[Experimental Salmonella dublin infection in calves]. / Eksperimentalna infektsiia sus Salmonella dublin pri teletata.

Calves, aged 20 days, were experimentally infected with Salmonella dublin. The animals of one-group were treated at the rate of 6.10(8), and those of another--at 2.10(10) up to 4.10(10) live bacterial cells. The calves of the first group showed no clear clinical symptoms of a disease; neither did they manifest regular shedding of bacterial cells. The calves of the second group presented a typical clinical picture, with more regular shedding of bacteria through nasal discharges and the feces. After killing the animals Salmonella dublin organisms were found in all parenchymal organs and in the lymph nodes. Morphologically, the prevalence was established of inflammatory necrobiotic processes in the liver, with activation and proliferation of the sinus endothelium of the lymph nodes, and catarrhal inflammation of varying manifestation in the small intestine.

[Immunoprophylaxis of Salmonella infection caused by S. dublin in calves]. / Vurkhu imunoprofilaktikata na salmonelozata po teletata, prichiniavana ot S. dublin.

Studied is the active immunoprophylaxis of calves on farms with a Salmonella dublin infection, using a live vaccine produced with a S. dublin attenuated strain. The disease was fully suppressed among calves through vaccination after the tenth day following birth. However, the source of infection was not done away with, and it was most likely to be found in adult cattle. This was reasonable to believe as there was a second outbreak of the disease in a group of unvaccinated, newborn calves. The regular vaccination is suggested of all newborn calves up to the time when the adult population would occasionally be replaced.

[Pathomorphology of gastroenteritis in newborn calves]. / Vurkhu patomorfologiiata na gastroenterita pri novorodenite teleta.

The morphologic changes were studied in the parenchymal and digestive organs of a total of 39 calves with gastroenteritis from which pathogenic Escherichia coli organisms were isolated. A correlation was established between the age of calves and the forms of gastroenteritis manifestation. In 1 to 3-day-old calves 63.6 per cent of the cases presented histologic changes of enteritis, and 36.3 per cent presented the septic form of the disease, while in 4 to 7 day-old calves these forms were presented in equal percent. In 8 to 12-day-old animals septic changes were seen in 71.4 per cent of the cases, and toxic changes-in 28.5 per cent. The same age group showed initial changes typical of catarrhal (28.2 per cent) and interstitial (37.7 per cent) pneumonia. With the advance in age the histologic changes of septicaemia showed a rising trend as against the enterotoxaemic and enterotoxic form. The coli infections in 90 per cent of the investigated cases were accompanied by degenerative changes in the kidneys. In calves with nervous symptoms there were hyperemia, perivascular and pericellular edema and status cribrosus of the brain, and occasionally - lymphocytic and leukocytic infiltrations in the leptomeninges.