Oxidative stress in dogs with multicentric lymphoma: Effect of chemotherapy on oxidative and antioxidant biomarkers.

INTRODUCTION: Lymphoma is one of the most common types of cancer in dogs, characterized by the proliferation of lymphoid cells. The treatment of this type of cancer is usually based on drugs with high toxicity, which can cause severe side effects. OBJECTIVES: Therefore, the aim of this study was to measure the levels of advanced oxidation protein products (AOPP), thiobarbituric acid reactive substances (TBARS), and ferric reducing antioxidant power (FRAP) in dogs with multicentric lymphoma before and after chemotherapy. METHODS: For this purpose, serum samples of 25 dogs diagnosed with multicentric lymphoma and 15 healthy dogs were used. The animals were exposed to CHOP chemotherapy (cyclophosphamide, vincristine, doxorubicin, and prednisone) and serum samples were collected 5 weeks after treatment. RESULTS: High levels of TBARS, AOPP, and FRAP were observed in sera of dogs with multicentric lymphoma when compared to healthy dogs (P < 0.01), and even higher levels (TBARS and AOPP) were found after chemotherapy i.e. treatment exacerbated the oxidative stress levels. On the other hand, FRAP levels did not differ statistically between animals with lymphoma before and after treatment (P > 0.05). Exacerbated oxidative stress was observed in dogs with multicentric lymphoma Group II (Stage IV-V: involvement of lymph nodes and organs) compared to those in Group I (Stage I-III: only affected lymph nodes) of the disease, as well as the dogs with clinical signs and T immunophenotype. Another important result was observed after chemotherapy, where FRAP levels were higher in dogs that showed complete disease remission compared to animals with progressive disease. CONCLUSIONS: Therefore, dogs with lymphoma showed protein oxidation and lipid peroxidation, as well as increased total antioxidants before and after chemotherapy compared to the control group.

Influence of experimental canine ehrlichiosis on the E-ADA activity and purine levels in serum and possible functional correlations with pathogenesis.

The aim of this study was to evaluate adenosine deaminase activity and purines levels in serum of dogs experimentally infected by Ehrlichia canis. Banked serum samples of dogs divided into two groups with five animals each: healthy animals and animals infected by E. canis. The concentration of purines (adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), adenosine, inosine, hypoxanthine, xanthine and uric acid), and adenosine deaminase (E-ADA) activity in sera were evaluated. Samples were collected on days 12 and 30 post-infection (PI). The E-ADA activity showed a significant reduction on day 12 PI, and increased on day 30 PI in dogs infected with E. canis. On day 12, an increase in seric concentration of ATP, ADP and adenosine was verified, and different levels of hypoxanthine, xanthine and uric acid had a drastic reduction in infected compared healthy dogs (P<0.05). However, on day 30 PI, the levels of seric ADP and AMP decreased, unlike the concentration of xanthine and uric acid that increased significantly in infected dogs (P<0.05). Therefore, the activity of E-ADA and purine levels are altered in experimental canine ehrlichiosis, probably with the purpose of modulating the pathogenesis of the disease related to immune response, oxidative stress and coagulation disorders in acute phase.

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.

Molecular characterization of Hepatozoon canis in dogs from Colombia.

Hepatozoonosis is a tick-borne disease whose transmission to dogs occurs by ingestion of oocysts infected ticks or feeding on preys infested by infected ticks. Until now, there is no previous report of molecular characterization of Hepatozoon sp. in dogs from Colombia. EDTA blood samples were collected from 91 dogs from central-western region of Colombia (Bogotá, Bucaramanga, and Villavicencio cities) and submitted to 18S rRNA Hepatozoon sp. PCR and blood smears confection. Phylogenetic analysis was used to access the identity of Hepatozoon species found in sampled dogs. From 91 sampled dogs, 29 (31.8%) were positive to Hepatozoon sp. (25 dogs were only positive in PCR, 1 was positive only in blood smears, and 3 were positive in both blood smears and PCR). After sequencing, the found Hepatozoon sp. DNA showed 100% of identity with Hepatozoon canis DNA isolates. The phylogenetic tree supported the identity of the found Hepatozoon sp. DNA, showing that the isolates from Colombia were placed in the same clade than other H. canis isolates from Venezuela, Spain, and Taiwan. This is the first molecular detection of H. canis in dogs from Colombia.