Intraoperative hemorrhage during patent ductus arteriosus ligation in dogs

OBJECTIVE: To determine the prevalence of intraoperative hemorrhage in a consecutive series of dogs undergoing patent ductus arteriosus (PDA) ligation at a veterinary teaching hospital, and to describe strategies to reduce the risk of ductus perforation and deal with hemorrhage when it occurs. STUDY DESIGN: Retrospective clinical study. ANIMALS: Sixty-four dogs. METHODS: The records of all dogs undergoing PDA ligation at the University Veterinary Center, Sydney between May 1989 and February 1998 were reviewed and the prevalence and nature of complications identified. RESULTS: Serious hemorrhage occurred in 4 of 64 dogs (6.25%) that underwent PDA ligation. In all cases, hemorrhage resulted from perforation of the craniomedial aspect of the ductus while attempting to expose the tips of the dissecting forceps. Hemorrhage was controlled in 3 dogs by clamping the main pulmonary artery, digital compression of the descending aorta, and completion of ductus ligation during an approximately 5-minute period of circulatory arrest. The remaining dog exsanguinated during an unsuccessful attempt to locate, clamp, and ligate the bleeding point. The mortality rate for PDA ligation was I of 64 dogs (1.6 %). CONCLUSIONS: The technique described in this report permits simple ligation of a range of different ductus morphologies in dogs of varying breeds, weights, and ages. In the event of serious hemorrhage, prompt ventricular outflow occlusion and ductus ligation followed by rapid whole blood transfusion is life saving in most cases.     

Expression of the ether-a-go-go (ERG) potassium channel in smooth muscle of the equine gastrointestinal tract and influence on activity of jejunal smooth muscle

OBJECTIVE: To determine whether ether-a-go-go (ERG) potassium channels are expressed in equine gastrointestinal smooth muscle, whether ERG channel antagonists affect jejunal muscle contraction in vitro, and whether plasma cisapride concentrations in horses administered treatment for postoperative ileus (POI) are consistent with ERG channels as drug targets. SAMPLE POPULATION: Samples of intestinal smooth muscle obtained from 8 horses free of gastrointestinal tract disease and plasma samples obtained from 3 horses administered cisapride for treatment of POI. PROCEDURE: Membranes were prepared from the seromuscular layer of the duodenum, jejunum, ileum, cecum, large colon, and small colon. Immunoblotting was used to identify the ERG channel protein. Isolated jejunal muscle strips were used for isometric stress response to ERG channel blockers that included E-4031, MK-499, clofilium, and cisapride. Plasma concentrations of cisapride were determined in 3 horses administered cisapride for treatment of POI after small intestinal surgery. RESULTS: Immunoblotting identified ERG protein in all analyzed segments of the intestinal tract in all horses. The selective ERG antagonist E-4031 caused a concentration-dependent increase in jejunal contraction. Clofilium, MK-499, and cisapride also increased jejunal contraction at concentrations consistent with ERG channel block; effects of E-4031 and cisapride were not additive. Peak plasma cisapride concentrations in treated horses were consistent with ERG block as a mechanism of drug action. CONCLUSIONS AND CLINICAL RELEVANCE: The ERG potassium channels modulate motility of intestinal muscles in horses and may be a target for drugs. This finding may influence development of new prokinetic agents and impact treatment of horses with POI.     

In vitro evaluation of biomechanical effects of multiple hemilaminectomies on the canine lumbar vertebral column

OBJECTIVE: To conduct an in vitro investigation of the biomechanical characteristics of the canine lumbar spinal column in flexion and extension and measure the destabilizing effects of multiple consecutive unilateral and bilateral hemilaminectomies. SAMPLE POPULATION: 30 isolated multisegmental spinal units (L1-L4) from nonhypochondroplastic dogs weighing 15 to 30 kg. PROCEDURES: Physically normal and surgically altered spinal specimens were subjected to 4-point bending in flexion and extension to determine effects of multiple consecutive hemilaminectomies on the basis of analysis of test system load-displacement data. Six groups with 5 spinal columns in each were defined on the basis of the following procedures: hemilaminectomy at L2-L3, 2 adjacent hemilaminectomies at L1-L3, 3 adjacent hemilaminectomies at L1-L4, bilateral hemilaminectomies at L2-L3, 2 bilateral hemilaminectomies at L1-L3, and no hemilaminectomy (intact). Spinal stability before and after surgery was determined in all groups. Each group served as its own control for nondestructive testing. Spinal strength was evaluated through destructive testing to determine deformation at failure, strength to failure, and mode of catastrophic failure. The intact group served as the control for destructive testing. RESULTS: Stability in extreme flexion and extreme extension did not change significantly following any hemilaminectomy procedure. Postoperative stability within the neutral zone was significantly decreased in all groups. Range of motion within the neutral zone was not significantly different from the intact condition in any group. CONCLUSIONS AND CLINICAL RELEVANCE: Multiple hemilaminectomies did not decrease stiffness of the lumbar spinal column during flexion and extension. These results support clinical recommendations regarding multiple consecutive hemilaminectomies in dogs.     

Supplementation of diets containing pea meal with exogenous enzymes: effects on weight gain,feed conversion,nutrient digestibility and gross morphology of the gastrointestinal tract of growing broiler chicks

1. The potential for the nutritional improvement of pea-based diets by supplementation with a cocktail of exogenous carbohydrases was investigated using growing broiler chicks. 2. Pea meals (grown in the UK) were included in wheat-based diets at 300 g/kg as a partial replacement for an approximately isonitrogenous mixture of wheat and soybean meal. A wheat/soybean meal diet served as a control and each diet was supplemented with a cocktail of alpha-amylase, pectinase and cellulase. The diets were fed to 1-d-old broiler chicks for a period of 21 d. Weight gain and feed conversion were monitored weekly and excreta were collected during the final week in order to determine nutrient digestibility coefficients and metabolisable energy. On d 21, the gastrointestinal (GI) tract was excised and gross morphology measured. 3. Inclusion of pea meal reduced weight gain, feed conversion, nutrient digestibility and also increased the relative sizes of the distal sections of the GI tract. 4. Enzyme addition partially ameliorated the detrimental effects of pea meal inclusion although similar improvements were also noted for birds fed on the control diet. 5. It is concluded that the nutritive value of pea-meal-based diets can be improved by the addition of carbohydrases, and that some pea cultivars show considerable potential as vegetable protein sources for broiler chicks.     

Priming of multiple T cell subsets by modified-live and inactivated bovine respiratory syncytial virus vaccines

T cell activity is a critical component of immunity to bovine respiratory syncytial virus (BRSV). We tested the effects of immunization by modified-live and inactivated BRSV vaccines on cell-mediated and humoral immunity in young calves. The two forms of vaccine stimulated similar serum neutralizing antibody production, although the early kinetics of those responses differed. CD4+, CD8+, and gammadelta T cells were analyzed before and after immunization for BRSV-specific in vitro recall responses, as evaluated by CD25 upregulation measured by flow cytometry. Modified-live virus (MLV) primed each of the three subsets for statistically significant in vitro responses to antigen. Inactivated vaccine also primed each T cell population for significant antigen-driven CD25 upregulation, including responses by CD4+ and gammadelta T cells that were stronger and longer-lasting than those primed by MLV. Monoclonal antibody was used in additional assays to block MHC class I during incubation of BRSV antigen with peripheral blood mononuclear cells from an animal in the inactivated vaccine group. The recall response by CD8+ T cells was more inhibited by this treatment than the other subsets, further suggesting that the inactivated vaccine had primed antigen-specific CD8+ T cells. In summary, the data indicate that balanced BRSV-specific T cell responses can be induced by inactivated, as well as modified-live, conventional vaccines, which may implicate an alternative pathway of MHC class I antigen presentation.     

Effect of vaccination with selective bacterins on conventional pigs infected with type 2 porcine circovirus

The objective of this study was to determine whether vaccination with bacterins commonly used in the USA, when administered at a time typical of US protocol, enhances porcine circovirus type 2 (PCV2) replication and the incidence and severity of clinical signs and lesions characteristic of postweaning multisystemic wasting syndrome (PMWS) in conventional pigs. Sixty-one pigs free of PCV2 were randomly assigned to four groups. Groups 1 (n = 15) and 2 (n = 15) pigs served as sham-inoculated negative controls. Groups 3 (n = 14) and 4 (n = 17) pigs were inoculated intralymphoid with PCV2 field isolate ISU-40895. Pigs in groups 2 and 4 were vaccinated with Actinobacillus pleuropneumoniae (APP) and Mycoplasma hyopneumoniae (M. hyopneumoniae) bacterins 21 days before and again 1 day before inoculation with PCV2. Mild transient respiratory disease and diarrhea were observed from 13 to 34 days postinoculation (DPI) in pigs in groups 3 and 4. Half the pigs from each group were necropsied at 22 and 34 DPI, respectively. Moderately enlarged, tan-colored lymph nodes were observed in the majority of pigs in groups 3 and 4. There was a significantly (P < 0.05) longer length of viremia (2.14 +/- 0.26 versus 4.44 +/- 0.23 weeks), a higher copy number of the PCV2 genome in serum, a wider range of tissue distribution of PCV2 antigen, and an increased severity of lymphoid depletion in pigs vaccinated with commercial APP and M. hyopneumoniae vaccines and inoculated with PCV2 compared with PCV2-inoculated unvaccinated pigs. Swine producers and veterinarians may need to consider changes in vaccination protocols in herds with recurrent PCV2-associated PMWS.     

Retrospective analysis of historical, clinical, ultrasonographic, serum biochemical and haematological data in prognostic evaluation of equine liver disease

REASONS FOR PERFORMING STUDY: Results of noninvasive tests of liver disease do not always correlate with the degree of hepatic disease nor outcome of the case. OBJECTIVE: To investigate the prognostic value of data collected using noninvasive tests during the investigation of cases of suspected liver disease in mature horses. HYPOTHESIS: Much of the data gathered during the investigation of suspected hepatopathy cases offers little prognostic guidance and interpretation of such data can be misleading. METHODS: The results from a range of common and noninvasive diagnostic techniques applied in 116 mature horses with suspected liver disease, were assessed for their ability to predict survival within a 6 month period. RESULTS: A significantly poorer prognosis was found in association with clinical signs suggestive of liver disease, presence of hepatic encephalopathy, ultrasonographic abnormalities, increased serum globulins, increased total bile acids (TBA), increased alkaline phosphatase (AP), increased gamma-glutamyl transferase (gammaGT), erythrocytosis, leucocytosis, low serum albumin and low serum urea. Additional significant novel findings of interest included an association between increased plasma fibrinogen and low serum creatinine concentrations with nonsurvival in cases of liver disease, an association between raised serum concentrations of AP and gammaGT with biliary hyperplasia and also an association between hepatic fibrosis, haemosiderosis and biliary hyperplasia with ultrasonographically detected hepatic abnormalities. CONCLUSIONS: The most useful noninvasive prognostic test in cases of suspected liver disease in mature horses is the severity of clinical signs. Other data may be of some limited prognostic value. POTENTIAL RELEVANCE: Application of the findings in this study may not be directly applicable to other case populations. However, the findings should at least be considered when prognosis is based on similar criteria.