Large Experimental Fistula of the Right Dorsal Colon in Horses

Studies in horses with experimental gastrointestinal fistulas may lead to rapid advancements in equine nutrition, as well as prevention and treatment of diseases such as colic and laminitis. The aim of this study was to devise a technique and a cannula to create a large fistula in the right dorsal colon (RDC). A total of 13 horses with normal gastrointestinal tract were used. After the administration of sedatives and local anesthetics, a segment of the right 16th rib was removed, a circular defect was created in the muscular wall, and the RDC was sutured to the muscular wall. The subcutaneous tissue and skin were closed over the attached RDC in eight horses (closed technique), or removed to expose the serosa of the colon sutured to the abdominal wall in five horses (open technique). A full thickness circular incision was made 2 to 6 weeks later to create a fistula. A cannula (diameter, 5 cm) made of natural rubber or silicon was inserted in the fistula. The open surgical technique was easier to perform and resulted in fewer complications. The cannula made of silicon resulted in less pruritus. One horse had a large colon torsion around the colopexy before fistula creation. One of the 12 fistulated horses had a large colon displacement 43 days after cannula insertion. These observations suggest that pexis of the RDC may predispose the horse to large colon displacement or volvulus. The open technique for the colopexy and the cannula made of silicon can be used for creation of a RDC fistula.     

CPIDS: a plant parameter selection program for erosion prediction modeling

Newly developed erosion prediction models require detailed input parameters including those describing cropping systems. Each model exhibits a different level of complexity for crop growth modeling, and many plant parameters for these models are difficult to obtain. Furthermore, numerous parameters require interpretation from other measurable plant characteristics. We developed a database containing measurable plant characteristics to supply users of these new erosion prediction technologies with the necessary parameters. The new database supports the Revised Universal Soil Loss Equation (RUSLE) and the Water Erosion Prediction Project (WEPP) erosion prediction models. The Crop Parameter Intelligent Database System (CPIDS) was developed to assist crop database builders and users of RUSLE and WEPP in interpretation of plant characteristics and selection of plant parameters. CPIDS is a Microsoft® Windows™-based program, currently running on a personal computer (PC) under Windows 3.1™, Windows 95™ and Windows NT 4.0™.     

Simulating landscape catena effects in no-till dryland agroecosystems using GPFARM

This study evaluated the site-specific applicability and efficacy of the GPFARM decision support system (DSS) based on underlying simulation model performance for dry mass grain yield, crop residue, total soil profile water content, and total soil profile residual NO₃-N across a landscape catena for dryland no-till experimental locations in eastern Colorado. Relative error of simulated mean, normalized objective function (root mean square error divided by the observed mean), and index of agreement evaluation statistics were calculated to compare modeled results to observed data. A one-way, fixed-effect ANOVA was also performed to determine differences among experimental locations and summit, sideslope, and toeslope landscape positions. GPFARM simulations matched observed data trends, with the model correctly distinguishing variations between the summit and toeslope landscape positions. In addition, experimental observations and GPFARM simulations both indicated that the toeslope landscape position was the most productive for grain yield and also exhibited higher amounts of crop residue, total soil profile water content, and total soil residual NO₃-N. The GPFARM crop model performed adequately but was inconsistent in simulating winter wheat, corn, and sorghum dry mass grain yield. GPFARM performance in simulating crop residue was poorer than for crop grain yield. GPFARM predicted mean total soil profile water content was generally within ±20% of the observed mean across locations and landscape positions, with the model somewhat biased towards overpredicting total soil profile water content at the summit and sideslope landscape positions. Total soil profile residual NO₃-N was underpredicted by GPFARM across all locations and landscape positions by an average of 30%. Although GPFARM appears to have reasonably simulated long-term output responses across a landscape catena for the eastern Colorado experimental locations (especially given the simplifying assumptions in many of the GPFARM simulation components and the inherent variability present at the experimental plot level), different interpretations of GPFARM performance can be made depending on the evaluation statistic of interest. Furthermore, the model cannot fully account for water and chemical movement across the landscape catena; simulation results suggest that addition of a spatially-distributed routing component should offer improvements in GPFARM prediction accuracy across a catena where surface runoff or lateral subsurface flow is occurring.     

Use of Ultrasound In Horses for Diagnosis of Left Dorsal Displacement of the Large Colon and Monitoring its Nonsurgical Correction

During a 28 month period, 82 horses with clinical signs of abdominal pain were examined for left dorsal displacement of the large colon (LDDLC) using percutaneous ultrasound. Left dorsal displacement of the large colon was diagnosed when a gas echo dorsal to the spleen obliterated the dorsal splenic border, or when the colon was observed lateral to the spleen. In 42 horses, ultrasound confirmed a diagnosis of LDDLC and 40 horses had no evidence of LDDLC. There were five false negative results and no false positives. In four horses with LDDLC, the colon was displaced between the spleen and body wall; three of these colic episodes resolved with medical therapy and the fourth required a celiotomy to relieve a sand impaction. The remaining 38 horses had a renosplenic entrapment; surgical correction was elected in 4 horses, 21 horses were corrected by a nonsurgical rolling procedure, 12 were corrected at surgery after an unsuccessful rolling attempt, and one was corrected by rolling but required surgery later because of an additional lesion. Percutaneous abdominal ultrasound was a valuable aid in the diagnosis of LDDLC and in confirming correction of the displacement after a nonsurgical rolling procedure.     

Clinical, Clinicopathologic, and Epidemiologic Features of Anhidrosis in Central Florida Thoroughbred Horses

A group of 834 Thoroughbred horses was surveyed on four central Florida farms for clinical and epidemiologic features of anhidrosis. In addition, comparative analysis was made of serum thyroxine, serum electrolytes, and fractional urinary electrolyte excretion ratios. An overall disease prevalence of 6.12% was observed. Training horses and nonpregnant broodmares had a predilection for the disease. Adolescent horses were infrequently affected. There was no correlation with sex or color. Comparative clinical signs, related to thermoregulatory compromise, included tachypnea and hyperthermia. Long-term effect included focal and generalized alopecia, decreased appetite, and impaired performance. Previously reported hypothyroidism and hypochloremia were not demonstrated; however, fractional urinary chloride excretion ratios indicated a significant relative conservation of chloride.     

Enumeration of Bradyrhizobium japonicum in soil subjected to high temperature: Comparison of plate count, most probable number and fluorescent antibody techniques

The survival of BradyrMzobium japonicum strains in autoclaved and non-autoclaved soil at various temperatures for up to 18 days was determined by plate count, plant infectivity-most probable number (MPN) and modified fluorescent antibody (FA) techniques. The high-temperature tolerant strains studied were BR587, NC1005 and NC1033, and the high-temperature intolerant strains studied were NCI028, 3Ilb24 and 311b123. Each strain was exposed individually in a sandy loam soil at 28, 33 or 37°C under humidity controlled conditions. Those strains reported to be tolerant to elevated temperature in pure culture decreased by <10^1.5 cells g⁻¹ when enumerated by plate count after high-temperature exposure in autoclaved soil. Based on plate counts, the population of two of the three high-temperature intolerant strains added to autoclaved soil decreased by more than 10³ cells g⁻¹ soil after exposure to elevated temperatures. In non-autoclaved soil, the population of all inoculated strains decreased after exposure to elevated temperature when enumeration was by the plant infectivity-MPN technique. In autoclaved soil at 28°C, the correlation between plate count and FA enumerations was significant at the 0.05 probability level for four of the six strains (r² = 0.65). After high-temperature incubation, counts based on the FA technique were not correlated with plate counts of intolerant strains or MPN enumeration of tolerant and intolerant strains (r² = 0.004). Differential survival of B. japonicum strains in autoclaved soil at high temperature as enumerated by plate counts confirms the designation of temperature tolerance made by Munevar and Wollum (1981). However. MPN enumeration of bradyrhizobia in the non-autoclaved system did not follow the original temperature tolerance classifications. Enumeration by FA procedures did not show a decrease in population after exposure to high temperature as observed with the plate and MPN counts. Thus, the FA technique may not adequately indicate population dynamics in short-term ecological studies.     

QUANTITATIVE ULTRASONIC ASSESSMENT OF LIVER SIZE IN THE DOG

Static and real-time B-mode hepatic ultrasound imaging was performed on 16 anesthetized dogs (7.7–29 kg). Sagittal static B-mode scans were acquired at 1–cm intervals, and transverse scans were made with both static and real-time units. Measurements were made from the surface of the liver to the diaphragm and were tested individually and when added or multiplied together for significant correlation with liver and body weight. Only one of the static B-mode measurements had a significant correlation ( p >0.05), and none of the real-time measurements was dependent on liver weight. Ultrasonographic assessment of canine liver size using these methods was of little value in predicting actual liver weight.     

Associations between the Exposure to Airborne Virulent Rhodococcus equi and the Incidence of R equi Pneumonia among Individual Foals

Rhodococcus equi is a significant cause of pneumonia, resulting in disease and sometimes death of foals. It is believed that infection occurs by inhalation of dust contaminated with virulent R equi. Although association between the airborne concentration of virulent R equi and the incidence of foal pneumonia at breeding farms has been documented, studies at the level of individual foals have not been reported. Thus, the objective of this study was to determine whether the magnitude of airborne virulent R equi was significantly associated with risk of R equi pneumonia for individual foals. The concentration of virulent R equi was significantly (P < .001) greater in stalls than paddocks among samples collected from 47 foals at a breeding farm in central Kentucky. The presence of airborne virulent R equi in stalls was significantly (P = .045) more likely at 7 days of age for foals subsequently found to be affected by rhodococcal pneumonia. Additionally, airborne concentrations of virulent R equi in stalls were significantly greater at 7 and 14 days of age than at birth. Presence of the mare and foal at the time of sampling was significantly (P < .001) associated with increased airborne concentrations of virulent R equi in stalls. These findings suggest that environments containing airborne virulent R equi during the first week of life may influence the risk of subsequent disease for a foal.