Acute radiation sickness in sheep affected by respiratory diseases

It is common knowledge that reduction of immunologic reactivity can increase susceptibility of an organism to exogenous infections and risk of death of animals following exposure to sublethal radiation doses. Respiratory diseases also reduce immunologic reactivity of an organism. Study of radiation sickness in animals affected by respiratory diseases will allow researchers to estimate possible losses of livestock due to radiological emergency. The article describes results of study of acute radiation sickness developed in sheep affected by chronic respiratory diseases. Experimental data were obtained at the Research Institute of Radiology and Agroecology, Obninsk. Healthy (control) sheep (5) and the animals (5) with chronic respiratory diseases used in the study were brought from farms of Kaluga oblast. All species had veterinary certificates, were quarantined at the institutional vivarium for 20 days. The use of the laboratory animals was governed by the Russian national standard GOST 33215-2014 determining laboratory animals care, management, housing conditions and performance of research procedures. The animals were gamma-irradiated, radiation dose was 4 Gy, radiation source - 137Cs, dose-rate 1 Gy/h. Irradiation ripple was less than 10-15%. Blood was taken in every 5 days in fasting state in mornings before and after irradiation during the follow up period of 30 days. health status of the animals was estimated by clinical examination, biochemical and microbiological tests. Respiratory diseases were found to exacerbate radiation sickness course. This can be caused by suppression of bone-marrow hemopoiesis, as well as by exacerbation of respiratory diseases, as it follows form radiological reports. In irradiated sheep affected by respiratory diseases the leucocytes content can be at the level of physiological norm due to high original level of white blood cells and reduced beta-lytic activity of the blood in the initial period of radiation sickness. That is why in order to predict the disease outcome it makes sense to use the lethality index, which is calculated with account of WBC content and b-lytic activity of the blood. The obtained information should be taken into account when analyzing surveillance of livestock animals irradiated as a result of radiological events.