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PATHOLOGICAL STUDIES OF GUINEA PIGS WITH EXPERIMENTAL
BRADZOT
O.A. Dzhuraev, c. v. s.
Uzbek Research Veterinary Institute
Resume:
The article presents the results of experimental studies on guinea pigs for infection
with a local strain of the causative agent of bradzot. The development of pathoanatomical and
morphological changes at the level of tissues and cells is outlined. The importance of timely
diagnosis in the fight against this infection is highlighted.
Key words:
bradzot, disease, pathological material, pathomorphological studies,
experiment, fixation, paraffin, histology, histosections, Cl. Oedematiens.
For the accelerated development of astrakhan breeding, which is one of the main ones in animal
husbandry, in order to obtain a healthy offspring and increase the productivity of the industry, it is
necessary to properly keep sheep and protect them from various diseases. A serious obstacle in this
case is the bradzot of sheep, which is often found in subjects engaged in astrakhan breeding and in
the personal courtyard of the population of Uzbekistan.
Mostly well-fed and inactive animals, regardless of breed, sex and age, get sick. The disease is
observed in all seasons (more often in the cold season) of the year. The main reasons contributing to
the emergence of bradzot are sheep grazing on pastures in late autumn, winter and early spring in
the presence of frost and dew, a decrease in the div's resistance due to animal diseases with
various helminth infections, as well as a lack of proteins, vitamins and minerals.
The disease proceeds at lightning speed or superacutely, while in the div of the animal the
pathogen releases a strong toxin, as a result of which sheep die very quickly (within 20-30 minutes,
sometimes 2-8 hours). The very large economic damage caused by bradzot is made up of the
disease of 30-35% of the sheep in the flock, the mortality rate of which reaches 90-100%, the
destruction of products and raw materials from the fallen and forcedly killed animals due to their
worthlessness, as well as the cost of preventive measures.
The causative agent of the disease - Cl. Oedematiens is a mobile anaerobe; it forms spores in the
external environment and in the div of dead animals. The spores of the pathogen enter the div of
healthy animals with food, water, soil and manure. The spores of the pathogen bradzot are highly
resistant to external stimuli, as a result of which they are constantly in the external environment and
their destruction is almost impossible.
For effective confrontation with this disease, it is necessary, first of all, to study the epizootology of
sheep bradzot, timely and correct diagnosis and improvement of preventive measures. In this
regard, the isolation of local strains of Cl. Oedematiens from pathological material from households
that are unfavorable for this disease, as well as the study of the cultural, morphological, biological
and pathogenic properties of this pathogen.
Materials and research methods.
In some farms of Kashkadarya, Samarkand and Jizzakh regions, pathological material (liver,
kidneys, lungs, heart, spleen, duodenum, abomasum and bone marrow) was taken from animals that
died on suspicion of bradzot, as well as diagnostically forcedly slaughtered sheep, which was
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subjected to thorough microbiological studies in the laboratory of the Research Institute of
Veterinary Medicine, and the causative agent of sheep bradzot was isolated. For identification,
isolated pure culture as Cl. Oedematiens, the cultural-morphological, tinctorial, biochemical and
biological properties of this pathogen strain were carefully studied.
To determine the 50 and 100 percent lethal dose of our culture of Cl. Oedematiens, a biological
sample was made on 16 heads of guinea pigs with a live weight of 300-350 grams. For this,
laboratory animals were divided into 4 groups of 4 animals each. The first three experimental
groups were infected with a daily culture of Cl. Oedematiens, isolated from the pathological
material brought by us and grown on the Kitt-Tarozzi medium, into the abdominal cavity at the
doses indicated in the table below. Group 4 of laboratory animals was not infected and served as a
control.
Results of studies to determine the lethal dose of the C l. Oedematiens strain for guinea pigs.
Groups
Number
of goals
Dose of
infection,
ml
Bioassay results (heads, %)
Perished
Survived
Lethal dose
1-experimental
2- experimental
3-experimental
4-experimental
4
4
4
4
0,26
0,28
0,30
-
2
3
4
-
2
1
-
4
LD
50
LD
75
LD
100
-
Research results:
Guinea pigs of the experimental and control groups were under clinical
observation for ten days. In laboratory animals of the experimental groups infected with the bradzot
pathogen, after 12-14 hours after infection, clinical signs of the disease began to appear. At the
same time, an increase in div temperature up to 41.5 °C, dullness and symptoms such as rapid
heartbeat, loss of appetite and inactivity were recorded. The guinea pigs, which developed clinical
signs of the disease, died after 48-52 hours in a severe coma. Thus, experimental studies have
established that for guinea pigs infected intraperitoneally with a daily culture of a local strain of the
pathogen bradzot, LD
50
is 0.26 ml, and when infected at a dose of 0.30 ml of the culture, all
laboratory animals die (LD
100
).
The pathological anatomical picture of the autopsy of laboratory animals that died as a result of
experimental infection was characterized by the presence of an unpleasant odor and rapid swelling
of the corpse of guinea pigs, slight pulling of the coat from the skin, and filling of the abdominal
cavity with fluid. The small intestine is filled with gases, the inner walls of the intestines and
stomach are prone to hemorrhages, the heart shirt contains a yellowish liquid, the heart ears are
blackened. There are multiple petechial hemorrhages on the lungs and liver, the capsule of the
kidneys is easily separated, the spleen is enlarged.
From the internal organs (lungs, heart, liver, kidneys and spleen) of guinea pigs subjected to
laboratory tests, pathological material was taken in the form of pieces 0.5-1 cm
3
in size at the border
of healthy and damaged tissue for further morphological studies.
All dead guinea pigs after post-mortem examinations and taking pathological material were
destroyed by incineration. The cages in which the laboratory animals were kept, as well as the sites
of pathological anatomical autopsies, were disinfected with 10% sodium hydroxide solution and 3%
Lysol solution.
In order to make a reliable diagnosis in experimental bradzot, the main attention was paid to
bacteriological examination of guinea pigs. At the same time, the basis for the initial diagnosis was
the clinical signs and pathoanatomical picture found in guinea pigs, as well as epizootological data
(intraperitoneal infection with the causative agent of bradzot). Of decisive importance for the
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establishment of a reliable diagnosis in our studies was again (repeated) isolation of Cl.
Oedematiens from the pathological material of guinea pigs and its identification based on the results
of the study of morphological, tinctorial, biochemical and pathogenic properties.
Pathological material for bacteriological studies were samples taken from fallen experimental
guinea pigs (heart, lungs, liver, kidneys, spleen and tubular bones).
Along with these studies, pathological material taken from the internal organs of experimental
animals was subjected to pathomorphological studies to study changes at the tissue and cellular
levels. For this, the organ pieces were fixed in 12% formalin solution, 96% ethanol, in Mueller and
Carnoy fluids, and then were embedded in paraffin. From all the fixed pieces on a sledge
microtome, sections were obtained, which were stained for further histological and histochemical
studies by several methods: hematosilin-eosin, Sudan-3, Weigert and Perls.
During histostudies of the obtained sections, very pronounced changes in the hemocirculatory
nature were established. At the same time, in the lungs, as a result of increased permeability of the
walls of blood vessels, in many alveolar spaces, along with erythrocytes and leukocytes, fibroblasts,
histiocytes, and small tissue pieces are observed. Similar changes in the hemodynamic system have
also been established in the structural structure of the heart muscle.
Changes in the hemocirculatory system of the central veins and interlobular capillaries of the liver
are characterized by destruction and necrobiosis of the walls of blood vessels, while some of the
hepatocytes are subjected to granular degeneration, necrobiosis and necrosis.
Changes in the structural structure of the walls of the gastrointestinal tract are more pronounced,
which are observed in the form of expansion and plethora of blood vessels, the development of
perivascular serous edema and focal extravasation, which also indicate a deep development of
vascular reactions.
Conclusion.
1.
Laboratory studies conducted on guinea pigs infected intraperitoneally with a local strain of Cl.
Oedematiens, isolated from sick sheep on the territory of Uzbekistan, it was found that for
guinea pigs, a 50% lethal dose of the pathogen is 0.26 ml of culture, and a dose of 0.30 ml
causes 100% mortality.
2.
In acute experimental bradosis in guinea pigs, the autopsy pathological and anatomical picture is
characterized by the following: gas formation in the small intestine, hemorrhages on the inner
walls of the stomach and intestines, blackening of the heart ears and fluid accumulation,
numerous petechial hemorrhages on the lungs and liver, and an increase in the volume of the
spleen.
3.
The picture of pathomorphological changes in the internal organs, especially in the
gastrointestinal tract, in experimental laboratory animals is expressed as a strong vascular
reaction, characterized by deep hemorrhagic and catarrhal-hemorrhagic processes.
List of used literature:
1.
Antonov B.I. and others.” Laboratory research in veterinary medicine. Bacterial infections." M.,
"Agropromizdat", 1986.
2.
Ibadullaev F.I. "Pathological anatomy of farm animals". T., "Uzbekistan", 2000.
3.
Merkulov G.A. “Course of Pathological and Histological Techniques”. Leningrad, Medgiz,
1976.
4.
Salimov Kh.S., Kambarov A.A. "Epizootology". T., 2016.
5.
Shevchenko A.L. other. “Prevention and measures for the elimination of bradzot in sheep and
goats”. Krasnodar, 2013.
