This study was performed to detect morphological changes of the gastric mucosa according to the prevalence of helicobacters in the gastric mucosa of domestic dogs (Canis familiaris) from the Small animal clinic of Faculty of Veterinary Medicine, Latvia within 2008 year period. Mucosal samples were taken from several places of cardiac, fundic and pyloric gland region of the stomach to detect helicobacters with light histological examination. Seventeen dogs of eighteen sampled animals showed presence of tightly spiraled helicobacters. Compared to gastric regions our study showed significantly higher prevalence of helicobacters in the cardiac and fundic gland region than in the less effected pyloric gland region of the stomach. Histological examination also showed the depth of location of helicobacters in gastric pits and deeper glandular epithelium of the gastric mucosa in different regions of the stomach. In the pyloric gland region helicobacters are located deeper in the gastric pits and glandular epithelium than in the gastric mucosa of cardiac and fundic gland region Morphological changes of gastric mucosa was divided into 4 groups: 1) mucosa without morphological changes, 2) mucosal hyperemia, 3) mucosal erosions, and 4) mucosal polips. Morphological changes especially mucosal polips are significantly more in the pyloric gland region than in the cardiac and fundic gland region. The amount of morphological changes in the helicobacter positive and negative samples were not significantly different in the cardiac and fundic gland region, but in the pyloric gland region morphological changes of the gastric mucosa are significantly more in the helicobacter positive samples than in the helicobacter negative samples.

Parafasciolopsosis is a parasitological disease which is caused by the liver fluke Parafasciolopsis fasciolaemorpha. This parasite which belongs to herbivores often causes invasion in elks (Alces alces). The aim of our study was to diagnose the parasite and investigate what kind of histopathological changes it caused in the liver tissue. The study took place in Latvia University of Life Sciences and Technologies, Faculty of Veterinary Medicine, Laboratory of Comparative Pathology and Laboratory of Parasitology. During the study from 2017 to 2018 we collected liver samples and faeces from 46 felled elks of different age and gender, from all over Latvia. Ten grams of faeces were examined for trematode eggs by sedimentation method and a section of liver was examined for the presence of flukes and the histological structure of the liver. In this study Parafasciolopsis fasciolaemorpha were found in 11 samples of liver from 46 elks, with invasion extensity of 24%. The histopathological examination of the liver samples revealed fibrosis, proliferation of bile ducts, pericholangitis, calcerous deposits in bile ducts and other notable histological changes in the liver tissue that can cause hepatic trematodes.

Natural defence mechanisms of the mammary gland tissues play a vital role in protecting the gland from infections. The progress of mammary infection depends on the ability of bacterial pathogens to adapt to milk and udder tissues, and on the various virulence factors they activate, as well as on the cow's response. The levels of immunoglobulins (lg) and lactoferrin (Lf) concentration in the milk from dairy cows with and without subclinical mastitis were determined. In this investigation it was stated that 82.5% of samples were negative, but 17.5% of samples were positive for pathogens. Cows had subclinical mastitis caused by Coagulase negative staphylococci observed in 48.60%, Streptococcus uberis - 32.10%, Staphylococcus aureus - 18.90% of cases in milk samples. There were no significant differences between all classes of immunoglobulins concentration in the milk without pathogens and with pathogens. The lactoferrin concentration was significantly increased for 40.33% in the milk with pathogens.