Liver pathology and immune response in experimental Fasciola hepatica infections of goats

The relationship between the immune response and the pathogenesis of the disease was studied in different primary and secondary experimental Fasciola hepatica infections of goats. The establishment of the infection, measured as percentage of recovered flukes at the necropsy, was similar in primarily and secondarily infected animals (between 19.7% and 24.3%), but the hepatic damage was much more severe in secondarily infected goats, as revealed by the levels of serum hepatic enzymes GGT and LDH. Primary infection evolves to chronic fasciolosis that did not induce the development of resistance, since goats were highly susceptible to secondary infection, showing severe acute and chronic hepatic lesions that led to the death of some animals in each group. The immune response to the infection was proved by the production of specific IgG antibodies to ESP of F. hepatica and the involvement of CD3+ T lymphocytes and lambda IgG+ plasma cells in the hepatic infiltrate. Secondary infection did not induce any difference in either IgG response or in the cellular composition of the infiltrate of hepatic lesions, although this was much more extended. However, neither antibodies nor cell-mediated response were protective: there was no correlation between IgG levels and fluke burden and there was no evidence of cell-mediated killing of the parasite. This suggests the existence of some immune evasion mechanisms in goat infection with F. hepatica. The parasite may depress the local inflammatory and immune response, as suggested by the scarcity of CD3+ T cells in the infiltrate surrounding acute migratory tunnels. Moreover, in secondary infected goats can be suspected an immunological damage of the liver, since a very severe infiltrate of immune cells replaced wide areas of hepatic parenchyma and an immune-mediated damage of hepatocytes could occur.     

Age and incubation time effects on in vitro caecal fermentation pattern in rabbits before and after weaning.

The caecal fermentation pattern was studied in four litters of rabbits. Rabbits were sequentially slaughtered at the age of 4 (before weaning), 6, 8 and 11 weeks. Their caecal contents were analyzed and incubated in vitro at 39 degrees C for 6 and 12 h. Net productions of short-chain fatty acids (SCFA), hydrogen and methane were determined. The average caecal weight increased three-times within two weeks after weaning, from 31.4 to 93.7 g. At the end of the experiment, the caecal weight was on average 134.4 g. A large variability of the SCFA concentration observed before weaning decreased after weaning. Measurements of caecal metabolite profiles and results of in vitro experiments indicated a certain decrease of propionate in favour of butyrate, associated with the weaning. The establishment of methanogens in rabbits was slow. Methanogenesis started in one out of four rabbits at the age of 6 weeks. Five weeks later, one of four rabbits still did not produce methane. The hydrogen recovery decreased between the 4th and the 6th week of age, due to the increase of the butyrate/propionate ratio. After the 6th week, the hydrogen recovery increased with age, apparently because of the increase in methane production. Hydrogen recovery tended to increase during incubation, suggesting a decrease of reductive acetogenesis. This increase was observed both in methanogenic and non-methanogenic rabbit caecal cultures. In former cultures, the ratio CH4/SCFA rose with time of incubation.     

Aggregation of sow lactobacilli with diarrhoeagenic Escherichia coli

A total of 20 strains of lactobacilli were isolated from the oesophagus and vagina of 20 sows at the time of partus. Aggregation activity was seen between six homofermentative autoaggregative lactobacilli and three strains of pathogenic Escherichia coli with F4, F5 and F6 fimbriae. The highest aggregation activity was observed between vaginal Lactobacillus acidophilus PV 32 or oesophageal OE 2/1 and E. coli with F4 (K88). The presence of aggregation-promoting factor (APF) was confirmed by polymerase chain reaction (PCR) with primers of a specific fragment the apf gene derived from human L. gasseri 4B2 in one oesophageal L. acidophilus strain OE 2/1. We propose that autoaggregative lactobacilli that aggregate with diarrhoeagenic E. coli can express a class of APF proteins that exhibit the function of an aggregation mediator.     

Penetration of parenterally administered ceftiofur into sterile vs. Pasteurella haemolytica-infected tissue chambers in cattle

The effect of bacterial infection on antibiotic activity and penetration of parenterally administered ceftiofur into implanted tissue chambers was studied in cattle. Tissue chambers were implanted subcutaneously in the paralumbar fossae of eight calves (256-290 kg body weight). Approximately 80 days after implantation, the two chambers on one side of each animal were inoculated with Pasteurella haemolytica (10⁶ CFU/chamber). Eighteen hours after inoculation, ceftiofur sodium was administered intravenously (5 mg/kg) to each of the calves. Non-infected chamber fluid, infected chamber fluid and heparinized blood samples were collected immediately before and at 1, 3, 6, 12 and 24 h after drug administration. Concentrations of ceftiofur and desfuroylceftiofur metabolites and ceftiofur-equivalent microbiological activity were measured by high-pressure liquid chromatography and microbiological assay respectively. Concentrations of ceftiofur and desfuroylceftiofur metabolites and antimicrobial activity in P. haemolytica -infected tissue chambers were significantly higher than those in non-infected tissue chambers at all sampling times, indicating that ceftiofur, regardless of the method used for analysis, localizes at higher concentrations at tissue sites infected with P. haemolytica . Antibiotic activity-concentration ratios were lower in plasma and infected chamber fluid compared with non-infected chamber fluid, suggesting that antibiotic was bound to proteins. However, higher antimicrobial activity in the infected chamber fluid compared with the non-infected chamber fluid suggests that active drug is reversibly bound to proteins. Protein-bound desfuroylceftiofur may represent a reservoir for release of active drug at the site of infection in the animal.     

Immunohistochemical demonstration of keratin in canine neuroepithelioma

Morphological features and immunoreactivity for cytokeratin (CK), glial fibrillary acidic protein (GFAP) and neuron-specific enolase (NSE) of three canine neuroepitheliomas and three canine ependymomas were investigated. Neuroepitheliomas were in three German shepherds as intradural-extramedullary solitary masses, with spinal cord displacement between T10 and L2. Histologically, they contained tubules and acini, lined by epithelial cells with focal squamous metaplasia, rosette-like structures, and polygonal to spindle-shaped cells between tubules. Acini were empty or filled with a homogeneous, eosinophilic periodic acid-Schiff (PAS)-positive material. Mitotic indices varied from low to moderate. Ependymomas occurred in the third (two cases) and fourth ventricle in adult boxers. Histologically, they were composed of cells with an ill-defined, scant amphophilic cytoplasm, with a central round euchromatic nucleus; cells formed pseudorosettes, with a central fibro-vascular stroma. Neuroepitheliomas stained for CK, but ependymomas did not. Both failed to stain for GFAP, NSE, or phosphotungstic acid hematoxylin (PTAH). Thus, antibodies to cytokeratin are useful to distinguish neuroepitheliomas from ependymomas.     

A clinical episode demonstrating variable characteristics of pseudorabies infection in cattle

An outbreak of pseudorabies (PR) with CNS signs and acute death losses in feeder cattle was investigated. The cattle were in direct contact with swine. Although pruritus was not a predominant sign, PR virus was isolated from brain, thoracic spinal cord and lung specimens of affected cattle. Histopathologic findings were characteristic of a herpes virus infection.     

Protection of laying hens against infectious bronchitis with inactivated emulsion vaccines

Commercially-reared laying chickens were challenged at 31 weeks of age with a virulent infectious bronchitis (IB) virus. They showed a sharp drop in egg production, despite having been vaccinated at four and eight weeks old with live attenuated IB vaccines to a recommended schedule. In contrast, similar birds that had been further immunised at point-of-lay with inactivated oil emulsion IB vaccine, or with a combined IB/Newcastle disease (ND) emulsion vaccine, showed no detectable fall in egg production after the same challenge. Unvaccinated susceptible specific pathogen-free birds challenged at the same time stopped laying almost completely. In the birds revaccinated with emulsion vaccine, measurement of haemagglutination inhibition antibody levels to IB showed their geometric mean titres to be raised from less than 5 log2 at the time of vaccination to over 10 log2 four weeks later. Their antibody levels did not rise further followining the IB challenge whereas in the birds that had not been revaccinated antibody rises to nearly 10 log2 were detected after the same challenge. For pullets vaccinated earlier with live IB vaccine, revaccination with inactivated IB or IB/ND oil emulsion vaccine at point-of-lay provides a safe and effective way of protecting their egg production against IB infection.     

Immunofluorescent studies on localization of secretory immunoglobulins in the intestines of turkeys recovered from turkey coronaviral enteritis

The present study concerns the production of specific secretory antibodies in turkeys orally inoculated with turkey coronavirus (TCV). Tissue localization of secretory antibodies in the intestines of recovered birds 4 and 5 months later was demonstrated by immunofluorescence technique. Intestinal sections were stained by sandwich method, using concentrated TCV antigen and anti-TCV conjugate. It was suggested that local synthesis of antibody might be responsible for life-long immunity seen in these birds after recovery from infection.     

PERCUTANEOUS NEPHROPYELOCENTESIS AND ANTEGRADE URETEROGRAPHY: A FLUOROSCOPICALLY ASSISTED DIAGNOSTIC TECHNIC IN CANINE UROLOGY

Fluoroscopically assisted percutaneous nephropyelocentesis and/or antegrade ureterography was performed on six dogs. These technics were useful for obtaining renal pelvic urine specimens for culture. Percutaneous nephropyelocentesis confirmed diagnoses of pyelonephritis. Injection of a radiopaque contrast medium into the ureter or renal pelvis was useful in evaluating the ureter in those dogs in which excretory urography provided insufficient detail. No complication was associated with the technics.     

Osteoarticular Allogeneic Bone Grafting in Dogs

A review of the clinical and pathologic evaluation of allogeneic bone grafts is presented with particular emphasis upon partial joint replacement. The histologic evaluation of cortical bone transplantation is reviewed. Radiographic evaluation of cortical bone transplants is presented in an attempt to understand the normal events that take place in incorporation of the graft by the host. The histologic and radiographic correlation is related to the healing process. Current methods of graft collection and storage are reviewed. While collection of the graft is fairly uniform, there are many varied treatment and storage procedures. General surgical procedures used in performing full cortical bone grafts are reviewed. The clinical use of an osteoarticular allogeneic bone graft in the elbow of a dog is presented, with a review of the operative and postoperative evaluation of the clinical patient.