The accuracy of the Doppler technique for indirect systolic blood pressure measurement was assessed in 16 anesthetized cats. Eight cats were anesthetized with isoflurane and 8 were anesthetized with halothane. Anesthetic depth and mode of ventilation were varied to obtain a wide range of arterial blood pressure. A Doppler transducer was placed on the palmer surface of the left fore-limb over the common digital branch of the radial artery to detect blood flow, and a blood pressure monitoring cuff with a width 37% the limb circumference was placed half way between the elbow and the carpus. To enable direct arterial pressure measurements, the left femoral artery was catheterized and the blood pressure waveforms recorded simultaneously. Systolic blood pressure measured by use of the Doppler ultrasonic technique was significantly lower than that obtained from the femoral artery catheter. Using linear regression, we determined a clinically useful calibration adjustment for Doppler indirect blood pressure measurement in cats: femoral systolic pressure = Doppler systolic pressure + 14 mm of Hg.

Efficacy of sulbactam, a beta-lactamase inhibitor, in combination with ampicillin, was evaluated for treatment of experimentally induced pneumonia caused by beta-lactam-resistant Klebsiella pneumoniae. Infection was experimentally induced in 18 healthy weanling foals that were randomly allocated to 3 treatment groups: sulbactam plus ampicillin (S/A, 3.3 and 6.6 mg/kg of body weight, respectively), ampicillin (6.6 mg/kg), or vehicle only. Foals were treated daily for 7 days; the observer was unaware of treatment status. Compared with ampicillin and vehicle, treatment with S/A resulted in a statistically significant (P < 0.05) decrease in severity of pneumonia, with regard to bronchoalveolar lavage cytologic findings (decreased total cell and neutrophil numbers, and increased lymphocyte numbers) and extent of macroscopic lesions in lung tissue of the noninoculated regions. Marked trends toward improvement of S/A-treated foals were observed for quantitative results of bacteriologic culture of bronchoalveolar lavage fluid samples (P < 0.07), macroscopic pathologic features of the whole lung (P < 0.1), and histopathologic variables (P < 0.07), compared with ampicillin- and vehicle-treated foals. Treatment effects were not observed for radiographic, hematologic, and blood gas abnormalities that resulted from infection. In conclusion, the combination of sulbactam plus ampicillin was found to have synergistic effects in vivo, to reduce the extent and severity of experimentally induced grain-negative lung infection in foals.

Effects of IV and aerosol administration of 5-hydroxytryptamine (5-HT) on ventilation, pulmonary mechanics values, pulmonary arterial pressure, and heart rate were investigated in healthy unsedated Friesian calves. Minute volume increased significantly, mainly because of an increase in respiratory rate. Except for total pulmonary resistance after bolus injection, continuous administration of 5-HT given by either route caused significant alterations of lung dynamic compliance and total pulmonary resistance, the former decreasing to one-fifth of its baseline value and the latter increasing twofold. Pulmonary arterial pressure increased significantly, whatever the speed or route of administration. Administration of a bolus did not affect heart rate, whereas continuous iv administration of 5-HT as well by perfusion or by aerosol resulted in sustained tachycardia. It was concluded that 5-HT induces reversible bronchoconstriction and pulmonary vasoconstriction in healthy unsedated calves, 5-HT-induced functional alterations depend on the speed of administration, and excess of 5-HT production or depression in uptake by the lungs during bovine respiratory tract diseases could contribute to pulmonary dysfunction.

Hematologic and rheologic changes were examined in 49 Thoroughbreds before and after competitive racing. Mean postrace values for RBC count, hemoglobin concentration, and PCV increased by 58 to 61%, whereas blood viscosity increased 2 to 3 times. Postrace echinocyte numbers were 162% greater than prerace values. Smaller, but statistically significant, changes were found for mean corpuscular hemoglobin concentration, red cell distribution width, plasma total protein concentration, total WBC count, neutrophil count, and lymphocyte count. Variables measured did not predict whether a horse was a bleeder not treated with furosemide, a bleeder treated with furosemide, or a nonbleeder.

The effects of intra-articular administration of methylprednisolone acetate (MPA) on the healing of full-thickness osteochondral defects and on normal cartilage were evaluated in 8 horses. In group-1 horses (n = 4), a 1-cm-diameter, full-thickness defect was created bilaterally in the articular cartilage on the dorsal distal surface of the radial carpal bone. Cartilage defects were not created in group-2 horses (n = 4). One middle carpal joint was randomly selected in each horse (groups 1 and 2), and treated with an intra-articular injection of 100 mg Of MPA, once a week for 4 treatments. Injections began 1 week after surgery in group-1 horses. The contralateral middle carpal joint received intra-articular injections of an equivalent volume of 0.9% sodium chloride solution (SCS), and served as a control. Horses were evaluated for 16 weeks, then were euthanatized, and the middle carpal joints were examined and photographed. Synovial and articular cartilage specimens were obtained for histologic and histochemical evaluation. Gross morphometric evaluation of the healing defects in group-1 horses revealed that 48.6% of the defect in control joints and 0% of the defect in MPA-treated joints was resurfaced with a smooth, white tissue, histologically confirmed as fibrocartilage. This replacement tissue was a firmly attached fibrocartilage in control joints and a thin fibrous tissue in MPA-treated joints. The articular cartilage in joints treated with MPA had morphologic changes, including chondrocyte cluster formation, loss of palisading architecture, and cellular necrosis in both groups of horses. Histochemical (safranin-0) staining intensity was reduced significantly (P < 0.05) in all layers of articular cartilage in MPA-treated joints in groups 1 and 2. In the replacement tissue, intense safranin-O staining was found only in the chondrocyte clusters deep in the tissue of control joints, confirming fibrocartilage repair. Intra-articular administration of MPA in this dosing regimen thus induced degenerative changes in normal articular cartilage and resulted in histomorphologic changes in the repair of full-thickness articular osteochondral defects in horses.

Pigs [9+/-1] weeks old) were inoculated with Streptococcus suis type 2, pseudorabies virus (PRV) or both. For each pig of groups A, B, and C the inoculum of S suis was 10(9) colony-forming units. For each pig of groups A, B, and D the inoculum of PRV was 5 X 10(3) TCID50 of either PRV strain 4892 (group A, n = 9) or PRV isolate B (group B, n = 9). The PRV strain 4892 is a highly virulent strain; isolate B causes mild clinical signs of infection in inoculated pigs. Group-C pigs (n = 9) were given S suis alone, and group-D pigs (n = 3) were inoculated only with PRV isolate B. Clinical signs of infection and development of lesions were readily seen in pigs of groups A, B, and C. Duration and severity of clinical signs of disease and lesions were reduced in pigs of group C, compared with those of the other 2 groups. Lesions, such as polyarthritis and fibrinous pericarditis, were more abundant and acute in the groups of pigs given mixed challenge exposure, compared with pigs inoculated exclusively with S suis type 2 (group C). The group of pigs inoculated with PRV isolate B alone did not manifest clinical signs of disease or lesions. Average daily gain for group-C pigs was higher, compared with that of other groups; the difference was statistically significant at P < 0.02 and P < 0.05 for groups B and D, respectively. Spread of S suis within the tissues of infected pigs was higher in pigs of groups A and B, compared with pigs of group C. Total number of isolations was 8, 15, and 7 for groups A, B, and C, respectively; S suis was isolated from more than 1 tissue specimen from some pigs. The rate of pigs carrying S suis was 4 of 4 in group-A, 7 of 9 in group-B, and 5 of 9 in group-C pigs. It was concluded that clinical disease associated with S suis type 2 was enhanced by concomitant infection with PRV and such effect was common to both PRV strains tested, the highly virulent strain and the strain with low virulence.

Glutamine has been shown to be an important metabolic substrate of enterocytes in many animals, including cats, dogs, hamsters, human beings, monkeys, rabbits, rats, and sheep. To determine whether glutamine is important in the metabolism of cells of the equine gastrointestinal tract, we examined transintestinal differences in glutamine concentrations in the arterial and venous circulation, and measured activity of the major glutamine catabolizing enzyme, glutaminase. Arteriovenous differences provide an index of the amount of a given substrate removed by the tissue across which the measurements are made, and commonly are expressed as a percentage of substrate removed, or percent extraction. Arteriovenous differences for glutamine were determined in 7 anesthetized adult horses (weight, 450 to 500 kg) before and after an IV glutamine infusion. The mean baseline arterial glutamine concentration (+/- SEM) was 572 +/- 24 microM; this concentration quadrupled (to 2,167 +/- 135 microM, P < 0.01) 1 minute after IV bolus infusion of a 17.5-g glutamine load. Baseline extraction by the portal-drained viscera was 7.5 +/- 1.5%; this value increased to 18 +/- 2% at 1 minute (P < 0.01) and had returned to baseline values 60 minutes later. Arteriovenous differences were greatest across the jejunum (11.8 +/- 1.8% in the baseline period vs 33.1 +/- 3.1% at 1 minute, P < 0.001), with smaller differences across the colon, suggesting that the jejunum was the more avid utilizer of glutamine. Glutaminase activity was 4.38 +/- 0.16 and 4.00 +/- 0.60 micromol/mg of protein/h under standard conditions in jejunal and ileal mucosa, respectively. Kinetic studies of jejunal glutaminase revealed the enzyme to have a Km of 3.81 +/- 0.35 mM and a Vmax of 8.08 +/- 0.54 micromol/mg of protein/h, suggesting that the small intestine of horses has a high capacity to extract and metabolize circulating glutamine.

Effect of fluoride was assessed on molars during and after mineralization. Two groups of 7 sheep each were dosed orally with 3.5 mg of fluoride/kg of body weight daily for 4 months (from 5 to 9 months after birth). Sheep of the first group were slaughtered immediately after fluoride administration; those of the second group were slaughtered 4 months later at the age of 13 months. Three control groups of 7 sheep each were slaughtered at 5 months (to determine the state of the teeth at the beginning of fluoride administration), and at 9 and 13 months. During fluoride administration, plasma fluoride concentration rapidly increased to about 0.50 micrograms/ml; after fluoride administration, it stabilized at 0.20 micrograms/ml in treated sheep, whereas controls had concentration of 0.10 micrograms/ml (P < 0.01). Parts of the molars that were in the process of mineralization during fluoride administration (mainly second molars) had thinning enamel, with pits, mainly close to the apex, marked decrease in hardness throughout the layer (< 100 Vickers U, compared with 240 Vickers U), and fluoride accumulation twice as high as that in controls (1,000 to 2,500 mg(kg [dry weight]). Fluoride accumulation was higher in dentine (2,700 to 4,200 mg/kg), but hardness was less affected. On parts of the molars that were already mineralized mostly, the first molar), changes in the appearance of enamel and cementum, decreased hardness (less important than in teeth during mineralization) affecting outer enamel more than inner enamel, high fluoride concentration (4,000 to 5,500 mg(kg [dry weight]) in outer enamel extending over 200 Km were observed. Thus, in sheep, fluoride has a substantial postsecretory effect that may be explained by a slower maturation phase of enamel in this species. Because molar wear is correlated to enamel hardness (dentine at the occlusal surface has low resistance--30 Vickers U), abnormal abrasion of molar teeth that have mineralized before and during fluoride intakes can be observed.

When Salmonella typhimurium and Clostridium perfringens were tested in conventional chickens, larger numbers of S typhimurium and C perfringens adhered to Eimeria tenella-infected ceca than to uninfected ceca. In germ-free chickens, S typhimurium and C perfringens adhered to the E tenella-infected cecal mucosa more than to the uninfected cecal mucosa, but fewer Bacteroides vulgatus and Bifidobacterium thermophilum adhered to the E tenella-infected ceca than to the uninfected ceca. Many bacteria adhered to the lesions caused by E tenella as observed by scanning electron microscopy. On the basis of our findings, we suggest that infection with E tenella upsets the balance of competitive adherence of bacteria, allowing more colonization of S typhimurium and C perfringens.