CONTRAST-ENHANCED ULTRASONOGRAPHY IN NORMAL CANINE LIVER. EVALUATION OF IMAGING AND SAFETY PARAMETERS

Contrast-enhanced ultrasonography, a new imaging modality in veterinary medicine, can provide data on tissue perfusion. The objective of this study was to use the ultrasonographic contrast agent SonoVue to evaluate various transit time indices in the normal canine liver, to examine the effect of anesthesia on these parameters, and to evaluate the safety of this agent in dogs. The liver of 11 healthy dogs was studied by ultrasound during an intravenous bolus injection of SonoVue. Each dog underwent the examination twice, first with and later without the use of anesthesia. A time-intensity curve was generated from a selected region of interest within the liver from each scanning session. Ratios derived from peak enhancement, time to peak enhancement, up-slope and full-width half-maximum (FWHM) of the curve were calculated from the time-intensity curves, and are reported. There were no statistically significant differences (P > 0.05) in peak enhancement, up-slope and FWHM between dogs that were anesthetized and dogs that were not. Time to peak enhancement, however, was significantly shorter when the dogs were anesthetized than when they were nonanesthetized (P < 0.05). There were no biologically significant changes in clinical laboratory findings. This study indicates that contrast-enhanced ultrasound using SonoVue gives reproducible liver perfusion data, and appears to be a safe and well-tolerated agent for use in dogs. When considering normal values, the use of anesthetic drugs has to be considered.     

Decreased platelet function in Cavalier King Charles Spaniels with mitral valve regurgitation

With aggregometry, increased platelet activity has been reported in Cavalier King Charles Spaniels (CKCS) without mitral regurgitation (MR). In contrast, dogs with MR have been found to have decreased platelet activity. The purpose of this study was to test an easy bedside test of platelet function (the Platelet Function Analyzer [PFA-100]) to see if it could detect an increase in platelet activity in CKCS without MR and a decrease in platelet activity in CKCS with MR. This study included 101 clinically healthy dogs > 1 year of age: 15 control dogs of different breeds and 86 CKCS. None of the dogs received medication or had a history of bleeding. The PFA-100 evaluates platelet function in anticoagulated whole blood under high shear stress. Results are given as closure times (CT): the time it takes before a platelet plug occludes a hole in a membrane coated by agonists. The CT with collagen and adenosine-diphosphate as agonists was similar in control dogs (median 62 seconds; interquartile interval 55-66 seconds) and CKCS with no or minimal MR (55; 52-64 seconds). The CT was higher in CKCS with mild MR (regurgitant jet occupying 15-50% of the left atrial area) (75; 60-84 seconds; P = .0007) and in CKCS with moderate to severe MR (jet > 50%) (87: 66-102 seconds; P < .0001). CKCS with mild, moderate, and severe, clinically inapparent MR have decreased platelet function. The previous finding of increased platelet reactivity in nonthrombocytopenic CKCS without MR could not be reproduced with the PFA-100 device.     

A review of aquatic weed biology and management research conducted by the United States Department of Agriculture-Agricultural Research Service

Ever-increasing demand for water to irrigate crops, support aquaculture, provide domestic water needs and to protect natural aquatic and riparian habitats has necessitated research to reduce impacts from a parallel increase in invasive aquatic weeds. This paper reviews the past 4-5 years of research by USDA-ARS covering such areas as weed biology, ecology, physiology and management strategies, including herbicides, biological control and potential for use of natural products. Research approaches range from field-level studies to highly specific molecular and biochemical work, spanning several disciplines and encompassing the most problematic weeds in these systems. This research has led to new insights into plant competition, host-specificity, and the fate of aquatic herbicides, their modes of action and effects on the environment. Another hallmark of USDA-ARS research has been its many collaborations with other federal, state action and regulatory agencies and private industry to develop new solutions to aquatic weed problems that affect our public natural resources and commercial enterprises.     

Safety and immunologic effects after inoculation of inactivated and combined live-inactivated dermatophytosis vaccines in cats

OBJECTIVE: To determine antidermatophyte immunologic effects of an experimental combined live-inactivated dermatophytosis vaccine (CLIDV) and a commercial inactivated dermatophytosis vaccine (IDV) in cats and to evaluate adverse effects associated with administration of these vaccines. ANIMALS: 20 healthy juvenile domestic shorthair cats. PROCEDURE: Cats were injected with 2 doses of CLIDV at the standard dosage or 1 dose of CLIDV at 10 times the standard dosage; IDV was administered at the manufacturer-recommended dosage. Cats were observed for illness and reactions at inoculation sites. Periodically, samples were obtained for fungal culture, lymphocyte blastogenesis test (LBT) as an indicator of cell-mediated immunity against dermatophyte antigens, and antidermatophyte IgG titers. Following vaccination, cats were challenge-exposed by topical application of Microsporum canis macroconidia and examined weekly for clinical signs of dermatophytosis. RESULTS: of 10 cats given CLIDV developed focal crusts at the injection site that resolved without treatment; these were areas of dermatophyte infection with the vaccine strain. Antidermatophyte IgG titers increased significantly with all vaccination protocols. Cellular immunity against M canis increased slightly and variably during the vaccination period and did not differ significantly between vaccinated and control cats. All cats developed dermatophyte infection after challenge exposure. Vaccination with CLIDV or IDV was associated with slightly reduced severity of initial infection. CONCLUSIONS AND CLINICAL RELEVANCE: Noculation with IDV or CLIDV did not provide prophylactic immunity against topical challenge exposure with M canis. Inoculation with either vaccine did not provide a more rapid cure of an established infection.     

Development of a rapid in vitro protein refolding assay which discriminates between peptide-bound and peptide-free forms of recombinant porcine major histocompatibility class I complex (SLA-I)

The extracellular domains of swine leukocyte antigen class I (SLA-I, major histocompatibility complex protein class I) were cloned and sequenced for two haplotypes (H4 and H7) which do not share any alleles based on serological typing, and which are the most important in Danish farmed pigs. The extracellular domain of SLA-I was connected to porcine beta2 microglobulin by glycine-rich linkers. The engineered single-chain proteins, consisting of fused SLA-I and beta2 microglobulin, were overexpressed as inclusion bodies in Escherichia coli. Also, variants were made of the single-chain proteins, by linking them through glycine-rich linkers to peptides representing T-cell epitopes from classical swine fever virus (CSFV) and foot-and-mouth disease virus (FMDV). An in vitro refold assay was developed, using a monoclonal anti-SLA antibody (PT85A) to gauge refolding. The single best-defined, SLA-I restricted porcine CD8(+) T-cell epitope currently known is a 9-residue peptide from the polyprotein of CSFV (J. Gen. Virol. 76 (1995) 3039). Based on results with the CSFV epitope and two porcine haplotypes (H4 and H7), the in vitro refold assay appeared able to discriminate between peptide-free and peptide-occupied forms of SLA-I. It remains to be seen whether the rapid and technically very simple in vitro refold assay described here will prove generally applicable for the screening of virus-derived peptides for SLA-I binding.     

Quantification of bioavailable chlortetracycline in pig feces using a bacterial whole-cell biosensor

Bacterial whole-cell biosensors were used to measure the concentration of chlortetracycline (CTC) in the feces of pigs. In this study, the Escherichia coli biosensor used has a detection limit of 0.03 mg/kg CTC in pig feces. The tetracycline concentration was correlated with the appearance and maintenance of fecal coliform bacteria resistant to tetracycline. Initially, large quantities of water-extractable CTC were excreted from the pigs and measurable amounts were detected even at 30 days after treatment cessation. This led to a sharp rise in the number of tetracycline resistant coliform bacteria in the feces, to within the same order of magnitude as the total coliform count. The high level of tetracycline resistance was maintained in spite of the declining concentration of tetracycline.     

Trends in antimicrobial susceptibility in relation to antimicrobial usage and presence of resistance genes in Staphylococcus hyicus isolated from exudative epidermitis in pigs

From 1996 to 2001 a total of 467 Staphylococcus hyicus isolates from exudative epidermitis (EE) in pigs in Denmark were examined for susceptibility to 13 different antimicrobial agents. The presence of selected genes encoding macrolide (erm(A), erm(B) and erm(C)), penicillin (blaZ), streptogramin (vat, vga, vga(B), vat(B), vat(D) and vat(E)), streptomycin (aadE) and tetracycline resistance (tet(K), tet(L), tet(M) and tet(O)) were determined in selected isolates.The occurrence of erythromycin resistance increased from 33% in 1996 to a maximum of 62% in 1997 and decreased to 26% in 2001. Resistance to sulphametazole increased from 17% in 1996 to 30% in 1998 but has since decreased to 4% in 2001. Resistance to trimethoprim increased to 51% in 1997 and decreased to 21% in 2001. Resistance to tetracycline (21-31%) remained relatively constant during 1996-2000, but increased to 47% in 2001. Resistance to penicillin (54-75%) streptomycin (33-53%) and tetracycline (21-47%) remained relatively constant over the time investigated.All 48 penicillin resistant isolates examined contained the blaZ gene and 40 (85%) of the streptomycin resistant isolates the aadE gene. It was not possible to detect any streptogramin resistance gene in four streptogramin resistant isolates. Of the 55 erythromycin resistant isolates examined, five contained erm(A), 13 erm(B), 35 erm(C) and two both erm(A) and erm(C). The presence of erm(B) was confirmed by hybridization to plasmid profiles in all 13 PCR-positive isolates. Of 52 tetracycline resistant isolates examined, two contained tet(L), 38 tet(K) and 12 both tet(K) and tet(L).     

Net portal appearance of volatile fatty acids in sheep intraruminally infused with mixtures of acetate, propionate, isobutyrate, butyrate, and valerate

The net portal appearance of volatile fatty acids (VFA) was investigated in four ruminally fistulated and multicatheterized sheep. During the experiments, the sheep were fed once every hour for 14 h and intraruminally infused with mixtures of VFA for the 12 h commencing 2 h after the initiation of the hourly feeding protocol. Paired arterial and portal blood samples were obtained hourly during the last 6 h of the experiments. In the control treatment (1), only water was infused intraruminally. In Treatments 2 through 4, the intraruminal infusion rates of propionate (40 mmol/h), isobutyrate (5 mmol/h), and valerate (5 mmol/h) were unchanged. In Treatments 2, 3, and 4, the acetate infusion rate was 100, 60, and 20 mmol/h, respectively, and the butyrate infusion rate was 10, 30, and 50 mmol/h, respectively. Thus, the infusion rate of VFA carbon was constant across Treatments 2 through 4. Portal recovery estimated from the increased net portal appearance in Treatments 2 through 4 compared to the control treatment was 85% for propionate and 60% for isobutyrate, and these recoveries were unaffected by treatment. The portal recovery of butyrate increased (from 21 to 32%) with increasing infusion rate of butyrate and decreasing infusion rate of acetate, as did the portal recovery of valerate (from 14 to 31%). The portal recovery of acetate was 55%, when measured as net portal appearance. Thus, it seems that the capacity for beta-oxidation in ruminal epithelium is limited, which would explain the increasing portal recovery of butyrate and valerate with increasing infusion rate of butyrate, when infusion rate of VFA carbon is unchanged.     

Veterinary cancer registries in companion animal cancer: a review

Current and prior veterinary cancer registries are few in number and scattered. Different inclusion criteria, dissimilar collection methods and variable reference population estimation methods pose obstacles in the comparisons between veterinary and human cancer registries. Veterinary cancer registries have yielded information on the risk and incidence of different cancer types in certain breeds and geographical regions, as well as provided information on genetic and environmental risk factors in some cancers. The objective of this article is to review the prior and current veterinary cancer registries, the information they have contributed and to discuss different issues relating to their structure including inclusion criteria, study populations, reference populations utilized in evaluations, recorded variables and the outcome from these.     

Intermittent suckling improves post-weaning feed uptake but does not change functional gut characteristics of piglets

Suckling pigs were separated from their dam for 24 h on day 21 (1 × 24 h fasting, n = 10) or day 21 and 24 (2 × 24 h fasting, n = 10). Pigs in the control group (n = 10) were not fasted before weaning. All pigs were weaned on day 28 postpartum. Feed intake during the first 4 days post-weaning was higher (P < 0.05) for pigs exposed to 1 × 24 h fasting compared with controls. Water consumption was not affected by fasting prior to weaning. The difference in post-weaning feed uptake was not reflected in any clinical traits, intestinal morphology, or activity of digestive enzymes (maltase, dipeptidylpeptidase IV, aminopeptidases A and N; P > 0.15). In conclusion, a short period of fasting prior to weaning can increase post-weaning feed uptake, although this had no clinical impact under the present experimental conditions.