The aim of our study was to investigate histopathologically the incidence of gastrointestinal tract tumours in dogs in the Czech Republic in relation to their age, sex and breed. In total, 29 gastric and 45 intestinal tumours from 3827 gastrointestinal tract biopsies were investigated. The average age of dogs with gastric lymphoma, adenocarcinoma, and other mesenchymal tumours was 7.3 years, 9.5 years, and > 10 years, respectively. Breed predisposition to adenocarcinoma was evidenced in the Belgian Shepherd and Leonberger, to lymphoma in the Doberman (P < 0.01). The most frequent site of adenocarcinoma was antrum pyloricum (66.7%); lymphomas involved gastric wall diffusely. The average age of dogs with intestinal adenoma, adenocarcinoma, lymphoma, leiomyoma or leiomyosarcoma and carcinoid was 7.5, 8.5, 8.5, 12, and 14 years, respectively. The age predisposition to intestinal adenoma and lymphoma was 7-8 years (P < 0.01) and to adenocarcinoma 7-8 years (P < 0.05); mesenchymal tumours occurred at the age of 11-12 years (P < 0.01). Breed predisposition to intestinal adenoma was evidenced in the Pug, Leonberger and English Setter (P < 0.01), to adenocarcinoma in the English Setter (P < 0.01) and Hovawart (P < 0.05), to lymphoma in the Doberman and Hovawart (P < 0.05). The most frequent site of occurrence of intestinal tumours was the colorectal region. The study revealing breed, sex and age predisposition to gastrointestinal tumours in dogs has not been described yet in the literature.

The aim of this study was to investigate the effects of subchronic exposure to atrazine on fish growth and the development of histopathological changes in selected organs (gill, kidney, liver) in Danio rerio. Juvenile growth tests were performed on D. rerio according to OECD method No. 215. For 28 days, fish at an initial age of 30 days were exposed to the environmental atrazine concentration commonly detected in Czech rivers (0.3 μg/L) and a range of sublethal concentrations of atrazine (3.0, 30.0 and 90.0 μg/L). The results showed decreasing growth rates and morphological changes in the liver (dystrophic lesions of hepatocytes) at 90.0 μg/L of atrazine. The environmental concentration of atrazine in Czech rivers did not have any effect on fish growth and development of histopathological changes in D. rerio. The value of NOEC was 30.0 μg/L and the value of LOEC was 90.0 μg/L.

Encephalitozoon cuniculi is an obligate intracellular pathogen that has a wide host distribution, but primarily affects rabbits. The aim of this study was to characterize both the cell-mediated and the antibody response in rabbits after experimental infection using 2 different infection routes: oral and ocular. SPF rabbits were infected with low (10³ spores) and high (10⁷ spores) infection doses. Monitored parameters included clinical signs, detection of spores in urine, antibody response detected with ELISA, and cell-mediated immunity detected by antigen-driven lymphocyte proliferation. At week 13 post-infection, half of the rabbits in each group were suppressed by intramuscular administration of dexamethasone. At week 18 post-infection, animals were euthanized. Clinical signs were mild with exacerbation after immunosuppression. Spores in urine and antigen-specific cell-mediated immunity were detected from weeks 5 and 4 post-infection, respectively. Specific IgM was detected 1 week after infection, and IgG antibodies followed 1 week later in rabbits infected with the high dose. Immunological responses were dose dependent. The authors can conclude that both oral and ocular experimental infection with E. cuniculi resulted in an immune response of the infected animals. Rabbits could be used as an experimental model for the study of ocular microsporidiosis.

The aim of study was to evaluate the effect of atrazine exposure (5, 15, 20, and 30 mg·L−1) on common carp and the ability of regeneration. During 96 h exposure we observed abnormal behavior in fish exposed to 20 and 30 mg·L−1. Mortality and histological alterations were noticed only in the group exposed to 30 mg·L−1. Most experimental groups showed significantly (P < 0.05) lower values of haemoglobin, haematocrit, leukocyte, and lymphocyte and significantly higher values of monocytes, segmented and band neutrophile granulocytes, and also metamyelocytes and myelocytes. A significantly lower (P < 0.05) leukocyte count was also recorded in experimental groups (5 and 15 mg·L−1) after recovery period. Statistically significant (P < 0.05) alterations in glucose, total protein, lactate, phosphorus, calcium, and biopterin as well as in activities of ALT, AST, ALP, and LDH were found in most experimental groups. These changes were most apparent in the groups exposed to 20 and 30 mg·L−1. Most of the indices were found to be restored after the 7-day recovery period with the exception of LDH, ALT, and lactate in the group exposed to 15 mg·L−1. Our results showed that atrazine exposure had a profound negative influence on selected indices and also on histological changes of common carp.

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The aim of this study was to investigate effects of subchronic exposure to sublethal levels of diclofenac on growth, oxidative stress, and histopathological changes in Danio rerio. The juvenile growth tests were performed on Danio rerio according to OECD method number 215. Fish at the age of 20 days were exposed to the diclofenac environmental concentration commonly detected in the Czech rivers (0.02 mg L−1) and the range of sublethal concentrations of diclofenac (5, 15, 30, and 60 mg L−1) for 28 days. A significant decrease (P < 0.01) in the fish growth caused by diclofenac was observed in the concentrations of 30 and 60 mg L−1. The identified value of LOEC (lowest observed effect concentration) was 15 mg L−1 of diclofenac and NOEC (no observed effect concentration) value was 5 mg L−1 of diclofenac. We did not find histopathological changes and changes of selected parameters of oxidative stress (glutathione S-transferase, glutathione reductase) in tested fish. The environmental concentration of diclofenac in Czech rivers did not have any effect on growth, selected oxidative stress parameters (glutathione S-transferase, glutathione reductase), or histopathological changes in Danio rerio but it could have an influence on lipid peroxidation.

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