A commercially available automated enzyme-multiplied immunoassay technique (EMIT) was used to determine serum caffeine concentration after oral and IV administrations of caffeine at dosage of 5 mg/ kg of body weight to 12 clinically normal dogs. Dogs were allotted to 2 groups of 6 dogs each; 1 group initially received caffeine orally and the other received caffeine IV. After 72 hours, caffeine administration was repeated in all dogs in the alternate manner. Serum samples were obtained at multiple intervals over 24 hours to determine distribution and elimination kinetics. Analysis of the drug concentration-time data indicated IV elimination half-life (t1/2) of 6.39 +/- 1.87 hours, volume of distribution at steady state of 685.3 +/- 132.2 ml/kg, total body clearance of 1.31 +/- 0.38 ml/min/kg, absorption t1/2 of 1.02 +/- 0.68 hour, oral elimination t1/2 of 6.53 +/ - 2.72 hours, lag time after oral administration of 0.0614 +/- 0.0661 hour, highest measured concentration of 5.29 +/- 1.17 micrograms/ml, time to peak concentration of 2.74 +/- 1.30 hours, and bioavailability of 99.4 +/- 19.4%. Data from 6 dogs best fit a 1-compartment open model and those from 6 other dogs best fit a 2-compartment open model. On the basis of data from the 6 dogs that best fit a 2-compartment model, t1/2 of distribution was 0.58 +/- 0.72 hour. Data for oral administration best fit a single absorption phase and a single elimination phase. The increased availability and simplicity of the EMIT offers an opportunity to study the application of caffeine elimination for clinical evaluation of dogs with liver disease. Data obtained from this study allow determination of t1/2 and clearance to be simplified by obtaining samples 4 and 8 hours after oral or IV administrations and establishes canine reference values for elimination kinetics of caffeine administered at dosage of 5 mg/kg and assayed by use of the EMIT.

Clinical trials have shown that currently available commercial vaccines against porcine pleuropneumonia provide inconsistent, serotype-specific protection from the disease. Recovery from naturally acquired infection, however, provides solid, serotype crossprotective immunity. We examined various serum responses of pigs receiving 1 of 4 commercial vaccines or a cell extract, and compared the serologic responses of these pigs after challenge exposure with virulent Actinobacillus pleuropneumoniae serotype 1. Evaluation of serum included complement-mediated killing opsonizing capacity, IgG titers to whole organisms, and cytotoxin neutralization titers. Pigs that received the cell extract had fewer clinical signs of pleuropneumonia than pigs in other vaccinated groups, and also were significantly (P < 0.05) better protected from development of lung lesions and death. Such vaccinates were the only pigs that developed significant (P < 0.05) serum antibody titers (ie, protective immune response) to whole-cell antigens and to cytotoxin.

Effects of 2 drugs commonly used for chemical restraint of cattle were evaluated for their effect on laryngeal and pharyngeal anatomy, function, and response to stimuli. Eighteen adult Jersey cows, free of respiratory tract disease, were studied. Cows were assigned at random to 1 of 3 treatment groups. Endoscopic evaluations were performed before and at a predetermined time interval after administration of each drug. Responses to stimuli were evaluated by stimulating 7 preselected sites (epiglottis, left and right arytenoid cartilages, left and right vocal folds, and left and right dorsolateral pharyngeal walls) with a closed, transendoscopic biopsy probe. Xylazine HCl (0.05 mg/kg of body weight, IV) was administered to group-1 cows (n = 6), and endoscopy was repeated 5 minutes after administration of the drug. Xylazine (0.07 mg/kg, IV) was administered to group-2 cows (n = 6), and endoscopy was repeated 5 minutes after administration of the drug. Acepromazine maleate (0.035 mg/kg, iv) was administered to group-3 cows (n = 6), and endoscopy was repeated 10 minutes after administration of the drug. Responses to stimuli were scored as brisk (0), moderate (1), slow (2), and absent (3). Scores for responses to stimuli were compared, using the Wilcoxon signed-rank test for data within groups, and a general linear models procedure, using the Kruskal-Wallis test between groups. Interobserver agreement rates were generated for each group. A value of P<0.05 was considered significant. Xylazine profoundly changed laryngeal sensitivity and function at both dosages. The corniculate processes of the arytenoid cartilages were observed to be in a markedly adducted position after sedation. Response to stimuli was significantly (P = 0.03) slower than normal after sedation, using both dosages. Displacement of the soft palate dorsal to the epiglottis was persistent in 50% of the cows after stimulation tests subsequent to sedation with xylazine. Acepromazine had a mild effect on laryngeal sensitivity and function. The corniculate processes of the arytenoid cartilages were observed in paramedian position after sedation. Acepromazine did not significantly affect responses to stimuli. Effects of sedation on responses to stimuli were not significantly different for groups 1 and 2. However, effects for group 3 were significantly different from those for groups 1 and 2 (P = 0.006 and 0.004, respectively). Endoscopic evaluation of the proximal portion of the respiratory tract of cattle should be performed without sedation, when possible. If sedation is required to facilitate restraint for endoscopy, acepromazine maleate is recommended over xylazine on the basis of results of this study.

Effects of low-flow ischemia and reperfusion of the large colon on mucosal architecture were determined in horses. Twenty-four adult horses were randomly allocated to 3 groups: sham-operated (n = 6), 6 hours of ischemia (n = 9), and 3 hours of ischemia and 3 hours of reperfusion (n = 9). Low-flow ischemia was induced in horses of groups 2 and 3 by reducing colonic arterial blood flow to 20% of baseline values. Systemic hemodynamic and metabolic variables were maintained constant and in a normal physiologic range. Full-thickness biopsy specimens were obtained from the left ventral colon for histomorphologic and morphometric examination at baseline and at 30-minute intervals for 6 hours; additional biopsy specimens were collected at 185, 190, and 195 minutes (corresponding to 5-, 10-, and 15-minute periods of reperfusion in group-3 horses). There were no differences among groups at baseline or across time in group-1 horses for any of the histopathologic variables. There were significant (P < 0.05) increases in percentage of surface mucosal disruption, estimated and measured percentage depth of mucosal loss, mucosal hemorrhage, mucosal edema, and cellular debris index during 0 hour to 3 hours, compared with baseline, and from 3 hours to 6 hours, compared with 3 hours in horses of groups 2 and 3. Estimated percentage depth of mucosal loss and cellular debris index were significantly (P < 0.05) greater in group-3 horses, compared with group-2 horses during the interval from 3 to 6 hours. There were trends toward greater percentage of surface mucosal disruption and mucosal edema during the early phase of reperfusion (3 to 4 hours) and greater mucosal hemorrhage, measured percentage depth of mucosal loss, and mucosal interstitial-to-crypt ratio during the late phase (4 to 6 hours) of reperfusion in group-3 horses vs group-2 horses. Reestablishment of colonic arterial blood flow after low-flow ischemia caused greater mucosal injury than did a comparable period of continued ischemia. Thus, reperfusion injury was detected in the large colon of horses after low-flow arterial ischemia. The serial mucosal alterations that developed in the colon were comparable in horses of groups 2 and 3; however, reperfusion exacerbated colonic mucosal injury.

Liposomes and immunostimulating complexes (ISCOM) are adjuvants that have been known to potentiate the immune response to membrane proteins. Adjuvanted outer membrane proteins (OMP) from Salmonella enteritidis were evaluated for their protective efficacy against S enteritidis infection in turkeys. The adjuvanted vaccines prepared for evaluation were: positive or negatively charged liposomes, lipid-conjugated ISCOM, and mineral oil vaccines. These preparations were compared with that of a whole cell bacterin and protein alone. After vaccination, turkeys were challenge-exposed with a nalidixic acid-resistant strain of S enteritidis. They were monitored for clinical signs of disease, antibody response, bacterial shedding pattern, and clearance of the challenge S enteritidis from internal organs. Results indicated a significantly (P < 0.05) higher antibody response to the positively charged liposomal OMP vaccine, compared with the whole cell bacterin. The antibody response to positively charged liposomal OMP vaccine was greater when a booster dose of this preparation was given. Shedding of S enteritidis was decreased in all vaccinated and challenge-exposed turkeys (P < 0.001). The tissues from a high percentage (90 to 100%) of birds that received a booster vaccination of the liposomal (+ or -) and ISCOM vaccine were culture-negative for S enteritidis.

Serum C-reactive protein (CRP) concentration was measured, using an automated immunoturbidimetric assay, in 44 clinically normal dogs and 67 dogs with band neutrophil count greater than or equal to 10(9) cells/L, and values were found to be significantly (P less than or equal to 0.05) different. Correlation of serum CRP concentration and band neutrophil count in the 67 dogs with greater than or equal to 10(9) band neutrophils/L resulted in a statistically significant P less than or equal to 0.05), but low correlation coefficient of 0.34. Serum CRP concentration and CBC values were determined for 6 clinically normal dogs undergoing anesthesia (controls) and 6 clinically normal dogs undergoing anesthesia and ovariohysterectomy. Significant alterations in CBC results and serum CRP concentration, compared with baseline values, were lacking in dogs of the control group. Serum CRP concentration was significantly (P less than or equal to 0.05) increased above baseline values in dogs undergoing surgery and was significantly (P less than or equal to 0.05) increased, compared with values in control dogs by 12 hours after surgery. In dogs undergoing surgery, serum CRP concentration was also significantly (P less than or equal to 0.05) different from values in control dogs at 28 and 36 hours, but not at the 76- and 124-hour sample collection times. Alterations in CBC values compatible with possible or convincing inflammation were detected in 83% of the dogs undergoing surgery at the 8- and 12-hour postsurgery sample collection times, 100% of dogs at 16, 22, 28, and 36 hours after surgery, 83% of dogs at 52 and 76 hours after surgery, 67% of dogs at 100 hours after surgery, and 0% of dogs at 124 hours after surgery. It was concluded that significant increases in CRP, concentration in dogs with surgical trauma were not detected earlier than CBC alterations compatible with possible or convincing inflammation.

Equine oxyntic mucosal cells were obtained by sequential exposure to pronase and collagenase. Acid production by parietal cells was assessed by uptake of [14C]aminopyrine (AP), a weak base that accumulates in intracellular acidic spaces. Incubation for various times revealed a maximal AP uptake at 10 minutes for histamine and carbachol. Similar secretagogue responses were observed for parietal cells from the mucosal cell preparation or after enrichment by elutriation. Histamine and isobutyl-methylxanthine (IBMX) stimulated AP uptake with a dose-dependent response and maximal effective concentration of 100 micromolar. Carbachol, 1 to 100 micromolar, and pentagastrin (PG), 1 to 1,000 nM, were ineffective stimulants of AP uptake. The AP uptake values for 100 micromolar IBMX, 1 micromolar carbachol, or 100 nM PG were 77 +/- 6%, 50 +/- 3.2%, and 40 +/- 4.5%, respectively, of that observed with maximal stimulation by 100 micromolar histamine (mean SEM, n = 4 to 14). Uptake of AP by nonstimulated control cells was 36 +/- 3.6% of maximal histamine stimulation. The AP accumulations during control conditions and after stimulation with 100 micromolar histamine and IBMX, 1 micromolar carbachol, or 100 nM PG were 1.18 +/- 0.39, 2.81 +/- 0.85, 1.93 +/- 0.48, 1.44 +/- 0.36, and 1.23 +/- 0.33 pmol of AP/10(5) parietal cells, respectively. Individual histamine dose-response curves were shifted to the right by increasing ranitidine and cimetidine concentrations (0.1 to 50 micromolar). These results indicate that isolated equine parietal cells are maximally stimulated by histamine and minimally stimulated by carbachol and PG.

Pharmacologically induced splenic contraction might be useful during certain medical or surgical procedures in horses. The effects of phenylephrine, an alpha 1-adrenergic receptor agonist, on hemodynamic function and splenic dimensions were examined in 6 healthy adult horses. Phenylephrine infusion (1, 3, or 6 microgram/kg of body weight/min for 15 minutes) resulted in a dose-related increase in mean pulmonary artery pressure; right atrial pressure; systolic, mean, and diastolic arterial pressures; and packed cell volume (P = 0.0001). Concurrent decreases in heart rate and specific cardiac output (P = 0.0001) were detected, but stroke volume did not vary significantly. The rate-pressure product was increased only at the highest phenylephrine dosage (P = 0.012). Bradycardia was observed at all dosages during drug infusion, and second-degree atrioventricular block was detected in 88% of horses during infusion. Phenylephrine administration caused dose-dependent splenic contraction, as detected by ultrasonographic measurements of splenic area and thickness (P = 0.0001). At the 3- and 6-microgram/kg/min infusion rates, splenic area was reduced to 28 and 17% of baseline measurement, respectively. Splenic dimensions had returned to baseline values by 35 minutes after the end of infusion. Infusion of phenylephrine at a dosage of 3 microgram/kg/min for 15 minutes can be used to induce splenic contraction in horses.

Consumption of chlortetracycline (CTC) at concentration of 220 mg/kg of feed for 4 weeks in experiment 1 and at concentrations of 110 and 220 mg/kg for 3 weeks and 440 mg/kg for 2 weeks in experiment 2 failed to eliminate streptococci-induced lymphadenitis from swine referred to as principals. Abscesses, mostly in the head and neck, developed in at least a third of all swine in the various groups fed these CTC concentrations. Feeding of 220 mg of CTC/kg of feed in experiment 1 began 12 weeks after exposure of principals to an untypeable group E streptococci (GES; isolate 3X29A). In experiment 2, feeding of 110 and 220 mg of CTC/kg of feed began 5 weeks after exposure of principals to GES and feeding of 440 mg of CTC/kg of feed began 6 weeks after exposure. One or more cohabitating sentinel swine of experiment 1 and one or more sentinels in all groups of principals of experiment 2, except group 2, developed abscesses that were mostly in the head and neck. In experiment 2, correlation between serum GES antibody titer and development of one or more abscesses in the principals was highly significant (P < 0.01); however, correlation between antibody titer and abscesses in the sentinels only approached significance (P < 0.10).

Force platform analysis of gait provides ground reaction force information that can be used to study limbs with normal or abnormal function. When combined, the interrelated variables of ground reaction forces give a more thorough description of gait than when used individually. To describe the pattern of ground reaction forces in clinically normal, conditioned, mesomorphic dogs, we studied the data from platform gait analyses of 43 dogs. Mediolateral (Fx), craniocaudal (Fy), and vertical (Fz) forces were measured and recorded. Torque (Tz) around the vertical axis also was calculated. Mean stance times for forelimbs and hind limbs were 0.278 and 0.261 second, respectively. Among dogs, ground reaction forces were normalized and expressed as percentage of body weight (%bw). The vertical (Fz) peak, average force during stance phase, and force vs time impulses were 106.68, 60.82, and 17.2 %bw in forelimbs, and were 65.11, 35.3, and 9.33 %bw in hind limbs. The forelimb braking/ propulsive (Fy) peaks were -16.74 and +6,73 %bw. In hind limbs, these peaks were -3.76 and +7.69 %bw. The usual mediolateral force (Fx) pattern found in forelimbs was laterally directed, with average peak magnitude of 6.69 %bw, whereas the hind limb patterns were variable.