Immunophysiological State of Dogs According to the Immunoregulatory Index of Their Blood and Spleens

Simple Summary Immunodiagnosis is essential for studying possible changes in the immune system, which, together with the nervous and endocrine systems, constitutes the only necessary regulatory system of the body. Among such studies, the state of the cellular link of immunity is critical. These studies play an essential role in preventing diseases and increasing the effectiveness of diagnostics. The immunoregulatory index, which allows us to assess the immunophysiological status of the direction of adaptive processes and the risk of autoimmune damage to cellular structures, is of critical importance in assessing the state of the immune system. The immunoregulatory index is sensitive to various effects and diseases of the body: liver disease, obesity, mononucleosis, and radionuclide contamination of an area. Scientific studies demonstrate that this index depends on the breed characteristics of animals, has seasonal fluctuations, and is proposed for determination in the selection process for the genetic improvement of already existing breeds. In current conditions, the use of service dogs to search for explosives, people under rubble, and narcotic substances is increasing. It is essential to observe the state of animals’ health because the quality of their official duties will depend on it. In this study, the immunoregulatory index was evaluated in dogs, which allows us to objectively assess the immune status of their body and prevent the development of a secondary immunodeficiency state. Abstract In this study, the immunological characteristics of a dog’s body were established, allowing for a quick reaction to any changes in the immune status and the development of an immunodeficiency state. The immunoregulatory blood index was determined to indicate the ratio of T-helpers and T-suppressors. The immunoregulatory index of the spleen was determined as the ratio of CD4+ cells to CD8+ cells in the field of view of a microscope (eyepiece 10, objective 40) after obtaining histological preparations according to generally accepted methods. It was found that the number of T-helpers decreased by 0.13 × 1012/L, while the number of T-suppressors increased non-significantly by 0.01 × 1012/L after intensive exercise during tasks. The immunoregulatory blood index of dogs was 2.1 ± 0.1 and 1.7 ± 0.13 before and after intensive exercise, respectively. Lymphocytes with markers CD4+ and CD8+ were located almost all in the white pulp; in the red pulp, they were found alone, and their share was 3.4% and 1.9%, respectively. Lymphocytes with CD4+ markers in the spleen’s white pulp were mainly concentrated in lymphoid nodules (60.7%), of which 20.1% were focused on the marginal zone, and slightly less in the light center (19.4%) and the periarterial zone (18.1%). Lymphocytes with CD8+ markers in the spleen’s white pulp were also mainly concentrated in lymphoid nodules, but their number was 8.1% higher (68.8%). The immunoregulatory index of the spleen is 1.9. These findings emphasize the need for the assessment of the immunoregulatory index in service dogs to prevent the development of secondary immunodeficiency and allow them to properly perform their official duties.