PATHOLOGY OF LYMPH NODES IN SHEEP
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Date
2006-12
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
ABSTRACT:
Lymph nodes are the prime organs to carry out various defensive
mechanisms. The lesions of lymph nodes are the reflections of lesions of the tissues
they drain. The present work was undertaken to study the pathology of lymph nodes
in sheep brought for slaughter, to overcome zoonotic threat and to enhance the
quality of consumable, disease free and whole-some meat. In the present investigation 2266 lymph nodes of sheep were collected from various slaughter houses in and around Hyderabad. The regional lymph nodes like
mesenteric, bronchial, mediastinal (anterior, middle and posterior) and prescapular
were collected and examined for gross pathological changes. Only 247 (10.90%)
lymph nodes were found to be abnormal. The tind~ngs ui this study revealed the incidence of various pathological
changes in the mesenteric, bronchial, mediastinal and prescapular were 120
(12.90°/t), 37 (10.78%), 38 (10.16%) and 52 (8.38%) respectively. Among the
different regional lymph nodes the lesion were more noted in mesenteric lymph
nodes followed by bronchial lymph nodes. The incidence of enlarged and edematous lymph nodes was high, followed
by haemorrhagic and lor hyperemic, parasitic lymphadenitis and pibmented lymph
nodes. The gross changes like enlarged and edematous in 89 (36.03%) lymph
nodes, hemorrhagic and /or hyperemic 62 (25.10%), probable parasitic mipation
tracts 48 (1 9.43%). pigmentation 32 (1 2.95%). abscesses 12 (4.85%). atrophic
3 (1.2 1%) and one (0.40%) cystic lymph node were recorded. Microscopically, reactive hyperplasia in 54 (21.86%) cases, edematous 27 (10.93%), haernorrhagic 32 (12.95%), hyperemia 30 (12.14%), discrete
eonsinophilic accumulations 48 (19.43%), melanosis 5 (2.02%). anthracosis
8 (3.23%), foreign debris accumulations 16 (6.47%), hemosiderosis 3 (1.21%),
lymphoid depletion 4 (1.61%), abscesses 12 (4.85%), chronic lymphadenitis
1 (0.40%) granulomatous lymphadenitis 6 (2.43%) and fibroma 1 (0.40%) were
observed. A total of 247 lymph node impression smears were examined for cytology.
The kind of cells observed were plasma cells, mast cells, neutrophils, red blood
cells, lymphoblasts, epithelioid cells, eosinophils, bipolars and acid -fast bacilli in
26, 20, 1 I, 18, 20, 1 1,23, 8 and 5 cases respectively. Out of 247 lymph nodes examined 56 cases showed positive for bacterial identification. Mycobacrerium sp. (5 cases), Pseudomonas sp. (l), Pasteurella sp.
(a), E.coli (37) and Slaphylococcus aureus (5) were identified either by cultural
isolation and by cytological smear examination. Based on the present investigation it can be concluded that -
1. The incidence of diseased sheep that are brought for slaughter is
around 11%. This indicates that moore vigilence is required during ante -
mortem examination. 2. The more changes in the mesenteric lymph nodes in the study indicates that
the spread of infections through oral route is more than respiratory route.
3. The microscopical examination revealed presence of various pigments and
granulomas. 4. The cytological examination of smears revealed the incidence of
M~~c~obacteriuSmp. which is of zoonotic importance and other important
diseases like Pasteurellosis and parasitic infestations. Thus the results of present study highlighted the importance of study of lymph node pathology in sheep, further studies with respect to imnunological and
molecular aspects are the areas of thrust, can be undenlken in future to determine
the causes.
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