The Intercarpal Ligaments of the Equine Midcarpal Joint, Part 1: The Anatomy of the Palmar and Dorsomedial Intercarpal Ligaments of the Midcarpal Joint

Objective— To describe in detail the structure of the medial palmar intercarpal ligament (MPICL), the lateral palmar intercarpal ligament (LPICL), and a dorsomedial intercarpal ligament (DMICL) of the equine midcarpal joint.
Study Design— Dissections of equine midcarpal joints.
Animals and Sample Population— Ten carpal joints from eight thoroughbred horses.
Methods— Detailed dissections of the midcarpal joint were performed, with particular attention paid to the MPICL, the LPICL, and the DMICL. The attachments and dimensions of these structures were recorded, as well as their behavior during joint movement.
Results— The DMICL arose from the dorsomedial surface of the radial carpal bone (CR) and coursed palmarodistally to insert on the dorsomedial aspect of the second carpal bone (C2). The LPICL attached proximally predominantly on the distal part of the palmaromedial surface of the ulnar carpal bone (CU). From here the ligament coursed distomedially and slightly palmarly to the proximal palmarolateral surface of the third carpal bone (C3). The structure of the MPICL was complex. It attached proximally to the distolateral surface of the CR and distally to the proximal palmaromedial surface of C3, and the proximal palmarolateral aspect of the C2. It could be divided into four fiber bundles in all carpi. The predominant direction of fibers was dorsoproximal to palmarodistal, whereas the palmaromedial bundle coursed palmaroproximal to dorsodistal.
Conclusions— The orientation of their fibers indicate that the MPICL and DMICL primarily resist dorsomedial displacement of CR, whereas the LPICL resists dorsolateral displacement of the CU and intermediate carpal bone.
Clinical Relevance An understanding of the structure of the intercarpal ligaments of the midcarpal joint is important in interpreting their function and the reasons for damage to their structure.     

Management of Subchondral Lucencies of the Medial Aspect of the Equine Antebrachiocarpal Joint

The objective of this study is to describe the management and outcomes of eight horses with subchondral lucencies (SCLs) of the medial aspect of the antebrachiocarpal (ABC) joint. The medical records and radiographs of the carpi of 8 horses with SCLs of the medial aspect of the ABC joint were reviewed. Follow-up clinical information was obtained for 6–60 months (the median duration of 14 months). Treatment was successful if radiographic healing was apparent or lameness was reduced or eliminated. Four horses had SCLs in the distomedial radius (DMR) and four in the proximal aspect of the radiocarpal bone (RCB). Lameness was present in all horses with DMR SCLs and in one horse with an RCB SCL. Treatments included restriction of exercise (n = 3), intra-articular administration of corticosteroids (n = 2), or placement of a screw across the SCL (n = 3). Exercise restriction alone was successful in three nonlame horses younger than one year with proximal RCB SCL and intra-articular corticosteroid administration in the ABC joint in two horses aged 2 years or younger with DMR SCLs. A yearling with a large proximal RCB SCL and two horses aged 5 years or older with DMR SCLs were successfully treated with screw placement across the SCL. Exercise restrictions and intra-articular administration of corticosteroids were successful in management of DMR SCLs in five horses. Placing a screw across the SCL of three horses resulted in resolution of lameness and substantial improvement of the radiographic appearance of the lesion in the RCB or DMR.     

The Intercarpal Ligaments of the Equine Midcarpal Joint, Part 2: The Role of the Palmar Intercarpal Ligaments in the Restraint of Dorsal Displacement of the Proximal Row of Carpal Bones

Objective— To determine the relative contributions of the palmar intercarpal ligaments in the midcarpal joint to the restraint of dorsal displacement of the proximal row of carpal bones.
Study Design— A biomechanical study of cadaver equine carpi.
Animals or Sample Population— Eight equine forelimbs from six thoroughbred horses.
Methods— With joints in full extension, the radius was dorsally displaced while midcarpal joint displacement was measured. The restraining force at a joint displacement of 1.5 mm was determined from the load-displacement curve. A ligament or pair of ligaments was then cut and the testing procedure repeated. Their contribution to restraining force was calculated as the percentage change in restraining force after the ligament was sectioned. Relative cross-sectional areas of the ligaments tested were measured at the level of the midcarpal joint.
Results— The collateral ligaments were the major contributors to the restraint of dorsal displacement ( P <.001). In all joints, the palmar intercarpal ligaments contributed a greater proportion than the palmar carpal ligament (PCL) ( P <.05). The mean percentage (±SEM) contributions to the restraint of dorsal displacement were 62.8 ± 3.4 for the collateral ligaments, 14.5 ±1.4 for the PCL, and 22.7 ± 2.2 for the palmar intercarpal ligaments. Mean cross-sectional area expressed as a percentage (±SEM) of the total ligamentous area were 9.0 ± 0.3 for the palmar intercarpal ligaments, 27.1 ± 3.0 for the PCL, and 63.8 ± 2.8 for the collateral ligaments.
Conclusions— Despite the small size of the palmar intercarpal ligaments, they play an important role in the restraint of dorsal displacement of the proximal row of carpal bones.
Clinical Relevance— Interpretation, as well as prevention and treatment of intercarpal ligament tearing requires an understanding of their function.     

Collateral Ligaments of the Tarsocrural Joint An Anatomic and Functional Study

Forty canine hock joints were used to study the anatomy and function of the medial and lateral tarsocrural collateral ligament complexes. Dissection of the ligaments was used to describe the anatomic arrangement, and location and tenseness in various positions. The component parts of the ligament complexes were evaluated for their contribution to stability of the tarsocrural joint. The medial and lateral tarsocrural collateral ligament complexes were composed of several components. The medial tibiotalar and lateral calcaneofibular short component parts were important static joint stabilizers in both flexion and extension. The long medial and lateral ligaments and the medial tibiocentral short component were less important in maintaining joint stability in flexion but were important in extension. The stability of the joint as a whole did not depend on any individual ligament component, but rather all components of the ligament complex, including the joint capsule and malleoli, acted together to stabilize the joint.     

Repair and Function of Synovium After Arthroscopic Synovectomy of the Dorsal Compartment of the Equine Antebrachiocarpal Joint

The reparative ability of equine synovium was determined by gross, histological, and ultrastructural examination. The functional potential of the synovium was estimated by examination of synovial cell organelles with transmission electron microscopy. Results from rested and exercised horses were compared to determine the effect of exercise on synovial healing. The response of the synovectomized joint to exercise was evaluated with a standardized lameness examination and by gross, histological, and histochemical observations of the articular cartilage. A 7-mm diameter motorized synovial resector was used to perform a subtotal synovectomy in 1 antebrachiocarpal joint of each of 8 horses; the contralateral joint served as a control. After 2 months rest, four randomly selected horses were rigorously exercised for the remainder of the study; the other four horses continued paddock rest. Lameness examinations and synovial fluid analyses were conducted at 0, 2, 30, 60, and 120 days. Synovium and articular cartilage from all horses were examined at necropsy at 120 days. None of the horses were lame during the study, and a transient synovitis occurred in the synovectomized joints. The hyaluronan concentration of treated joints decreased at 2 days but returned to normal by 60 days. Synovial fluid composition, including hyaluronan concentration, was unchanged by exercise. Significant cartilage damage was not observed in any of the joints. At 120 days, the healing synovium was devoid of villi and its subintima was fibrotic, however transmission electron microscopy confirmed that an intimal layer was present within the repair tissue. The cells within the repair tissue appeared actively engaged in both synthesis and phagocytosis. Exercise did not modify any of these findings. The results of this study suggest that 120 days after subtotal synovectomy, the joint environment was maintained and the resected synovium had evidence of restoration and increased metabolic potential. Synovectomized joints withstood exercise but synovial repair was not accelerated by exercise.     

Morphometric and Structural Examination of the Collateral Ligaments of the Canine Elbow Joint

The aim of this study was to describe morphological differences between the lateral collateral ligament (LCL) and the medial collateral ligament (MCL) of the canine elbow joint. Forty forelimbs of 22 dogs (adult German shepherd dogs and shepherd mongrels) were dissected. The length and width of defined segments of the ligaments (i. e. total length, areas of origin and insertion, 'free part', 'humeral part', 'antebrachial part') were measured in extension (160°) and flexion (30°). Statistical analyses of the data were performed using the data analysis software SAS 8.0. In addition the collateral ligaments of ten forelimbs of five shepherd mongrels were studied histologically. The LCL differs from the MCL in the following morphological items: a) the areas of origin and insertion are larger and in consequence the 'free part' of the lateral ligament is shorter; b) the caudal crus of the LCL is fan-shaped with a broad insertion area at the ulna whereas the caudal crus of the MCL remains slim; c) in the LCL the 'humeral part' varies in length depending on extended or flexed position of the joint, which is due to the spiral shape of the capitulum humeri; d) the microscopical structure of the LCL is organized less tightly; the collagen fibre bundles cross in varying angles. Referring to these details the LCL seems to allow and to limit a slight rotation of the forearm when the elbow joint is extremely flexed.     

The Intercarpal Ligaments of the Equine Midcarpal Joint, Part 3: Clinical Observations in 32 Racing Horses With Midcarpal Joint Disease

Objective— To characterize the clinical features of intercarpal ligament pathology and to determine the relationship among palmar intercarpal ligament tearing, dorsomedial intercarpal ligament (DMICL) hypertrophy, and other intraarticular lesions.
Study Design— Prospective clinical observations.
Animals or Sample Population— Twenty-eight thoroughbred and four standardbred race horses.
Methods— Clinical, radiographic, and arthroscopic examination of 53 midcarpal joints of 32 horses.
Results— Palmar intercarpal ligament tearing was observed in 30 joints of 22 horses. Some tearing of the medial palmar intercarpal ligament (MPICL) was present in 27 joints of 20 horses, and tearing of the lateral palmar intercarpal ligament in 9 joints of 7 horses. There was no correlation between the severity of clinical signs recorded and the degree of MPICL tearing. Joints with grade 2–4 MPICL tearing had significantly less cartilage and bone damage than joints with grade 1 or no ligament damage ( P <.05). There was a significant inverse relationship between the number and size of intra-articular fractures, as assessed radiographically, and ligament damage ( R = -.31). The DMICL was identified in all joints, and in 18 joints the ligament was enlarged. There was a significant correlation between MPICL damage and hypertrophy of the DMICL ( R =.35). There was no correlation between DMICL hypertrophy and articular cartilage damage or subchondral bone damage.
Conclusions— Severe subchondral bone and MPICL damage rarely occur in the same joint and DMICL hypertrophy may be associated with, rather than a cause of, joint disease.
Clinical Relevance— There are no clinical or radiographic findings that will differentiate intercarpal ligament injury from other carpal injuries. Diagnosis is only possible by arthroscopic examination of the midcarpal joint.     

Replacement of the Collateral Ligaments of the Canine Tarsocrural Joint: A Proposed Technique

A technique for replacement of the medial and lateral collateral ligaments of the tarsocrural joint in dogs was developed based on studies of normal anatomy and function. The medial or lateral tarsocrural joint was made unstable by removal of the respective malleolus, ligaments, and joint capsule; the component parts of the collateral ligaments were replaced using suture material to function as ligament prostheses. The technique was found to be effective in maintaining near normal joint motion and adequate joint stability in cadavers immediately following surgery, and in dogs observed for up to 39 months postoperatively. No degenerative joint disease was noted upon gross or radiographic examination.     

Ultrasonography of the Collateral Ligaments of the Distal Interphalangeal Joint in Horses: Technique and Reference Images

This study describes ultrasound (US) technique and reference images of the equine distal interphalangeal joint collateral ligaments (CLs), and evaluates the portion of the CLs assessable by US in a series of normal forelimbs. Transverse and longitudinal US images were obtained on five healthy horses and on 25 equine cadaver forelimbs. On six limbs, a needle was placed under US-guidance at the distal limit of visualization of each CL, and the portion of CL visible at US was evaluated on computed tomographic (CT) images. The normal CLs appear as oval structures located abaxial to the fossae of the middle phalanx in the transverse sections, obtained at the level of the coronary band. A centrodorsal hypoechoic image appears with increasing proximodistal probe inclination, demonstrating different fiber orientations within the ligament. Two main fascicles, a deep and a superficial, distally divergent, are visible on longitudinal images obtained in the central part of the ligament. The proportion of CL visible at US examination was more than 50% of the total ligament length in nine of the 12 CLs assessed by CT. Awareness of the estimated portion of distal interphalangeal joint CLs visible at US and detailed knowledge of the US technique and CLs morphology are essential to efficiently use US examination on clinical cases.     

Histopathological Findings in the Medial Palmar and Dorsomedial Intercarpal Ligaments of the Equine Midcarpal Joint; Book Review

Medial palmar intercarpal ligaments (MPICL) and dorsomedial intercarpal ligaments (DMICL) from the midcarpal joints of 11 adult horses in training were examined histopathologically. These were compared with ligaments from seven horses less than 12 months of age, and 10 grossly enlarged DMICLs of adult horses. Tearing of the MPICL was observed in 15 of 22 joints from adult horses. Collagen fibre bundles of the MPICLs generally were disorganized and poorly aligned, and there were large areas of loose connective tissue. In young horses there was more parallel alignment of collagen bundles and less loose connective tissue. Collagen bundles of adult DMICLs were well organized and showed parallel alignment, whereas in foals the structure appeared more like that of fibrous joint capsule. Grossly enlarged DMICLs in adults consistently had discrete areas of fibrovascular infiltration. Degeneration of the MPICL was associated with increasing age and could explain the high incidence of tearing of the ligament. Enlargement of the DMICL was associated with low-grade tearing and repair.     

The Apical Ligaments of the Penis of the Goat and Sheep

The penile apical ligaments of 13 goats and 8 sheep were dissected and described. Unlike the single apical ligament of the bull penis, both goats and sheep had one ligament on each side of the apex of the penis with no apparent connection over the dorsal surface. These lateral apical ligaments consisted of substantial connective tissue fibers that arose from the outer layers of the tunica albuginea and varied from 6.0 to 10.0 cm in length. The left apical ligament was longer and thicker than the right. The left apical ligament of the sheep penis was divided into a dorsal and a ventral branch. Both the goat and sheep possessed flattened perivenous ligaments that originated from the apical fascia and extended caudally along each side of the dorsal vein of the penis.     

Innervation of the Canine Cruciate Ligaments

A search for mechanoreceptors within the substance of the cruciate ligaments was undertaken using the modified gold-chloride technique. Abundant Pacinian, Vater-Pacini, Ruffini end organs and Ruffini-type receptors were found within the substance of the anterior and posterior cruciates. The receptors were innervated by axons of 5 to 10 micrometers in diameter penetrating from the synovium investing the ligaments. The findings support the contention that the cruciate ligaments have important mechanoreceptive and proprioceptive functions.     

从基层视角看动物防疫工作中的政府职能

政府在动物防疫工作中承担着管理和服务两种职能。政府要动员社会资源,控制、预防和扑灭动物疫病,必须依法办事,行使管理职能;同时通过防治动物疫病,增加农民收入,就要行使服务职能。有效地协调两者的关系,对贯彻落实《中华人民共和国动物防疫法》,发展畜牧业生产以及保障公共卫生都是十分重要的。     

Structure and Innervation of the Equine Supraspinous and Interspinous Ligaments

Pain related to the osseous thoracolumbar spine is common in the equine athlete, with minimal information available regarding soft tissue pathology. The aims of this study were to describe the anatomy of the equine SSL and ISL (supraspinous and interspinous ligaments) in detail and to assess the innervation of the ligaments and their myofascial attachments including the thoracolumbar fascia. Ten equine thoracolumbar spines (T15‐L1) were dissected to define structure and anatomy of the SSL, ISL and adjacent myofascial attachments. Morphological evaluation included histology, electron microscopy and immunohistochemistry (S100 and Substance P) of the SSL, ISL, adjacent fascial attachments, connective tissue and musculature. The anatomical study demonstrated that the SSL and ISL tissues merge with the adjacent myofascia. The ISL has a crossing fibre arrangement consisting of four ligamentous layers with adipose tissue axially. A high proportion of single nerve fibres were detected in the SSL (mean = 2.08 fibres/mm²) and ISL (mean = 0.75 fibres/mm²), with the larger nerves located between the ligamentous and muscular tissue. The oblique crossing arrangement of the fibres of the ISL likely functions to resist distractive and rotational forces, therefore stabilizing the equine thoracolumbar spine. The dense sensory innervation within the SSL and ISL could explain the severe pain experienced by some horses with impinging dorsal spinous processes. Documentation of the nervous supply of the soft tissues associated with the dorsal spinous processes is a key step towards improving our understanding of equine back pain.     

云南省彝良县生猪生产发展中疫病防控作用

近年,规模化生猪养殖产业发展迅猛,疾病发生越来越复杂,对生猪养殖业造成严重危害。在生猪养殖中,部分老的疫病如猪瘟、猪气喘病不断加重,新疫病如蓝耳病、圆环病毒病感染,再加上2018年以来,非洲猪瘟疫情肆意蔓延,对生猪养殖产业造成严重威胁。该文探讨疫病防控在生猪生产发展中的作用,分析彝良县生猪养殖现状的基础上,探讨疫病防控措施。     

Hyperextension of fetlock joints in German Holstein and German Holstein-Limousin crossbred calves

In two different dairy farms six calves exhibiting bilateral flexion of the fetlock joints in front or rear legs were born in 2000 to 2002. Four of the affected calves from the same farm were crossbred between German Holstein cows with red and white coat colour and a bull of the breed Limousin. The other two affected calves born on another farm were purebred German Holsteins with a black and white coat colour. The tests for BVD virus antigen and antibodies were negative in all affected calves. Three of the calves showed a lower selen and a higher glutamate dehydrogenase concentration in the analyses of blood metabolites. Two crossbred calves showed a degeneration of the liver with a progressive periportal fibrosis in a histological examination. In one calf an edema of astrocytes of the central nervous system was seen. The analysis of the pedigrees revealed for the four crossbred calves the Limousin bull as common ancestor and the mothers of the calves as relatives. For the affected purebred German Holstein calves also a sire was identified as a common ancestor. The pedigrees support inheritance through a monogenic autosomal recessive locus or more recessive gene loci with variable expressivity. However, the analysis could not clarify whether different gene loci are responsible for the congenital anomalies observed in the calves from the two farms and thus, the observed anomalies may be different genetic entities. Obvious environmental reasons were not found.