After the pathomorphological and histological studies of innards of fallen experimental animals in all realized experiments it was found that sheep and lambs infected with pneumoviral infections (Parainfluenza-3, Adenoviridae, respiratory streptococcosis infection) with their additional infestation with radioactive substances there was stated the acceleration of infectious process, and disease recrudesced up to 2-5 and more times (depending on irradiation doze). The immunity of sheep and lambs decreased caused by reproduction of viruses, and in acute cases animals died but in cases of mild forms the disease transformed into chronic form and caused animal death.

Results of studies of peculiar properties of progesterone content in blood serum of outbred female rats under the influence of intensive ionizing radiation against the background of stress stimulation realized in the conditions of the Republic of Belarus were presented. There were the following animal groups: 1. controlled rats; 2. irradiated rats; 3. stressed animals; 4. rats subjected to ionizing radiation and stress. Research results showed that concentration of progesterone in serum blood of female rats in 3 days after immobilized stress decreased on 40% in comparison with the control indexes. More intensive decreasing of hormone level took place after irradiation in dose of 1 Gy (on 62% in comparison with the controlled group). Combine activity of ionizing radiation and stress involved the decreasing of hormone concentration on 25% in comparison with the controlled group. In ten days there was the restoration of changes. Increase of progesterone concentration in blood serum took place in all tested groups. Hormone level in blood serum of irradiated rats increased on 46,04 nmol/l in comparison with results of the third day after irradiation. Hormone level in blood serum of stressed animals increased on 11,63 nmol/l, in group subjected to the combined activity of ionizing radiation and stress – on7,65nmol/l. On the thirtieth day the indexes of progesterone concentration in blood serum of irradiated rats, stressed rats and rats subjected to ionizing radiation and stress were almost similar to the control indexes