We investigated the effect of adding psyllium to a standard electrolyte solution in 10 calves with diarrhea. The calves were tested with the standard solution on one day and standard solution plus psyllium on the alternate day. The order of treatments was randomized. Psyllium converted the solution into mucilage, but did not affect fecal consistency. Mean +/- SEM area under the glucose absorption curve was lower for mucilaginous than for nonmucilaginous solutions, 2.1 +/- 0.62 vs 3.75 +/- 1.18 mmol.h, respectively, but the difference was not significant. The area under the breath hydrogen curve was marginally lower for mucilaginous than nonmucilaginous solutions, 102 +/- 20 and 209 +/- 60 ppm.h, respectively. The usefulness of such decreased bacterial fermentation is doubtful.

A histochemical and morphometric study of fiber types in a variety of skeletal muscles of healthy young adult cats was undertaken to provide normative data not available previously. Using a standardized system of nomenclature, fiber types 1, 2A, 2B, and 2C were identified in most cat muscles on the basis of myosin ATPase staining at pH 4.45. Type-2M fibers were present in temporalis (TEM) and masseter (MAS) muscles. Type-1 fibers predominated in medial head of triceps (MHT) and soleus muscles. Type-2B fibers were dominant in biceps femoris, lateral head of gastrocnemius, cranial tibial, long head of triceps, and superficial digital flexor muscles; type-2A fibers were dominant in buccinator muscle samples; and type-2M fibers were dominant in TEM and MAS muscles. Numbers of type-2C fibers did not exceed 2 to 3% of the myofiber population in any muscle. In CT and LHT muscles, a gradient of fiber type distribution was observed, with significant (P < 0.05) increase in numbers of type-1 and type-2A fibers in deeper regions of the muscles. The distribution of fiber types was compartmentalized in MHT and MAS specimens. Diameter of type-2B fibers was significantly (P < 0.05) larger than that of type-1 and type-2A fibers in biceps femoris, lateral head of gastrocnemius, cranial tibial, long head of triceps, and superficial MHT muscles. Diameter of type-2M fibers was significantly (P < 0.05) larger than that of type-1 fibers in TEM and MAS muscles. The soleus type-1 muscle fibers were the largest fibers encountered in any muscle. In MHT muscle, fiber diameter of type-1 and type-2B fibers varied significantly (P < 0.05) in oxidative and glycolytic compartments. Variability coefficients were less than 200 in all muscles. In every muscle specimen, the number of fibers with internal nuclei was less than or equal to 2%.

Hyperxanthinuria and xanthine uroliths have been recognized with increased frequency in dogs with ammonium urate uroliths that had been given allopurinol. We hypothesized that dietary modification might reduce the magnitude of uric acid and xanthine excretion in urine of dogs given allopurinol. To test this hypothesis, excretion of metabolites, volume, and pH were determined in 24-hour urine samples produced by 6 healthy Beagles during periods of allopurinol administration (15 mg/kg of body weight, PO, q 12 h) and consumption of 2 special purpose diets: a 10.4% protein (dry matter), casein-based diet and a 31.4% protein (dry matter), meat-based diet. Significantly lower values of uric acid (P = 0.004), xanthine (P = 0.003), ammonia (P = 0.0002), net acid (P = 0.0001), titratable acid (P = 0.0002), and creatinine (P = 0.01) excreted during a 24-hour period were detected when dogs consumed the casein-based diet and were given allopurinol, compared with the 24-hour period when the same dogs consumed the meat-based diet and were given allopurinol. For the same 24-hour period, urine pH values, urine volumes, and urine bicarbonate values were significantly (P = 0.0004, P = 0.04, and P = 0.002, respectively) higher during the period when the dogs were fed the casein-based diet and given allopurinol than when they were fed the meat-based diet and given allopurinol. Endogenous creatinine clearance was significantly (P = 0.006) lower when dogs were fed the casein-based diet and given allopurinol than when they were fed the meat-based diet and given allopurinol. Significantly lower concentrations of plasma uric acid (P = 0.0001), plasma xanthine (P = 0.01), and serum urea nitrogen (P = 0.0001) were detected when dogs consumed the casen-based diet and were given allopurinol than when they consumed the meat-based diet and were given allopurinol. On the basis of these results, use of the casein-based diet and allopurinol in protocols designed for dissolution of urate uroliths may be beneficial in preventing hyperxanthinuria and xanthine urolith formation.

A rapid subjective method for estimating the extent of gross pneumonia lesions in slaughtered pigs was compared with dissection of lungs in 51 slaughtered pigs. After standardization for prevalence in the regional industry, regression analysis indicated that the subjective method was highly predictive of the extent of pneumonic lesions (R2 = 0.88). Part of the error with the subjective method was attributed to approximations used for the relative proportions of lung lobes, which result in overestimation of the affected tissue by approximately 90%. Retrospective analysis of data from a slaughter monitoring program revealed strong associations (R2, 0.54 to 0.91) between prevalence, mean, median, and maximal lung scores in groups of pigs. Maximal lung score was biased by sample size, but prevalence and mean or median lung scores could be used to describe pneumonia severity in groups of pigs. Our results indicate that error in measurement of the extent of pneunomic tissue in slaughtered pigs is unimportant if the time of onset, clinical severity, and duration of disease are not quantified.

Six horses, highly trained for dressage competition, were used to study the stride kinematics of the walk, and to compare the kinematics of the collected, medium, and extended walks. Horses were filmed in a sagittal plane at a rate of 150 frames/s; temporal, linear, and angular data were extracted from the films. Results of ANOVA and Duncan's multiple range test indicated that the speed of the collected walk (1.37 m/s) was significantly (P < 0.01) slower than that of the medium (1.73 m/s) and extended (1.82 m/s) walks, values for which were not significantly different from each other. The increase in speed was associated with a significant increase in stride length, from 157 cm in the collected walk to 193 am in the extended walk. This was a result of an increase in the over-tracking distance, whereas there was no significant difference in the distance between lateral placements of the limbs. Stride duration decreased (P < 0.01) from the collected walk (1,159 ms) to the extended walk (1,064 ms). Angles of the metacarpal and metatarsal segments, measured on the palmar/plantar aspect, were higher at impact and lower at lift off in the collected than in the extended walk (P < 0.01). This indicated greater range of angular motion of this segment during the stance phase in the extended walk. Only 1 of the 6 horses had a regular 4-beat rhythm of the footfalls, with equal time elapsing between the lateral and diagonal footfalls.

Intraocular pressure (IOP) was measured, using applanation tonometry, in both eyes of 20 horses after topical application of 0.5% proparacaine to the cornea. Ultrasonic pachymetry was used to measure central, mid-peripheral, and peripheral corneal thickness (CT) in all 4 quadrants of both eyes of 25 horses. All measurements were repeated after auriculopalpebral nerve block, sedation by IV administration of xylazine, or combination of nerve block and sedation. Mean IOP after topical anesthesia of the cornea was 20.6 +/- 4.7 mm of Hg for the left eye and 20.35 +/- 3.7 mm of Hg for the right eye. Mean central CT was 793.2 +/- 42.3 micrometers. The peripheral part of the cornea was significantly (P < 0.05) thicker, on average, than the central part of the cornea. Auriculopalpebral nerve block had no significant effect on IOP or CT. Intravenous administration of xylazine resulted in a significant (P < 0.05) decrease in IOP, but had no effect on CT.

To investigate the effect of chloramphenicol, a cytochrome P-450 inhibitor, on the pharmacokinetics of propofol, either chloramphenicol (50 mg/kg of body weight, IV) or saline solution was administered IV to 5 Greyhounds in randomized manner, with at least 2 weeks between trials. Thirty minutes after either chloramphenicol or saline treatment, a bolus dose of propofol (10 mg/kg IV) was administered, followed by a 2-hour infusion of propofol (0.4 mg/kg/min, IV). Samples for determination of blood propofol concentration were collected sequentially over a 6-hour period during each trial. After termination of propofol infusion, the time to spontaneous head lift, extubation, sternal recumbency, and standing was recorded. Blood propofol concentration was determined by use of high-performance liquid chromatography. Concentration-time data were fitted to a two-compartment open pharmacokinetic model and pharmacokinetic variables were determined, using a microcomputer program for modeling and simulation of concentration-time data. The effect of chloramphenicol on the pharmacokinetics of propofol and recovery time were evaluated, using paired t-tests and Wilcoxon's test for parameters that are not normally distributed (t1/2(beta), Vd(ss), Cl(B)). Significant (P < 0.05) effects of chloramphenicol pretreatment included increased t1/2(5) (by 209%), and decreased Cl(B) (by 45%), and prolonged recovery indices (by 768 to 946%). These results indicate that cytochrome P-450 metabolic pathways have an important role in propofol clearance and propofol anesthetic recovery in Greyhounds.

A repeated-measures study was conducted on 5 dogs to clinically, radiographically, and echocardiographically characterize the actions of the angiotensin-converting enzyme inhibitor, enalapril, before and after development of experimentally induced heart failure. Heart failure was artificially induced, using a surgically implanted programmable ventricular pacemaker, which stimulated the heart at a rate of 245 beats/min until a low-output cardiomyopathic a state developed. This condition was then stabilized by decreasing the pacing rate to 190 beats/min. Pacing-induced heart failure was successfully induced in a mean +/- SD 4.2 +/- 1.95 weeks. The condition closely resembled the clinical, radiographic, and echocardiographic features of naturally acquired idiopathic dilated cardiomyopathy in dogs. Enalapril was well tolerated by dogs, and clinical adverse reactions did not develop. Results of echocardiographic studies indicated that enalapril treatment during the control period resulted in a significant (P < 0.05) increase in velocity of circumferential fiber shortening and a significant (P < 0.05) decrease in left ventricular ejection time. Therapeutic responses to enalapril were evident after development of heart failure. These included reduced severity of clinical signs of disease, evidence of decreased radiographically determined cardiac size (2 of 5 dogs), radiographic evidence of a reduction in pulmonary edema and congestion (4 of 5 dogs), significant (P < 0.05) reductions in left atrial and ventricular chamber dimensions (left atrial dimension, diastolic left ventricular internal dimension as determined echocardiographically), and improvement in some echocardiographic indices of left ventricular performance (velocity of circumferential fiber shortening and left ventricular ejection time).

Thirty-five heifers were allotted to 3 groups. Group 1 (contro]) consisted of 10 heifers that were not vaccinated and were challenge exposed by breeding to infected bulls. Group 7 (natural challenge exposure) consisted of 10 heifers that were vaccinated and challenge exposed by breeding to infected bulls. Group 3 (experimental challenge exposure) consisted of 15 heifers that were vaccinated and challenge exposed by breeding to infected bulls and by intravaginal inoculation with 10(7) Tritrichomonas foetus. Total immunoglobulin concentrations and specific trichomonal antibodies were determined in serum and vaginal secretions of heifers, using radial immunodiffusion and ELISA procedures. Control heifers remained infected for a mean of 10.6 weeks (range, 0 to 18 weeks), and heifers of the natural and experimental challenge-exposure groups remained infected for 3.2 and 5.0 weeks, respectively (range, 0 to 12 weeks). Total serum and cervicovaginal mucus concentrations of IgM, IgA, IgG1, and IgG2 did not change significantly after vaccination or challenge exposure. However, ELISA titers of total trichomonal antibodies increased up to 1:10,000 (range, 1:400 to 1:10,000) in serum after vaccination, and increased approximately tenfold above background in cervicovaginal mucus. In serum, the predominant trichomonal antibody isotype was IgG1, although trichomonal IgA and IgM antibodies also increased. The predominant trichomonal antibody detected in cervicovaginal mucus was IgA. Antibody titers in serum and cervicovaginal mucus of vaccinated heifers were not increased by infection. However, in control heifers, the total local trichomonal antibody response increased three- to fivefold after infection. In these heifers, specific antibodies in serum were predominantly IgG1 and local (cervicovaginal) antibodies were predominantly IgA.

In gas exchange studies addressing the storage and transport of CO2 in dogs, a model in which cardiac output (QT) can be precisely controlled and measured would be beneficial. We identified problems with described extracorporeal circuits and implemented right atrial bypass (RAB) in dogs. In 6 anesthetized (chloralose and urethane), heparinized dogs (mean +/- SD, 24 +/- 4 kg) with open thorax, cannulas were inserted in both vena cavas to drain venous blood return to a reservoir (anaerobic bag or bubble oxygenator). A roller pump then drove blood through a heat exchanger back to the right atrial appendage. After 1.8 +/- 1.4 hour of RAB, physiologic variables remained within reference limits for dogs (QT, 1.5 +/- 0.3 L/min; blood pressure, 92 +/- 25 mm of Hg; arterial P(CO2), 35 +/- 4 mm of Hg; P(O2), 513 +/- 39 mm of Hg; pH, 7.39 +/- 0.08; and tissue CO2 production, 126 +/- 56 ml/min). To permit study of gas exchange, venous return (and thus, QT) and venous P(CO2), and P(O2) could be accurately regulated and measured over a wide range. Maintenance of native pulsatile lung perfusion and cardiogenic oscillations minimizes mismatching of pulmonary ventilation and perfusion and facilitates studies addressing pulmonary gas exchange. This RAB model is designed so that investigators can establish the preparation in a few hours.