Mortality (including euthanasia) among Danish dairy cows (1990-2001)

Mortality among Danish dairy cows was examined using data from the Danish Cattle Database (DCD) and a questionnaire survey. Mortality risk has increased from approximately 2% in 1990 to approximately 3.5% in 1999. The increased mortality was seen for all dairy breeds and all age groups. Mortality among older dairy cows (parity 3 and older) was approximately twice the mortality among younger cows. 30-40% of deaths were during the first 30 days of the lactation. Approximately, 58% of dead dairy cows had been euthanised. Replies from the questionnaire indicate that the proportion of euthanised cows has increased in the past 5 years. In 86% of all deaths (questionnaire survey) a primary reason could be identified; 25% were for locomotor disorders.     

Hepatocellular carcinoma in black-tailed prairie dogs (Cynomys ludivicianus): tumor morphology and immunohistochemistry for hepadnavirus core and surface antigens

From 1994 to 2002, tissues from 61 prairie dogs were submitted to Northwest ZooPath for histopathology. Of these, 12 (20%) had hepatocellular carcinoma (HCC). Three were pets submitted from private veterinary practices. The others were submitted from zoos in the United States. All were adults, ranging from young adult to 7 years of age, with average age of 5.1 years. The most common clinical signs were weight loss, lethargy, palpable abdominal mass, and respiratory difficulty. All tumors were well-differentiated HCCs in which four histologic patterns were recognized. The trabecular pattern was predominant in nine tumors, and the pseudoglandular pattern was predominant in two tumors. The pelioid pattern was also represented in eight tumors. A papillary pattern was present in one case. In seven cases vacuolar change resembling lipidosis was present in the neoplastic hepatocytes of both primary and metastatic tumors. Anaplasia was mild to moderate in most tumors, but a marked degree of anaplasia was noted in the metastatic foci of the case with papillary differentiation. Metastasis to lung was noted in five cases. One of these also had metastasis to the spleen, and another had metastasis to heart and mediastinum. In two cases there was concurrent hepatitis and in two cases, cirrhosis. All tumors and nonneoplastic liver stained negatively for woodchuck hepatitis virus surface and core antigens, and orcein and Victoria blue positive staining of hepatocytes typical of hepadnavirus infection in humans and woodchucks was not present. HCC is apparently common in captive prairie dogs. The hepatic neoplasia observed in prairie dogs was similar to that associated with hepadnaviral infection in humans, woodchucks, and ground squirrels, but no direct evidence of hepadnaviral infection was detected. The rate of metastasis in captive prairie dogs was higher than that reported in woodchucks.     

Reverse effects of tetraarsenic oxide on the angiogenesis induced by nerve growth factor in the rat cornea

To compare the antiangiogenic effects of tetraarsenic oxide (As4O6) with those of diarsenic oxide (As2O3) in the rat cornea, rat cornea micropocket assay was conducted to induce angiogenesis by implantation of the pellet contained 1.0 ng of nerve growth factor (NGF). Ten of thirty eyes of Sprague-Dawley rats were randomly assigned to one of three groups, namely, control group (no medication), As2O3 group (50 mg/kg As2O3, PO, s.i.d.), and As4O6 group (50 mg/kg As4O6, PO, s.i.d.). After implantation, the number of new vessels, vessel length and clock hour of neovascularization were examined under the microscope from day 3 to day 7. The area of neovascularization was calculated using a mathematical formula. Although new vessels in control and As2O3 groups were first noticed at day 3, whereas those of As4O6 group were first observed on day 5. The number, length, clock hour of neovascularization and areas of the vessels in As4O6 group showed more significant inhibition than those of control and As2O3 groups from day 5 (P<0.05). However, there were no differences in all parameters between control group and As2O3 group during the entire study period. These results showed that As4O6 had antiangiogenic effects on the new vessels induced by NGF in the rat cornea.     

Antibodies to Anaplasma marginale major surface proteins 1a and 1b inhibit infectivity for cultured tick cells

Major surface protein 1 (MSP1) of the cattle pathogen Anaplasma marginale (Rickettsiales: Anaplasmataceae) is a complex of two proteins, MSP1a and MSP1b. Previous studies demonstrated that MSP1a and MSP1b are adhesins for bovine erythrocytes, while only MSP1a proved to be an adhesin for tick cells. In this study, a tick cell culture system for propagation of A. marginale was used to develop an infection inhibition assay for testing the ability of antisera to block infection of A. marginale for cultured tick cells. A. marginale derived from cell culture was incubated with various antisera prior to inoculation onto cell monolayers. The monolayers were harvested 7 days post-inoculation and A. marginale in the cultures was quantified using an antigen detection ELISA. Antisera tested in the infection inhibition assay were derived from persistently infected cattle, from cattle immunized with A. marginale purified from bovine erythrocytes, and from rabbits and cattle that were immunized with the recombinant MSP1a, MSP1b and MSP1 complex. Antibodies from cattle persistently infected with A. marginale, cattle immunized with A. marginale from bovine erythrocytes or cattle immunized with the recombinant MSP1 complex did not inhibit the infectivity of A. marginale for tick cells. Antiserum from rabbits immunized with MSP1a and MSP1b (individually or combined) reduced infection of both the Virginia and Oklahoma isolates of A. marginale for tick cells by 25-70%. Likewise, antisera from cattle immunized with recombinant MSP1a or MSP1b inhibited infection of tick cells by 26-37%. These results further confirm the role of MSP1 complex proteins in infection of tick cells. Lack of inhibition of infection by antisera from naturally infected cattle or cattle immunized with whole organisms suggests that the bovine immune response is not directed toward blocking infection of A. marginale for tick cells and may contribute to the continued infectivity of the pathogen for ticks.     

Vaccinology of classical swine fever: from lab to field

There are two types of classical swine fever vaccines available: the classical live and the recently developed E2 subunit vaccines. The live Chinese strain vaccine is the most widely used. After a single vaccination, it confers solid immunity within a few days that appears to persist lifelong. The E2 subunit vaccine induces immunity from approximately 10-14 days after a single vaccination. The immunity may persist for more than a year, but is then not complete. The Chinese strain vaccine may establish a strong herd immunity 1-2 weeks earlier than the E2 vaccine. The ability of the Chinese vaccine strain to prevent congenital infection has not been reported, but the E2 subunit vaccine does not induce complete protection against congenital infection. Immunological mechanisms that underlie the protective immunity are still to be elucidated. Both types of vaccine are considered to be safe. A great advantage of the E2 subunit vaccine is that it allows differentiation of infected pigs from vaccinated pigs and is referred to as a DIVA vaccine. However, the companion diagnostic E(rns) ELISA to actually make that differentiation should be improved. Many approaches to develop novel vaccines have been described, but none of these is likely to result in a new DIVA vaccine reaching the market in the next 5-10 years. Countries where classical swine fever is endemic can best control the infection by systematic vaccination campaigns, accompanied by the normal diagnostic procedures and control measures. Oral vaccination of wild boar may contribute to lowering the incidence of classical swine fever, and consequently diminishing the threat of virus introduction into domestic pigs. Free countries should not vaccinate and should be highly alert to rapidly diagnose any new outbreak. Once a new introduction of classical swine fever virus in dense pig areas has been confirmed, an emergency vaccination programme should be immediately instituted, for maximum benefit. The question is whether the time is ripe to seriously consider global eradication of classical swine fever virus.     

Portosystemic shunts: diagnosis,prognosis, and treatment of 64 cases (1993-2001)

Cases diagnosed with portosystemic shunting between the years 1993 and 2001 were reviewed. Sensitivities of screening tests and abdominal ultrasonographic evaluation for the detection of portosystemic shunting were evaluated. Prognosis for surgically treated shunts was also evaluated. Results indicated that both paired serum bile acids and blood ammonia levels were useful screening tests for portosystemic shunting. However, paired bile acid tests were significantly more sensitive than blood ammonia levels. Overall postoperative mortality rates for extrahepatic shunts and intrahepatic shunts were 8.7% and 20%, respectively. Postoperative mortality rates were slightly higher for animals treated with partial ligation when compared to those treated with ameroid ring placement, although this did not reach statistical significance. Long-term complication rates for animals with single extrahepatic portosystemic shunts treated with complete ligation, ameroid ring placement, and partial ligation alone were 9%, 15.4%, and 42%, respectively. Animals >2 years of age with extrahepatic shunts had almost identical postoperative mortality and long-term complication rates as animals < or = 2 years of age. No animal in this study had paired bile acid samples within the reference range postoperatively, indicating continued abnormal liver function after surgery.     

Effects of lipopolysaccharide and phenylbutazone on gastric contents in the horse

REASONS FOR PERFORMING STUDY: Endotoxaemia causes a disruption of gastrointestinal motility in the horse but there is no information on its effects on gastric secretion. Lipopolysaccharide (LPS) administration is known to affect gastric secretion in other species. HYPOTHESIS: That LPS, a toxic component of Gram-negative bacteria, would reduce gastric acid secretion and that pretreatment with phenylbutazone (PBZ) would block the effects of LPS. METHODS: The effects of LPS and PBZ on gastric contents were investigated in fasted, mature horses, with permanent gastric cannulae. Horses were pretreated with either saline or PBZ 15 mins before a 60 min infusion of either LPS or saline. Gastric contents were collected at 15 min intervals for 3 h, beginning 15 mins after the start of the LPS or saline infusion. RESULTS: Lipopolysaccharide significantly decreased gastric acid output, [K+] and potassium output and increased [Na+] and sodium output. Phenylbutazone did not affect basal gastric acid secretion but decreased LPS-induced changes in the secreted volume, [Na+] and sodium output. CONCLUSIONS: This study provides evidence that LPS affects gastric acid secretion in the horse and that these LPS-induced changes are mediated, in part, by prostaglandins. POTENTIAL RELEVANCE: Lipopolysaccharide administration can induce changes in the composition of gastric contents in the horse but further work is needed to determine the source of these changes.