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Three strains of chicken anemia virus (CAV) were detected in 11 to 14-weeks old chickens, showing depression, wasting, and increased mortality, from three farms in eastern Japan. Another strain was detected in 12-weeks old chickens from one farm without clinical signs. Bacterial infections were suggested in three farms with clinical signs and its involvement in the occurrence of the diseases might be suspected. Sequence analysis of the VP1, VP2, and VP3 genes of four CAV strains revealed that the three from farms with clinical signs belonged to genotype A2, whereas that from the apparently-normal farm belonged to A3. This may be a rare case report about the diseases suspected of the involvement of the CAV infection in older birds.

Canine squamous cell carcinoma (SCC) shows highly invasive and locally destructive growth. In animal models and human cancer cases, periostin plays a critical role in the enhancement of cancer growth; however, the mechanism of involvement in canine cancers remains unknown. The aim of this study was to examine the involvement of periostin in the pathophysiology of SCC in dogs. We examined the localization of periostin and periostin-producing cells in 20 SCC and three squamous papilloma specimens. Furthermore, we focused on transforming growth factor (TGF)-β1, which was assumed to be an inducing factor of periostin, using culture cells. By immunohistochemistry, limited periostin expression in the stroma was observed in all squamous papillomas. In SCC, periostin protein diffusely expressed at the tumor invasion front of cancer growth. In situ hybridization revealed that periostin mRNA was expressed in the stromal fibroblasts in SCC. In vitro analysis determined that canine SCC cells expressed significantly higher levels of TGF-β1 mRNA compared with canine keratinocytes. In addition, recombinant TGF-β1 induced secretion of periostin from cultured dermal fibroblasts. These data suggest that periostin produced by stromal fibroblasts may be involved in the pathophysiology of canine SCC. TGF-β1 derived from SCC cells may stimulate fibroblasts to produce periostin.

Atopic dermatitis (AD) is a chronic, pruritic, and allergic skin disease in humans and animals, particularly dogs. Canine AD (cAD) has received attention as a spontaneous atopic animal model because domesticated dogs inhabit a human environment, and cAD shares several clinicopathological features with human AD (hAD). In hAD, periostin (PO) is suggested to play a critical role in the enhancement and chronicity of allergic skin inflammation; however, PO involvement in the pathogenesis of cAD is unknown. Here we aimed to clarify PO involvement in the pathophysiology of cAD and focused on the inducing factor and function of PO in canine atopic skin. Using double-labeled in situ hybridization (ISH), interleukin (IL)-13 mRNA-positive cells were detected near the keratinocytes and dermal fibroblasts expressing PO mRNA in atopic skin. Using an in vitro assay, IL-13 induced PO gene expression in both canine dermal fibroblasts and keratinocytes. PO enhanced in vitro growth of canine keratinocytes. Moreover, among PO-induced genes in cultured canine keratinocytes detected using a microarray, we identified IL-25 as a possible mediator in canine atopic skin. In addition, real time polymerase chain reaction (PCR) analysis revealed upregulation of IL-25 gene expression in PO-stimulated keratinocytes. These data suggest that IL-13 possibly derived from T helper 2 (Th2) cells stimulates PO production in both keratinocytes and fibroblasts, and then PO may play a critical role in the pathophysiology of cAD, particularly in the enhancement and chronicity of skin lesions via IL-25.

Phospholipase A2 receptor (PLA2R) expressed in human podocytes has been highlighted as a causative autoantigen of human idiopathic membranous nephropathy. However, its expression was found to be minimal or absent in murine and rat podocytes. In this study, immunofluorescence revealed the expression of PLA2R in the glomerular podocytes in the kidney tissue sections of dogs. We then attempted to culture canine podocytes and investigate the expression of PLA2R in these cells. Glomeruli were isolated from dog kidneys and cultured to obtain podocytes using nylon mesh-based isolation method as followed for isolating rat podocytes. The cultured cells expressed PLA2R mRNA and protein in addition to other podocyte markers (synaptopodin, podocin and nephrin). These results indicate that the canine podocytes express PLA2R.

Feline morbillivirus (FmoPV) is a new virus species and its detection is important, since correlation has been reported between FmoPV virus infection and tubulointerstitial nephritis in cats. Here, we report a real-time reverse transcription (RT)-PCR system that can detect the FmoPV L-gene sequence with more than 10-time higher sensitivity than a conventional PCR system, resulting in detection of less than 10 copies of the template DNA. The total FmoPV positive rate of urine samples from veterinary clinics and hospitals in Japan was 15.1% (25/166) using this system. This study demonstrates usefulness of the real-time RT-PCR system for detection of FmoPV for cat urine samples.

The renal biopsy tissue from a 9-month-old, male Pyrenean Mountain dog with renal disorder and severe proteinuria was examined. Ultrastructural examination revealed multilaminar splitting and fragmentation of the glomerular basement membrane (GBM) and diffuse podocyte foot process effacement. Immunofluorescent staining for α(IV) chains revealed presence of α5(IV) and complete absence of α3(IV) and α4(IV) chains in the GBM. Immunohistochemistry also revealed decreased and altered expression of nephrin and podocin in the glomeruli compared with normal canine glomeruli. These results suggested that the glomerular disease of the present case might be consistent with canine hereditary nephropathy resembling human Alport syndrome caused by genetic defect of type IV collagen, and indicated possible contribution of podocyte injury to severe proteinuria in this case.

A 12-year-old mixed-breed neutered female dog was referred with cutaneous tumors at the left auricle. Histologically, the cutaneous tumor located in the dermis comprised numerous clefts and cavernous channels lined by neoplastic endothelial cells with no erythrocytes. Bone tissue without direct contact with neoplastic cells was seen in the well-developed stromal connective tissue. The neoplastic endothelial cells exhibited mild to moderate atypia. Immunohistochemically, neoplastic cells were positive for vimentin and negative for cytokeratin and factor VIII-related antigen. Basement membrane around the neoplastic lumens was positive for laminin in a linear or granular pattern. Ultrastructural examination revealed discontinuous basement membrane beneath the tumor cells. Histopathological features of this case were consistent with lymphangiosarcoma, and stromal ossification was characteristic.

A two-month-old female Chihuahua was diagnosed as severe pulmonary valvular stenosis (PS). Although balloon valvuloplasty (BV) was successfully performed, restenosis was observed 19 months after the procedure. Euthanasia was chosen due to low output syndrome during the surgical repair attempted when the dog was 5 years old. Postmortem examination revealed markedly thickened pulmonary valve due to the increase of extracellular matrix which might be produced by increased α smooth muscle actin-positive myofibroblasts. The thickening of the valve was associated with restriction of the valve's motion, resulting in restenosis in the present case. This is the first case report documented histopathological and immunohistochemical findings of the restenotic pulmonary valve in dogs with PS after BV.

Histopathological and immunohistochemical examinations were made on a cutaneous tumor on the head of an 11-year-old female mixed-breed dog. The tumor was well demarcated and comprised multilobular structures of neoplastic epithelial cells with abundant plump peritumoral stromal cells. The neoplastic cells formed irregular cell cords or trabeculae and were arranged in characteristic palisades at the periphery. Immunohistochemically, neoplastic cells were positive for p63 and the several cytokeratins examined. In contrast, the plump peritumoral stromal cells were positive for vimentin and unevenly for nestin, a neuroepithelial stem cell protein. The stromal cells prominently proliferated in proximity to epithelial neoplastic cells, suggesting a close interaction between these two cell types.

To the best of our knowledge, we present here the first report of a case involving granulomatous pododermatitis caused by Fusarium proliferatum in a 10-year-old female cat. A cutaneous mass developed on the foot-pad of the right hind leg. Nodular granulomatous dermatitis with numerous macrophages and multinucleated giant cells containing cytoplasmic fungal structures were revealed on histological examination. Periodic acid-Schiff reaction and Fungi-Fluor staining clearly revealed irregular, septate fungal hyphae englobed by macrophages and multinucleated giant cells. Polymerase chain reaction and sequence analysis targeting three domains of the extracted fungal DNA revealed 100% amplicon homology with F. proliferatum.

A new-born (8-day-old) male marmoset (Callithrix jacchus) was found dead in a zoo. The littermate and parents had no clinical abnormalities. By gross observations at necropsy, there were moderate to severe multiple necrotic foci in the liver and heart. Histopathological examinations also revealed mild focal necrosis with neutrophilic infiltration in the cerebral cortex. By Giemsa stained sections, intracytoplasmic bundles of large bacilli were observed in the hepatocytes, intestinal epithelial cells, cardiac myocytes and neuronal cells around the necrotic lesions. Immunohistochemically, these bacilli were intensely positive for rabbit sera against Clostridium piliforme, RT and MSK strains. Although Tyzzer's disease has been rarely reported in primates, the central nervous system (CNS) lesions by Clostridium piliforme infections are very unusual.

This report describes an atypical mammary adenoma with a rare histological feature characterized by proliferating single-layered cystic ducts composed of basaloid cells with frequent myoepithelial differentiation. A 9-year-old, intact female Miniature Pinscher dog had mammary tumors on the thorax. Histologically, one of tumors comprised the proliferation of two types of tubular structures; the single-layered cystic ducts lined by flattened cells and double-layered tubules with luminal cells and outer spindle cells. The former ducts were predominant in the tumor and contained pale basophilic mucus, which was Alcian blue (pH 2.5)-positive, but periodic acid Schiff-negative. Immunohistochemical staining indicated that the cells lining single-layered cystic ducts were negative for the luminal epithelial marker, cytokeratin (CK) CAM5.2, but were constantly positive for basal cell markers CK14 and p63 and frequently positive for SMA. Electron microscopy revealed fine, parallel myofilaments within these single-layered neoplastic cells. These histological and immunohistological examinations suggested that the origin of the tumor was bipotential mammary progenitor cells with predominant differentiation into the myoepithelial progenitor linage.

Multiple, pigmented, verrucous, cutaneous lesions in a 2-year-old female cat were pathologically examined. The lesions were linearly arranged on the right side of the body, and had developed along with moderate pruritus since infancy. Histologically, prominent exophytic, papillomatous outgrowths of the epidermis and acanthosis with intense ortho and parakeratotic hyperkeratosis were characteristic of the lesions. Dermal inflammation with mononuclear cells, neutrophils, and eosinophils was also noted. Inclusion bodies, cellular degeneration, and intranuclear viral particles suggesting papillomavirus infection in the keratinocytes were not observed. Papillomavirus antigen and DNA were not detected in the lesions by immunohistochemistry and polymerase chain reaction, respectively. In accordance with these clinical and histopathological features, the cutaneous lesions of the present cat were diagnosed as epidermal nevi, which were consistent with human inflammatory linear verrucous epidermal nevi.

A 10-month-old cat was diagnosed with congenital subvalvular aortic stenosis. To resolve its hypoxia, oxygen therapy was administered a couple of times a week during two months. The oxygen partial pressure in the chamber was maintained between 30 and 35%, and the time for one procedure was 12-24 hr. The animal died due to severe respiratory failure. At necropsy, the lungs were voluminous and had a rubbery texture. Histologically, large type II pneumocytes with occasional atypia had diffusely proliferated within the lungs. Interstitial fibrosis was not observed, although some alveolar septa were thickened along with fibrinous exudates and neutrophilic infiltration. The histology of these lesions was consistent with diffuse alveolar damage (DAD), which might have been partially due to oxygen toxicity.

In order to understand ovarian toxicity of aryl hydrocarbon receptor (AhR) agonists, in situ gene expression of the AhR was examined during follicle development in immature rats. In situ hybridization on frozen sections of ovaries from 24-day-old Sprague-Dawley rats showed that the AhR mRNA was localized in the granulosa cells and occasionally in the theca cells of the follicles irrespective of the developmental stage. In situ gene quantification on granulosa cell layers collected by laser microdissection further revealed that the granulosa cells expressed less AhR mRNA according to development of belonging follicles, but more β-subunit of inhibin A mRNA, a quality control gene. These results may help to elucidate vulnerable developmental stages of follicles to toxicities of the AhR agonists.

Multiple yellowish-white, cauliflower-like mass lesions on the skin of the head and back in a 4-month-old piglet were pathologically examined. These lesions had developed before the weaning period. Histologically, the cutaneous neoplasms were characterized by papillary outgrowth of connective tissue covered by thick epidermis. Hyperplasia of the epidermis was corresponded with proliferation of capillaries, lympho-plasmacytic infiltration, and proliferation of fibroblasts in the dermal stroma. There were no inclusion bodies and significant degeneration in the keratinocytes. Papillomavirus antigen and DNA were not detected in these lesions by immunohistochemistry and polymerase chain reaction, respectively. Accordingly, the fibropapillomatosis of the present case might be hamartomatous rather than infectious.

A percutaneous renal biopsy was performed on a 3-year-old female Japanese domestic cat with pleural effusion, mild azotemia, hypoalbuminemia, hypercholesterolemia, and proteinuria. Glomerular lesions included mild diffuse hypercellularity and numerous capsular adhesions with segmental sclerosis/hyalinosis of glomerular tufts. Electron microscopy revealed many subendothelial dense deposits with characteristic outer protrusion of glomerular basement membrane. Diffuse and global granular deposits of IgG and C3 were detected along the capillary walls. Tubulo-interstitial changes were mild at the time of biopsy, but progression of the disease was predicted because of the many capsular adhesions of the glomerular tufts. The cat was fed a prescription diet without any other specific or symptomatic therapy after renal biopsy, and died 43 weeks after the biopsy. At necropsy, extensive tubulo-interstitial fibrosis and mononuclear cell infiltration had developed throughout the cortex and outer medulla, and most glomeruli had extensive global sclerosis or obsolescence with less prominent depositions of IgG and C3.

Progressive glomerular injury associated with early-onset proteinuria was investigated in male Osborne-Mendel (OM) rats aged 5 to 20 weeks. Age-matched male Fischer 344 (F344) rats were used for comparison. OM rats developed mild hypertension and selective proteinuria (albuminuria) from 5 weeks of age, and non-selective proteinuria from 7 weeks of age. Light microscopy of OM kidney revealed hyaline droplets in the podocyte at 5 weeks of age and vacuolation of podocytes and adhesion of the capillary loop to the Bowman's capsule at 7 weeks of age. Segmental glomerulosclerosis developed in OM rats from 15 weeks of age, and global sclerosis appeared at 20 weeks of age. Desmin, a marker of podocye injury, was expressed in podocytes from 10 weeks of age, and the intensity of expression increased with age. Ultrastructurally, damage to podocytes such as effacement of foot processes, decreasing number of filtration slits, and rearrangement of the actin cytoskeleton were observed from 5 weeks of age in OM rat. Glomerular volume in OM rats increased with age and was consistently higher than in age-matched F344 rats. The number of WT-1-positive podocytes and vimentin-positive podocyte area were lower in OM rats and decreased with age. These findings suggest that glomerulonephropathy in male OM rats is associated with glomerular hypertrophy, progressive podocytopathy, and a reduction in podocyte number and area. Renal injury in OM rats was associated with development of early-onset proteinuria and was more progressive than in age-matched F344 rats.

A 10-year-old, castrated, mixed-breed dog presented with a 1.5-month history of scattered, crateriform ulcers on the trunk and extremities. Some skin lesions appeared to regress spontaneously, but new lesions developed. Thoracic radiography revealed pulmonary consolidated lesions suggestive of tumor. A skin biopsy was performed for histopathological, immunohistochemical and clonality analyses. Histopathological examination of the cutaneous lesion revealed an intense infiltration of atypical lymphoid cells with some other cell populations around the blood vessels in the dermis. Atypical lymphoid cells were shown to be CD3-positive in the immunohistochemical analysis. The presence of clonally expanded T-cells was revealed by the clonal rearrangement of T-cell receptor gamma-chain gene. From the above findings, the dog was diagnosed with lymphomatoid granulomatosis.

Cytological, histopathological and immunohistochemical examinations were carried out on a presumed 10-year-old Japanese cat showing vomiting and emaciation. On cytologic examination of the mass of the upper abdominal cavity, many yeast-like organisms were detected in the macrophages. At necropsy, the upper part of colon was markedly dilated with a thickened wall. The lung did not show significant changes. Histologically, severe necrotic and granulomatous lesions were observed in the colon. In the colonic lesion, the cytoplasm of the macrophages contained yeast-like organisms with irregularly shaped dots, and the cell walls of these organisms were stained black by Grocott-Gomori methenamine-silver stain. Immunohistochemically, they were found to be positive for anti-histoplasma yeast antibody. This is the first report of feline histoplasmosis in Japan.

A 5-year-old, male Bichon-Frise dog presented with a cutaneous mass in the basal region of the auricle. Histologically, the cutaneous neoplasm was comprised of lobules with solid cellular proliferation separated by thin fibrous septa. Neoplastic cells varied in size, with moderate to abundant amounts of PAS-positive cytoplasm, large nuclei and prominent nucleoli. Immunohistochemical examinations showed that tumor cells were positive for pan-cytokeratin (CK) (AE1/AE3 and CAM5.2), CK8 and CK18, but negative for pan-CK (KL1), CK7, CK14, CK16 and CK20. Double-labeled immunofluorescence testing indicated that neoplastic cells frequently co-expressed CK and vimentin, suggesting divergent differentiation of tumor cells. Based on these findings, the tumor was diagnosed as canine clear cell adnexal carcinoma.

This report describes the morphological and immunohistochemical findings of a case of apparent collagenofibrotic glomerulonephropathy in a 7-month-old dog. Clinical examination showed moderate protenuria with elevated blood urea nitrogen and creatinine. Histopathological examination of the glomerular capillary walls and mesangial areas revealed diffuse and global accumulation of eosinophilic homogeneous or fine fibrous materials, which were immunohistochemically positive for type III collagen. On electron microscopy, the randomly crossed fibrils had transverse bands with a periodicity of approximately 60 nm. The clinical, histopathological, immunohistochemical and electron microscopic findings of the present dog were consistent with those of the human, childhood form of collagenofibrotic glomerulonephropathy.

We report herein a case of multicentric myelolipoma in an 11-year-old beagle dog that presented with vomiting. Laparotomy demonstrated the presence of a large mass adherent to the greater omentum and multiple small white maculae in the spleen. Cytological and histological examinations revealed that the mass and maculae comprised mature adipocytes and hematopoietic elements including granulocytic, erythrocytic and megakaryocytic series in several phases of maturation and macrophages containing hemosiderin deposits, resembling bone marrow. Multicentric myelolipoma was diagnosed. This is first report of multicentric myelolipoma in a dog.

A 14-year-old, spayed female Shih-tzu dog presented with masses in the dorsal aspect of cervical region and digit of the right anterior limb. Extensive necrosis was seen in the dermal tissue overlying the tumor, and diffuse round cell proliferation and infiltration were seen histologically from the superficial dermis to the deep dermis. Two types of proliferating cells were present: lymphoblast-like cells with round-oval, vesicular nuclei and moderate-large nucleoli; and smaller cells with characteristic irregularly shaped nuclei. Electron microscopy of these smaller cells showed cerebriform, pleomorphic nuclei with a chromatin pattern characteristic of lymphoid cells, as seen in lymphoblast-like tumor cells. Immunohistochemically, both types of tumor cells were positive for CD3. Most vessel walls had been invaded by tumor cells, resulting in extensive dermal necrosis and hemorrhage. Based on these histopathological findings, the tumor was diagnosed as vasotropic and vasoinvasive nonepitheliotropic lymphoma, characterized by a notable presence of unusual tumor cells with irregularly shaped nuclei and extensive dermal necrosis.

An adult, Japanese domestic cat presented with bilateral swelling, distortion, and erythema of ears and deformation of the limbs. Biopsy of the pinnae confirmed auricular chondritis. These lesions and the cat's general condition subsequently deteriorated, and the cat died. At necropsy, chondral changes were present in the pinnae, costae, larynx, trachea, and limbs. Histopathologically, these chondral tissues showed marked deformation with lymphocytic inflammation. The limb joint inflammation was associated with chondral erosion, deformation of subchondral bones with pannus, and thinning of cancellous bones. These lesions were consistent with the diagnostic criteria for human relapsing polychondritis. However, the cat had erosive arthritis, which appeared to be different from human relapsing polychondritis.

A 9-month-old male Japanese domestic cat showed pleural effusion, ascites, azotemia, hypoproteinemia and severe proteinuria. Histopathology of the percutaneous renal biopsy specimen revealed that all glomeruli showed intense mesangial hypercellularity with an increased mesangial matrix and thickening of the capillary walls, resulting in lobular accentuation of the glomerular tufts. Frequent duplication of the capillary walls was also observed. Immunostaining for alpha-smooth muscle actin distinctly revealed mesangial interposition. Diffuse global and linear deposition of C3 and IgG was observed mostly along the peripheral capillary loops. Electron microscopy confirmed frequent circumferential mesangial interposition and subendothelial dense-deposits in the glomerulus. The glomerular lesion was consistent with human membranoproliferative glomerulonephritis type I, and might be a rare case that developed at young age.

To investigate the relationship between the decreased immunity associated with infirmity and low body weight at birth as a consequence of intrauterine growth retardation in Japanese Black calves with stillbirth/perinatal weak calf syndrome, the thymuses and spleens of 13 calves with this syndrome, weighing less than 20 kg at birth, were examined histopathologically. Cytokeratin staining of the thymus was also carried out to examine its composition. The thymus and spleen were classified as grades 0-4 and I-III according to their hypoplasia, respectively. All calves showed a decreased number of thymocytes. One calf was classified as grade 1, which was characterized by a starry sky appearance. Five calves were classified as grade 2, demonstrating a reversion of the cortex-to-medulla ratio, and the rest were classified as grades 3 and 4 showing an indistinguishable boundary between the cortex and medulla. The thymuses of grade 3 and 4 were occupied by stroma cells, and their Hassall bodies and other structures were rarely observed. Six of 13 calves showed a decreased number of splenocytes, grade II or III, and their red and white pulp regions were unclear. The intrauterine growth retardation caused by lack of growth factors during the fetal period might have induced thymic hypoplasia associated with decreased immunity in the calves with stillbirth/perinatal weak calf syndrome. Therefore, intrauterine growth retardation might be associated with one of the causes of decreased immunity involved in infirmity in this syndrome.

Angiogenesis is essential for tumor progression and is regulated by several angiogenic factors such as vascular endothelial growth factor (VEGF). We investigated the expression and distribution of VEGF and its receptor flt-1 in twelve normal canine tissues in six beagle dogs using immunohistochemistry, RT-PCR and real-time RT-PCR. Immunochemical staining showed that both VEGF and flt-1 were expressed in many tissues and their mRNAs were detected in all organs examined by RT-PCR. Levels of VEGF164 and flt-1 mRNA expression were high in tissues containing many intensely immunopositive cells. The expression levels of VEGF164 and flt-1 mRNA tended to be similar. These results indicated that VEGF and flt-1 are closely associated in canine, as in human tissues, and quantifying their mRNAs might be helpful in evaluating angiogenesis.

Five raccoon dogs (Nyctereutes procyonoides) and two domestic dogs (Canis familiaris) were subcutaneously infected with 100 infective larvae (L3) of Dirofilaria immitis. Two and five worms, respectively, were collected from two of three raccoon dogs. Villous endarteritis was found in the raccoon dog with five worms and two dogs at 116 days after infection. The number of recovered worms in the raccoon dogs was significantly smaller than that of the domestic dogs having 22 and 29 worms, while histopathological features and the severity of the lesions in the raccoon dogs were similar to those in the domestic dogs. The vascular lesions in two chronically-infected raccoon dogs turned into much severe at 565 and 590 days after inoculation.

In order to determine the epidemiological link between the Salmonella Enteritidis contamination in a rat-infested chicken layer farm, an attached egg processing facility and liquid egg samples, several S. Enteritidis isolates were analyzed by pulsed-field gel electrophoresis (PFGE) and bacteriophage typing. A total of 33 S. Enteritidis strains were isolated from a total of 4,081 samples. Similar pulsed-field patterns were generated by S. Enteritidis isolates from liquid eggs, rats and effluent water. Additionally, only two phage types were detected among the S. Enteritidis isolates, PT 1b and PT 6. These results suggest that S. Enteritidis isolates from rats, egg processing facility, and liquid eggs are genetically related. Furthermore, S. Enteritidis infection in rats in layer farms poses a serious public health concern and should be included in future epidemiological studies.

We encountered an extremely rare tumor, a pericardial mesothelioma, in a neonatal calf. The patient calf showed severe abdominal distention, and died immediately after birth. The thoracic cavity was contained a huge heart with a large amount of pericardial fluid. A number of granular and cobblestone-like nodules were dispersed over the epicardium and pericardium. The nodules consisted of papillary proliferations of neoplastic cells, and the neoplasm occasionally showed mesenchymal proliferations. Immunohistochemistry revealed that they had the characteristics of mesothelial cells (cytokeratin-and vimentin-positive), and the neoplasm was diagnosed as mesothelioma.

A 3-month-old female tortoise-shell cat showing azotemia died with a marked swollen abdomen. Necropsy revealed a huge perirenal cyst (8.5 x 6.0 x 4.5 cm) on the ventral aspect of the right kidney. The cyst was filled with the pellucid yellow fluid with a smell of urine. The lumen was connected with irregularly dilated renal pelvis by a narrow channel passing through the renal parenchyma. The cyst was lined by epithelial cells and its wall was consisted of collagen fibers and smooth muscle cells as that of the renal pelvis and ureter. Renal parenchyma adjacent to the channel showed interstitial infiltration of the lymphoid cells. The cyst was a diverticulum of the renal pelvis due to an impaired development.

Renal allograft transplantation was performed in four beagles. Immunosuppressive treatment using cyclosporine, mizoribin and prednisolone was continued from Day 5 pre- until Day 20 post-transplantation. Between Days 28 and 32 post-transplantation, an abrupt elevation of the serum creatinine values followed by the development of uremia was seen in all recipients. Histopathology of the allografts examined between Days 28 and 37 revealed edema, necrosis, hemorrhage and severe diffuse interstitial cellular infiltration as well as tubulitis. Glomerular changes notably included swelling of the tufts due to hypercellularity, which was consistent with transplant glomerulitis. The intrarenal arteries exhibited fibrinoid necrosis of the walls and intimal or transmural cellular infiltration. These renal lesions were consistent with those of acute vascular and interstitial rejection in humans.

The effectiveness of 6 antitumor agents has been evaluated for canine mammary gland tumor (CMG-6) serially transplanted into severe combined immunodeficiency (SCID) mice. CMG-6 diagnosed as a solid carcinoma was subcutaneously transplanted into SCID mice and six antitumor agents were intravenously given to the mice as a single injection. The effectiveness was evaluated by Treatment group/Control group percent (T/C %) and statistical significance determined by Mann-Whitney's U-test in tumor volume. The minimum effective doses (MEDs; mg/kg) of mice were as follows; cyclophosphamide (CPM) 65, doxorubicin (DXR) 6, cisplatin (CDDP) 5, vincristine (VCR) 1.6, vinblastine (VLB) more than 5.5, 5-fluorouracil (5-FU) 105. Clinical effects of the drugs were predicted based on area under the curve (AUC) of dogs given a clinical dose (AUCdog)/AUC of mice given a MED (AUCmouse) ratios from published references. The AUC ratios were as follows; CPM 2.24, DXR 0.19, CDDP 1.20, VCR 0.04, VLB <1.24 and 5-FU 1.15. Drugs indicating more than 1.0 in AUCdog/AUCmouse ratio were CPM, CDDP and 5-FU, and would be suggested as effective in the original patient with CMG-6. The combination chemotherapy using clinically equivalent doses in CDDP and CPM, which were the two highest values in AUCdog/AUCmouse ratio by single agent therapy, was performed and shown to have additional effects as compared to the responsiveness of each agent against CMG-6.

A transitional type of combined hepatocellular and cholangiocellular carcinoma developed in a 12-year-old male Yorkshire terrier dog. The tumor was histologically composed of both hepatocellular carcinoma and cholangiocellular carcinoma components, and both elements were closely intermingled. Intraluminal mucin accumulation in cytokeratin-positive tubular/glandular structures was observed within the cholangiocellular carcinoma components and this feature was useful histological marker for a differential diagnosis between combined hepatocellular and cholangiocellular carcinoma and a pseudoglandular type of hepatocellular carcinoma. This primary hepatic tumor is extremely rare in dogs.

Ultrastructural alteration of anionic sites (ASs) in the glomerular basement membrane (GBM) was studied in glomerulonephritis characterized by linear capillary IgG deposition in four dogs infected with Dirofilaria immitis and two normal control dogs using polyethyleneimine. ASs were identified as small dense particles distributed regularly in the lamina rara externa (LRE), but there were no ASs in the lamina densa (LD) of the GBM of the control dogs. In the glomeruli of the infected dogs, ASs were distributed regularly or irregularly in the thickened LD. ASs were in addition localized over the characteristic continuous bands of subendothelial dense deposits. The number of ASs of the LRE increased in all four infected cases as compared to the controls (p<0.01).

A total of 4,418 samples of commercial layer feeds obtained in 1998 were investigated for the presence of salmonellae. A total of 146 strains of salmonellae which consisted of 32 serovars, including 20 strains of Salmonella Enteritidis, were isolated from 143 feed samples.

A number of pale-stained cell foci were observed within a well-differentiated hepatocellular carcinoma which developed in a 10-year-old male mongrel dog. The foci were composed of hepatocyte-like cells, but did not contain glycogen granules in their cytoplasm. Immunohistochemically, the focus cells coexpressed both bile duct type cytokeratin and vimentin. Electronmicroscopically, they were abundant in cytoplasmic organelles and contained bile pigments. Bile canaliculi were noted between the focus cells. The focus cells in the present case were considered to be neoplastic hepatocytes expressed bipotential features of hepatic stem cells.

Intrahepatic pylephlebitis was detected in 17 Japanese beef cattle. Grossly, the intrahepatic vessels in the caudate lobe and/or in the periphery of the other hepatic lobes were thickened and protruded above the lobar surface. The vessel lumina were packed with white to red, waste thread-like contents. A few immature flukes were found in the bile ducts in 3 of the 7 cases with biliary thickening. Foci of hepatic necrosis and hemorrhage were scattered around the thickened vessels in 8 cases. Histologically, the interlobular veins were thickened due to severe intimal hyperplasia with endothelial proliferation and eosinophilic accumulation and medial hypertrophy, accompanied by fibrosis and eosinophilic infiltration in the portal areas. Hepatic tissues with necrosis and hemorrhage were surrounded by eosinophils and histiocytes including a granulomatous reaction. One immature fluke was detected in one of these regions of necrosis. Immunoperoxidase staining revealed that the small fluke, Kupffer cells, and histiocytes in the liver of all cases were positively stained with anti-Japanese Fasciola sp. antiserum. Enzyme-linked immunosorbent assay of the sera of 15 cases revealed that all were positive for the anti-Fasciola antibody. On the basis of these findings, the present cases were regarded as an atypical form of fascioliasis, characterized by eosinophilic proliferative pylephlebitis of the liver.

To investigate the pathogenesis of porcine serum (PS)-induced liver fibrosis in rats, two experiments were carried out, taking into consideration of hypertension and vascular changes. In Experiment I, spontaneous hypertensive rats (SHRs), two-kidney, one clip hypertensive F344 rats (2K1C rats), and normotensive F344 rats were given an intraperitoneal injection of PS of 0.5 ml twice a week for 8 weeks. Histopathological, immunohistochemical, and electron microscopical examinations were performed on the liver from each rat. Histological features of liver fibrosis in hypertensive and normotensive rats were essentially identical. However, in the PS-treated SHRs, 2 of 5 animals showed the most severe fibrosis in all PS-treated groups. Electron microscopically, degranulated mast cells, eosinophils, and macrophages engulfing apoptotic cells were rarely observed in the late stage of fibrous septa (FS) in the PS-treated SHR liver. In Experiment II with normotensive F344 rats, histopathological features of early FS in the liver were compared with those of late FS observed in Experiment I using serial sections, and we found that FS developed along the wall of newly formed vessels to connect between neighboring central veins. However, the effect of hypertension on this fibrosis could not be clearly demonstrated in the present study using SHRs and 2K1C rats.

A hepatoblastoma was found in a 13-year-old female Maltese dog. Histologically, the tumor showed a wide trabecular pattern and was frequently accompanied with vascular lake formation. Tumor cells were positive for cytokeratin and neuron specific enolase, but negative for chromogranin. Electronmicroscopically, tumor cells were accompanied with continuous basement membrane and had poorly developed desmosomes. Sinusoidal endothelia had fenestration and were surrounded by myofibroblast-like cells. To the best of our knowledge, this paper is the first report of morphological studies on canine hepatoblastoma.

Ultrastructural alteration of anionic sites (ASs) in the glomerular basement membrane (GBM) was studied in 10 cases of swine mesangial proliferative glomerulonephritis using a cationic ultrastructural tracer, 0.5% polyethyleneimine (M.W. = 1,800). Glomerular ASs were seen as discrete electron-dense particles in the GBM, mesangial matrix and epithelial cell surfaces by electron microscopy. In the lamina rara externa (LRE) of the normal GBM, ASs were distributed regularly in a single layer. In those areas of the LRE that contained electron dense deposits or clusters of spherical microparticles (SMPs), however, a distinct reduction or loss of ASs was observed in all the pigs. Quantitative assessment of ASs in the LRE over 1,000 nm of the GBM revealed a significant reduction in ASs in one case with diffuse global thickening of the GBM as compared with the remaining nine pigs without GBM thickening (P < 0.001, Mann-Whitney's U-test). There were no ASs in the lamina densa (LD) of the normal GBM, but an irregular distribution of ASs was seen within the LD of the pig showing diffuse global thickening of the GBM. These results suggest that a disturbance of the charge-selective barrier in the GBM may be induced by electron-dense deposits or SMPs, in the LRE as well as thickening of the GBM in swine glomerulonephritis.

In order to clarify the pathogenesis of porcine serum (PS)-induced rat liver fibrosis, three experiments differing in dose of PS or duration of treatment were performed on male Fischer 344 rats. The rats were given an intraperitoneal injection of PS twice a week for 3 to 16 weeks and euthanized 7 days after the last injection for each treatment group. Liver tissues from these animals were subjected to detailed morphological and immunohistochemical examinations. Biochemical tests on treated rat serum revealed an increase in globulin concentration but no elevation in AST, ALT and ALP activities. There were no relationships among the dose of PS, the extent of fibrosis, and the anti-PS antibody titer. A number of alpha-smooth muscle actin-positive non-myofibroblastic cells, desmin-positive cells, and lipofuscin-laden Kupffer cells were found around the central veins and in the fibrous septa. In advanced stages of fibrosis, a proliferation of elastic fibers were observed in the septa. These findings were considered to indicate gradually occurred hepatocellular necrosis. The vascular endothelial cells in the fibrous septa expressed factor VIII-related antigen, exhibited fenestration accompanied by basement membrane formation, and were surrounded by Ito cells. Most of the portal vein branches showed hypertrophic thickening of the smooth muscle layer, resulting in narrowing of the lumen. These vascular changes suggested that hemodynamic alterations of the intrahepatic circulation induced hepatocellular necrosis/apoptosis and played an important role in the pathogenesis of porcine serum-induced liver fibrosis in rats.

Immunohistochemical and ultrastructural studies were performed on the sinusoidal lining cells of eight canine hepatocellular carcinomas. The sinusoidal endothelial cells of the tumors had a positive reaction for both Factor VIII-related antigen and peanut agglutinin, but did not bind with Ulex europaeus agglutinin-1. Desmin- and lysozyme-positive cells were present along the sinusoids and perisnusoidal spaces of the tumor tissues, respectively, but were fewer in number compared with those of normal canine liver. Alpha-Smooth muscle actin-positive cells outlining the sinusoids were frequently observed. Electron microscopy revealed that basement membranes were often formed beneath the sinusoidal endothelial cells, with rare fenestration. Macrophages were present around or within the sinusoids and tended to increase in number relative to the degree of tumor differentiation. Myofibroblast-like cells with various morphological features, consistent with alpha-smooth muscle actin-positive cells, were frequently found in the perisinusoidal space. The present study indicates that the sinusoidal lining cells of canine hepatocellular carcinoma have some phenotypic characteristics.

Intermediately differentiated mast cell tumors in two dogs were subcutaneously xenotransplanted into severe combined immunodeficiency (SCID) mice. Both tumors primarily grew and were serially transplantable in SCID mice. The histological features of the xenografts were similar to those of original tumors in dogs. Both of these subcutaneous tumors were judged as connective tissue mast cells by toluidine blue stain. One of the two xenografts metastasized to the tracheobronchial lymph nodes, omentum, mesentery, subpleural region and retroperitoneum of the SCID mouse. These canine mast cell tumor xenografts in SCID mice may be valuable tools for investigating the growth and metastatic behaviors of the tumor.

Hepatic nodular fibrosis occurred in an 8-year-old male Papillon dog. Fibrous nodules, consisting of broad bands of collagen fibers, spindle cells, and lipofuscin-laden foamy macrophages, were well-circumscribed and frequently linked up with the portal areas. Because the spindle cells were positive for desmin and/or alpha-smooth muscle actin, they might be Ito cells or myofibroblasts. These results suggest that both the spindle cells and macrophages play an important role in the pathogenesis of hepatic nodular fibrosis, which might arise from the portal area.

Nine feline tumors resected at surgery were subcutaneously xenotransplanted into SCID mice. The primary take rate of the benign and malignant tumors was 50% (1/2) and 100% (7/7) respectively. Six of the eight primary tumor xenografts transplanted and grown in the first recipient were successfully transplanted serially. One feline mammary adenocarcinoma xenograft metastasized to the lung of a SCID mouse. The primary take rate of feline tumors to SCID mice was high and the established xenografts appear to be valuable tools for investigating growth and metastasis mechanisms, and various therapies for feline neoplasms.

A dwarf male Large White neonate showing various external abnormalities was diagnosed to be chondrodysplasia. Microscopy revealed massive accumulation of eosinophilic homogeneous substance in the renal glomeruli, mainly along the capillary walls. The homogeneous substance, mainly consisted of type-III collagen, was not found in the primitive glomeruli in the superficial cortex, and was most frequently and intensely deposited in the mature glomeruli in the deep cortex. Electron microscopically, the deposits consisted of the collagen fibrils with various structural abnormalities. Glomerular fibrosis might be attributed to in situ production of type-III collagen by glomerular cells with differentiation and maturation, most likely by the mesangial cells.

Lymphangiosarcoma was seen in the subcutis of right chest in a 11-year-old female Poodle. No metastasis was observed clinically. Tumor cells were vimentin positive and formed irregular space or slit without erythrocytes in the tumor tissue. Lymphocytic foci and edema were seen in the stroma. Only a few tumor cells had factor VIII-related antigen. Electronmicroscopically, tumor cells did not accompany with basement membrane and intercellular junctional complex.

Canine tumors resected at surgery or autopsy were subcutaneously xenotransplanted into SCID mice. Thirty of the seventy-three tumors (41.1%) grew primarily in SCID mice. The primary take rate of mammary tumors and skin and subcutaneous tumors was 55.9% (19/34) and 28.6% (8/28), respectively. One thyroid carcinoma, one oral leiomyosarcoma and one osteosarcoma also underwent successful primary growth. Thirteen of the forty-one benign tumors (31.7%) and 17 of the thirty-two malignant ones (53.1%) were successfully transplantable. The histological features of the primary xenografts and their original tumors were similar to each other in all the cases. Three xenografts of the four malignant tumors with metastasis in the canine patients were shown to grow also in SCID mice and two mammary tumor xenografts out of the three metastasized to the lungs of SCID mice as well. All the 30 primary tumor xenografts grown in the first recipient were successfully transplantable to the second generation of the SCID mice. Xenotransplantation using SCID mice appears to be a valuable tool for investigating the biological characteristics of canine neoplasmas.