Changes in the serum urea: creatinine ratio in dogs with babesiosis, haemolytic anaemia, and experimental haemoglobinaemia

The purpose of this study was to determine serum urea and creatinine concentrations, the derived urea : creatinine (UC) ratios, haemoglobin concentrations and glomerular filtration rates (GFR) in dogs with haemolytic anaemia and those with experimentally induced anaemia and/or haemoglobinaemia. There were 25 dogs with babesiosis (group 1), 13 control animals (group 2), six dogs with induced haemoglobinaemia and anaemia (group 3), six with induced haemoglobinaemia (group 4), and 14 with immune-mediated haemolytic anaemia (IMHA) (group 5). The median serum urea concentration was 11.18 mmol/L (group 1), 4.3 mmol/L (group 2), 4.3 mmol/L (group 3), 4.35 mmol/L (group 4), and 8.5 mmol/L (group 5). Median serum creatinine was 67 μmol/L (group 1), 75 μmol/L (group 2), 78.5 μmol/L (group 3), 84 μmol/L (group 4), and 82 μmol/L (group 5). Median serum haemoglobin was 1.3g/L (group 1), 0.8 g/L (group 2), 9 g/L (group 3), 3g/L (group 4), and 1.3g/L (group 5). The median UC ratio was 41.35 (group 1), 15.36 (group 2), 14.18 (group 3), 13.6 (group 4), and 14.15 (group 5). GFR was normal in all five groups. Serum urea concentration and the UC ratio were significantly greater in dogs with babesiosis than in those with IMHA, experimentally induced anaemia and/or haemoglobinaemia.     

The response of the pituitary-adrenal and pituitary-thyroidal axes to the plasma glucose perturbations in Babesia canis rossi babesiosis

This prospective, cross-sectional, interventional study was designed to determine the association between the hormones of the pituitary-adrenal and pituitary-thyroid axes and other clinical parameters with the blood glucose perturbations in dogs with naturally occurring Babesia canis rossi babesiosis. Thirty-six dogs with canine babesiosis were studied. Blood samples were obtained from the jugular vein in each dog prior to treatment at admission to hospital and serum endogenous adrenocorticotrophic hormone (ACTH), pre-ACTH cortisol, thyroxine, free thyroxine and TSH concentrations were measured. Immediately thereafter each dog was injected intravenously with 5 microg/kg of ACTH (tetracosactrin). A 2nd blood sample was taken 1 hour later for serum post-ACTH cortisol measurement. Three patient groups were recruited: hypoglycaemic dogs (glucose < 3.3 mmol/l, n = 12); normoglycaemic dogs (glucose 3.3-5.5 mmol/l, n = 12); hyperglycaemic dogs (glucose > 5.5 mmol/l, n = 12). Basal and post-ACTH serum cortisol concentrations were significantly higher in hypoglycaemic dogs, whereas body temperature, serum thyroxine and free thyroxine were significantly lower in hypoglycaemic dogs. Haematocrit was significantly lower in both hypo-and hyperglycaemic dogs compared with normoglycaemic dogs. Low blood glucose concentrations were significantly associated with high basal and post-ACTH cortisol concentrations and with low serum thyroxine and free thyroxine concentrations in dogs suffering from B. canis rossi babesiosis.     

Detection of Leishmania amastigotes in peripheral blood from four dogs--Short communication

The authors carried out microscopic examination of blood smears of 1438 dogs infected with Leishmania infantum. Unusual findings of leishmaniosis associated with circulating parasitised cells are described in four dogs. Most of the dogs presented severe illness, with lethargy, dysorexia, emaciation and alterations of the haematological pattern (anaemia, thrombocytopenia, neutrophilia and monocytosis). In three cases, leishmaniosis was associated with ehrlichiosis. On examination of peripheral blood smears, Leishmania sp. amastigotes were observed both in various circulating leukocytes (neutrophil, monocyte, macrophage) and free. In conclusion, parasites can rarely be detected in blood smears (in 0.28% of the animals examined); thus, the time-consuming microscopic search for amastigotes can make only a weak contribution to the conventional diagnosis of canine leishmaniosis.     

Concurrent babesiosis and ehrlichiosis in the dog: blood smear examination supplemented by the indirect fluorescent antibody test, using Cowdria ruminantium as antigen

Giemsa-stained, peripheral blood smears of 67 dogs, showing clinical signs typical of babesiosis or reminiscent of concurrent babesiosis and ehrlichiosis, were examined for the presence of Babesia canis and Ehrlichia canis. Since Cowdria ruminantium cross-reacts with Ehrlichia, the sera of these dogs were also subjected to the indirect fluorescent antibody (IFA) test in which C. ruminantium was used as antigen. Fifty-five per cent of these dogs had mixed infections of B. canis and E. canis, as judged by blood smear examination and serology. The serum of 32% of these dogs with mixed infections reacted positively in the IFA test. Six out of 9 dogs, the blood smears of which were negative for both B. canis and E. canis, were serologically positive for E. canis. Furthermore, sero-conversion from a negative in the initial serum sample to titres of up to 1:160 in a subsequent sample was recorded in 9 out of 13 dogs with suspected mixed infection on blood smear.     

Theileria orientalis MPSP types in Australian cattle herds associated with outbreaks of clinical disease and their association with clinical pathology findings

Between September 2010 and November 2011, 350 EDTA blood samples were received from 73 Australian cattle herds, as cases suspected to be infected with Theileria orientalis. Beef cattle were predominantly affected, with Angus and Angus-crossbred cattle representing 48% of smear positive samples examined. DNA extracts were tested in conventional polymerase chain reaction (PCR) assays for genes encoding the p32, Ikeda, Chitose and Buffeli major piroplasm surface proteins (MPSP). PCR findings were compared with results of clinical pathology examinations of stained blood smears for parasitaemia and packed cell volume (PCV). PCR testing was much more sensitive than clinical pathology examinations in detecting T. orientalis infections, and concurrent testing of neat and diluted extracts gave significantly more PCR positive results than testing of neat extract alone. Significant associations and correlations were shown between PCR results of p32 and Ikeda assays with PCV levels indicative of anaemia, and with the level of parasitaemia estimated by smears. A high proportion of samples had concurrent Ikeda and Chitose infection, and significantly more clinical cases of theileriosis were associated with the Ikeda MPSP type as the sole infection, compared with sole infection with types Chitose or Buffeli. The findings indicate Ikeda type organisms were significantly associated with clinical parameters of theileriosis in cattle herds in eastern Australia, and that this type is most likely to be responsible for outbreaks of theileriosis experienced in affected Australian herds. In New South Wales, 11 of 14 regulatory districts yielded Ikeda positive samples, with five (Mid-Coast, Cumberland, Central North, Hume and Lachlan) containing 234/307 (76%) of the Ikeda positive samples.     

Serological survey for Ehrlichia canis in urban dogs from the major population centres of northern Australia

OBJECTIVE: To detect evidence of Ehrlichia canis infection of dogs from the major population centres of northern Australia, if present. DESIGN: Serological investigation for E. canis. PROCEDURE: The sera of 316 domestic dogs, collected from the northern Australian population centres of Townsville, Cairns, Darwin, Kununurra and Broome from May 1997 to August 1999, were investigated for evidence of infection with E. canis. Samples were tested for antibodies to E. canis using an indirect fluorescent antibody (IFA) test. The buffy coats from blood of dogs whose serum reacted in the IFA test were subsequently tested with a nested PCR to detect E. canis DNA. When available, blood from these dogs was injected into suckling mice, which were then examined for clinical disease and tested for the presence of E. canis antibodies. RESULTS: Of the 316 samples tested seven reacted in the IFA test for E. canis. None of the dogs from which these samples were obtained exhibited clinical signs of acute or chronic ehrlichiosis. The six positive samples available for testing were negative when tested with the nested PCR. Suckling mice inoculated with blood from three of the dogs whose serum was positive by IFA test showed no signs of clinical disease nor did their give positive reactions in the IFA test. CONCLUSIONS: No evidence of E. canis infection was confirmed in any of the dogs examined. Northern Australia would appear to remain free of this obligate parasite.     

Factitious Hyperkalemia in Dogs With Thrombocytosis

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.     

The accuracy of the Lactate Pro hand-held analyser to determine blood lactate in healthy dogs

OBJECTIVES: The objective of this study was to determine the accuracy of the Lactate Pro hand-held analyser in measuring blood lactate levels. METHODS: Blood was drawn from 15 healthy dogs into five tubes containing Na-EDTA. Lactate was measured immediately using the Lactate Pro analyser and a laboratory reference method. Further samples were analysed 120, 240, 480 and 1440 minutes later to artificially increase the lactate levels. Lactate was measured in blood samples of 60 healthy dogs using the Lactate Pro analyser to determine the reference interval of lactate concentration in normal dogs. RESULTS: The correlation between the lactate concentration measured with the Lactate Pro analyser and the reference method was high. Lactate levels were lower when measured with the hand-held analyser than with the traditional laboratory determination. The reference interval for blood lactate concentrations in healthy dogs established by the Lactate Pro analyser was from the detection limit (0.8 mmol/l) up to 3.3 mmol/l. CLINICAL SIGNIFICANCE: The Lactate Pro analyser provides quick and reliable measurements of blood lactate in dogs with blood lactate levels up to 10 mmol/l. Because of its small sample size, this analyser will be particularly appropriate for use in small animal intensive care.     

Clinico-pathological findings and coagulation disorders in 45 cases of canine babesiosis in Spain

A retrospective study of clinical cases of babesiosis in dogs examined at the Veterinary Teaching Hospital, Rof Codina, from January 2003 to October 2004 is presented. The diagnosis was confirmed by direct observation of large piroplasms in stained blood smears. Dogs with concurrent diseases were excluded from the study. Clinical signs, complete blood count, serum biochemistry and hemostasis profiles were obtained. The observed clinical signs were due to hemolytic anemia and inflammatory responses but the most relevant clinico-pathological findings were related to alterations in hemostasis. All dogs presented with thrombocytopenia and 20% had disseminated intravascular coagulation syndrome. Anemia of variable severity was observed in most of the dogs.     

Qualification of the Stewart variables for the assessment of the acid-base status in healthy dogs and dogs with different diseases

Peter Stewart criticized the traditional theory of the acid-base status by Henderson-Hasselbalch as too simple and incomplete. He developed a new model with 3 independent variables: (1) pCO2, (2) SID (strong ion difference) and (3) Atot (Acid total). In healthy and ill dogs the diagnostic usefulness of both acid-base models were compared. This study included n=58 healthy dogs and 3 clinical cases of sick dogs.The age of the healthy dogs was 5.0 (2.0-7.0) years (= median (1.-3. quartil)).The 3 clinical cases included (1) a dog with septic shock, (2) with acute renal insufficiency, and (3) with hypovolaemic shock due to gastric torsion.Venous blood was taken of all dogs and the acid-base parameters were determined within < or =30 minutes. Electrolytes and albumin were determined in blood serum and used for calculation of the Stewart variables. Limits of reference intervals (x+/-1.96 - s) were determined for the healthy dogs yielding pCO2 = 3.6-6.5 kPa, [SID3] = 33.1-50.9 mmol/l resp. [SID4] = 31.8-49.6 mmol/l and [Al = 8.5-13.1 mmol/l. In Case 1 the Henderson-Hasselbalch parameters demonstrated the presence of a strong metabolic acidosis with mild respiratory influence (pH, [HCO3-], [BE] and PCO2 at upper range of normal). Analysis of the Stewart variables [SID3] resp. [SID4] revealed an electrolyte imbalance with [Cl-] and [lactate-] as the reason for metabolic acidosis. Case 2 showed a metabolic acidosis with respiratory compensation (pH, [HCO3-], [BE] and PCO2). Analysis of the Stewart variables with [SID3] resp. [SID4 caused by [K+], [Na+] and [lactate-]demonstrated the acidotic metabolism due to a renal malfunction. Case 3 had a metabolic acidosis (pH-value in the lower range) caused by electrolyte imbalances ([SID4]. The Stewart variables allow a better understanding of the causes of acid-base-disturbances in animals with implications for successful therapy via infusion.     

Two cases of severe iron-deficiency anaemia due to inflammatory bowel disease in the dog

Two dogs were referred for investigation of lethargy and anaemia. Preliminary examinations by the referring veterinary surgeons had revealed severe anaemia, which was poorly regenerative. In one case, the anaemia was microcytic and, in the other, it was hypochromic. These findings were suggestive of chronic blood loss anaemia. Neither dog had external signs of gastrointestinal disease, although one had vomited on a single occasion during the two weeks preceding referral. Although both dogs were producing grossly normal faeces, further investigations detected faecal occult blood. Multiple full thickness gastrointestinal biopsies were taken at laparotomy. These showed segmental eosinophilic enteritis of the duodenum and proximal jejunum in one case, and marked chronic lymphocytic gastritis in the other. Both cases illustrate the fact that severe systemic disease can result from gastrointestinal pathology in the absence of clinical signs of gastrointestinal disease.     

Serial haematology results in transfused and non-transfused dogs naturally infected with Babesia rossi

This prospective longitudinal study investigated the progression of haematological changes in 32 transfused and 54 non-transfused dogs naturally infected with Babesia rossi over the 1st 6 days following diagnosis and treatment. The effect of patient age on the results of complete blood counts was determined. Haematology data were analysed at presentation and at 24 hours, 3 days and 6 days after presentation. Dogs were treated with diminazene aceturate at diagnosis and a blood transfusion was given if deemed clinically required. Mildly to moderately regenerative normocytic normochromic anaemia was observed in all dogs throughout the study period. Transfused dogs more often had an inflammatory leukogram at presentation and at 24 hours, than dogs that were not transfused. In dogs with a left shift, a concurrent normal or decreased segmented neutrophil count was found more commonly than neutrophilia. Severe thrombocytopenia that resolved within a week was common. Blood transfusion alleviated the anaemia, but had no significant effect on white blood cell or platelet responses. Blood cell responses were not significantly influenced by age. In conclusion, the red blood cell and white blood cell responses were less than expected in dogs with babesiosis, given the degree of anaemia and inflammation present. The magnitude of thrombocytopenia and rapid return of the platelet count to normal suggested a possible immune-mediated mechanism for the thrombocytopenia.     

Plasma disappearance of creatinine as a renal function test in the dog

The serum concentration of creatinine at 120 minutes (SC120) after intravenous injection of 88 mg kg-1 of creatinine, the plasma half-life (t1/2) and the plasma clearance of creatinine (PCC) were evaluated as renal function tests in 30 healthy adult dogs and six adult dogs with known or suspected renal disease. The mean SC120 in the normal dog was 0.31 +/- 0.08 mmol litre-1 and in the clinical cases 0.71 +/- 0.19 mmol litre-1. The correlation coefficients between SC120 and renal creatinine clearance (RCC) for the normal dogs and the clinical cases were -0.76 and -0.69, respectively. At 120 minutes after injection, 95 per cent of normal dogs would be predicted to have a serum creatinine concentration below 0.46 mmol litre-1. The mean plasma t1/2 of creatinine for the normal dogs was 107.7 +/- 17.96 minutes, while the clinical cases had a wide range of values (148.8 to 620.1 minutes). Plasma t1/2 of creatinine was correlated with RCC for both the normal dogs and the clinical cases (r = -0.55, r = -0.91, respectively). The mean PCC for the normal dogs was 7.42 +/- 2.22 ml min-1 kg-1 (range 4.95 to 13.28 ml min-1 kg-1). There was a good correlation between RCC and PCC (r = 0.7). The PCC for the clinical cases ranged from 0.76 to 3.37 ml min-1 kg-1. The correlation between RCC and PCC was significant (r = 0.91). Thus SC120, t1/2 and PCC may be useful methods of assessing renal function in dogs with renal impairment insufficient to cause azotaemia.     

Occurrence of filaria in domestic dogs of Samburu pastoralists in Northern Kenya and its associations with canine distemper

Samples of blood (serum, smears and blood preserved with ethanol) were collected from dogs during a vaccination campaign in northern Kenya in the years 2006 and 2007. Blood was screened for filarial parasites using molecular and microscopy methods and sera were tested for antibodies against canine distemper virus (CDV). Parasitological examination revealed the presence of two species of canine filariae: Acanthocheilonema dracunculoides and A. reconditum. The DNA from the former species was detected in 58% dogs sampled in 2006 and 36% dogs sampled in 2007, whereas the latter was found only in 4.2% samples collected in 2007. Microfilariae were found in 33.8% blood smears collected in 2006 and 10.6% blood smears collected in 2007. The seroprevalence of CDV was 33.4% in 2006 and 11.2% in 2007. The effect of sex, age and CDV-seropositivity/seronegativity on the occurrence of A. dracunculoides was evaluated. Infection by A. dracunculoides was more common in males and in dogs with a positive antibody titer for canine distemper, but evenly distributed among different age groups. The difference in the prevalence of A. dracunculoides in two isolated mountain ranges was not statistically significant. Methodologies available for detection and determination of canine filariae are compared, underlining methodical pitfalls arising through the determination of less common filarial species. The role of single epidemiological factors and possible association between canine distemper and filariasis are discussed.     

Apparent pseudohyperkalemia in a Chinese Shar Pei dog

Whole blood in a serum clot tube and EDTA-anticoagulated samples from an 8-year-old spayed female Chinese Shar Pei dog were submitted by an external clinic to the diagnostic laboratory at Atlantic Veterinary College for routine biochemical and hematologic analysis prior to entropion surgery. Laboratory abnormalities included mild hyperkalemia (6.3 mmol/L, reference interval 3.6-6.0 mmol/L), mild normocytic, hypochromic, nonregenerative anemia (HCT 0.31 L/L, reference interval 0.37-0.55 L/L; MCHC 290 g/L, reference interval 320-360 g/L), and increased red cell distribution width (RDW; 26.2%, reference interval 11-14%). A small subpopulation of macrocytic, slightly hypochromic erythrocytes was noted on Wright's-Giemsa-stained blood smears. Biochemical and hematologic data obtained from this patient over the previous 7.5 years indicated that serum (and in 1 case, heparinized plasma) potassium concentration was increased (range, 6.3-10.9 mmol/L) in 5 of 8 samples (HCT ranged from 0.31-0.43 L/L, Hgb 91-124 g/L, MCHC 280-312 g/L, and RDW 18.2-26.9%). Clinical signs suggestive of hyperkalemia were not observed at any time, suggesting pseudohyperkalemia as the cause of the increased potassium concentrations. An erythrocyte lysate prepared from a heparinized blood sample had a high potassium concentration (16.8 mmol/L) compared with that of a clinically healthy, non-Shiba control dog (6.7 mmol/L). An osmotic fragility test of the patient's erythrocytes showed 50% hemolysis at 0.57% NaCl, compared with 0.48% NaCl for the control dog, indicating increased fragility. On scanning electron microscopy, a small subpopulation of erythrocytes were large, flattened, and had a tendency to fold. These findings supported the provisional diagnosis of pseudohyperkalemia due to increased intracellular RBC potassium concentration. High-potassium erythrocytes have been reported in Akitas, Shibas, Jindos, other East Asian dog breeds, and occasionally, in mixed-breed dogs. Pseudohyperkalemia should also be considered when an otherwise unexplained elevation in serum or plasma potassium concentration is observed in Chinese Shar Pei dogs, and may be accompanied by increased RDW, low MCHC, and increased osmotic fragility with or without mild anemia.     

Clinical and hematologic findings in canine ehrlichiosis

The clinical and hematologic findings for 56 dogs with ehrlichiosis were studied retrospectively. All dogs had a high serum antibody titer to Ehrlichia canis. The frequency of bleeding disorders, thrombocytopenia, and pancytopenia in these dogs was lower than previously described for dogs so affected. A bleeding disorder caused by a suspected qualitative platelet defect was found in some dogs that did not have thrombocytopenia. Megakaryocytic hyperplasia and high numbers of plasma cells were observed frequently on marrow aspirate smears. The clinical and laboratory findings of dogs were variable and were considered nonspecific for ehrlichiosis.     

Hemorrhagic disease in dogs infected with an unclassified intraendothelial piroplasm in southern Brazil

A hemorrhagic disease affecting dogs in Brazil, referred to popularly as "nambiuvú" (bloody ears) and believed to be transmitted by ticks, has been observed in animals infected with an organism described originally in 1910 as a piroplasm, and known locally as Rangelia vitalli. In this series of 10 cases, the disease was characterized by anaemia, jaundice, fever, spleno- and lymphadenomegaly, hemorrhage in the gastrointestinal tract, and persistent bleeding from the nose, oral cavity and tips, margins and outer surface of the pinnae. The ixodid ticks Rhipicephalus sanguineus and Amblyomma aureolatum infested affected dogs from suburban and rural areas, respectively. Laboratory findings included regenerative anaemia, spherocytosis, icteric plasma and bilirubinuria. Those intracellular organisms were found in bone marrow smears but not in blood smears. Microscopically, zoites were seen within the cytoplasm of blood capillary endothelial cells. Parasitized and non-parasitized endothelial cells were positive immunohistochemically for von Willebrand factor (vWF). Langhans-type multinucleate giant cells were observed in the lymph nodes and choroid plexus. There was prominent erythrophagocytosis by macrophages in the lymph node sinuses and infiltration of the medullary cords by numerous plasma cells. Ultrastructurally, this organism had an apical complex that included a polar ring and rhoptries but no conoid. This parasite was contained within a parasitophorous vacuole that had a trilaminar membrane with villar protrusions and was situated in the cytoplasm of capillary endothelial cells. This organism tested positive by immunohistochemistry for Babesia microti. This pathogen was also positive by in situ hybridization for B. microti. Tentative clinical diagnosis in these cases was based on the history, clinical picture, haemogram and favorable response to therapy, and confirmed through microscopic examination of smears from the bone marrow or histological sections of multiple tissues, especially lymph nodes where zoites were most frequently found. The disease was reproduced by intravenous inoculation of blood from a naturally infected dog into an experimental dog. The authors demonstrate in this study that this organism is a protozoa of the phylum Apicomplexa, order Piroplasmorida. This piroplasm seems to be different from Babesia since it has an intraendothelial stage. Molecular phylogenetic analysis is necessary to better characterize this parasite and clarify its taxonomic status.     

Acquired Myasthenia Gravis

Serum samples from 152 dogs with a clinical diagnosis of idiopathic megaesophagus without detectable generalized muscle weakness were tested for the presence of antibodies to acetylcholine receptors by immunoprecipitation radioimmunoassay. Positive serum antibody titers (mean, 3.1 nmoL/L; range, 0.77-30 nmoL/L; reference values less than 0.6 nmoL/L) were found in 40 dogs (26%), with German Shepherd dogs (8/25, 32%) and Golden Retrievers (7/20, 35%) having a greater percentage of positive submissions. By immunocytochemical methods, localization of immune complexes at the neuromuscular junction after incubation of serum with normal canine muscle was documented in an additional 17 cases (11% of all samples submitted) that did not have increased antibody titers to acetylcholine receptors. Of the 40 seropositive dogs, 17 (48%) had a clinical improvement or remission of clinical signs associated with decreasing AChR antibody titers. Idiopathic megaesophagus has been associated with a poor prognosis; however, this study demonstrates that a large percentage of the dogs have myasthenia gravis and that with supportive treatment, the clinical signs may improve or resolve.     

Serum cobalamin concentrations in dogs with leishmaniosis before and during treatment

Hypocobalaminemia in dogs is most commonly associated with gastrointestinal disorders leading to impaired absorption and utilization of cobalamin. The objectives of this study were to compare serum cobalamin concentrations between dogs with leishmaniosis and clinically healthy dogs, and to assess possible alterations of serum cobalamin concentrations in dogs with leishmaniosis at different timepoints during treatment. Fifty-five dogs with leishmaniosis and 129 clinically healthy dogs were prospectively enrolled. Diagnosis of leishmaniosis was based on clinical presentation, positive serology and microscopic detection of Leishmania amastigotes in lymph node aspiration smears. Twenty of the dogs with leishmaniosis were treated with a combination of meglumine antimonate and allopurinol for 28 days and serum cobalamin concentrations were measured in blood samples that were collected before initiation of treatment (timepoint 0) and on days 14 and 28. In order to estimate alterations of serum cobalamin concentrations during treatment, cobalamin concentrations were measured in blood samples from 20 out of 55 dogs with leishmaniosis at all timepoints. Serum cobalamin concentrations were significantly lower in dogs with leishmaniosis before treatment (median: 362 ng/L; IQR: 277−477 ng/L) compared to clinically healthy dogs (median: 470 ng/L; IQR: 367−632 ng/L; P = 0.0035). Serum cobalamin concentrations increased significantly in dogs with leishmaniosis on day 14 of treatment compared to timepoint 0 (P = 0.02).In the present study, serum cobalamin concentrations were significantly lower in dogs with leishmaniosis compared to clinically healthy dogs. In addition, there was an increase in serum cobalamin concentrations during treatment. The clinical significance of hypocobalaminemia in dogs with leishmaniosis remains to be determined.