Objective-To evaluate a model for atopic dermatitis (AD) and to measure the effect of sensitization in Beagles genetically predisposed to produce high serum concentrations of allergen specific IgE. Animals-22 laboratory Beagles. Procedure-Seventeen dogs were sensitized from birth to 3 allergens (recombinant birch pollen, Dermatophagoides pteronyssinus, and D farinae). Five nonsensitized dogs from the same litters served as controls. Clinical scoring, regular intradermal testing, measurement of serum concentrations of allergen-specific IgE, and collection of biopsy specimens of skin at 23, 32, and 43 weeks of age were performed. Serial tissue sections were stained for identification of IgE+ cells, mast cells and their subtypes, T-cells, Langerhans cells, and major histocompatibility complex class-II+ cells. At the age of 15 months, dogs were continuously exposed to 2 µg of mite allergen/ g of dust. Results-Sensitized dogs had positive intradermal test reactions and significantly higher serum concentrations of allergen specific IgE, compared with nonsensitized dogs. In sensitized and nonsensitized dogs, a significantly higher number of mast cells was found at predilection sites, compared with the control biopsy site. The number of mast cells at predilection sites increased with age. Sensitization significantly increased the number of epidermal Langerhans cells by 23 weeks of age. The number of epidermal Langerhans cells significantly increased in nonsensitized dogs by 32 weeks of age. Clinical scoring only revealed mild transient erythema in some dogs. Conclusion and Clinical Relevance-Increases in concentrations of serum allergen-specific IgE and exposure to allergens is not sufficient to induce clinical signs of AD in genetically predisposed dogs.

Objective-To evaluate postexposure prophylaxis (PEP) in dogs experimentally infected with rabies. Procedure-29 Beagles. Procedure-Dogs were sedated and inoculated in the right masseter muscle with a salivary gland homogenate from a naturally infected rabid dog (day 0). Six hours later, 5 dogs were treated by administration of 2 murine anti-rabies glycoprotein monoclonal antibodies (mAb) and commercial vaccine; 5 received mAb alone; 5 received purified, heat-treated, equine rabies immune globulin (PHT-ERIG) and vaccine; 5 received PHT-ERIG alone; 4 received vaccine alone; and 5 control dogs were not treated. The mAb or PHTERIG was administered at the site of rabies virus inoculation. Additional vaccine doses for groups mAb plus vaccine, PHT-ERIG plus vaccine, and vaccine alone were administered IM in the right hind limb on days 3, 7, 14, and 35. Results-All control dogs and dogs that received only vaccine developed rabies. In the PHT-ERIG and vaccine group, 2 of 5 dogs were protected, whereas none were protected with PHT-ERIG alone. Use of mAb alone resulted in protection in 4 of 5 dogs. Administration of mAb in combination with vaccine provided protection in all 5 dogs. Conclusions and Clinical Relevance-Current national guidelines recommend euthanasia or a 6- month quarantine for unvaccinated animals exposed to rabies. Findings from this study document that vaccine alone following severe exposure was unable to provide protection from rabies. However, vaccine combined with mAb resulted in protection in all treated dogs, revealing the potential use of mAb in PEP against rabies in naïve dogs.

Objective-To evaluate the efficacy of an orally administered vaccine of Mycoplasma hyopneumoniae that was prepared by spray drying or solvent evaporation. Animals-Thirty 6-week-old, crossbred, specificpathogen- free (SPF) pigs. Procedure-Pigs were randomly allocated into 5 groups and housed in an SPF facility. Pigs in 2 groups (groups AQ and CAP) were fed M hyopneumoniae enteric-coated vaccine on days 0, 10, and 20. A third group (group IM) received an IM injection of M hyopneumoniae vaccine with aluminium hydroxide as an adjuvant on days 0, 10, and 20. The last 2 groups (nonvaccinated- challenged [NV-C] and nonchallenged [NC]) were fed a sham treatment. All 24 pigs in groups AQ, CAP, IM, and NV-C were challenge exposed with 5 ml of a 10% pneumonic lung suspension administered on day 40 via intubation of the trachea. All pigs were slaughtered and the lungs removed and examined for lesions on day 68. Results-In vitro studies indicated that these 2 microencapsulation techniques formed an effective shell and protected mycoplasmal antigen from gastric acid. Results of inoculation and challenge tests indicated that microencapsulated M hyopneumoniae were sufficiently potent to induce an immune response and provide good protection. Conclusions and Clinical Relevance-Orally administered microencapsulated M hyopneumoniae vaccines induced an immune response and reduced the severity of lung lesions in challengeexposed pigs. Results suggest that this novel method can be applied to other antigens, because the spray-drying process yielded an orally administered M hyopneumoniae vaccine that induced a good immune response.

Objective-To correlate serum concentrations of fibrinogen (Fib), haptoglobin (Hap), serum amyloid-A (SAA), and alpha-1 acid glycoprotein (AGP) with clinical respiratory tract disease and response to treatment in transport-stressed feedlot cattle fed vitamin E-supplemented diets. Animals-387 heifer calves (mean initial weight, 197 kg). Procedure-Calves purchased from an order buyer were delivered to a feedlot to study the effects of dietary supplementation with 2,000 IU of vitamin E for 0, 7, 14, or 28 days after arrival. Serum or plasma Fib, Hap, SAA, and AGP concentrations were measured on days 0, 7, and 28 after arrival as well as at the time of treatment for respiratory tract disease with antimicrobial drugs and after completion of treatment. Results-Vitamin E supplementation was associated with decreased treatment costs. In cattle that were not recognized as sick or responded positively to 1 antimicrobial treatment, serum Hap concentrations were significantly lower on days 0 and 7 than concentrations for cattle that required > 1 treatment. Serum Hap concentrations and ratios of Hap to SAA on day 0 significantly correlated with the number of antimicrobial treatments required. Serum Hap concentrations at the time of initial treatment were significantly lower for cattle that required only 1 treatment, compared with those that required > 1 treatment. Conclusions and Clinical Relevance-Serum Hap concentrations are of potential value for use in assessing feedlot cattle that may become ill as a result of respiratory tract disease and for use in monitoring treatment efficacy.

Objective - To evaluate the effectiveness of various sampling techniques for determining antimicrobial resistance patterns in Escherichia coli isolated from feces of feedlot cattle. Sample Population - Fecal samples obtained from 328 beef steers and 6 feedlot pens in which the cattle resided. Procedure - Single fecal samples were collected from the rectum of each steer and from floors of pens in which the cattle resided. Fecal material from each single sample was combined into pools containing 5 and 10 samples. Five isolates of Escherichia coli from each single sample and each pooled sample were tested for susceptibility to 17 antimicrobials. Results - Patterns of antimicrobial resistance for fecal samples obtained from the rectum of cattle did not differ from fecal samples obtained from pen floors. Resistance patterns from pooled samples differed from patterns observed for single fecal samples. Little pen-to-pen variation in resistance prevalence was observed. Clustering of resistance phenotypes within samples was detected. Conclusions and Clinical Relevance - Studies of antimicrobial resistance in feedlot cattle can rely on fecal samples obtained from pen floors, thus avoiding the cost and effort of obtaining fecal samples from the rectum of cattle. Pooled fecal samples yielded resistance patterns that were consistent with those of single fecal samples when the prevalence of resistance to an antimicrobial was > 2%. Pooling may be a practical alternative when investigating patterns of resistance that are not rare. Apparent clustering of resistance phenotypes within samples argues for examining fewer isolates per fecal sample and more fecal samples per pen.

Objective-To determine whether small intestinal ischemia and reperfusion induces bacterial translocation and proinflammatory cytokine response in either the systemic or portal circulation in dogs. Animals-17 healthy adult Beagles. Procedure-The superior mesenteric artery (SMA) was occluded for 0 (group-3 dogs), 30 (group-1 dogs), or 60 (group-2 dogs) minutes, followed by reperfusion for 180 minutes; serum lactate and endotoxin concentrations and tumor necrosis factor-alpha (TNF-alpha), interleukin- 1beta (IL-1beta), and IL-6 activities in the systemic and portal circulation and intramucosal pH were measured at various time points. Results-In group-2 dogs, TNF-alpha activity was found to be significantly increased in the portal circulation, peaking at 60 minutes of reperfusion; TNF-alpha activity, in the systemic circulation, gradually increased from 60 minutes of reperfusion to the end of the experiment; however, the increase was not significant. In group-1 and -2 dogs, IL-6 activities significantly and gradually increased in the systemic and portal circulation during the reperfusion phase, and the magnitude of these increases was dependent on the duration of the ischemic phase. There were no significant changes in IL-1beta activity or endotoxin concentration in any dog group. Conclusions and Clinical Relevance-Results of the our study indicate that intestinal ischemia and reperfusion leads to significant increases of the circulating TNF-alpha and IL-6 activities, depending on the duration of the ischemia phase, in the absence of detectable endotoxin in the circulation. This finding suggests that intestinal ischemia and reperfusion induces a systemic proinflammatory cytokine response in dogs.

Objective-To study the antiviral activity of genistein, a soya isoflavone, on in vitro replication of bovine herpesvirus type 1 (BHV-1). Sample Population-Madin-Darby bovine kidney (MDBK) cells. Procedure-Effects of genistein on the magnitude and kinetics of inhibition of BHV-1 phosphorylation of glycoprotein E (gE) and in vitro replication of BHV-1 in MDBK cells were evaluated. Antiviral activity of genistein was compared with 2 compounds, estradiol-17β (EST) and tamoxifen (TAM), that have estrogenic and antiestrogenic activity, respectively. High-performance liquid chromatography (HPLC) was used to determine the concentration of genistein in medium from infected and uninfected MDBK cultures. Results-Genistein reduced BHV-1, but not gE-deleted BHV-1 (BHV-1gEΔ3.1), replication by 90% at 18 hours after inoculation. This inhibition was not sustained through 24 hours after inoculation. The genistein concentration in media from MDBK cells was decreased by 40% during BHV-1 infection, compared with 16% for uninfected cells, at 24 hours after inoculation. Genistein inhibited gE phosphorylation and BHV- 1 replication in a dose-dependent manner. Dosing with 25 µMgenistein at 0 and 12 hours after inoculation of BHV-1 was optimal for decreasing BHV-1 replication. Estradiol-17β EST and TAM did not affect BHV-1 replication. Conclusions and Clinical Relevance-The decrease in genistein concentration was a viral infection-dependent event. Genistein is an inhibitor of BHV-1 replication because of its ability to inhibit tyrosine kinase activity. A possible application may be for the control of BHV-1 infection in cattle by feeding soya products rich in genistein prior to or during periods of stress.

Objective-To examine the role of bovine viral diarrhea virus (BVDV) biotype on the establishment of fetal infection in cattle. Animals-30 mixed-breed pregnant cows. Procedure-Pregnant cows were inoculated oronasally with either i-VVNADL, originating from an infectious BVDV cDNA clone of the National Animal Disease Laboratory (NADL) isolate, or the parental virus stock, termed NADL-A. Results-All cows developed neutralizing antibodies to BVDV, and virus was commonly isolated from peripheral blood mononuclear cells or nasal swab specimens of NADL-A inoculated cows; however, virus was rarely isolated from specimens of i-VVNADL inoculated cows. i-VVNADL did not cause fetal infection, whereas all fetuses harvested from NADL-A inoculated cows at 6 weeks after inoculation had evidence of infection. Immunoblot analysis of fetal virus isolates revealed the absence of NS3, confirming a noncytopathic (NCP) biotype BVDV in the NADL-A stock. The sequence of the NCP contaminant (termed NADL-1102) and the i-VVNADL genome were virtually identical, with the exception of a 270 nucleotide-long insert in the i-VVNADL genome. Phylogenetic analyses revealed that NADL-1102 forms a monophyletic group with 6 other NADL genomes. Conclusions and Clinical Relevance-These data suggest that the contaminating NCP virus in the NADL-A stock was the ancestral NADL virus, which originally infected a bovine fetus and recombined to produce a cytopathic (CP) variant. Following oronasal infection of pregnant cows, viremia and transplacental transmission of CP BVDV to the fetus is rare, compared with the high occurrence of maternal viremia and fetal infection observed with NCP BVDV.

Objective-To determine whether Haemobartonella canis and Mycoplasma haemofelis (formerly known as H felis [large form]) can be differentiated by use of comparative analysis of gene sequences. Sample Population-Blood samples obtained from 3 dogs infected with H canis and 2 cats infected with M haemofelis. Procedure-The partial 16S rDNA and ribonuclease P RNA (RNase P) genes were amplified, cloned, and sequenced in blood samples obtained from H canis-infected dogs and M haemofelis-infected cats. The DNA sequences were subjected to comparative analysis. Results-The 16S rDNA sequences of H canis and M haemofelis were nearly identical (homology of 99.3 to 99.7%). In contrast, RNase P gene sequences had a lower degree of sequence homology between the 2 organisms (94.3 to 95.5%). Conclusions and Clinical Relevance-Haemobartonella canis and M haemofelis are not identical organisms. Molecular differentiation of H canis and M haemofelis is more clearly evident by use of comparative analysis of RNase P gene sequences than by comparative analysis of 16S rDNA gene sequences.

Objective-To determine the effect of growth and training on metabolic properties in muscle fibers of the gluteus medius muscle in adolescent Thoroughbred horses. Animals-Twenty 2-year-old Thoroughbreds. Procedure-Horses were randomly assigned to 2 groups. Horses in the training group were trained for 16 weeks, and control horses were kept on pasture without training. Samples were obtained by use of a needle-biopsy technique from the middle gluteus muscle of each horse before and after the training period. Composition and oxidative enzyme (succinic dehydrogenase [SDH]) activity of each fiber type were determined by use of quantitative histochemical staining procedures. Whole-muscle activity of SDH and glycolytic enzyme (phosphofructokinase) as well as myosin heavy-chain isoforms were analyzed biochemically and electrophoretically, respectively. Results-The SDH activity of type-I and -IIA fibers increased during growth, whereas whole-muscle activity was unchanged. Percentage of type-IIX/B muscle fibers decreased during training, whereas that of myosin heavy-chain IIa increased. The SDH activity of each fiber type as well as whole-muscle SDH activity increased during training. An especially noticeable increase in SDH activity was found in type-IIX/B fibers. Conclusions and Clinical Relevance-Changes in muscle fibers of adolescent Thoroughbreds are caused by training and not by growth. The most noticeable change was for the SDH activity of type-IIX/B fibers. These changes in the gluteus medius muscle of adolescent Thoroughbreds were considered to be appropriate adaptations to running middle distances at high speeds.