Upgrading a 1/20,000 soil map with an apparent electrical conductivity survey

Despite their shortcomings, choropleth soil maps remain the most widespread source of information on soil resources. Since most nationwide soil surveys were conducted in the second half of the previous century, a need for upgrading emerges. We evaluated the potential of detailed observations made by a mobile, non-invasive proximal soil sensor to upgrade a part of the 1/20,000 choropleth soil map of Belgium. This study was conducted on a 14 ha area which had been mapped twice in the 1950s: first, during the national soil survey yielding a 1/20,000 soil map, and second, during a detailed investigation resulting in a 1/5000 map. The first map failed to identify the presence of a Tertiary clay substratum at variable depths, while the second map indicated this substratum to be present within 1.2 m below the soil surface for about a third of the area. A recent survey with the EM38DD soil sensor provided 9192 measurements of the apparent electrical conductivity (EC_a) within the study area. The depth of the substratum (D_ts) was noted at 60 calibration locations by augering and the relationship between EC_a and D_ts was modelled by an exponential curve with an R² of 0.80. This allowed the detailed mapping of D_ts by regression kriging. The predictions were validated using 46 independent observations of D_ts indicating a reasonable average error of 0.24 m and a very good correlation coefficient between observed and predicted values of 0.94. A map accuracy assessment indicated that even after classification, the D_ts classes were better predicted by the sensor data than the 1/5000 map which was based on many more auger observations. Finally an upgraded 1/20,000 soil map was presented, illustrating the potential of combining existing soil maps with proximal soil sensing technology.     

Key soil and topographic properties to delineate potential management classes for precision agriculture in the European loess area

Recent advances in on-the-go soil sensing, terrain modelling and yield mapping have made available large quantities of information about the within-field variability of soil and crop properties. But the selection of the key variables for an identification of management zones, required for precision agriculture, is not straightforward. To investigate a procedure for this selection, an 8 ha agricultural field in the Loess belt of Belgium was considered for this study. The available information consisted of: (i) top- and subsoil samples taken at 110 locations, on which soil properties: textural fractions, organic carbon (OC), CaCO₃ and pH were analysed, (ii) soil apparent electrical conductivity (EC_a) obtained through an electromagnetic induction based sensor, and (iii) wetness index, stream power index and steepest slope angle derived from a detailed digital elevation model (DEM). A principal component analysis, involving 12 soil and topographic properties and two EC_a variables, identified three components explaining 67.4% of the total variability. These three components were best represented by pH, EC_a that strongly associated with texture and OC. However, OC was closely related to some more readily obtainable topographic properties, and therefore elevation was preferred. A fuzzy k-means classification of these three variables produced four potential management classes. Three-year average standardized yield maps of grain and straw showed productivity differences across these classes, but mainly linked to their landscape position. In the loess area with complex soil-landscape interactions pH, EC_a and elevation can be considered as key properties to delineate potential management classes.     

Reconstructing the paleotopography beneath the loess cover with the aid of an electromagnetic induction sensor

During the last glacial period (Weichselian), wind-blown loess was deposited over the undulating landscape of central Belgium, which had been formed in surfacing Tertiary marine sediments. Since valleys were filled up with a thicker loess layer than hill tops, the present topography is much smoother. This smoothing was enhanced by subsequent erosion processes. Reconstructing the paleolandscape at a detailed scale is almost impossible by conventional procedures based on soil augerings. Therefore, the use of the electromagnetic induction sensor, EM38DD, was evaluated as an alternative for mapping the depth to the Tertiary clay substrate. On our 2.7 ha study site, located in the loess belt of central Belgium, a strong non-linear relationship (R² = 0.86) was found between the apparent electrical conductivity (ECa), measured by the vertical dipole orientation of the EM38DD and the depth to a Tertiary clay substrate. These predictions were validated by independent observations of the depth to the Tertiary clay and a correlation coefficient of 0.83, with an average error of 0.22 m, was found. So, our dense ECa measurements (2 by 2 m resolution) allowed us to build a three-dimensionall surface of the depth to the Tertiary substrate, reconstructing the paleotopography beneath the loess cover. This paleotopography revealed distinct erosion patterns on the surface of the Tertiary clay. The continuity of these was confirmed by an analysis of surface flow patterns conducted on the reconstructed paleotopography. The non-invasive, time- and cost-effective electromagnetic induction sensor was found to offer new perspectives to reconstruct and analyse in detail the Quaternary paleotopography beneath the loess cover.     

Search for Borrelia burgdorferi in kidneys of dogs with suspected "Lyme nephritis"

BACKGROUND: "Lyme nephritis" is a poorly characterized condition associated with proteinuria and often fatal renal failure in dogs with serological evidence of infection with Borrelia burgdorferi. OBJECTIVE: The aim of this study was to determine if intact B. burgdorferi organisms were present in the kidneys of serologically Lyme-positive dogs with histopathologic features of Lyme nephritis. ANIMALS: Twenty-six affected and 10 control dogs were identified over an 8-year period (1996-2004) in databases at Cornell University's College of Veterinary Medicine. Case inclusion required serologic evidence of natural exposure to B. burgdorferi and availability of renal tissue (frozen or paraffin embedded) exhibiting pathology consistent with Lyme nephritis. METHODS: Renal tissue samples were assessed using modified Steiner (silver) (MS) staining, immunohistochemistry (IHC), polymerase chain reaction (PCR) using 4 primer sets (eubacterial, B. burgdorferi, Bartonella, and canine genomic DNA), and fluorescence in situ hybridization (FISH) using a 5'-cy3-eubacterial probe for 16S rRNA. RESULTS: MS stain was positive in 1 case; IHC was negative in all cases. None of the B. burgdorferi or Bartonella PCR reactions was positive. Two of the B. burgdorferi FISH analyses were positive. CONCLUSIONS AND CLINICAL IMPORTANCE: Minimal evidence of the presence of intact B. burgdorferi or any other bacterial organism was found in the renal tissue of dogs with suspected Lyme nephritis. Direct renal invasion by B. burgdorferi organisms does not appear to be responsible for this syndrome.     

Outcome of cats with low-grade lymphocytic lymphoma: 41 cases (1995-2005)

OBJECTIVE: To evaluate factors associated with response to treatment, remission duration, and survival in cats with low-grade lymphoma affecting various organ systems. DESIGN: Retrospective case series. Sample POPULATION: 41 cats with histologically confirmed low-grade lymphocytic lymphoma. PROCEDURES: Medical records and biopsy specimens of cats with histologically confirmed low-grade lymphocytic lymphoma of various organ systems treated with prednisone and chlorambucil between 1995 and 2005 were reviewed. The Kaplan-Meier method was used to estimate remission duration and survival. Factors potentially associated with prognosis were compared. RESULTS: Common clinical signs were weight loss (83%), vomiting (73%), anorexia (66%), and diarrhea (58%). Seventy-eight percent of cats tested had low serum cobalamin concentrations. Lymphoma was confined to the gastrointestinal tract in 68% of cats. Fifty-six percent of cats achieved a complete response to treatment, and 39% achieved a partial response. Five percent of cats had no response. No association was found between any risk factors (including anatomic site) and response to treatment. Partial response was associated with shorter remission duration, compared with complete response; median remission duration was 428 days for cats achieving a partial response, compared with 897 days for cats achieving a complete response. No other factors were associated with remission duration. Overall median survival time was 704 days. No factors were significantly associated with survival time. CONCLUSIONS AND CLINICAL RELEVANCE: Most cats with lymphocytic lymphoma responded to treatment with prednisone and chlorambucil, and most factors evaluated were not associated with outcome.     

Cardiac troponin I is elevated in dogs and cats with azotaemia renal failure and in dogs with non-cardiac systemic disease

OBJECTIVE: To determine if dogs and cats with renal failure, or other severe non-cardiac disease, and no antemortem evidence of cardiac disease on basic clinical evaluation, have elevated levels of cardiac troponin I (cTnI). DESIGN: Cross-sectional study using 56 dogs and 14 cats with primary non-cardiac disease (39 dogs with azotaemic renal failure, 14 cats with azotaemic renal failure, 17 dogs with non-cardiac systemic disease); 7/25 dogs and 6/14 cats had murmurs detected on physical examination. Serum or heparinised plasma was collected and analysed for cTnI. RESULTS: Cardiac troponin I concentrations were elevated above reference intervals in 70% of dogs and 70% of cats with azotaemic renal failure and in 70% of dogs with a variety of systemic non-cardiac diseases. Cardiac troponin I concentrations did not correlate with the degree of azotaemia, presence of murmurs, hypertension or type of non-cardiac illness. CONCLUSIONS: Cardiac troponin I concentration is often elevated in dogs and cats with azotaemic renal failure and in dogs with other systemic non-cardiac illness, suggesting that these conditions often result in clinically inapparent myocardial injury or possibly altered elimination of cTnI.     

Clinical evaluation of the locking compression plate for fetlock arthrodesis in six thoroughbred racehorses

Objective— To report use of a locking compression plate (LCP) for fetlock arthrodesis in Thoroughbred racehorses after catastrophic disruption of the suspensory apparatus.
Study Design— Retrospective case study.
Animals— Racing Thoroughbreds (n=6) with a catastrophic breakdown injury of the suspensory apparatus.
Methods— Medical records (2004–2006) of horses that had fetlock arthrodesis using an LCP were reviewed. Preoperative recorded variables were: age, gender, affected limb, injury type and occurrence, limb support used and time to surgery. Recorded surgical variables were: implants used and cost, surgery time, and anesthetic recovery method. Postoperative recorded variables included: treatment, physical status, complications, and outcome.
Results— Of 6 Thoroughbred racehorses that had LCP arthrodesis, 4 were sound for breeding purposes the next year and 2 horses were euthanatized (1 at 16 days, 1 at 68 days) because of proximal interphalangeal joint (PIJ) luxation. No surgical complications were associated with implant application. Postoperative complications were similar to those reported for other arthrodesis techniques.
Conclusions— LCP is a viable option for fetlock arthrodesis in Thoroughbred racehorses after catastrophic suspensory apparatus disruption.
Clinical Relevance— Adequate fetlock stability can be achieved with an LCP, and although the repair is likely more stable it is ∼3 times more expensive than using a limited contact dynamic compression plate (LC-DCP) with cortical screws.     

Retrospective analysis of selected predictors of mortality within a veterinary intensive care unit

The records of 204 cats entering the intensive care unit (ICU) at the University of Edinburgh Small Animal Hospital between December 2002 and October 2006 were retrospectively analysed. Of these, 37 cats over 12 months of age had a systolic blood pressure recorded on entry into the ICU, and this group comprised our study population. Of these 37 cats, 36 had both heart rate and respiratory rate recorded on entry into the ICU, whilst 24 of these cats also had body temperature recorded. The relationship between (i) survival to discharge and (ii) survival until 21 days after admission to the ICU was analysed using univariate generalised linear models with binomial errors. The robustness of any significant relationship was assessed using multivariate analysis methods. In addition, receiver operator curves (ROC) were generated for any of the significant predictors of mortality and from these curves the threshold values, optimal sensitivity and specificity were calculated. Using these values survival curves were generated for any significant prognostic indexes. A decreased blood pressure at the time of admission to the ICU was found to be a significant negative predictor of survival until discharge from the hospital. Overall, a systolic blood pressure of 124 mmHg or higher at the time of admission to the ICU has a sensitivity of 47.8% and a specificity of 85.7% for predicting that a cat will survive until discharge from the hospital.