Ethiopathogenesis of caseous lymphadenitis in goats
Caseous lymphadenitis (CLA) is an economically important disease of sheep and goats worldwide. However, paucity of literature on CLA research in goats in Malaysia led to this study to investigate the mechanism by which Corynebacterium pseudotuberculosis and its exotoxin, phospholipase D (PLD) ad...
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| Format: | Thesis |
| Language: | English |
| Published: |
2015
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/106010/1/FPV%202015%207%20-%20IR.pdf |
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| Summary: | Caseous lymphadenitis (CLA) is an economically important disease of sheep
and goats worldwide. However, paucity of literature on CLA research in goats
in Malaysia led to this study to investigate the mechanism by which
Corynebacterium pseudotuberculosis and its exotoxin, phospholipase D (PLD)
adversely affects reproduction in mice and goats. This study was also designed
to test the hypothesis that acute phase proteins, specifically, haptoglobin and
serum amyloid A can be used as diagnostic biomarkers for CLA.
One hundred and five clinically healthy mice of both sexes aged between 10 to
12 weeks, weighing 25-35 g and twenty six clinically healthy crossbred Boer
goats (13 bucks and 13 does) aged between 12 to 14 months, weighing 30-35
kg were used in this study. The does were non-pregnant, non-lactating and
have been housed separately from the bucks. At the beginning of the
experiments, two types of inoculum were used that involved live C.
pseudotuberculosis and its exotoxin, PLD. The mice were divided into three
equal groups of 35 mice each. The crossbred Boer goats were also divided into
three groups, the first group consisted of 6 goats, the second group consisted
of 10 goats and the third group consisted of 10 goats. The control groups 1
(mice and goats) were inoculated with sterile phosphate buffered saline (PBS 1
ml/mouse intra-peritoneal and 1 ml/goat subcutaneous) whereas group 2 were
inoculated with live C. pseudotuberculosis (1x109 cfu intra-peritoneal in mice
and subcutaneous in goats) and group 3 were inoculated with PLD (1
mllmouse intra-peritoneal and 1 ml/20 kg B.W. in goats). Mice were observed
during the entire experiment, blood was collected into heparinized tubes for sex
hormones analyses. Post mortem examination of gross lesions was conducted
on ovaries, uterus, testes and epididymis and tissue samples were fixed for histopathological examination. Goats were also observed during the entire
experiment for clinical signs and serial blood collections were conducted. Blood
was placed into heparinized, plain, EDTA and sodium citrate tubes for acute
phase proteins (APPs), haematology and sex hormones analyses. Post
mortem examination of gross lesions was conducted on lungs, heart, liver,
spleen, kidneys and lymph nodes and tissue samples were fixed for
histopathology and cellular changes were scored.
Mice inoculated with C. pseudotuberculosis showed significant decrease
(p<O.05) in testosterone concentration. Both inoculated groups showed no
gross changes in the reproductive organs. However, microscopic examination
revealed that C. pseudotuberculosis inoculation caused congestion, oedema,
infiltration of inflammatory cells, degeneration and necrosis in the ovaries,
uterus, testes and epididymis. In addition, mice in PLD inoculated group
showed congestion, degeneration and necrosis in the ovaries, uterus, testes
and epididymis as well as thrombosis in the ovaries and uterus only.
Goats inoculated with both C. pseudotuberculosis and PLD showed significant
increase (p<O.05) in haptoglobin concentration with significant decrease
(p<O.05) in albumin concentration. Goats also showed significant increase
(p<O.05) in body temperature, heart rate, respiratory rate during different times
of the experiment post inoculation with both C. pseudotuberculosis and PLD.
Moreover, body score showed significant decrease (p<O.05) in both treated
groups toward the end of the experiment. Additionally, the site of inoculation
and the superficial lymph nodes showed abscess formation in C.
pseudotuberculosis inoculated group only.
Corynebacterium pseudotuberculosis inoculated goats showed significant
decrease (p<O.05) in red blood cell count, haemoglobin, creatine
phosphokinase concentrations and significant increase (p<O.05) in neutrophils
count. Both C. pseudotuberculosis and PLD inoculated goats showed
significant increase (p<O.05) in packed cell volume, mean corpuscular volume,
white blood cells, lymphocytes, monocytes, eosinophils and basophils counts
and aspartate transaminase, total bilirubin, calcium, creatinine, gamma
glutamyltransferase, urea, total protein, globulin, lactate dehydrogenase
concentrations, prothrombin time and activated partial thromboplastin time
whilst both inoculated groups showed significant decrease (p<O.05) in mean
corpuscular haemoglobin concentration, neutrophils count, alanine
transaminase and alkaline phosphatase concentrations. Inoculation with PLD
showed significant decrease (p<O.05) in creatine phosphokinase concentration.
Testosterone, progesterone, estrogen hormones, scrotal circumference and
semen volume, pH, wave pattern, motility and concentration showed significant
decrease (p<O.05) post inoculation with C. pseudotuberculosis and PLD. In
addition, dead sperm and abnormal sperm percentage showed significant
increased (p<O.O~) in both treated groups. Microscopic examination of the
ovaries showed fibrous tissue formation post inoculation with C.
pseudotuberculosis, whilst in PLD inoculated group the ovaries showed severe
congestion, degeneration and necrosis of the stromal cells. In addition, the
uterine tissues showed congestion, degeneration and necrosis post inoculation
with both C. pseudotuberculosis and PLD. The testes showed irregular and
shrinkage of seminiferous tubules with oedema, degeneration and necrosis of
spermatogonia cells and Leydig cells post inoculation with both C.
pseudotuberculosis and PLD. Similarly, the epididymis showed oedema,
degeneration and necrosis of the lining epithelium of the epididymal tubules
post inoculation with both C. pseudotuberculosis and PLD.
Corynebacterium pseudotuberculosis inoculated group showed gross changes
in lungs represented by grey and red hepatization, deeper inside, spots of
congestion and abscess formation. The heart appeared oedematous and the
pericardium showed some degree of opacity. The liver showed multiple
abscess formation on its surface. The kidneys appeared friable with opaque
capsule whilst the spleen showed mosaic appearance. The Iym.ph nodes
appeared enlarged, fluctuating and filled with purulent pus. The PLD Inoculated
group also showed gross changes in the lung represented by some spots of
grey hepatization with no abscess formation in its parenchyma. T~e he~rt
showed no obvious gross changes. The liver appeared congested With white
line along the edges of almost all the liver lobes. The kidneys ~ppear~d
congested with opaque spots on its capsule. The spleen appeared friable With
mosaic appearance. The lymph nodes showed no abscess formation; however,
when cut, it revealed a rusty yellow discoloration. Microscopic examination of
C. pseudotuberculosis inoculated group showed significant congestion,
oedema, and infiltration of inflammatory cells, degeneration and necrosis in the
lungs, heart, liver, kidneys and spleen. The lymph nodes also showed
significant granuloma formation with micro-foci of abscess formation. The PLD
inoculated group showed significant congestion, oedema, degeneration and
necrosis. In addition, hepatic tissue showed significant increase (p<O.05) in
Kupffer cells number. The lymph nodes showed no abscess formation with
some haemosiderin deposits.
Therefore, from this study, it can be concluded that C. pseudotuberculosis had
detrimental effects on testosterone concentration and reproductive organs in
mice. However, in goats, C. pseudotuberculosis and PLD had negative effects
on testosterone, estrogen and progesterone hormone concentrations as well as
semen quality and reproductive organs in both genders. Acute phase reactant.
mainly, haptoglobin, showed Significant sensitivity in both treated groups; this
sensitivity may have potential as diagnostic biomarker for CLA in goats.
Similarly, C. pseudotuberculosis resulted in classical clinical manifestation of
CLA specifically abscess formation in superficial lymph nodes, yet, PLD,
showed different clinical manifestation with no abscessation. In addition, C.
pseudotuberculosis and PLD showed significant changes in all haematological parameters, yet, PLD showed different response pattern which may indicate a
different mechanism of action. The gross and cellular changes were of typical
CLA lesions in C. pseudotuberculosis inoculated group whilst PLD inoculated
group showed less gross changes; however, the cellular changes were severe,
this may indicate or reflect the toxic effects of PLD on tissues. |
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