Objective-To determine the comparative virulence of 5 isolates of bovine viral diarrhea virus (BVDV) type II by inoculating 6- to 9-month-old beef calves with isolates originating from the tissues of cattle affected with naturally occurring, transient, acute, nonfatal infections or naturally occurring, peracute, fatal infections. Animals-22 calves that were 6 to 9 months old. Procedure-The study used BVDV isolates 17011, 713, and 5521 that originated from fetuses aborted from cows with transient, nonfatal, acute BVDV infections and isolates 23025 and 17583 that originated from the tissues of cattle with peracute, fatal BVDV infections. Calves were allotted to 6 groups (1, mockinfected control calves [n = 2]; 2, inoculated with BVDV 17011 [4]; 3, inoculated with BVDV 713 [4]; 4, inoculated with BVDV 5521 [4]; 5, inoculated with BVDV 23025 [4]; and 6, inoculated with BVDV 17583 [4]). Rectal temperatures and clinical signs of disease were recorded daily. Total and differential WBC and platelet counts were performed. Histologic examination and immunohistochemical analysis were conducted to detect lesions and distribution of viral antigens, respectively. Results-Calves inoculated with BVDV 23025 or 17583 developed more severe clinical signs of disease (fever and diarrhea), more severe lymphopenia, and more severe lesions (alimentary epithelial necrosis, lymphoid depletion, and BVDV antigen deposition in lymphatic tissues), compared with calves inoculated with BVDV 713, 5521, or 17011. Conclusions and Clinical Relevance-Relative severity of experimentally induced infections corresponded to severity of clinical signs of naturally occurring infections with respective BVDV isolates.

Objective-To evaluate effects of age and body size of dogs on intestinal permeability (unmediated diffusion) as measured by the ratio of urinary lactulose to L-rhamnose (L:R) and absorption (carrier-mediated transport) as measured by the ratio of urinary D-xylose to 3-O-methyl-D-glucose (X:MG) and to determine whether these variables correlated with fecal quality. Animals-6 Miniature Poodles, 6 Standard Schnauzers, 6 Giant Schnauzers, and 6 Great Danes. Procedure-A solution that contained lactulose and rhamnose or xylose and 3-O-methyl-D-glucose was administered orally to dogs that were 12, 22, 36, and 60 weeks old. Urine was collected 6 hours later, and urinary L:R and X:MG were calculated. Fecal moisture and scoring were recorded during the same periods. Results-Age and breed did not affect intestinal absorption, and we did not detect a relationship between X:MG and fecal variables. In contrast, we detected significant effects of age and body size on intestinal permeability. Puppies (12 weeks old) and large dogs had higher intestinal permeability than adult (60 weeks old) and small dogs. The increased intestinal permeability in large dogs was associated with lower fecal quality as indicated by the significant positive correlations between L:R and fecal moisture (r, 0.61) and L:R and fecal scores (r, 0.86) in adult dogs. Conclusion and Clinical Relevance-These results indicate that age and body size should be considered when assessing intestinal permeability by use of the L:R urinary excretion test in dogs. High intestinal permeability could be a possible cause of poor fecal quality in large dogs.

Objective-To evaluate subchondral bone density patterns in elbow joints of clinically normal dogs by use of computed tomographic (CT) osteoabsorptiometry. Sample Population-20 cadaver forelimbs from 10 clinically normal dogs. Procedure-Each elbow joint was imaged in parasagittal and transverse planes of 1.5-mm thickness. Slice data were converted to dipotassium phosphate equivalent density (PPED) values. Sagittal, parasagittal, and transverse medial coronoid process topographic maps were constructed. Defined zones were created for each of the 3 CT planes, and confluence and peak PPED values were determined. Results-The lowest PPED value was 340 mg/ml (articular and subchondral confluence), and the highest was 1780 mg/ml (peak subchondral density). Detectable effects of joint laterality were not found in the confluence or peak PPED measurements or in the peak-to-confluence PPED ratio for all 3 CT planes. Significant differences were found among zones in all 3 planes for confluence and peak PPED measurements and between sagittal and transverse planes for peak-to-confluence PPED ratios. Subjectively, the pattern of density distribution among dogs was fairly consistent for the sagittal and parasagittal slices. Three specific patterns of density distribution were apparent on the transverse topographic maps of the medial coronoid process that corresponded to conformational differences. Conclusions and Clinical Relevance-The use of CT osteoabsorptiometry provides a repeatable technique that can be used to noninvasively examine bone density and the effects of stress acting on joints in vivo. Variability in density values for any of the CT planes was not identified among clinically normal dogs.

Objective-To develop an endoscopic technique for use in monitoring devlopment of gastric ulcers via a gastric cannula during withholding of feed and administration of a finely ground diet to pigs. Animals-6 pigs weighing between 60 and 70 kg. Procedure-A gastric cannula was surgically inserted adjacent to the pars esophagea in each pig. Pigs were fed a finely ground diet for two 7-day periods that were separated by a 48-hour period during which feed was withheld. Endoscopic examination via the gastric cannula was used to monitor development of ulcers in the pars esophageal region of the pigs during the 48-hour period of feed withhold and subsequent 7-day feeding period. An ulcer score was assigned during each endoscopic examination. A final examination was performed during necropsy and compared with results for the final endoscopic examination. Results-Consumption of a finely ground diet for 7 days resulted in progressive erosive damage to the pars esophageal region of the stomach. Further significant increases in ulcerative damage were detected after 24 and 48 hours of withholding of feed. Final examination during necropsy did not reveal significant differences from results obtained during the final endoscopic examination. Conclusions and Clinical Relevance-Endoscopic examination via a gastric cannula was an effective means of monitoring ulcer development in the pars esophagea of pigs. Feeding a finely ground diet and withholding of feed induced endoscopically observable ulcers in the stratified squamous epithelial region of the stomach. Direct visual examination during necropsy confirmed the accuracy of endoscopic examination.

Objective-To identify and characterize motilin receptors in equine duodenum, jejunum, cecum, and large colon and to determine whether erythromycin lactobionate competes with porcine motilin for binding to these receptors. Sample Population-Specimens of various segments of the intestinal tracts of 4 adult horses euthanatized for reasons unrelated to gastrointestinal tract disease. Procedure-Cellular membranes were prepared from smooth muscle tissues of the duodenum, jejunum, pelvic flexure, and cecum. Affinity and distribution of motilin binding on membrane preparations were determined by use of 125I-labeled synthetic porcine motilin. Displacement studies were used to investigate competition between 125I-labeled synthetic porcine motilin and erythromycin lactobionate for binding to motilin receptors in various segments of bowel. Results-Affinity of 125I-labeled synthetic porcine motilin for the equine motilin receptor was estimated to be 6.1nM. A significantly higher number of motilin receptors was found in the duodenum than in the pelvic flexure and cecum. The jejunum had a significantly higher number of motilin receptors than the cecum. Erythromycin lactobionate displacement of 125I-labeled porcine motilin from the equine motilin receptor did not differ significantly among various segments of bowel. Conclusions and Clinical Relevance-Motilin receptors were found in the duodenum, jejunum, pelvic flexure, and cecum of horses. The highest number of motilin receptors was in the duodenum, and it decreased in more distal segments of bowel. Erythromycin lactobionate competed with motilin binding in the equine gastrointestinal tract. This suggests that 1 of the prokinetic actions of erythromycin in horses is likely to be secondary to binding on motilin receptors.

Objective-To determine the effects of initial handling and training on autonomic nervous functions in young Thoroughbreds. Animals-63 healthy Thoroughbreds. Procedure-All horses were trained to be handled and initially ridden in September of the yearling year and then trained until the following April by conventional training regimens. To obtain the heart rate (HR), electrocardiograms were recorded in the stable before initial handling and training and following 7 months of training; variations in HR were then evaluated from the power spectrum in terms of the low frequency (LF; 0.01 to 0.07 Hz) power and high frequency (HF; 0.07 to 0.6 Hz) power as indices of autonomic nervous activity. To evaluate the fitness, the V200 (velocity at HR of 200 beat/min), which is reflective of the aerobic capacity of the horse, was measured. Results-Mean (+/- SE) resting HR decreased significantly from 41.5 +/- 0.8 to 38.7 +/- 0.4 beat/min following 7 months of training. The LF power of horses increased significantly from 1,037 +/- 128 milliseconds2 in September of the yearling year to 2,944 +/- 223 milliseconds2 in the following April. Similarly, the HF power increased significantly from 326 +/- 30 milliseconds2 to 576 +/- 39 milliseconds2 at the corresponding time points. The V200 increased significantly following training. Conclusions and Clinical Relevance-Increases in LF and HF powers indicate that parasympathetic nervous activity increases in horses by 7 months of training. The decrease in resting HR may be dependent on the training-induced increase of parasympathetic nervous activity in Thoroughbreds.

Objective- To determine the hemodynamic effects of IM administration of romifidine hydrochloride in propofol-anesthetized cats. Animals-15 adult domestic shorthair cats. Procedure-Cats were randomly assigned to receive romifidine (0, 400, or 2,000 µg/kg, IM). Cats were anesthetized with propofol and mechanically ventilated with oxygen. The right jugular vein, left carotid artery, and right femoral artery and vein were surgically isolated and catheterized. Heart rate; duration of the PR, QRS, and QT intervals; mean pulmonary artery pressure; mean right atrial pressure; systolic, diastolic, and mean arterial pressures; left ventricular systolic pressure; left ventricular end-diastolic pressure; and cardiac output were monitored. Systemic vascular resistance, rate of change of left ventricular pressure, and rate pressure product were calculated. Arterial and venous blood samples were collected anaerobically for determination of pH and blood gas tensions (PO2 and PCO2). Results-Administration of romifidine at 400 and 2,000 µg/kg, IM, decreased heart rate, cardiac output, rate of change of left ventricular pressure, rate pressure product, and pH. Arterial and pulmonary artery pressures, left ventricular pressure, left ventricular end-diastolic pressure, and right atrial pressure increased and then gradually returned to baseline values. Arterial blood gas values did not change, whereas venous PCO2 increased and venous PO2 decreased. Significant differences between low and high dosages were rare, suggesting that the dosages investigated produced maximal hemodynamic effects. Conclusion and Clinical Relevance-Romifidine produces cardiovascular effects that are similar to those of other α2-agonists. High dosages of romifidine should be used with caution in cats with cardiovascular compromise.

Objective-To develop a model for measuring rotary stability of the canine elbow joint and to evaluate the relative contribution of the anconeal process (AN), lateral collateral ligament (LCL), and medial collateral ligament (MCL). Sample Population-18 forelimbs from 12 canine cadavers. Procedure-Forelimbs were allocated to 3 experimental groups (6 forelimbs/group). Each intact forelimb was placed in extension at an angle of 135° and cycled 50 times from -16° (pronation) to +28° (supination) in a continuous manner at 2.0 Hz. Cycling was repeated following sectioning of the structure of interest (group 1, AN; group 2, LCL; and group 3, MCL). Torque at -12° (pronation) and +18° (supination) was measured for each intact and experimentally sectioned limb. A Student t test was performed to compare torque values obtained from intact verses experimentally sectioned limbs and for comparison with established criteria for differentiation of primary (≥ 33%), secondary (10 to 33%), and tertiary rotational stabilizers (< 10%). Results-In pronation, the AN was the only primary stabilizer (65%). For supination, the LCL was a primary stabilizer (48%), AN was a secondary stabilizer (24%), and MCL was a tertiary stabilizer (7%). Conclusions and Clinical Relevance-With the elbow joint in extension at an angle of 135°, the AN is a primary rotational stabilizer in pronation, and the LCL is a primary stabilizer in supination. Disruption of the AN or LCL may affect rotary range of motion or compromise stability of the elbow joint in dogs.

Objective-To evaluate hematologic and serum biochemical changes in Salmonella ser Typhimurium infected calves. Animals-16 male 3- to 4-week-old dairy calves. Procedure-13 calves were experimentally infected with S Typhimurium (strains IR715 and CS401, which are derivatives of ATCC 14028), and 3 calves were uninfected controls. Several hematologic and serum biochemical parameters were measured. Results-Hematologic changes included increases in PCV, RBC count, and hemoglobin concentration, associated with a transitory leukopenia characterized by neutropenia and lymphopenia. Biochemical findings included hypoglycemia, increased BUN, creatinine, and fibrinogen concentrations, and decreased sodium, total CO2, calcium, total protein, and albumin concentrations. Increased total bilirubin concentration associated with decreased conjugated bilirubin concentration was also observed. No significant changes in aspartate aminotransferase, gamma-glutamyltranspeptidase, alkaline phosphatase, and creatinine kinase activities were detecte Conclusions and Clinical Relevance-Experimental salmonellosis of calves results in marked to severe dehydration, accompanied by metabolic acidosis, hypoglycemia, and an acute inflammatory response associated with increased fibrinogen concentrations and severe neutropenia immediately after inoculation.

Objective-To estimate sensitivity and specificity of 4 commonly used brucellosis screening tests in cattle and domestic water buffalo of Trinidad, and to compare test parameter estimates between cattle and water buffalo. Animals-391 cattle and 381 water buffalo. Procedure-4 Brucella-infected herds (2 cattle and 2 water buffalo) and 4 herds (2 of each species) considered to be brucellosis-free were selected. A minimum of 100 animals, or all animals > 1 year of age, were tested from each herd. Serum samples were evaluated for Brucella-specific antibodies by use of standard plate agglutination test (SPAT), card test (CT), buffered plate agglutination test (BPAT), and standard tube agglutination test (STAT). A Bayesian approach was used to estimate sensitivity and specificity of diagnostic tests without the use of a gold standard, assuming conditional independence of tests. Results-Sensitivity and specificity estimates in cattle, respectively, were SPAT, 66.7 and 98.9; CT, 72.7 and 99.6; BPAT, 88.1 and 98.1; and STAT, 80.2 and 99.3. Corresponding test estimates in water buffalo, respectively, were SPAT, 51.4 and 99.3; CT, 90.4 and 99.4; BPAT, 96.3 and 90.7; and STAT, 75.0 and 98.8. Sensitivity of the CT and specificity of the BPAT were different between cattle and water buffalo with at least 95% probability. Conclusions and Clinical Relevance-Brucellosis serologic test performance varied by species tested, but BPAT had the highest sensitivity for screening cattle and water buffalo. Sensitivity and specificity of more than 2 screening tests can be estimated simultaneously without a gold standard by use of Bayesian techniques.