The distal sesamoidean impar ligament: Comparison between its appearance on magnetic resonance imaging and histology of the axial third of the ligament

Reasons for performing study: There is limited knowledge about the interpretation of alterations in the distal sesamoidean impar ligament (DSIL) detected using magnetic resonance imaging (MRI) and their correlation with histopathology. Hypotheses: There would be: 1) a correlation between histopathology and MRI findings; and 2) a relationship between MR abnormalities at the origin and the insertion of the DSIL, between insertion and body; and origin and body. Methods: Fifty limbs from 28 horses were examined using high‐field MRI and histopathology. MR abnormalities of the DSIL, its origin on the navicular bone and its insertion on the distal phalanx were graded. Sections of the axial third of the DSIL were examined histologically and graded according to fibre orientation, integrity of fibroblasts, collagen architecture and vascularity. Associations between MRI and histology findings were tested by Spearman rank correlation and Chi‐squared tests. Results: There were significant correlations between the presence of a cystic structure in the distal third of the navicular bone, or a distal border fragment, or increased signal intensity in fat suppressed images at the insertion of the DSIL on the distal phalanx and the histological grade of the body of the DSIL. There were significant associations between a cystic structure in the distal third of the navicular bone and the presence of either a distal border fragment or entheseous new bone at the insertion of the DSIL, swelling of the DSIL and increased signal intensity in the DSIL in fat suppressed images; between distal elongation of the flexor border of the navicular bone and the presence of one or more distal border fragments and between swelling of the body of the DSIL and irregularity of its palmar border or increased signal intensity in fat suppressed images in the DSIL. Conclusions and clinical relevance: The presence of a cystic structure in the distal third of the navicular bone detected using MRI, a distal border fragment or increased signal intensity at the insertion of the DSIL are suggestive of significant alterations in the infrastructure of the DSIL.     

SCINTIGRAPHIC EVALUATION OF THE PROXIMAL METACARPAL AND METATARSAL REGIONS OF HORSES WITH PROXIMAL SUSPENSORY DESMITIS

The aim of the study was to characterize radiopharmaceutical uptake patterns in horses with clinical and ultrasonographic evidence of proximal suspensory desmitis. It was hypothesized that radiopharmaceutical uptake in the proximal palmar (plantar) aspect of the third metacarpal (metatarsal) bone would be greater in lame limbs of horses with proximal suspensory desmitis than in sound limbs and that there would be a positive correlation between the severity of ultrasonographic abnormalities and the degree of radiopharmaceutical uptake. Nuclear scintigraphic evaluation of the proximal metacarpal or metatarsal regions of 126 horses with ultrasonographic evidence of proximal suspensory desmitis was performed. In all horses lameness was substantially improved by perineural analgesia of the palmar metacarpal (subcarpal) or plantar metatarsal (subtarsal) nerves. Scintigraphic images were assessed subjectively, by profile analysis and using region of interest analysis. Associations between the degree of ultrasonographic abnormality and radiopharmaceutical uptake ratios and the presence of radiographic abnormalities and radiopharmaceutical uptake ratios were analyzed. Subjectively, the majority of horses had normal radiopharmaceutical uptake. Profile analysis provided little additional information. However with region of interest analysis there was greater radiopharmaceutical uptake ratios in plantar images in the proximal metatarsal regions of lame limbs compared with nonlame limbs. There was no association between radiological abnormalities and radiopharmaceutical uptake ratios. In forelimbs there was no association between ultrasonographic lesion grade and radiopharmaceutical uptake ratios, however in hindlimbs there was a significant relationship between ultrasonographic grade and radiopharmaceutical uptake ratios.     

Revised post-mortem inspection procedures for cattle and pigs slaughtered Australian abattoirs

Revised procedures for the post-mortem inspection of cattle and pigs at Australian abattoirs were developed as minimum national requirements. Comparative trials of current and revised procedures were conducted at 3 and 4 Australian abattoirs for pigs and cattle respectively. Residual pathological changes after inspection and removal of lesions from heads, carcases or viscera were recorded by an evaluation team with the data used to determine relative effectiveness. For cattle, there was no significant difference between current and revised procedures. Although it had been proposed to eliminate routine incision of cervical lymph nodes for pigs, it was found necessary to retain this procedure. The data also revealed a significant variation in detection of pathology between abattoirs for both species. Parasitic conditions accounted for the greatest proportion of undetected lesions in both species for both current and revised procedures. These comprised mainly fascioliasis in cattle and ascariasis in pigs. The former was associated with the study being conducted in eastern Australia. Chronic interstitial nephritis was also a common undetected lesion, reinforcing the need for intensified inspection of kidneys. However, such residual pathology was considered to be of only limited significance to human health. The revised procedures and findings are discussed in the context of animal and human health and of the importance of the meat industry to Australian exports. Some attention has been given to specific conditions likely to be affected by the proposals including tuberculosis, bovine cysticercosis, fascioliasis, porcine arthritis and salmonellosis. The role of meat inspection in monitoring for specific diseases is discussed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Protection of Animals (Anaesthetics) Act, 1954—I. Legal Aspects

Abstract— The paper deals briefly with the historical development of the Act, the operative part of the Act itself, which clearly gives the maximum possible protection to those animals to which it applies, and particularly with the power of the appropriate Ministers to amend the Schedule to the Act, the content of which is to some extent a matter of compromise having regard to the practical necessity of striking a proper balance between the various interests concerned.
Résumé— L'article traite briévement du développement historique du Décret, de la clause essentielle du Décret qui offre le maximum possible de protection aux animaux qu'il concerne, et surtout des droits des différents Ministéres de modifier L'annexe du Décret, dont le contenu constitue en quelque sorte un compromis en faveur de la nécessité pratique d'établir un équilibre equitable entre les différents intérets concernés.
Zusammenfassung— Die Arbeit befasst sich kurz mit der geschichtlichen Entwicklung des Gesetzes, dem gültigen Teil des Gesetzes selbst, der deutlich denjenigen Tieren, auf die es sich bezieht, den grösstmöglichen Schutz bietet, und besonders mit der Machtbefugnis der betreffenden Minister, die Ausführungsbestimmungen zu dem Gesetz zu ändern, dessen Inhalt in gewissem Masse eine Sadie des Kompromisses ist in anbetracht der praktischen Notwendigkeit, zwischen den verschie-denen Interessen die richtige Mitte zu finden.     

SCINTIGRAPHIC ASSESSMENT OF THE METACARPOPHALANGEAL AND METATARSOPHALANGEAL JOINTS OF HORSES WITH JOINT PAIN

Our aims were to evaluate the pattern of radiopharmaceutical uptake in horses with lameness related to the metacarpophalangeal and/or metatarsophalangeal joint and compare the results with similar information from sound horses. It was hypothesized that there would be a difference in radiopharmaceutical uptake between the lame and contralateral limb in unilaterally lame horses and that there would be a difference between lame and sound horses. Nuclear scintigraphic images of 43 horses with forelimb lameness and 30 horses with hindlimb lameness were evaluated. In all horses lameness was improved by intraarticular analgesia of the joint, or by perineural analgesia of the palmar/plantar (at the junction of the proximal 3/4 and the distal 1/4 of the metacarpal/metatarsal regions) and palmar/plantar metacarpal/metatarsal nerves. All images were assessed subjectively and a quantitative image analysis was performed by drawing a vertical line profile through the center of each joint in the lateral images and using region of interest analysis in both lateral and dorsal/plantar images. Ratios of radiopharmaceutical uptake were compared for each region between lame and contralateral limbs in unilaterally lame horses and between lame and control horses. There was a significant difference in the ratio of radiopharmaceutical uptake in the proximal aspect of the proximal phalanx between lame and nonlame forelimbs in unilaterally lame horses and in both lame and contralateral limbs of lame horses compared with control horses for the regions of the distal aspect of the third metacarpal/metatarsal bone and the proximal sesamoid bones. However, the profile analysis was of limited clinical value.     

Vaccines for bluetongue

Isolation of 8 serotypes of bluetongue virus (BTV) in Australia has led to widespread debate on how to prepare for an outbreak of bluetongue disease and the type of vaccine best suited to control bluetongue in Australia. This article describes the vaccine options under consideration by research workers and animal health administrators. The most widely discussed options are live attenuated virus, killed virus and virus-like particles (VLP) generated by recombinant baculoviruses. Attenuated virus vaccines are cheap and easy to produce and are administered in a single dose. They replicate in sheep without causing significant clinical effects and provide protection against challenge with virulent virus of the same serotype. The possibility that insects could acquire vaccine virus by feeding on vaccinated animals and transmit it to sheep or cattle cannot be eliminated. This poses a risk because attenuated viruses are teratogenic if ewes are infected in the first half of pregnancy. In addition, vaccine virus replication in insects and ruminants may lead to a reversion to virulence. Killed virus vaccines have been shown to be efficacious in small laboratory trials and cannot be transmitted to other animals in the field, but are significantly more expensive to produce than attenuated viruses and require at least 2 doses with adjuvant to elicit an immune response. More work is needed to properly assess their effectiveness and determine their cost of production. Recombinant VLP contain the 4 major structural proteins of BTV but no nucleic acid. VLP are relatively easy to isolate, but it is unlikely that the purification methods currently used in laboratories will be adapted for use commercially. Despite the enthusiasm of recent years, little commercial progress appears to have been made. Although scientific research in Australia and overseas has provided a number of options for development of bluetongue vaccines, the decisions on which to use in an outbreak are complex and will require, not only consideration of factors discussed here, but also agreement from industry and government.     

CLINICAL AND DIAGNOSTIC IMAGING FINDINGS IN HORSES WITH SUBCHONDRAL BONE TRAUMA OF THE SAGITTAL GROOVE OF THE PROXIMAL PHALANX

Eight sports horses with unilateral (4) or bilateral (3) forelimb or unilateral hindlimb (1) lameness had subtle radiologic abnormalities of the subchondral bone of the sagittal groove of the proximal phalanx associated with moderate or intense increased radiopharmaceutical uptake. High‐field or low‐field magnetic resonance (MR) imaging confirmed the presence of a fissure fracture or subchondral and trabecular bone trauma. Seven of eight lesions were located approximately midway between the dorsal and palmar cortices of the proximal phalanx; the eighth was sited more dorsally. Two horses underwent follow‐up MR imaging and abnormal signal intensity persisted, with little change.