الفهرس 
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Abstract
Brain is one of the vital organs of the body and remains in an exalted position protected within the cranial cavity cushioned by cerebrospinal fluid and protected from the external noxious agents by the blood brain barrier and perivascular spaces.
The present study was done to explore the important brain affections which affect sheep and goats by application of macroscopic and microscopical examination.
The present study was performed on 70 brain samples from sheep and goats (60 sheep and 10 goats) fro a small ruminant’s herd belongs to Badr military farm, Suwz governorate.
Necropsies were performed immediately after death. Animals were subjected to a full post-mortem examination, the PM lesions were reported.
The whole brain was fixed in 20%formol saline .Coronal sections were sliced across the brain tissue. The brain was sliced coronally through the longitudinal axis at 5mm intervals to ensure examination of wide range of neuroanatomical structures and to detect the presence of any cysts, tumors, and abscesses. Dimensions of the cyst and different location were recorded and photographed. Eight coronal slices were selected as the follow:
a) Frontal cortex rostoral to the corpus callosum.
b) Diencephalon at the mamillary body.
c) Diencephalon at the hypophyseal infundibulum -optic tract level.
d) Mesencephalon through the rostoral coliculi.
e) Middle of the pons.
f) Middle transverse section of the cerebellum.
g) Medulla at the obex.
h) Medulla at the caudal cerebellar peduncles.
After fixation, the specimens were thoroughly washed. For preparation of paraffin sections, the specimens were dehydrated in ascending concentrations of ethyl alcohol followed by clearing in methyl benzoatethen it transferred to paraffin wax (60 °C). Sections 5-7 µ were cut on rotatory microtome and stainedwith routine and some special stains.
The results of the present study were variable in type and severity. They cauld be summarized as follow:
1- meningitis 2- degeneration, malacia and pigmentation
3- Vascular changes 4- Encephalitis 5- Cystic formation
In conclusion, not all animals reported to have shown nervous signs before death brought for necropsy revealed histopathological lesions. At the same time some of those having no nervous signs revealed considerable lesions in the brain. It is worthy to mention that some of the cases that showed microscopical lesions in the form of degeneration and inflammation had no gross lesions in the brain.
Non suppurative encephalitis was more common in viral infectin such as, visna, louping ill, rabies, CAE, RVF, Borna, Akabane Diseases and pseudo- rabies .This would suggest the presence of unrecognized viral infections in these species in our area, which should be investigated further.