Malignant catarrhal fever (MCF) is a systemic disease of ruminants caused by a gamma herpesvirus, ovine herpesvirus 2 (OvHV-2). Dot blot hybridization (DBH) protocols for detecting and differentiating this MCF virus were developed. OvHV-2 specific primer pairs, 556/555, were used for the amplification of target DNA. Then, the amplified DNA was labeled with incorporation of digoxigenin (DIG). The Dig-labeled probe was able to detect and differentiate specifically OvHV-2 DNA. This DBH technique can be applied to confirm the presence of MCF virus on clinical samples and to differentiate specifically between OvHV-2 infection and other viral infections.

Malignant catarrhal fever (MCF) is a systemic disease of ruminants caused by a gamma herpesvirus, ovine herpesvirus 2 (OvHV-2). Four 1-year old goats (Capra hircus), which were infected with MCF virus, OvHV-2, by being housed together with MCF virus-infected seep, were referred with a I-month history of chronic dermatitis. On the other hand, MCF virus-negative goats, which were isolated for negative control, had not those kinds of skin problems. Examination of the affected goats revealed generalized alopecia, patchy erythema, and superficial erosions with histologic evidence of mural folliculitis. Fungal culture tests and external parasite tests with the scraping skin samples were negative. However, polymerase chain reaction revealed the existence of MCF virus DNAs in the lesion. These results suggested that MCF virus may induce mural folliculitis and alopecia in goat.

Antigen retrieval (AR) techniques were widely used to recover the antigenicity from the fixed tissues, which were guided by the philosophy of rendering immunohistochemistry (IHC) applicable to routine formalin-fixed, paraffin-embedded tissues for wide application of IHC in research and clinical filed for morphological observation like as anatomy, histology and pathology. Protease antigen recovery (PAR) is an AR technique, which is obtained the antigen retrieve by using enzyme digestion, and commonly used in IHC field. However, during the IHC for the detection of ovine herpesvirus 2 (OvHV-2) antigen, we noted lymphocyte-like cells-specific staining in the infiltrated cells into various organs like as liver and kidney, which was also shown in the IHC tissues with isotype control. However, those signals were not observed in the tissues conducted with in situ hybridization. Therefore, we analyzed the specificity of the IHC detection results. We found that PAR may induce false-positive result during IHC in lymphocyte-like cells, which were infiltrated mainly around vessels and in interstitial tissues. Through the Phenotyping, we realized that those false-positive cells were B-cell-related cells. These results suggest that PAR, a AR using protease, may induce non-specific false-positive reactions during IHC.

From February to September in 1996, a lot of blind cattle were reported in Dangjin Area of Chungnam Province. Blindness were observed in the 143 calves of the 1,496 calves from 79 farms. Blind cattle were found only in the farms where green pasture was not fed. After administration of vitamin A as the type of feed additives and parenteral injection, the blindness cases were not occurred in those farms. Both pupils were totally dilated with the absence of pupillary light reflex in all blind cattle. In the ophthalmoscopic examination, the fundus revealed multi focal linear white mottling which was more severe in nontapetal fundus than tapetal fundus. Serum vitamin A concentration was as low as 4.1 ,$\mu\textrm{g}$/dl in the calves of the affected farms. Narrowing of optic foramen, retinal degeneration and optic disc atrophy were shown in pathological findings.

Newcastle disease (ND) is acute respiratory disease with high mortality in chicken and pet birds. Two ostriches aged on 51 days old submitted had showed clinical signs of severe torticolis and poor locomotion. In gross, fibrinous air-sacculitis and hemorrhagic enteritis were present. The significant lesions were histopathologically lymphocytic encephalitis such as perivascular cuffings and gliosis in neuropil. The velogenic ND virus was isolated ftom 10 day-old embryonated eggs inoculated with hemogenized cecal tonsils. These results suggest that NO occurred in the ostrich in Korea.

The purpose of this study was to evaluate the effect of a subsequent infection of porcine reproductive and respiratory syndrome(PRRS) virus to pigs with A. pleuropneumonia in pigs. Twenty three 7-weeks-old commercial pigs were infected with PRRS virus and/or A. pleuropneumoniae serotype 5 intratracheally. Feed conversion, clincal signs, gross and histopathological lesions and immunohistochemical findings were examined. 1. Feed conversion ratio in dual-infected pigs with PRRS virus and A. pleuropneumoniae were higher than that of single- infected pigs with PRRS virus or A. pleuropneumoniae. 2. Dual-infected pigs with PRRS virus followed by A. pleuropneumoniae showed more severe clinical signs and gross, histopathological and immunohistochemical pulmonary lesions. The results indicated that dual infections with PRRS virus and A. pleuropneumoniae caused more severe respiratory lesions and growth retardation in pigs than single infection with PRRS virus or A. pleuropneumoniae.

The purpose of this study was to investigate protective effects against transmissible gastroenteritis virus (TGEV) infection in piglets by administration of the TGEV antiserum orally at 2hrs, 24hrs and 36hrs after birth. Five piglets administered with the TGEV antiserum were experimentally challenged with TGEV at four-day-old. Control group was four piglets challenged with TGEV only. Clinical signs and gross, histopathological and immunohistochemical findings were examined. In clinical signs, piglets of the control group appeared the typical signs such as severe watery diarrhea, depression and anorexia but piglets of the TGEV antiserum adminstered group recovered progressively. In clinical signs, piglets of the control group appeared the typical signs such as severe watery diarrhea, depression and anorexia but piglets of the TGEV antiserum adminstered group recovered progressively. In mortality, control group showed 75%, but TGEV antiserum adminstered group showed 20.0 %, respectively. In gross findings, piglets of the control group appeared the typical findings of congestion, distension of lumen, contaning curdes of undigested milk in stomach. But gross findings of piglets of the TGEV antiserum adminstered group appeared milder than them of control group. In histopathological findings, piglets of the control group appeared the typical findings of villous atrophy and fusion, congesion, exfoliation, vacuolation, squamation, loss of cilia and proliferation of crypt. But histopathological findings of piglets of the TGEV antiserum adminstered group appeared milder than them of control group. In immunohistochemical findings, piglets of the TGEV antiserum adminstered group showed more intensive in reaction for IgA and IgG than them of control group. The recation for IgA was stronger than that of IgG. It was concluded that oral administration of TGEV antiserum to piglets was effective to prevent TGEV infection and reduce their mortality.

A nine-year-old female Yorkshire terrier dog showing mammary secretion mixed with blood and pus for 5 month duration was presented. Cytologically mammary secretion consisted of many pleomorphic tumor cells, RBC, and neutrophil. Tumor cells were characterized by polyhedral pleomorphic nuclei with smudged chromatin and basophilic cytoplasm with many secretory vacuoles. N/C ratio was very high. Therefore it was diagnosed as mammary gland adenocarcinoma. Histological examination confirmed cytological diagnosis. From these results cytology isfor the diagnosis of secreting mammary gland adenocarcinoma is very simple and accurate for the diagnosis of secreting mammary gland adenocarcinoma.

A two-year-old pointer dog showed a liver failure for long duration. By radiographic examination, barium or gas filled intestine was detected in the pericardium. Although liver function was bad, surgery was tried to repair hernia due to the poor prognosis. Intestine, omentum, and liver with gall bladder were dislocated in the pericadial sac by peritoneopericardial diaphragmatic hernia (PPDH). Intestine was easily removed from pericardial sac but omentum and liver were not because of strong adhesion to the pericardial sac. Postmortem examination was performed because the patient was died after surgery. Grossly, herniated liver whose right medial lobe was strongly adhered to the pericardial sac was severely congested with fibrin adhesion on the surface. Hypoplastic abnormally up-located heart had a fissure in the outside of lower right venticulum bordered apex and depressed large vessels including vena cava and aortic arch into the base of heart. It was suggested that formation of a fissure and depression of vessels might be due to the pressure of herniated organs. In the veterinary literature as far as we knew, PPDH associated with liver failure due to adhesion of liver to the pericardial sac has not been reported.

A 10-year-old Korean native female Jin-do dog revealed two growing subcutaneous masses measuring 7.0 ${\times}$ 7.0 ${\times}$ 2.5 cm and 5.0 ${\times}$ 4.0 ${\times}$ 2.0 cm in the left shoulder and lower part of chest, respectively. Grossly tumor masses were well-circumscribed and exhibited ulcerated surface and purulent exudate on the cut surface. Histologically tumor masses were characterized by cystic structures some of which were fused together. Although the cells of cyst wall differentiated to those similar to infundibulum, isthmus, inferior segment of hair follicles, respectively, the most cyst wall consisted of cells similar to infundibulum The luminal content of cysts depended on the cells of cysts; infundibulum-like cyst contained lamellar keratin, isthmus-like cyst was amorphous keratin, and inferior segment-like cyst had shadow cells. From these results, these tumor masses were diagnosed as multiple trichoepithelioma. To our knowledge, this is the first report of canine multiple trichoepthelioma in a dog in Korea.

Three mature layer chickens from a farm in which chickens showed green diarrhea, cyanosis, lethargy, loss of appetite were pathologically examined. Grossly, multiple variable sized caseous nodules were detected in the liver, intestinal serosa and mesentery. In addition, parathypoid nodules in the liver and fibrous serositis on the several peritoneal organs and tissues were noticed. One of spleens had multiple infarction areas. Histologically caseous nodules consisted of central caseous core and peripheral epithelioid cells overlying the fibrous connective tissue. Multinucleated giant cells were scattered between the epithelioid cells and fibrous connective tissue. In these nodules Gram negative cocobacilus bacterial colonies were present, whereas Periodic Schiff reaction and Ziehl-Neelsen stain detected neither fungi nor acid fast bacteria. From these results multiple granulomas might be induced by Escherichia coli. In addition, severe Ascafdiodf and Salmonellosis were coinfected in these chickens.