MAGNETIC RESONANCE IMAGING OF DISTAL SESAMOIDEAN LIGAMENT INJURY

Distal sesamoidean ligament injury is a recognized cause of lameness but diagnosis using ultrasonography is sometimes difficult. Herein, we describe the normal appearance of the distal sesamoidean ligaments on magnetic resonance (MR) images and the changes that occur when the ligaments are injured. The appearance of the distal sesamoidean ligaments on MR images from 66 control horses and 58 horses with distal sesamoidean desmitis were described and the cross‐sectional area and signal intensity of the ligaments measured. In control horses, the ligaments had a characteristic appearance and strong left–right symmetry, and the lateral oblique sesamoidean ligament was larger and had higher signal intensity than the medial ligament. Cross‐sectional area and signal intensity were significantly greater in injured straight sesamoidean ligaments compared with the controls. Signal intensity increased significantly with oblique sesamoidean desmitis compared with the controls. Lesions of the distal sesamoidean ligaments were considered the sole cause of lameness in only 2 of 58 horses. Eighty percent of lesions in the distal sesamoidean ligaments were not detected using ultrasonography.     

Experimental Large Colon Resection at the Cecocolic Ligament in the Horse

Ten normal horses had approximately 95% of the length of the large colon resected with a side-to-side anastomosis between right ventral and right dorsal colon performed with surgical stapling equipment. Four horses died shortly after surgery of colitis (1 horse) or failure of the TA 90 transection staple line (3 horses). Another horse died 4 months after surgery from disseminated streptococcal infection but had recovered well from the colon resection. Five horses survived long term (18 months) with no clinical evidence of adverse effects of the resection. Surviving horses had weight loss and soft fecal consistency for 3 to 12 weeks after surgery but returned to preoperative values within 12 months. At a second surgery 1 year later (5 horses) or at necropsy 4 months later (1 horse), fibrous omental adhesions were present over the transection staple line in four horses and over the anastomotic staple line in two horses. Omental adhesions to the everted staple line were moderate but not associated with any clinical sequellae. An incisional hernia was present in one horse. The anastomotic stomata measured between 8 and 9 cm, which was 60% of the size of the original surgically created stomata. Failure of the transection staple line occurred in the first three of five horses in which the procedure was attempted due to improper configuration of the staples or crushing of the tissue between the staples. Experience corrected this complication.     

Haemangiosarcoma of bone in the dog

Twenty-two dogs with osseous haemangiosarcoma were examined in the University of Pennsylvania School of Veterinary Medicine from July 1952 to September 1972. A detailed case report of a primary haemangiosarcoma of the proximal humerus in a 21/2-year old spayed Irish Setter is given along with the salient features of twenty-one other cases. The three breeds most commonly involved were Boxers, Great Danes and German Shepherd Dogs. The ages ranged from 2–11 years with a median age of 6 years. The male to female ratio was 1·6:1·0. The proximal humerus and ribs were the bones most commonly affected. The long bone to flat bone ratio was 1·0:1·33. In some cases it was difficult or impossible to ascertain whether the haemangiosarcoma in bone was primary or metastatic. Histological grading appeared of little or no prognostic value. Résumé. De juillet 1952 à septembre 1972, on a examiné à l'Ecole de Médicine Vétérinaire de l'Université de Pennsylvanie, vingt-deux chiens atteints d'hémangiosarcome osseux. On donne un protocole détaillé d'observation d'un cas d'hémangiosarcome primaire de l'humérus proximal chez un setter irlandais châtré avec les traits caractéristiques saillants de vingt et un autres cas. Les trois races les plus communes dont il s'agissait, étaient les Boxers, les Grands Danois et les Bergers Allemands. Les âges variaient de deux à onze ans avec une moyenne d'âge de six ans. La proportion mâle à femelle était de 1·6:1·0. L'humérus proximal et les côtes étaient les os lesplus communément affectés La proportion de l'os long à l'os plat était de 1·0:1·33. Dans certains cas, il était difficile ou impossible de constater si l'hémangiosarcome de l'os était primaire ou métastatique. Une gradation histologique a semblé n'avoir que peu ou pas de valeur prognostique. Zusammenfassung. Zweiundzwanzig Hunde mit ossalen Hämangiosarkomen wurden in der Universität der Pennsylvanischen Schule für Veterinäre Medizin in der Zeit von Juli 1952 bis September 1972 untersucht. Ein in Einzelheit gehender Krankenbefund von einem primären Hämangiosarkom des Humerus proximalis in einem zweiundhalbjährigen irischen Setter (dem die Eierstöcke entfernt waren) wurde, zusammen mit den hervorstechenden Merkmalen von zweiundzwanzig anderen Fällen, veröffentlicht. Die drei Rassen, am Meisten einbegriffen, waren Boxer, dänische Doggen und deutsche Schäferhunde. Ihr Alter belief sich von zwei bis elf Jahren mit einem Durchschnittsalter von sechs Jahren. Das männliche zum weibliche Verhältnis stand bei 1·6:1·0. Der Humerus proximalis und die Rippen waren die Knochen, welche am Meisten befallen waren. Die Röhrenknochen standen zu den Plattenknochen im Verhältnis von 1·0:1·33. In einigen Fällen war es schwierig oder unmöglich zu ermitteln ob das Hämangiosarkom in Knochen primär oder metastatisch war. Histologische Einstufung schien von wenig oder keinem prognostischem Wert.     

USE OF CONTRAST-ENHANCED COMPUTED TOMOGRAPHY TO ASSESS ANGIOGENESIS IN DEEP DIGITAL FLEXOR TENDONOPATHY IN A HORSE

We compared contrast-enhanced computed tomography (CT) and high field magnetic resonance (MR) imaging in a horse with deep digital flexor tendonopathy. Lesions in the distal extremity were documented grossly and histopathologically. In contrast-enhanced CT, the deep digital flexor tendon lesions were markedly contrast enhancing with evidence of angiogenesis in the core and dorsal border lesions. The lesion morphology was clearly delineated on MR imaging, but without contrast media angiogenesis cannot be identified. Gross examination, histopathologic examination, and CD31 immunohistochemistry confirmed the tendonopathy and an increased presence of small blood vessels. In this horse, deep digital flexor tendon lesions appeared similarly on contrast-enhanced CT and MR imaging. Contrast-enhanced CT may be an alternative to MR imaging for assessing tendon and ligament injury in the digit of the horse.     

半干旱草地上的生态地理响应: 综述

The ecogeomorphic processes occurring on semiarid rangelands are reviewed, with emphasis on the source-sink relations and positive feedback loops that existed between shrub patches and intershrub areas, and the way livestock presence affected these interactions. Compared with intershrub areas, the shrub patches had a higher soil porosity, infiltration capacity, water-holding capacity, hydraulic conductivity, structural stability, and organic matter content, and lower bulk density. These differences derived from a host of processes whose intensity was less in the shrub patches, including raindrop impact, mechanical crust formation, overland water flow, soil erosion, evaporative moisture loss, and flock trampling. There was also greater shading of the soil surface; soil and litter deposition; water accumulation; microbial, fungal, and mesofaunal activities in the shrub patches. The overland flow of water carried soil and litter from the intershrub areas to the shrub patches and resulted in microtopographic modifications that tended to strengthen these source-sink relations. Grazing had an impact on these processes, not only at the shrub-intershrub scale but also within the intershrub areas, through the creation of highly compacted trampling routes. The combined role of the above ecogeomorphic processes was to maintain the rangeland’s functionality. Without these inter-relationships, water loss, soil erosion, and nutrient depletion would occur at the hillside scale, causing degradation of the landscape.     

Surgical management of acquired megacolon in the cat

The surgical management of acquired megacolon is described in three cats. The aetiology could not be definitely established in two cats but in the third case megacolon occurred as a result of pelvic narrowing secondary to multiple pelvic fractures. Medical therapy was ineffective and long term resolution was achieved by partial colectomy.     

Adsorption and degradation of chlorsulfuron and metsulfuron-methyl in soils from different depths

Adsorption and degradation rates of chlorsulfuron and metsulfuron-methyl were measured in soil taken from depths of 0–20, 20–40 and 40–60 cm at eight sites. Adsorption of both herbicides was negatively correlated with soil pH, and positively correlated with soil organic matter content. When two soils with very high organic matter were excluded from the calculations, the correlations with organic matter content were no longer statistically significant but those with soil pH were affected only slightly. Degradation rates of both herbicides generally decreased with increasing depth in the soil and were positively correlated with microbial biomass and negatively correlated with soil pH. The possible significance of the results to persistence of the herbicides in the field is discussed.     

Simulation of physically mediated variability in prey resources of a larval fish: a three-dimensional NPZ model

A three-dimensional biophysical nutrient–phytoplankton–zooplankton model was used to investigate the spatial and temporal dynamics of food resources for young walleye pollock in the western Gulf of Alaska, to further understanding of recruitment processes for pollock. We modeled nitrogen, phytoplankton, a large herbivorous grazer parameterized as Neocalanus spp. (the biomass dominant copepod in the Gulf), and the 13 stages (egg, naupliar and copepodite) of Pseudocalanus spp. (a major constituent of the diet of pollock) so that the appropriate size class of food for each size of larval pollock was represented. Model results identified an area between the Semidi and Shumagin Islands that may not be suitable as a nursery area early in the year due to low prey abundance. Modeled mesoscale eddies, previously hypothesized to be important for larval pollock retention in Shelikof Strait, contained higher prey concentrations than the surrounding waters when they were cyclonic. This work also help to understand the consistency of pollock spawning in time and space in Shelikof Strait, by examining the timing and location of prey availability which, along with transport, narrows the window for optimal spawning.     

USE OF FORCE PLATE ANALYSIS TO EVALUATE THE EFFICACY OF EXTERNAL BEAM RADIATION TO ALLEVIATE OSTEOSARCOMA PAIN

A standard of therapy for osteosarcoma includes amputation with or without adjuvant chemotherapy. There is a subset of dogs with osteosarcoma that are unsuitable for amputation. We evaluated kinetic variables in dogs with appendicular osteosarcoma treated with a single 8 Gy dose of radiation. Eighteen pet dogs with appendicular osteosarcoma received one 8 Gy fraction of palliative radiation on day 0. Force plate measurements and clinical assessments were made on days 0, 7, 14, and 21. Peak vertical forces ( F _z) were recorded for each limb and a symmetric index (SI) was calculated. There were no significant changes in kinetic parameters after one 8 Gy dose of radiation therapy. Nine of these 18 dogs exhibited increased limb function at day 21 based on force plate analysis. Significant factors affecting F _z included gender and tumor location. There was a significant correlation between F _z and response to therapy based on SI at day 21. SI seems to be useful to objectively assess response in this mixed population of dogs. One 8 Gy fraction of radiation therapy alone did not reduce lameness associated with appendicular osteosarcoma, but a subset of dogs did have improved limb function after a single dose.