Systemic inflammatory response syndrome in dogs naturally infected with Babesia canis: Association with the parasite load and host factors

Age, sex and breed effect on laboratory parameters in natural Babesia canis infection

We tested the hypothesis that age, breed, and sex are related to hematology, biochemistry, acute phase proteins (APPs), seroreactivity and level of parasitemia in dogs with an acute phase response (APR) due to Babesia canis infection. The study enrolled 61 privately owned dogs that naturally acquired B. canis infection. Groups were formed according to the age: young dogs less than one year, and adult dogs more than one year old. Moreover, the group of males was compared to females and purebred to mixed breed dogs. Seroreactivity was tested with immunofluorescence antibody test, level of parasitemia with real-time polymerase chain reaction (real-time PCR), hematology, and biochemistry with automatic analyzers, serum amyloid A with enzyme-linked immunosorbent assay, fibrinogen with heat precipitation and ceruloplasmin and paraoxonase-1 with manual spectrophotometric methods. For protein separation agarose gel electrophoresis was used. The main changes in the whole population of B. canis-infected dogs were fever, pancytopenia, and change in APPs level. One-third of young, and 96% of adult dogs were seropositive (P < 0.001). The level of parasitemia was higher in the young dogs (P < 0.001). Erythroid lineage parameters (P < 0.01), and leukocytes (P < 0.05) were lower in the young, when compared to the adult dogs. Young dogs had lower total globulins (P < 0.001), β- and γ-globulins (P < 0.001), and higher α-globulins (P = 0.022) than adult dogs. Young dogs had higher concentrations of phosphate (P = 0.003) and cholesterol (P < 0.001) and lower amylase (P = 0.014) and lipase activity (P = 0.020) than adult ones. Male dogs had lower neutrophil count than females (P = 0.035), and purebred dogs had more band neutrophils than mixed breed dogs (P = 0.004). In conclusion, dogs with natural Babesia canis infection at a young age have more severe anemia and APR including leukopenia than adults. Male and purebred dogs might also have more severe APR than females and mix-breeds, as they have more pronounced changes related to the myeloid lineage.

The Diverse Pathogenicity of Various Babesia Parasite Species That Infect Dogs

Babesia species infect a very wide range of mammal hosts across the globe, and zoonotic infections are of growing concern. Several species of the Babesia genus infect dogs, and some of these cause significant morbidity and mortality. The Apicomplexan parasite resides within the red cell and infections result in direct damage to the host through intra- and extravascular hemolysis. An exuberant inflammatory response by the host to some species of Babesia parasites also results in significant collateral damage to the host. Canine infections have been the subject of many studies as the well-being of these companion animals is increasingly threatened by the spread of tick vectors and an increasingly mobile dog population. There are currently no widely available and effective vaccines, and effective treatment can be challenging. Understanding disease pathogenesis underlies the development of new treatments. The varying pathogenicity of the various Babesia parasite species that infect dogs offers an opportunity to explore the molecular basis for the wide range of diseases caused by infection with this parasite genus. In this review, we focus on what has been reported about the clinical presentation of Babesia-infected dogs in an attempt to compare the severity of disease caused by different Babesia species.

Prognostic Potential of Thrombocyte Indices, Acute Phase Proteins, Electrolytes and Acid-Base Markers in Canine Parvovirus Infected Dogs With Systemic Inflammatory Response Syndrome

Dogs with canine parvovirus enteritis (CPVE) that develop systemic inflammatory response syndrome (SIRS) frequently have a poor prognosis. The aim of the study was to assess the prognostic potential of thrombocyte indices, acute phase proteins, electrolytes, and acid-base markers in CPVE puppies with SIRS (CPVE-SIRS+) at admission. A case-controlled, prospective, and observational study was performed on 36 CPVE puppies. Mean concentrations of C-reactive protein (CRP), albumin, thrombocyte count, mean platelet volume (MPV), platelet distribution width (PDW), sodium (Na+), potassium (K+), chloride (Cl-) and ionized calcium (iCa) were measured and strong ion difference 3 (SID3), ATOT-albumin and ATOT-total protein were determined in CPVE-SIRS+ survivors and nonsurvivors. A prognostic cut-off value for predicting the disease outcome was determined by receiver operating characteristic (ROC) curve analysis. The mean values of MPV, PDW and CRP were significantly higher and the mean values of albumin, Cl- and ATOT-albumin were significantly lower in CPVE-SIRS+ nonsurvivor than CPVE-SIRS+ survivor puppies on the day of admission, but the thrombocyte count, Na+, K+, iCa, SID3 and ATOT- total protein values did not differ significantly. The positive predictive values (PPVs) for survival using cut-off value of MPV (≤15.08 fL), PDW (≤14.85%), CRP (≤180.7 mg/L), albumin (≥1.795 g/dL), Cl- (≥96.00 mmol/L), and ATOT-albumin (≥7.539) were determined as 100%, 100%, 100%, 80%, 100%, and 80%, respectively with better area under ROC curve and sensitivity. Based on sensitivity, specificity, and PPVs from ROC analysis, it is concluded that the determination of Cl- concentration and MPV at admission followed by CRP will serve as the most appropriate biomarkers in predicting the disease outcome of CPVE puppies that develop SIRS.

Autochthonous Babesia canis infections in 49 dogs in Germany

BACKGROUND

Vector-borne diseases are of increasing importance in Germany. Since 2015, autochthonous cases have been increasingly documented in Berlin/Brandenburg.

OBJECTIVES

Describe autochthonous Babesia canis infection in the Berlin/Brandenburg region.

ANIMALS

Forty-nine dogs with autochthonous B. canis infection.

METHODS

Evaluation of history, clinical signs, laboratory abnormalities, treatment, and outcome.

RESULTS

Dogs were presented between March and August (9) and September and January (40) in the years 2015-2021. Historical and clinical findings were lethargy (100%), pale mucous membranes (63%), fever (50%), and pigmenturia (52%). Common clinicopathological findings were thrombocytopenia (100%), anemia (85%), intravascular hemolysis (52%), pancytopenia (41%), and systemic inflammatory response syndrome (SIRS; 37%). Babesia detection was based on blood smear evaluation (n = 40) and PCR targeting the 18S rRNA gene of piroplasms (n = 49). Sequencing indicated 99.47% to 100% identity to B. canis sequences from GenBank. All dogs were treated with imidocarb (2.4-6.3 mg/kg; median, 5 mg/kg); 8 dogs received 1, 35 received 2, and 1 dog each received 3, 4, or 5 injections, respectively. Continued PCR-positive results were detected in 7 dogs after the 1st, in 5 after the 2nd, in 2 after the 3rd, and in 1 28 days after the 4th injection. Four dogs were euthanized and 3 dogs died.

CONCLUSIONS AND CLINICAL IMPORTANCE

Autochthonous B. canis infections in Berlin/Brandenburg were associated with severe clinicopathological changes, SIRS, and multiorgan involvement. Testing by PCR during and after treatment is advisable to monitor treatment success. Screening of blood donors in high-risk areas and year-round tick protection is strongly recommended.

Canine babesiosis in Austria in the 21st century - A review of cases

A retrospective study on 699 cases of canine babesiosis presented to veterinary clinics in eastern Austria were evaluated for the location where infection had presumably taken place. Of these, 542 (77.54%) had acquired the infection in Austria, while the majority of non-autochthonous cases came from neighboring countries, most notable Hungary. Both groups were recorded primarily in Vienna, eastern Lower Austria and Burgenland, but cases from the southern (Styria, Carinthia) and western (Upper Austria, Tyrol, Salzburg) provinces of the country were also recorded. Records were made all year round, with most cases in spring (46.6%) and fall (48.4%). The annual cases ranged from four to 58 (mean: 31.8) with large fluctuations and no visible trend for an in- or decrease. The tick vector of Babesia canis, Dermacentor reticulatus, is present in Austria but displays a very patchy distribution, and its occurrence and activity are not readily foretold, which might be a reason why its presumably increasing density in Europe is not reflected by increased incidences of canine babesiosis. Another factor that may influence the numbers of cases per year could be the application (or non-application) of acaricidal or repellent compounds. A limitation of this study is that bias is exerted by the location of the participating clinics, and by the unknown rate of infections that does not induce clinical symptoms and is likely not presented in veterinary practices and clinics. The data, however, clearly show that at least the lowlands of Austria are endemic for B. canis, and appropriate tick control must be advised all year round.

Electrocardiographic Findings and Cardiac Troponin I Assay in Dogs with SIRS Diagnosis

Several studies performed in humans have demonstrated that the onset of systemic inflammatory response syndrome (SIRS) represents a high risk condition to develop myocardial damage and arrhythmias. Therefore, we also hypothesized cardiac involment for dogs affected by SIRS. To assess this hypothesis, 24 dogs with a diagnosis of SIRS (13 entire males, 7 entire females, and 4 spayed females) with an age ranging from 4 to 11 years (mean 5.6 years) and an average weight of 24 kg (range from 5 to 47 kg) were enrolled. The dogs were divided into two groups according to their prognosis: Survivors (G1) and not survivors (G2), composed by 13 and 11 dogs, respectively. Moreover, healthy dogs were included as the control group (CTR). All the dogs with a history of cardiac or renal disease were excluded. At the inclusion, each patient underwent a physical examination and a complete cell count, and a biochemistry panel (including electrolyte profile) was performed; moreover, the blood cardiac Troponin I (cTnI) was measured. For each clinical variable indicative of SIRS, a score between 0 (absence) and 1 (presence) was applied. Furthermore, an electrocardiographic examination was recorded. Seventeen out of 24 (70.8%) dogs with SIRS showed arrhythmias, of which n. 6 belonged to the G1, while n. 11 belonged to the G2. Most represented findings were sinus tachycardia (7/17; 41.1%), followed by monomorphic premature ventricular beats (6/17; 35.3%), less common were first-degree atrioventricular block (2/17; 11.7%) and sinus bradycardia 1/17; 5.8%). Notably, in G1 dogs, only sinus tachycardia and premature ventricular beats were observed. G2 dogs presented a number of total and banded leukocytes significantly higher than those of G1 (p = 0.002 and 0.049), in the same manner, the clinical score suggestive of SIRS (3 vs. 2.1) was significantly higher in G2 than in G1 dogs (p = 0.01). Moreover, a significantly higher value of cTnI was observed in the G2 group compared to the G1 group (p = 0.006). Data presented here suggested a cardiac involvement in dogs with SIRS, analogously to humans, that may significantly influence the patient's prognosis.

Seasonal differences in the intensity of acute phase response in dogs infected with Babesia canis

The highest number of acute Babesia canis cases in dogs is recorded over the February-May (Feb-May) period, which also represents the optimal climate conditions for tick activity in Belgrade, Serbia. A possibility that the acute phase response is more intense in dogs developing the disease in the Feb-May period compared with the response in other time periods of the year was tested. A total of 63 client-owned dogs with acute B. canis infection were enrolled and the routine hematology and biochemistry parameters-serum amyloid A (SAA), IgG against B. canis, level of parasitemia, ceruloplasmin (CER), paraoxonase-1 (PON-1), and fibrinogen-were measured. Acute phase indexes (API) were calculated as (SAA×CER)/(Iron×PON-1) and (SAA×CER)/(Albumin×Iron). Statistics included Kruskal-Wallis test and logistic regression analysis. The results showed that in the Feb-May period, the following parameters were lower: creatinine, albumin, iron, and level of parasitemia. Furthermore, increased API values were more probable in the Feb-May than in the other periods. Together, higher acute phase response intensity and presumptive hemodilution in the Feb-May period indicate a more acute course of B. canis infection than in other time periods of the year.

Low serum levels of promatrix metalloproteinase-2 and -9 occur during acute Babesia canis infection in dogs

Inflammation is a hallmark of the acute Babesia canis infection. Promatrix metalloproteinase (proMMP)-2 and -9 are involved in inflammation, but their levels have not been analyzed in canine babesiosis. We hypothesized that in dogs infected with B. canis, serum proMMP-2 and -9 levels change between presentation and recovery. Degree of the change differs if dogs develop systemic inflammatory response syndrome (SIRS). This study included 24 dogs with an acute B. canis infection, at presentation and after two weeks. We used routine hematology and biochemistry methods, spectrophotometry for the acute-phase proteins, microscopy for parasitemia and zymography for (pro)MMPs. In vitro endothelial cells and leukocyte short-term cultures, and platelet lysates were used to detect specific MMP activity. Statistical analyses included Wilcoxon test for paired samples, Mann-Whitney U test and Spearman's rank correlation. Our results showed that endothelial cells, leukocytes and platelets are the source of proMMP-2 and proMMP-9. Furthermore, both proMMPs were lower at presentation than after recovery (p < 0.001). At presentation, proMMP-9 levels correlated with parasitemia (rho = -0.616, p = 0.009), total leukocyte (rho = 0.704, p < 0.001) and neutrophil counts (rho = 0.741, p < 0.001). Extent of alterations in proMMP-2 levels between presentation and recovery was lower (p = 0.038) in dogs with SIRS than in non-SIRS dogs, while levels of proMMP-9 were comparable between these groups. Our conclusion is that during the acute B. canis infection, low serum levels of proMMP-2 and proMMP-9 at presentation reflect thrombocytopenia and leukopenia. Decreased proMMP-2 level could be associated with SIRS.

Relationship between Changes in Hematological Parameters, Levels of Acute Phase Proteins and Redox Homeostasis during Acute Babesia canis Infection in Dogs

Hemolysis and systemic acute inflammation characterize canine babesiosis caused by the intraerythrocytic protozoan parasite Babesia canis. Our hypothesis was that blood redox homeostasis of patients that suffered acute B. canis infection might be disturbed even after treatment with imidocarb-dipropionate and successful clinical recovery. Eight owner dogs with acute B. canis infection were used for this study. We analyzed the complete blood count, acute phase proteins (ceruloplasmin, haptoglobin, paraoxonase-1) in the serum, antioxidant enzymes (catalase and glutathione peroxidase) in the erythrocytes, and oxidative stress markers (malondialdehyde in erythrocytes and thiol groups in serum) at presentation and 15 days after treatment. Results were evaluated by corresponding statistical tests. At presentation, anemia, low/normal leukocyte count and severe thrombocytopenia occurred together with increased ceruloplasmin, haptoglobin levels within the reference interval, decreased paraoxonase-1 and compromised antioxidant defense in the red blood cells. After treatment and successful clinical recovery, hematological values generally fitted within the reference intervals, acute phase proteins were within the physiological levels in the majority of cases and the activities of the antioxidant enzymes were increased. However, elevated malondialdehyde levels indicated increased oxidative damage of erythrocytes that remained as a deleterious sequel despite a successful clinical recovery of the dogs.