PATHOMORPHOLOGICAL STUDIES ON SPONTANEOUS KIDNEY LESIONS IN SLAUGHTERED PIGS
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Date
2022-06
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
The present study was undertaken to know the occurrence of various
spontaneous kidney lesions in slaughtered pigs, to describe the
pathomorphological features of kidney lesions and to identify the probable
etiological agents.
A total of 320 slaughtered pigs of either sex were screened for various
pathological conditions of kidney, if any, at different locations in Krishna District,
Andhra Pradesh. Gross and microscopic kidney lesions of pathological
significance were observed in 130 animals (40.6%) that were grouped under
circulatory disturbances (13.85%), degenerative changes (6.92%), inflammatory
conditions (60%), parasitic (11.54%) and miscellaneous (7.69%) conditions.
Circulatory disturbances comprised of congestion (10.77%) and
haemorrhages (3.08%). Renal congestion was characterized by dark red coloured
kidneys with engorged blood capillaries in the cortex and medulla. Renal
haemorrhages revealed diffuse petechial and large ecchymotic haemorrhages on
the surface with numerous extravasated RBCs in the interstitium and within the
tubules.
Nephrosis refers to the degenerative changes in the renal parenchyma, was
characterized by enlarged and pale kidneys with cloudy swelling and vacuolar
degeneration of tubular lining epithelium along with the formation of protein and
cellular casts in the tubules.
Nephritis was categorized into glomerulonephritis (26.93%), interstitial
nephritis (32.31%) and tubulo-interstitial nephritis (0.77%). Glomerulonephritis
was comprised of acute (3.08%), sub-acute (21.54%) and chronic (2.31%) types.
Acute lesions were characterized by pale and edematous kidneys with petechiae
on the cortex along with glomerular lesions of congestion, swelling,
hypercellularity and reduced Bowman’s space with protein accumulation.
Sub-acute type revealed enlarged and pale kidneys with epithelial cresents and
synechiae formation, sclerotic glomeruli, peri-glomerular mononuclear cells
infiltration and perivasculitis. Chronic type revealed smaller sized kidneys with
finely granular surface and lesions of diffuse global glomerular shrinkage, atrophy
and necrosis with severe fibroplasia and mononuclear cells infiltration.
Interstitial nephritis was comprised of sub-acute (29.23%) and chronic
(3.07%) types. Sub-acute condition was characterized by variable sized whitish
foci on the renal surface with nodular and diffuse aggregation of
lymphoplasmacytic cells around the tubules, glomeruli and blood vessels. In
chronic cases, kidneys were hard with diffuse pale areas and revealed diffuse and
extensive proliferation of connective tissue all over the interstitium along with
severe mononuclear cells infiltration.
Tubulo-interstitial nephritis (0.77%) revealed kidneys with greyish white
foci surrounded by hyperemic rim and lesions of multi-focal tubular necrosis and
liquefaction with infiltrating polymorphs and mononuclear cells, and diffuse
interstitial mononuclear cells infiltration.
Stephanurosis (kidney worm) affections were characterized by numerous
parasitic nodules in the perirenal fat, renal pelvis and around the ureter harbouring
the adult and larval forms of the parasite. Microscopically, thick fibrous nodules
containing cross section of parasites and severe infiltration of plasma cells,
lymphocytes, macrophages and giant cells in the nodule wall were noticed.
In the present study, 7.69% of renal cysts was recorded under miscellaneous
conditions. Renal cysts were characterised by clear cystic cavities in the renal
parenchyma with clear watery fluid with thick limiting membrane.
Microscopically, empty or fluid filled cavities lined by single layer of flattened
epithelial lining surrounded by proliferative connective tissue proliferation were
noticed.
Etiological studies revealed isolation of pathogenic bacterial species in 20%
samples that comprised of Staphylococcus spp., Streptococcus spp., Escherichia
coli and Klebsiella spp. in association with renal congestion, nephrosis, nephritis
and kidney worm affections.
The present study concluded that a significant occurrence of spontaneous
renal lesions exist in slaughtered pigs and the most common pathological condition
encountered being nephritis with consistent lesion of mononuclear cell infiltration.
Further, this study suggests that a detailed investigations by involving large sample
size and employing different molecular detection methods for wider range of
etiological agents including zoonotic importance if any, so as to implement proper
preventive measures in pig farming and to minimise the economic losses and to
curtail zoonotic spill over, in any.
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