RADIOGRAPHIC AND ULTRASONOGRAPHIC EVALUATION OF THE PATELLAR LIGAMENT FOLLOWING TIBIAL TUBEROSITY ADVANCEMENT

Effect of tibial tuberosity advancement (TTA) on the patellar ligament has not been described. Our purpose was to evaluate the patellar ligament radiographically and ultrasonographically before and after a TTA. Twenty‐one stifles (20 dogs) were evaluated preoperatively (T0), and at six (n=18) (T1) and 16 weeks (n=17) (T2) postTTA. Radiographically, proximal and distal thickness of the patellar ligament was assessed and a ratio to the total length of the ligament was calculated to compensate for the magnification. Ultrasound evaluation included measurements of the transverse thickness and cross‐sectional area at three different levels, as well as a subjective score of ligament changes. In comparison with T0, all radiographic and ultrasonographic measurements increased significantly, 6 weeks postoperatively (P≤0.04), and did not change 16 weeks postoperatively compared with T1. The subjective score worsened significantly from T0 to T1 and T0 to T2 (P<0.0001), and improved significantly from T1 to T2 (P=0.02). Larger cage size was associated with a more severe increase in radiographic proximal thickness to total length ratio and ultrasonographic middle transverse area at both follow‐up examinations (P0.02). Dogs in which arthrotomy was not performed appeared to have ultrasonographically less changes. In conclusion, patellar desmopathy was a common postoperative sequel to TTA. Surgical trauma, arthrotomy, perfusion injury, complete vs. partial cranial cruciate ligament rupture, larger tibial advancement, postoperative activity or altered insertion angle of the patellar ligament at the tibial tuberosity are suggested causes, that should be elucidated in a larger study cohort.     

EFFECT OF CONTRAST MEDIUM INJECTION DURATION ON PEAK ENHANCEMENT AND TIME TO PEAK ENHANCEMENT OF CANINE PULMONARY ARTERIES

Our goal was to investigate the effect of contrast medium injection duration on pulmonary artery peak enhancement and time to peak enhancement. Fourteen dogs were allocated into one of seven predefined weight categories, each category contained two dogs. Dogs in each weight category were assigned to group A or B. Animals in each group received a different contrast medium injection protocol. In group A, a fixed injection rate of 5 ml/s was used. In group B, the contrast injection rate was calculated as follows: flow rate=contrast volume/scan duration+10 s. Time to peak enhancement and peak enhancement of the main left and right pulmonary arteries were measured on single‐level, dynamic CT images for a fixed time of 30 s. Rank correlation (Spearman's) coefficients between injection duration and time to peak enhancement and between body weight and peak enhancement were calculated. For group A, there was a significant negative correlation between peak enhancement and weight (r=?0.94; P=0.005), while for group B, there was no significant correlation (r=?0.64 and P=0.18). There was a significant correlation between time to peak enhancement and injection duration in both groups (group A: r=0.99; P=0.006 and group B: r=0.85; P=0.02). In conclusion, injection duration is a key feature in a CT angiography injection protocol. A protocol with an injection duration adjusted to the scan duration seems to be particularly suitable for veterinary applications where a population with great weight variability is studied.     

Ecophysiological study on weed seed banks and weeds in Cambodian paddy fields with contrasting water availability

Weed infestations are a major cause of yield reduction in rice (Oryza sativa) cultivation, particularly with direct‐seeding methods, but the relationship between weed dynamics and water availability in Cambodian paddy fields has not been documented previously. We surveyed the weed abundance and weed seed banks in the soil of paddy fields with inferred differences in their water regime in 22 farm fields in three provinces of Cambodia in the 2005 and 2006 rainy seasons. We studied rain‐fed lowland fields in upslope and downslope topographic positions and fields at different distances from the irrigation water source inside an irrigation rehabilitation area. The weed seed banks were estimated by seedling emergence in small containers and weed abundance and vigor were estimated by a simple scoring system. The estimated weed seed bank in the top 5 cm of soil ranged from 52.1 to 167 × 10³ seeds m^?2 (overall mean of 8.5 × 10³ seeds m^?2) and contained a high proportion (86%) of sedge species, such as Fimbristylis miliacea L. and Cyperus difformis. Several fields had particularly large seed banks, including one near the reservoir. No clear difference was found in the weed seed banks between the irrigated fields that were located close to (upstream) and distant from (downstream) the water source or between the irrigated and rain‐fed lowland fields, but the weed scores were larger in the rain‐fed fields and the downstream fields within the irrigated area. A water shortage during the late growing season in 2005 led to a proliferation of weeds in some fields and an associated increase in weed seedbank size in 2006. However, the weed scores in 2006 were more strongly associated with that year's water conditions than with the weed seedbank size.     

THORACIC COMPUTED TOMOGRAPHY FINDINGS IN DOGS EXPERIMENTALLY INFECTED WITH ANGIOSTRONGYLUS VASORUM

To characterize the computed tomography (CT) features of thoracic lesions caused by infection with Angiostrongylus vasorum, pre‐ and postcontrast CT was performed in six experimentally infected Beagles 13 weeks postinoculation and in four of these 9 weeks postchemotherapy. Findings were compared with survey radiographs and necropsy findings. A multicentric bronchoalveolar pattern more pronounced at the lung periphery was present radiographically. On CT, the predominant abnormality underlying this alveolar pattern was multiple large nodules merging to areas of consolidation, and containing air bronchograms of varying extent. These nodular changes corresponded to histopathologic granulomata, consisting mainly of macrophages, multinucleated giant cells, and lymphocytes that had accumulated around larvae and eggs. Morphologically, no bronchial changes were observed on CT or histologically. Quantitatively, however, on CT there was evidence of bronchial thickening at 13 weeks postinoculation and mild very peripheral bronchiectasia 9 weeks postchemotherapy. Regional lymph nodes were enlarged after infection, and smaller after treatment. On postcontrast CT, several suspicious intraluminal filling defects suggestive of thrombosis were found; however, the tortuosity of some pulmonary arteries seen radiographically was not present in CT images. After treatment, the consolidations and large nodules had almost completely disappeared. A remaining radiographic interstitial pattern was characterized on CT as ground‐glass opacifications, subpleural interstitial thickening, subpleural lines, and interface signs. These interstitial changes reflected fibrosis as documented histopathologically. CT allowed very detailed and accurate characterization of pulmonary parenchymal lesions, bronchi, and lymphnodes and closely reflected histopathological changes.