Ehrlichia canis and canine Babesia spp. are widely distributed tick-borne pathogens of veterinary and One Health relevance. Contemporary nationwide data on canine exposure and associated determinants in Portugal are limited. This study aimed to estimate seropositivity proportions and explore epidemiological determinants of exposure to E. canis and Babesia spp. in clinically suspected dogs from Portugal over an 11-year period (2015-2025). Serum samples from 2960 dogs collected between 2015 and 2025 were analysed using commercial enzyme-linked immunosorbent assay kits to detect immunoglobulin G antibodies to E. canis and Babesia spp. Associations with demographic and geographic variables were assessed using chi-square and Fisher's exact tests. Univariable and multivariable logistic regression were used to identify potential risk factors (P < 0.05), and model performance was evaluated using the Hosmer-Lemeshow test, Nagelkerke's R2, and the area under the receiver operating characteristic curve. Overall seropositivity was 4.0% (116/2,872) for E. canis and 12.0% (337/2,818) for Babesia spp. Borderline results accounted for 3.0% (88/2,960) and 4.8% (142/2,960), respectively. E. canis seropositivity varied significantly by Nomenclature of Territorial Units for Statistics level 2 region (P < 0.001), with highest values in the Algarve (15.3%; odds ratio [OR] = 4.3, P < 0.001) and Setúbal Peninsula (50.0%; OR = 23.9, P = 0.025). Age was associated with E. canis exposure (P = 0.014), with increased odds in dogs aged 6 to < 11years and ≥ 11years (both OR = 2.1, P < 0.05). No significant geographical association was observed for Babesia spp. (P = 0.803), and sex and age were not significant predictors. Seropositivity to Babesia spp. was a risk factor for seropositivity to E. canis (OR = 3.6, P < 0.001). Multivariable models retained no independent predictors (Nagelkerke R2 = 0.15; area under the curve = 0.71). This study provides a nationwide, long-term retrospective assessment of serological exposure to E. canis and Babesia spp. among clinically suspect dogs in Portugal. Exposure to E. canis showed marked regional heterogeneity, particularly in southern Portugal, whereas Babesia spp. showed no significant regional association. Co-seropositivity, although uncommon, is consistent with shared tick-borne exposure pathways. These findings support risk-based tick control and continued surveillance within a One Health framework.

In Cambodia, livestock production plays an important role in the national economy and food security, yet tick-borne diseases remain an underrecognized constraint on animal health and productivity. Domestic animals may also serve as reservoirs of zoonotic pathogens in this predominantly rural setting. To address the lack of baseline molecular data on tick-borne pathogens in Cambodia, we conducted a cross-sectional study of ticks collected from November 2022 to April 2023 across 24 provinces. Ticks were collected from various hosts and environments, including cats, cattle, dogs, goats, pangolins, pythons, wild pigs, and bat cave floors, representing urban, rural, farm, wildlife rescue center, and forest fringe habitats. A total of 1526 ticks belonging to nine species were pooled into 352 samples and screened using conventional PCR (cPCR) targeting Anaplasma, Ehrlichia, Babesia, and Coxiella. Additionally, a subset of Rhipicephalus microplus ticks was analyzed using metatranscriptomic next-generation sequencing (NGS). Rhipicephalus microplus ticks collected from cattle tested positive for Anaplasma marginale (1.1% of pools) and Ehrlichia minasensis (0.9% of pools), whereas Rhipicephalus linnaei ticks collected from dogs were positive for Anaplasma platys (0.3% of pools) and Babesia canis (2.0% of pools). A high prevalence of Coxiella-like endosymbionts (15.6% of pools) was found in R. microplus from both cattle and goats. Metatranscriptomic analysis also identified six tick-associated viruses in R. microplus from cattle; with Guangdong tick manly virus being the most dominant (32.5% of samples); followed by Zhangzhou Totiv tick virus 1 (15.0%), Jingmen tick virus (5.0%), and Mogiana tick virus; Rhipicephalus-associated rhabdo-like virus; and Rhipicephalus-associated flavi-like virus; each at 2.5%. These findings provide the first molecular evidence of numerous bacterial, protozoal, and viral pathogens circulating in R. microplus and R. linnaei in Cambodia. The study highlights the need for integrated One Health surveillance to better understand, prevent, and control tick-borne diseases in the region.

Canine babesiosis caused by Babesia canis is considered an emerging disease in Central and Eastern European countries, including Germany. Imidocarb dipropionate is recommended for treatment of acute B. canis infections. A nine-year-old, male intact Golden Retriever living in Saxony, Germany, was presented in November 2025 due to lethargy, inappetence, vomiting, fever (39.6 °C), and darkened urine to a small animal veterinary practice. Ectoparasite prophylaxis was discontinued three months before the onset of clinical signs. An acute B. canis infection was diagnosed based on microscopic detection of large merozoites in peripheral blood smears, followed by Babesia spp. PCR and sequencing. Hematological examination revealed marked thrombocytopenia, mild non-regenerative anemia, lymphopenia, and eosinopenia. The dog remained PCR positive after two imidocarb dipropionate injections (2.0 mg/kg bodyweight and 5.0 mg/kg bodyweight s.c.), and hematological abnormalities were still present. Prednisolone (2.0 mg/kg bodyweight s.c., continued orally) was applied, after which merozoites were still detected in peripheral blood smear analysis, so prednisolone was discontinued. After two further imidocarb dipropionate injections (9.4 mg/kg bodyweight s.c. each), the dog presented as clinically healthy, and a subsequent PCR testing was negative. From this report, different measures for dogs suffering from an acute B. canis infections can be derived: Dogs should be treated with a high dosage of imidocarb dipropionate of 6.6 mg/kg bodyweight as approved by the FDA, and the treatment success should be monitored by PCR 14 days post treatment. If treatment fails after two administrations at either dose of imidocarb dipropionate, i.e. if PCR remains positive, it is recommended to verify a B. canis infection by molecular species differentiation, e.g. via sequencing. Furthermore, dogs with treatment failure should be screened for coinfections and underlying comorbidities, which may complicate the course of an acute B. canis infection. Due to the authors’ personal experience, application of corticosteroids, even in non-immunosuppressive dosages, should be avoided, especially if blood transfusions are not necessary and/or marked hemolytic anemia is absent. Furthermore, this report highlights the importance of efficient year-round tick control, even in winter months.

A novel development of Gold Nano-based indirect ELISA for sero-diagnosis of Babesiacanis.

Tick-borne pathogens (TBPs) represent a major constraint to livestock health and productivity worldwide. Water buffaloes (Bubalus bubalis) are an important livestock species in Türkiye; however, molecular data on TBPs in this host remain limited. This study aimed to investigate the prevalence and molecular diversity of Babesia, Theileria, Anaplasma, and Ehrlichia species in water buffaloes from Iğdır Province, Eastern Türkiye. A total of 200 blood samples were analysed using genus-specific PCR assays targeting the 18S and 16S rRNA genes, followed by Reverse Line Blot (RLB) hybridisation and Sanger sequencing. Genus-level prevalence was 28.0% for Theileria spp., 6.0% for Babesia spp., and 2.5% for Anaplasma spp., while Ehrlichia spp. were not detected. Six species were identified: Theileria annulata (22.0%), T. ovis (5.0%), T. buffeli (1.0%), Babesia canis (5.0%), B. ovis (1.0%), and Anaplasma phagocytophilum (2.5%). This study provides the first molecular evidence of B. canis and B. ovis DNA in water buffaloes. However, the detection of parasite DNA alone does not confirm active infection and likely reflects incidental or spillover events associated with shared tick vectors in multi-host grazing systems. Phylogenetic analyses based on 18S and 16S rRNA genes revealed high sequence similarity with isolates from neighbouring regions, supporting regional circulation of closely related strains. These findings highlight the exposure of Anatolian water buffaloes to a broad spectrum of TBPs and underline the need for integrated studies combining vector surveillance, multilocus genotyping, and serological approaches to clarify host competence and transmission dynamics.

Canine babesiosis is a tick-borne disease caused by protozoan parasites belonging to the genus Babesia, with Babesia canis and Babesia gibsoni being the most common species. The disease is characterized by hemolytic anemia, thrombocytopenia, and multiple organ dysfunction due to the destruction of red blood cells. A detailed study was conducted on 50 naturally occurring cases of canine babesiosis at the Small Animal Clinics, Teaching Veterinary Hospital, Orathanadu, focusing on clinical observations, including clinical history, physical examination, and hematobiochemical alterations. Blood samples were taken from the cephalic vein of the infected dogs. The diagnosis was based on clinical symptoms and the detection of Babesia organisms in Giemsa-stained thin blood smears, which was further confirmed by PCR. The affected dogs showed a significant reduction in Hb, TEC, and PCV levels, along with a notable increase in serum bilirubin, ALT, ALP, BUN, and creatinine levels. These hematobiochemical findings highlighted the severity of babesiosis in the dogs studied. This research delves into the pathophysiology of the disease and underscores the importance of various blood parameters in diagnosis and prognosis.

Canine vector-borne diseases (CVBDs) are caused by pathogens transmitted by several invertebrates, posing a significant threat to both animal and human health worldwide. In recent years, the geographical distribution of CVBDs has changed in many countries, driven by climate change, increased pet travel, movements of goods, and anthropization of wildlife habitats. This study investigated the exposure to major CVBDs in 423 owned dogs from Italy and Greece. Individual serum samples were analyzed using serological methods. The SNAP® 4Dx IDEXX test was used to detect Dirofilaria immitis circulating antigens and antibodies against Anaplasma spp., Ehrlichia spp. and Borrelia burgdorferi. Additionally, an indirect immunofluorescence antibody test (IFAT) was used to detect antibodies against Rickettsia conorii and Babesia canis. Overall, 171 (40.4%) dogs were positive for at least one pathogen. Antibodies against R. conorii, Ehrlichia spp., Anaplasma spp., B. canis and B. burgdorferi were detected in 118 (27.9%), 28 (6.6%), 29 (6.8%), 5 (1.2%) and 3 (0.7%) dogs, respectively. Dirofilaria immitis antigens were found in 7 dogs (1.6%). A Binomial Logistic Regression was performed and revealed a statistically significant association between age (dogs > 7 years old) (p = 0.005; OR = 1.903; 95% CI = 1.215-2.2981) and presence of at least one clinical sign (p = 0.028; OR = 4.082; 95% CI = 1.168-14.262) and positivity to at least one vector-borne pathogen. These findings confirm that dogs in both Italy and Greece are exposed to a range of vector-borne pathogens and highlight the importance of continuous epidemiological surveillance in European regions.

Canine babesiosis is a significant tick-borne hemoprotozoan disease of dogs, caused mainly by Babesia canis and B. gibsoni. The present study was undertaken to evaluate the epidemiological occurrence of canine babesiosis in dogs presented to the Department of Veterinary Medicine, Veterinary College, Hebbal, Bangalore. Out of 40 suspected cases, 24 were confirmed positive by PCR and analyzed for epidemiological factors. Breed-wise, Labrador Retrievers recorded the highest occurrence (16.6%), followed by German Shepherds, Shih Tzus, Golden Retrievers, and Siberian Huskies. Age-wise, young adults showed the higher occurrence (54.16%), while gender-wise, males were more affected (58.33%) than females. Grey-coated dogs (29.16%) exhibited higher occurrence compared to other coat types. Routine vaccination (70.83%) and regular deworming (75.0%) did not offer protection against babesiosis, indicating the need for targeted preventive measures. The findings highlight that breed, age, gender and coat type play a significant role in the epidemiology of the disease, while control strategies should focus on tick management and development of specific vaccines.

ABSTRACTDogs, being companion animals, serve a variety of economic, social and cultural purposes. However, diseases caused by the tick‐borne protozoans are drawing attention globally due to their zoonotic transmission. In this context, the present study aimed to observe the occurrence of tick‐borne protozoan infections as well as some selective haematological parameters of stray dogs in Dhaka city, Bangladesh. A total of 160 dogs from various places were selected randomly and examined for both tick and protozoan infection. Only one species of hard tick, Rhipicephalus sanguineus, was identified, where 49 (30.62%) among the study population were found to be infested with this tick. Ticks ranging from 1–16 were removed from dogs, where most of the ticks were collected from the neck and chest regions (P < 0.001). On the other hand, examinations of blood smears confirmed three protozoan species (Babesia canis, Babesia gibsoni and Hepatozoon spp.) comprising 23.13% of the overall infection. Among the protozoan species, B. canis (11.88%) was the most prevalent protozoan. Subsequently, only 10.81% of the infected samples showed multiple infections. In both cases, females were more infected than males. Among the haematological parameters, the RBC counts, haemoglobin and PCV of all infected dogs were significantly lower (P < 0.001) compared to the non‐infected group. Moreover, the eosinophils of the infected groups showed higher values (11.00 % and 12.70% for protozoa and ticks, respectively) than the normal range, indicating parasitic infections. Therefore, these results suggest the necessity of frequent blood examinations to enhance animals’ welfare and disease prevention.

Clinicopathological abnormalities and outcome of acute Babesia canis infections in 23 dogs treated with imidocarb dipropionate.

In Serbia, Babesia canis is the predominant cause of canine babesiosis, while B. gibsoni and B. vulpes have been reported only sporadically. Limited awareness of these small Babesia species often leads to misdiagnosis and inappropriate treatment. International reports indicate that American Staffordshire Terriers (ASTs) and related breeds are particularly affected. This study examined 101 ASTs over a two-year period to determine the occurrence of small Babesia species and identify dog- and owner-related risk factors. Collected data included age, sex, body condition score (BCS), clinical signs, presence of scars, history of vector-borne diseases (VBD), living conditions, antiparasitic prophylaxis, and tick exposure. Molecular identification using PCR and Sanger sequencing revealed that 37 dogs were positive for Babesia spp.; among them, 36 were infected with B. gibsoni and one with B. vulpes. Significant risk factors associated with infection included the presence of scars, low BCS, history of VBDs, tick exposure, and living in rural areas. These findings demonstrate a notably high occurrence of B. gibsoni and the presence of B. vulpes in ASTs in Serbia. The results highlight the need for improved awareness, accurate molecular diagnostics, and targeted preventive and therapeutic measures. Additionally, observed risk factors suggest chronic infection and support transmission pathways linked to dog bites and tick exposure.

A 7-year-old female Beagle, diagnosed with diabetes mellitus six months earlier and on insulin therapy, presented with haematuria, dysuria, and abdominal discomfort. Diagnostic workup included complete blood count, blood smear, mean blood glucose estimation, serum amylase and lipase, rapid Snap 4DX test, Babesia spp. antigen tests, radiography, and ultrasonography. All infectious disease tests (E. canis, Anaplasma spp., Dirofilaria immitis, Borrelia burgdorferi, Babesia canis, B. gibsoni) were negative. Complete blood count showed a platelet count of 399,000/µL. Random blood glucose was 600 mg/dL, reduced to 224 mg/dL post-insulin. Imaging revealed a 3.52 cm hyperechoic, radio-opaque structure in the lower abdomen, consistent with cystic calculi, along with a thickened urinary bladder wall (0.61 cm), suggestive of cystitis likely associated with diabetes and uroliths. Surgery was performed, and a 24.42 g, yellowish, apricot seed-shaped calculus (3.1 × 2.4 × 1.3 cm) was removed.

Splenomegaly with diffuse heterogeneous parenchyma was detected in a 6-year-old female Lagotto Romagnolo from Germany during routine ultrasonographic examination. The cytologic examination of a fine needle aspirate of the spleen revealed reactive lymphoid hyperplasia and extramedullary hematopoiesis. During diagnostic workup, babesiosis with high Babesia antibody levels and evidence of Babesia canis was diagnosed as the cause of the splenic parenchymal findings. At no time, the dog showed any clinical signs or clinicopathologic findings associated with the infection, although active babesiosis was diagnosed. Due to the high antibody level, it can be postulated that the dog had already been exposed to the pathogen at an earlier stage or that she had a subacute course of the disease.To the authors' knowledge, this is one of the few descriptions of babesiosis with structural splenopathy with evidence of extramedullary hematopoiesis as the only indication of the presence of the infectious disease and without corresponding clinicopathologic findings.

Babesiosis is a tick-borne disease caused by apicomplexan hemoprotozoan parasites that infect red blood cells. The condition can develop from small species of Babesia , such as B . gibsoni , B. conradae , and B. vulpes , as well as larger species like B. vogeli , B. canis , and B. rossi . The number of Babesia infections has been increasing globally in the world, and that is a significant problem for wild and domestic animals and for humans. Babesia is found throughout the world. Climate change, including rising temper a tures, altered precipitation patterns and prolonged warm spells , fosters tick reproduction and expand s their habitats into new regions. This shift significantly increases the risk of babesiosis being transmitted to areas where it was previously uncommon. Additionally, climate change may affect the seasonal behavior of ticks, extending their active periods and thereby elevating the risk of infection for both humans and animals. The overall health of animals can also be compromised by climate change, making them more su s ceptible to infections, which further facilitates the spread of various diseases. Recent reports highlight that Babesia canis is the most prevalent species found in Ukraine. However, information regarding the hematological and biochemical changes in dogs naturally infected with B. canis , particularly in Dnipro city, remains scarce. This study focuses on a retrospective analysis of clinical cases of Babesia infection in dogs. For this research, a complete biochemical profile was obtained and analyzed for 25 dogs diagnosed with babesiosis. Treatment administered within the first 24 hours for dogs with B. canis infection demonstrated improvement in several biochemical parameters in the blood, including superoxide dismutase (SOD), inorganic phosphorus, lactate dehydrogenase (LDH), and various protein fractions. This treatment effectively reduced renal and oxidative stress, as well as improved electrolyte, protein, and lipid metabolism. While some indicators, such as urea, creatinine, potassium, albumin, cholesterol, calcium, and sodium, did not show significant changes, the overall trends suggest that the therapy was effective in stabilizing the dogs' conditions and all e viating symptoms of hemolytic anemia. Ongoing monitoring and possible additional therapeutic interventions may be required to achieve a complete normalization of biochemical parameters.

Abstract This report describes a case of severe, sudden‐onset, widespread vasculitis affecting a dog concurrently infected by E hrlichia canis and Babesia canis . Following diagnostic investigations, the dog was suspected of an immune‐mediated vasculitis, possibly triggered by E. canis, B. canis or their combination. The lesions completely resolved after a multimodal treatment protocol including prednisolone, ciclosporin, pentoxifylline, doxycycline and imidocarb dipropionate.

Canine babesiosis is a vector-borne disease caused by protozoan parasites of the genus Babesia, primarily transmitted by ixodid ticks. The disease is widespread globally, including across most regions of Ukraine. Babesia canis is the most prevalent species affecting dogs, with increasing clinical relevance in both domestic and wild carnivores. Infection leads to intravascular hemolysis, hypoxic tissue injury, and multi-organ dysfunction. Despite advances in diagnostics, early hematological changes in the initial stages of infection remain underexplored. This study aims to compare the hematological parameters of dogs in the early stage of babesiosis with healthy controls to identify reliable indicators for early diagnosis and disease monitoring. This study was conducted on 13 clinical cases of Babesia canis infection in dogs, with data collected directly from animals presented at the Peredovyi Veterinary Complex (Dnipro, Ukraine) between February and April 2024. Blood smears confirmed parasitemia, and complete blood counts were performed using the MicroCC-20 Plus automated analyzer. Results showed a statistically significant decrease in red blood cell count (3.59±0.37×106/μL) and hemoglobin (83.42±2.96 g/L) in infected dogs compared to controls (6.36±0.17×106/μL and 158.58±5.87 g/L, respectively). Hematocrit values were also markedly reduced (22.54±1.45 % vs. 43.51±2.39 %; P&lt;0.0001). Significant thrombocytopenia (38.23±6.20×103/μL) and leukopenia (7.08±0.60×109/L) were observed, with a concurrent neutrophilic shift and lymphopenia. Mean corpuscular volume (MCV) was significantly lower in the infected group (63.45±2.49 fL), while other red cell indices (MCHC, RDW) and total protein levels showed no statistically significant differences. These findings highlight the pronounced hematological disturbances associated with early-stage Babesia canis infection. The changes in erythrocyte count, hemoglobin concentration, hematocrit, and platelet levels may serve as early diagnostic markers. Further research is needed to refine hematological profiling for improved clinical decision-making and timely intervention in canine babesiosis.

Apicomplexan haemoprotozoa, including piroplasms from the genera Babesia and Theileria, along with Hepatozoon spp., are tick-borne protozoans that affect domestic animals, wildlife, and humans. Employing a broader-spectrum 18S rDNA PCR assay for Apicomplexa haemoprotozoa, the present study investigated 155 owned dogs presented to the Veterinary Teaching Hospital of the University of Bologna and previously tested by routine diagnostic assays for Anaplasmataceae and Babesia spp. infection. The presence of three different species of Apicomplexan hemoprotozoa was observed. Specifically, Babesia canis was confirmed in two dogs, while the presence Hepatozoon canis (eight dogs), and Theileria orientalis (one dog) was also newly detected. Hepatozoon canis positive dogs mainly showed clinical history of comorbidities. Phylogenetic analysis highlighted genetic diversity among H. canis strains detected in this study, and from H. canis sequences from canid. Hosts. This study emphasizes the importance of using comprehensive diagnostic techniques to detect a wide range of hemoprotozoan infections, particularly in cases of vector-borne diseases with potential co-infections. This is the first report in Italy of T. orientalis in a canine host. Further researches are required to elucidate the role of dogs in the epidemiology and transmission of Theileria spp. and to explore the pathogenicity of Hepatozoon canis strains in the region.

ABSTRACTBackground and Aim:Canine babesiosis, primarily caused by Babesia canis vogeli in Thailand, is a significant tick-borne disease of veterinary concern. Molecular diagnostics targeting the 18S rRNA gene have enhanced detection sensitivity and specificity compared to conventional methods. This study aimed to identify and characterize B. canis vogeli in naturally infected dogs in Khon Kaen, Thailand, to compare the diagnostic performance of two primer sets (Bab7/Bab9 and Babf/Babc), and to perform phylogenetic analysis of the isolates.Materials and Methods:A total of 159 ethylenediaminetetraacetic acid blood samples from client-owned dogs presented to the Veterinary Teaching Hospital, Khon Kaen University, between July and October 2024, were examined. Samples underwent Giemsa-stained blood smear microscopy and PCR amplification of the 18S rRNA gene using both primer sets. Positive amplicons were sequenced and analyzed phylogenetically using the Maximum Likelihood method. Limit of detection (LOD), sensitivity, specificity, and positive predictive value (PPV) were calculated for each primer set using sequence-confirmed results as the reference.Results:Microscopy detected B. canis in 19/159 (11.9%) of samples, while PCR increased detection to 23/159 (14.47%). Babf/Babc detected all positive cases (100% sensitivity), while Bab7/Bab9 detected 95.65% of positives. Both primer sets achieved 100% specificity and PPV, with an equal LOD of 105 DNA copies. Bab7/Bab9 also amplified Hepatozoon canis at a distinct amplicon size (503 base pair). Sequence analysis confirmed all Babesia-positive samples as B. canis vogeli, showing 96.34%–100% identity with global isolates. Phylogenetic analysis grouped the sequences with B. canis vogeli from multiple geographic regions, revealing minimal intraspecific variation.Conclusion:B. canis vogeli was the only subspecies identified in naturally infected dogs in Khon Kaen during the study period. Babf/Babc demonstrated superior diagnostic sensitivity for B. canis vogeli, whereas Bab7/Bab9 offered broader detection, including H. canis. Phylogenetic analysis revealed close genetic relationships with isolates worldwide. These findings support the use of Babf/Babc for specific diagnosis and Bab7/Bab9 for broader screening in endemic regions.

IntroductionCanine babesiosis, caused by Babesia canis, is a tick-borne hemolytic disease requiring rapid, reliable diagnostic tools to protect canine health in resource-limited settings.MethodsWe developed a colloidal gold immunochromatographic assay (CGIA) strip using a recombinant BcMSA1-BcSA1 fusion protein, expressed in Escherichia coli with a yield of 2.5 mg/L, combining hydrophilic domains of merozoite surface antigen (BcMSA1) and secreted antigen (BcSA1). Seventy-two serum samples from veterinary clinics in Shanxi Province, China (ethical approval SXAU-2022-013), were tested against a commercial ELISA kit (Anigen Rapid B. canis Ab Test Kit), with infections confirmed by microscopy and PCR. Specificity was assessed using sera positive for Theileria spp., Toxoplasma gondii, Ancylostoma caninum, Eimeria canis, Canine distemper virus, and Canine parvovirus.ResultsThe CGIA strip showed no cross-reactivity, a detection limit of 1:8 for B. canis-positive sera, and retained efficacy after 18 months at room temperature. Sensitivity was 84%, specificity 93.6%, and Cohen’s Kappa was 0.935 compared to ELISA.DiscussionThis stable, user-friendly CGIA strip offers an efficient point-of-care solution for B. canis detection, overcoming limitations of traditional methods and supporting epidemiological and clinical applications.

Babesia canis infections are of rising importance in Germany. This retrospective study aimed to correlate hematological and biochemical parameters with acute-phase proteins, levels of parasitemia and antibodies, as well as stays abroad in dogs with acute B. canis infection. Dogs in Germany tested PCR-positive for B. canis and negative for Anaplasma phagocytophilum from January 2018 to December 2024 were included if data on hematocrit, leukocytes, and platelets were available. Hematological scoring (HES) was performed by addition of points for mild (+ 1), moderate (+ 2), and marked (+ 3) anemia, thrombocytopenia, and leukopenia, as well as for the presence of pancytopenia (+ 3) and leukocytosis (+ 1). Results of biochemical and CRP analysis, Babesia antibody determination, and pathogen quantification were included, if available. P ≤ 0.05 in Spearman's rank correlation was considered statistically significant. 342 dogs were included. History of stays abroad was known for 191/342 dogs (55.8%; no stays abroad 113/191 (59.2%), imported 55/191 (28.8%), travel 23/191 (12.0%)). The most common clinicopathologic findings were increased CRP (87.4%), thrombocytopenia (85.1%), anemia (78.7%), hyperbilirubinemia (74.2%), decreased iron levels (51.1%), and leukopenia (49.7%). Dogs without stays abroad showed significantly higher HES (n= 113, median: 6), CRP (n= 60, median: 116.2mg/l), and levels of parasitemia (n= 92, median: 2916 × 103parasites/ml), but lower serum antibody levels (n= 59, median: 1.5 TE) compared with imported dogs (HES: n= 55, median: 2; CRP: n= 23, median: 40.0mg/l; levels of parasitemia: n= 29, median: 23 × 103 parasites/ml; antibodies: n= 37, median: 60.6 TE) (P < 0.001 each). Positive correlations were found between CRP and levels of parasitemia (ρ = 0.444), CRP and HES (ρ = 0.406), as well as levels of parasitemia and HES (ρ = 0.348), while negative correlations were observed between levels of antibodies and parasitemia (ρ = -0.666), as well as antibody levels and HES (ρ = -0.652) (P < 0.001 each). About 60% of dogs with acute B. canis infection had no history of stays abroad, thus representing autochthonous infections. Most dogs without stays abroad were immunologically naive, in contrast to most imported dogs showing positive and high antibody levels. Dogs with high antibody levels showed less severe clinicopathological alterations and lower levels of parasitemia in the peripheral blood, explained by protective antibody activity.