Relationship between oxidative stress and clinical–pathological aspects in dogs experimentally infected with Rangelia vitalii

Surface immunoglobulins of erythrocytes and platelets in dogs naturally infected by Rangelia vitalii

Rangelia vitalii is a protozoan of the Babesiidae family that parasitizes domestic and wild dogs in South American countries. The main laboratory findings in blood samples from animals infected by R. vitalii are anemia and thrombocytopenia. The aim of this study was to detect IgM and IgG immunoglobulins on the surface of red blood cells and platelets, as well as to determine the percentage of reticulated platelets and reticulocytes in dogs naturally infected by R. vitalii. Blood samples from twenty dogs seen at the Veterinary Hospital of the Federal University of Santa Maria (UFSM) were divided into two groups: the diseased group consisted of blood samples from 10 animals with the diagnosis of rangeliosis, and the healthy group (control) consisted of samples from 10 healthy animals. All diseased dogs showed normocytic normochromic anemia but showed no differences (p > 0.05) in reticulocyte counts compared to healthy dogs. Moreover, IgM and IgG immunoglobulins were detected on the surface of the plasma membrane of red blood cells from both groups, but the amounts did not differ between groups (p > 0.05). Thrombocytopenia in infected animals was classified as severe. The percentage of reticulated platelets was higher (p < 0.001) in diseased dogs than in healthy animals. Diseased animals showed more IgM immunoglobulins bound to the surface of platelets than did the healthy group (p < 0.001). However, the amount of IgG bound to the surface of platelets was not different between groups. In conclusion, we showed that R. vitalii caused immune-mediated thrombocytopenia since IgM immunoglobulins were found on the surface of platelets of diseased dogs. We suggest that the binding of immunoglobulins on platelet surfaces contributes to early destruction of these cells and, consequently, alterations in hemostasis. An increase in reticulated platelets was noted in response to thrombocytopenia, indicating active thrombopoiesis.

Investigation of the 8-hydroxy-2'-deoxyguanosine, total antioxidant and nitric oxide levels of serum in dogs infected with Babesia vogeli

Oxidative stress was defined as corruption of balance between oxidant-antioxidant states in favor of oxidants. In this study, it was aimed to determine oxidative stress in naturally infected dogs with Babesia vogeli. The 8-hydroxy-2'-deoxyguanosine (8-OHdG), nitric oxide (NO) and total antioxidant capacity (TAC) levels in the sera were analyzed by ELISA. 8-OHdG levels increased in B. vogeli infected dogs compared to control group (P<0.05). Also, NO levels increased while TOC levels decreased in B. vogeli infected dogs but these variations were not found as statistically important (P>0.05).

Oxidative stress in cancer-bearing dogs assessed by measuring serum malondialdehyde

Background

Oxidative stress, an excess of reactive oxygen species (ROS), causes lipid peroxidation resulting in cell and tissue damages. It may be associated with the development and progression of cancers in dogs. Malondialdehyde (MDA), the end product of lipid peroxidation, is commonly used as a marker of oxidative stress. The objective of this study was to assess oxidative stress in cancer-bearing dogs by measuring serum MDA levels. All client-owned dogs underwent physical examination at the Veterinary Teaching Hospital, Faculty of Veterinary Medicine, Khon Kaen University to determine the health status with the owner’s consent. Blood samples of cancer-bearing dogs (N = 80) and clinically normal dogs (N = 101) were obtained and subjected for determination of MDA levels. In addition, complete blood count, creatinine, and alanine aminotransferase were measured.

Results

Serum MDA was significantly higher in cancer-bearing dogs than in clinically normal dogs (mean ± SD, 4.68 ± 1.32 μmol/L vs 2.95 ± 0.61 μmol/L, respectively; p < 0.001). Packed cell volume (mean ± SD, 36.18 ± 7.65% vs 44.84 ± 5.54%), hemoglobin (mean ± SD, 11.93 ± 2.88 g% vs 15.17 ± 2.00 g%) and red blood cells (median (IQA), 6.05 (2.15) vs 8.09 (1.34)) were all significantly lower in cancer-bearing dogs than in clinically normal dogs. However, the reverse was true for white blood cells (median (IQA), 18.20 (11.95) vs 14.90 (5.10)). Neither creatinine nor alanine aminotransferase levels were significantly different between groups.

Conclusions

This study supports the conclusion that oxidative stress is associated with many types of cancers in dogs, as serum MDA levels were significantly higher in cancer-bearing dogs compared to clinically normal dogs.

Increase nitric oxide and oxidative stress in dogs experimentally infected by Ehrlichia canis: effect on the pathogenesis of the disease

The aim of this study was to evaluate nitric oxide levels, lipid peroxidation, protein oxidation and glutathione reductase activity in serum of dogs experimentally infected by Ehrlichia canis. Banked serum samples of dogs divided into two groups were used: negative control (n=5) and infected by E. canis (n=5). The concentration of nitrite/nitrate (NOx), lipid peroxidation (TBARS), advanced oxidation protein products (AOPP), and glutathione reductase (GR) activity in sera were evaluated. Samples were collected on days 0, 3, 6, 18 and 30 post-infection (PI). NOx and TBARS levels were significantly (P<0.05) higher in the infected group at 18 and 30 days PI, as well as AOPP levels at 30 days PI when compared to samples from control group. The GR activity was significant (P<0.05) increased in serum of dogs infected by E. canis on days 18 and 30 PI. Based on the increased levels of NOx, TBARS, AOPP and GR activity we concluded that dogs experimentally infected by E. canis develop a state of redox imbalance and that these changes might be involved in the pathophysiology of the disease.

Increased cytokine and nitric oxide levels in serum of dogs experimentally infected with Rangelia vitalii

This study aimed to measure the levels of interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), interleukin 1 (IL-1), interleukin 6 (IL-6), and nitrite/nitrate (NO_x) in serum of dogs experimentally infected with Rangelia vitalii. Twelve female mongrel dogs were divided into 2 groups; group A (uninfected controls) composed by healthy dogs (n=5) and group B consisting of dogs inoculated with R. vitalii (n=7). Animals were monitored by blood smear examinations, which showed intraerythrocytic forms of the parasite on day 5 post-infection (PI). Blood samples were collected through the jugular vein on days 0, 10, and 20 PI to determine the serum levels of IFN-γ, TNF-α, IL-1, IL-6, and NO_x. Cytokines were assessed by ELISA quantitative sandwich technique, and NO_x was measured by the modified Griess method. Cytokine levels (IFN-γ, TNF-α, IL-1, and IL-6) were increased (P<0.01) in serum of infected animals. Serum levels of NO_x were also increased on days 10 PI (P<0.01) and 20 PI (P<0.05) in infected animals. Therefore, the infection with R. vitalii causes an increase in proinflammatory cytokines and nitric oxide content. These alterations may be associated with host immune protection against the parasite.