (APP) are ideal biomarkers for inflammation due to their stability, relative ease of assay and apparent relation between their concentration and the extent of the insult to tissue. C-reactive protein (CRP) is a positive major APP in dogs and can be used as a predictive marker for risk of disease and to monitor the response to treatment. Increased concentrations in certain diseases are associated with poor outcome. This cross-sectional, observational study of 75 dogs naturally infected with Babesia rossi, a cause of virulent canine babesiosis, was designed to examine the association of CRP concentration at admission and the magnitude of CRP change 24 hours after admission with outcome. Dogs were excluded if there was evidence of concurrent inflammatory diseases at the time of admission, infection with subtypes other than B. rossi, concurrent Ehrlichia canis infections or euthanasia for reasons other than poor prognosis. Diagnosis was confirmed by polymerase chain reaction and reverse line blot. CRP concentrations were determined by an automated human CRP Turbidometric Immunoassay (TIA), previously validated for use in dogs (Bayer CRP TIA, Newbury, UK), on serum samples collected by jugular venipuncture on admission, prior to any therapy, and thereafter daily until discharge or death. There was no significant difference in admission CRP concentration between survivors (n = 57; median = 97.4 mg/l; mean ± SD = 107.5 ± 49.5), and non-survivors (n = 11; median = 101.4 mg/l; mean ± SD = 122.1 ± 64.6) (p = 0.39). After elimination of non-significant predictors, a multiple exact logistic regression model for predicting mortality contained glucose and CRP. Mortality was associated with decreased glucose levels (p = 0.0002) and increased CRP levels (p = 0.045) on admission. Multiple regression analysis failed to show a significant relationship between admission CRP concentration and number of days of hospitalization in the survivors, adjusting for age and sex (p = 0.65). No significance was found in the relationship between the magnitude of change in CRP concentration 24 hours after admission, and the number of days of hospitalization in survivors, (p = 0.34). Using an admission CRP concentration cut-off of 60 mg/l, survival proportions between the two groups were no different (p = 0.34) and when applied to the group of dogs that survived, it was not associated with length of hospitalization (p = 0.25). In corroboration with previous reports glucose was identified as a major prognostic marker for mortality, but additionally the pro-inflammatory marker CRP was identified as a significant co-prognosticator. Copyright / Dissertation (MMedVet)--University of Pretoria, 2009. / Companion Animal Clinical Studies / unrestricted

This observational study of 100 dogs naturally infected with Babesia rossi determined whether severity of parasitaemia was associated with outcome of infection and documented the relative distribution of parasitised red blood cells (pRBC) in capillary and venous circulation. The association between increased parasitaemias and outcome with a clinically compromised circulation was also investigated. Outcome was defined as either hospitalisation with death, or hospitalisation with eventual recovery or treatment as an outpatient. Dogs were enrolled if large babesias were found on stained thin capillary blood smears made from an ear prick. Thin venous smears were prepared from jugular or cephalic blood. Parasitaemias were manually counted and expressed as the percent pRBC. Ten dogs died, 50 recovered after hospitalisation and 40 were treated as outpatients. Venous sampling site did not affect venous parasitaemia (P = 0.6). Both capillary and venous parasitaemias of dogs that died were significantly higher than those of dogs that recovered after hospitalisation (P = 0.002) and dogs that were treated as outpatients (P < 0.0001). When assessing the whole group, capillary parasitaemia (median 0.61%, range <0.05-71.6%, interquartile range (IQR) 0.22-3.75%) was significantly higher than venous parasitaemia (median 0.14%, range 0-30.6%, IQR 0.046–0.52%) with P < 0.0001. The 21 dogs with a clinically compromised circulation were more likely to die (P <0.0001) and had significantly higher capillary (median 5.98%, range 0.09-71.6%, IQR 2.44-19.41%) and venous (median 2.81%, range <0.05-30.6%, IQR 0.17-9.03%) parasitaemias than the 79 dogs with a clinically normal circulation (capillary median parasitaemia 0.38%, range <0.05-12.87%, IQR 0.16-1.42%; venous median parasitaemia 0.096%, range 0-6.13%, IQR <0.05-0.33%; P < 0.0001). This study shows that high parasitaemia is significantly associated with death in B rossi infected dogs. Unfortunately, there was a wide overlap in the parasitaemias of the three outcome groups with the result that neither capillary nor venous parasitaemias appear prognostically useful. The previous clinical suspicion that capillary parasitaemias are usually higher than venous parasitaemias is confirmed. Thus capillary samples are the most appropriate diagnostic samples. Prior observations that a clinically compromised circulation is associated with death are confirmed. This association provides a rapid means of identifying patients in need of intensive monitoring and treatment. Despite the highly significant association between compromised circulation and higher parasitaemia, it is thought unlikely that parasite burden is the sole trigger for circulatory collapse. Copyright 2006, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Bohm, M 2006, The comparative assessment of capillary and venous Babesia rossi parasitaemias on thin blood smears and their association with disease manifestation, MMedVet dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-05042007-154527 / > / Dissertation (Master of Veterinary Medicine (Small Animal Medicine))--University of Pretoria, 2006. / Companion Animal Clinical Studies / unrestricted