During investigations of the evolution of experimental laboratory infections of woodchucks (Marmota monax) with the woodchuck hepatitis virus (WHV), eight hepatocellular carcinomas (HCC) were observed, six in newborns and two in young adult animals, all within 17-36 months after infection. The absence of an external cocarcinogenic effect in the well-monitored woodchucks indicates the carcinogenicity of WHV and suggests the same for the genetically and biologically similar human hepatitis B virus (HBV). Laboratory infections of woodchucks with two strains of WHV, not reported here in detail, resembled human and chimpanzee HBV infections histologically and serologically. In these studies, eight woodchucks became carriers of surface antigen of WHV for >1 year. All eight woodchucks developed HCC, indicating a 100% risk of HCC in experimentally infected chronic WHV antigen carriers, which is analogous to the high risk of HCC in human hepatitis B surface antigen carriers. Histologically, the absence of cirrhosis in the examined pericarcinomatous tissue permits recognition of gradual transition from normal parenchyma to neoplastic nodules to HCC of rising anaplasia, indicating a continuum of increasingly more malignant neoplastic stages, as known for chemical carcinogenesis. The HCC developed in carrier woodchucks infected as newborns with only minor, if any, hepatitic changes but is associated with antigen-carrying hepatocytes and sometimes with hyperplastic nodules. This stage was preceded in infected adults by an early, acute, weeks-long hepatitis coinciding with the appearance of surface antigen. These findings are also analogous to typical HBV infection in human newborns and young adults, respectively. At the time of HCC development in all animals with adequate histologic material, an acute recent necroinflammation appeared around the tumor, associated with abnormal hematopoietic cells around and within the tumor. A promoting role in carcinogenesis of this necroinflammation of yet unestablished pathogenesis is being postulated, to be confirmed by determination of the status of the WHV DNA in the HCC and by prospective histologic study of the inflammatory reaction.Recently, several viruses have been associated with the induction of carcinomas in humans on epidemiologic and virologic evidence. This includes the Epstein-Barr virus in Burkitt lymphoma, the papilloma virus in cervical carcinoma, the group of human T lymphotropic viruses in lymphomas, and the hepatitis B virus (HBV) in hepatocellular carcinoma (HCC) (1). Despite the strong evidence for the carcinogenicity of these viruses, the requirement of a cocarcinogen is not fully excluded, although through the years this essentiality has become less probable. In chronic HBV infections, a potential role of aflatoxin (2, 3) is not excluded to date. HBV is a member of the hepadnaviruses, which show great homologies in DNA and its gene products but limited crossinfectivity (4, 5). In the eastern woodchuck (Marmota monax), in the Beechey ground squirrel in Cali...

The results of liver cytology and corresponding biopsy specimens submitted to the Pathology Department at Angell Memorial Animal Hospital during 1998 were retrospectively reviewed to objectively assess the diagnostic value of liver cytology. A "corresponding" biopsy was defined as a biopsy specimen obtained within 1 day of the cytology specimen. Fifty-six cases were reviewed, including 25 from dogs and 31 from cats. Results were in complete agreement in 34 cases, in partial agreement in 11 cases, and in disagreement in 11 cases. Agreement occurred most often in cases of fatty change (10 cases) and neoplasia (7 cases of lymphoma and 3 cases of epithelial tumor). Disagreement was most common in cases of hepatitis (6 cases) in which inflammation was not seen in cytologic specimens. Other causes for disagreement included fibrosis (2 cases), and 1 case each of amyloidosis, hemangiosarcoma, and lymphoma. Three cytologic specimens were considered suggestive of hepatitis because of leukocytosis in the background, although clinicians were advised to compare cytologic observation to CBC results. Cytologic evaluation of the liver was useful for determining disease processes, especially when disease distribution was diffuse.

Summary The historical, clinical, laboratory, surgical and necropsy findings in 54 cases of gastric rupture in horses are described. Eleven per cent of the deaths of horses undergoing exploratory coeliotomy for colic during the period of the study were a result of gastric rupture. Comparison with all horses which had exploratory coeliotomies for colic over an eight year period did not show that horses with gastric rupture were different from these reference horses regarding age, breed or season. There were fewer stallions than expected in the gastric rupture group. Horses with histories of both acute and chronic (more than 36 h) colic were susceptible to gastric rupture. Primary and idiopathic causes of gastric dilation and rupture accounted for about one‐third of the horses. All but one of these cases resulting from secondary causes fell into three aetiologically‐related groups: obstructive, peritoneal and enteric, with approximately equal numbers of horses in each group. Most of the ruptures occurred along the greater curvature of the stomach. At least six horses ruptured their stomachs post‐operatively in the presence of an indwelling nasogastric tube. The presence or absence of gastric reflux following nasogastric intubation was not a reliable indicator, on its own, of gastric dilation. Horses that later died from gastric rupture had markedly elevated heart rate, hypochloraemia, peritoneal exudative effusion (particularly with evidence of sepsis), pre‐and/or postoperative gastric reflux and small or large intestinal disease. However, no distinctive feature of these horses was shown to place them at risk of gastric rupture.

Abstract. Sixty fatal cases of traumatic reticulitis in cattle were reviewed. Fifty-nine cases were caused by fragments of wire. A nail perforated the reticulum of 1 animal. Common clinical signs included decreased milk production, anorexia, fever, and weight loss. Abnormal or muffled heart sounds associated with pericarditis and epicarditis was the most common sequela, occurring in 40 cases. Fibrous adhesions found at necropsy in all cases suggest that initial clinical signs are difficult to recognize and in most cases it takes weeks to months for abnormalities to be observed.Traumatic reticulitis due to the perforation of the reticulum by sharp foreign bodies that have been ingested has been a concern of veterinarians for many years. 3,8 The prevalence of traumatic reticulitis in adult dairy cattle has been attributed to management practices and the lack of discriminatory dietary habits of cattle.