[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.

[Specific prophylaxis of gangrenous mastitis in sheep]. / Spetsifichna profilaktika na gangrenozniia mastit po ovtsete.

Staphylococci were isolated from the udder of dead sheep and sheep that were emergency-slaughtered because of a gangrenous mastitis infection. The organisms proved to be hemolytic and mannite- and catalase-positive, and were referred to various phage types, being most frequently lysed by phages 78 and 42E. Toxin production depended on the quality of the medium used, the amount of atmospheric carbon dioxide, the period of incubation, and the individual strain qualities. Strains of high hemolysin production were used to prepare a vaccine which was applied to sheep both experimentally and in the conditions of the practice at the time of active lactation. Following treatment of the vaccinated animals parallel to a number of controls with one and the same challenging agent morbidity with the first group ran as high as 25 per cent with no death cases, while with the second group it was 100 per cent, and mortality with the latter was 50 per cent. Immunity with the use of the vaccine lasted but four months, therefore, revaccination was needed by the end of this period.

[Properties of Bacteroides nodosus isolated from cattle]. / Svoistva na Bacteroides nodosus, izoliran ot goveda.

A total of five strains of Bacteroides nodosus were isolated from cattle with interdigital dermatitis on a number of farms. With regard to their cultural and morphologic properties and response to carbohydrates these strains did not differ from B. nodosus strains that caused foot rot in sheep. However, their K-antigen was different from the one of the B. nodosus strains isolated from sheep with foot rot as established via the hemagglutination test. No antigenic variations were found with the strains isolated from cattle. The tests with the proteolytic activity of the isolated strains showed that it was considerably lower than the activity of the strains isolated from sheep.

[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.

[Decarboxylase and hemolytic activity in Listeria]. / Otnosno dekarboksilaznata i khemolitchnata aktivnost na listeriite.

Investigated were a great number of Listeria monocytogenes strains of 1/2a, 4b, 5, and 6 serotypes for the production of decarboxilase, hemolysin, and pathogenicity for albino mice. It was found that only representatives of 1/2a serotype (40 out of 93 studied strains) produced decarboxilase for glutamic acid. The hemolytic activity was evaluated by means of a Spekol after the hemolysis of sheep erythrocytes. A correlation was established between hemolytic activity and pathogenicity, consisting in that albino mice were killed in a higher percent by strains that showed higher hemolytic activity.

[Streptococcal infection in newborn lambs]. / Streptokokova infektsiia po novorodeni agneta.

A disease was observed in newborn lambs with a high mortality rate. Streptococcus zooepidemicus was isolated from dead lambs. The disease was reproduced through the intratracheal infection of lambs with a culture of the isolated organism. The picture of septicaemia was observed, strong symptoms of the disease being noticed with the involvement of the respiratory system. The morphologic changes were mainly seen within the region of the lungs, pleura, and pericardium. Histologically, there were lesions characteristic of an acute septic process. It was concluded that Streptococcus zooepidemicus was highly pathogenic for young lambs.

[Respiratory diseases in sheep due to Mycoplasma ovipneumoniae]. / Prouchvaniia vurkhu respiratorni zaboliavaniia po ovtse s uchastie Mycoplasma ovipneumoniae.

Mycoplasma ovipneumoniae was isolated from sheep and lambs affected with a respiratory disease. It was established that the pneumonic disease caused by this organism was a severe one, with high mortality rate in young lambs. Adult sheep and older lambs remained chronically affected. Susceptibility varied, depending on the breed of the animals, some imported animals running a more severe course of the disease than the local ones. The disease was artificially induced in lambs at the joint infection with M. ovipneumoniae and P. haemolytica. The morphologic changes in the lungs consisted in a prevailing proliferation of the septal cells and polynuclear cells in the alveoli, an interseptal histiocyte proliferation, and a serous leukocyte infiltration.

[Active immunoprophylaxis of Salmonella abortion in sheep]. / Prinos kum aktivnata imunoprofilaktika na salmonelozniia abort po ovtsete.

A live vaccine was produced against the salmonellosis abortion in sheep with the use of an attenuated (chemically) strain of Salmonella abortus ovis. It was tested comparatively with a killed vaccine in sheep under experimental conditions. The dynamics of the agglutinating antibodies was followed up after immunization with the two vaccines, studying also the class of the immunoglobulins. It was found that the production of class IgG antibodies in sheep treated with the live vaccine proceeded more rapidly and at a higher level. After challenging with a virulent Salmonella abortus ovis strain te animals treated with the killed vaccine and those left as controls miscarried, while the sheep immunized with the live vaccine lambed normally. The vaccine was applied in field conditions to more than 400 000 sheep without postvaccinal accidents whatever. On farms where Salmonella abortus ovis infection was recorded in sheep the disease has no longer been a problem with the regular annual vaccinations of these animals.

[Experimental induction of foot rot in sheep]. / Eksperimentalno predizvikane na kopiten gnilets po ovtsete.

By means of local strains Bacteroides nodusus was reproduced experimentally a case of foot-rot with sheep. For the appearance and the development of the disease it was necessary, before the infection, to keep the sheep in damp and uncleaned from fecal impurities room. Besides that, of decisive importance was the scarification of the skin-horny junction in the interungular slit. The combination of Bacteroides nodusus with Spirohaeta penorta and Corynebacterium piogenes resulted in more serious changes in the infected hooves.

[Experiments with vaccination against infectious epididymitis in rams]. / Opiti za vaksinatsiia sreshtu zarazniia epididimit po kochovete.

Two killed vaccines were produced, differing by the adjuvant used--a hydroxide one and an oil one--employing four strains of Brucella ovis. They were applied twice at an interval of 20 days to rams under experimental conditions as well as to rams in filed conditions. On the 45th day following vaccination the experimental rams were challenged with a virulent Brucella ovis strain. To determine the acquired resistance the rams were investigated after the complement-fixation test, hemagglutination reaction, and agar gel immunodiffusion as well as through clinical and bacteriological examination of sampled semen for the presence of bacteria. It was established that rams treated with an oil vaccine built up a solid immunity. The postvaccinal antibodies disappeared after the third month of vaccination. It is suggested to carry out vaccinations with rams of the infected flocks each 6 months. The infected animals can be identified by means of serologic examination three months following vaccination. Vaccination makes it possible to use valuable animals for a longer period, which, though infected are not hazardous in spreading the infection in the flock. A programme is referred to for the curing of flocks by means of vaccination applied to the intact rams and gradual elimination of the infected animals.

[Epizootiology of foot rot in sheep]. / Prouchvane vurkhu epizootologiiata na kopitniia gnilets po ovtsete.

Investigations were carried out on the outbreak and spread of foot rot in sheep as well as on the ways of its restriction and eradication. It was found that the disease had been introduced with the import of breeding animals, its further spread being associated with the activity of the Breeding Centers for pedigree animals. The diseased animals have been 25 per cent, on an average, for the whole country, and the economic losses, as expressed in production parameters, have amounted to: produce of animal origin--20 per cent; culling of animals--15 per cent; mortality--1 per cent. Best in the group treatment of the affected animals prove: the dipping in a 5--10 per cent solution of formalin or a 20 per cent solution of copper sulfate, combined with the respective surgical and orthopedic handling and the disinfection of premises. The individual parenteral treatment and the local application of antibiotics and chemotherapeutics have proved suitable and successful in the cases of moderate spread of the disease. The eradication of foot rot can be achieved only via the planned and complex application of pertinent measures.