Search PubMed⌕ Search

Biomedical subjects

A Barneveld

Publications and source records attributed to A Barneveld.

At least 55 records · Page 3Linked to original sources
PubMed1999

Differences in second-intention wound healing between horses and ponies: macroscopic aspects.

Second-intention healing of deep wounds was studied in 5 horses and 5 ponies. Standardised wounds were created on the distal limbs and hind quarters. Wounds on the metatarsi extended onto the metatarsal bone; the depth of the wounds in the femoral biceps muscle was 18 mm. The wound margins were marked by tattoos. Photographs were taken at weekly intervals to determine the wound area. The relative contribution of contraction and epithelialisation to wound closure was quantified by means of the tattoos. Swelling of the limbs was measured; and regularity and aspect of the granulation tissue were semi-quantitatively scored. Second-intention wound healing occurred significantly faster in ponies than in horses, and muscle wounds healed significantly faster than metatarsal wounds. These marked differences reflected the greater contribution of contraction to wound healing. Moreover, demarcation was seen earlier and a healthy granulation bed developed more rapidly in ponies, whereas in horses the granulation tissue remained irregular and purulent for longer. Healing of the metatarsal wounds of horses differed markedly from that of all other wounds: these wounds increased to almost twice their original size in the first 2 weeks, exuberant granulation tissue was persistent, epithelialisation started later, and contraction played a minor role in wound closure. Limb swelling was greater in horses than in ponies. Periosteal new bone formation was more extensive, and was active over a longer period in the metatarsal bones of horses than of ponies. From this study it is concluded that second-intention healing of deep wounds occurs faster in ponies than in horses. This difference can be largely attributed to a more pronounced and faster wound contraction in ponies than in horses. Therefore, attempts to improve second-intention wound healing in clinical practice should be directed at stimulation of wound contraction.

Animals↗
PubMed1999

Differences in second-intention wound healing between horses and ponies: histological aspects.

The histological aspects of second-intention healing were studied in 5 horses and 5 ponies. Biopsies were taken weekly from standardised wounds on the metatarsus and femoral biceps muscle of one horse and one pony. Sections were stained to enable cell counting and the detection of DNA synthesis, fibrin, smooth muscle actin (SMA), collagen, and bacteria. In the ponies, the number of polymorphonuclear leucocytes (PMNs) was high during the first 3 weeks and subsequently decreased rapidly. In the horses, the initial number of PMNs was lower, but remained persistently elevated during the evaluation period. PMNs were found mainly in the superficial zones. Significantly more fibrin was present in the wounds of the horses. No significant differences were observed in the number of fibroblasts, the amounts of SMA and collagen. However, myofibroblasts were significantly less regularly organised in the wounds of the horses, particularly in the metatarsal wounds. The mitotic activity of the epithelium was temporally reduced in week 3. The mitotic activity of the granulation tissue was initially high but declined rapidly from week 1 onwards, with the exception of the metatarsal wounds of the horses, in which mitotic activity remained significantly higher. Histology confirmed and explained the macroscopical differences in wound healing between horses and ponies by the strict organisation of the myofibroblasts and the more effective acute inflammation in the ponies. Stimulation of the organisation of myofibroblasts and improvement of the efficacy of the inflammatory response in horses may therefore result in better second-intention wound healing in horses in clinical practice.

Actins↗
PubMed1999

A comparison between the trot of pony and horse foals to characterize equine locomotion at young age.

The trot at 3 m/s of 24 Shetland foals ('ponies') and 24 Dutch Warmblood foals ('horses') was recorded at age 4 months on a treadmill using a modified CODA-3 apparatus to characterise equine locomotion at young age. Locomotor variables of the ponies were qualitatively and, after scaling, quantitatively compared with those of horses. Ponies made shorter strides than horses, evidenced by a shorter stance and swing duration, although their relative stance durations were similar. Neither linear nor dynamic scaling procedures could completely compensate for differences in height at the withers comparing ponies and horses. The patterns of the joint angle-time curves were similar. Ponies had a larger range of pro- and retraction, with a more protracted forelimb and a more retracted hindlimb, therefore demonstrating a more extended trot. The horses trotted with more extended elbow, stifle and tarsal joints and a more flexed hip joint, which is in accordance with the conformation for the Warmblood. The ponies moved with a stiffer trot in contrast to the more supple trot of the horses, which showed a larger maximal fetlock extension during the stance phase. In conclusion, ponies and horses move qualitatively similarly at age 4 months, but characteristic breed differences in conformation and gait quality can already be detected. Scaling methods to compensate for differences in height at the withers cannot be applied when animals move at the same velocity.

Aging↗
PubMed1999

The effect of exercise on the distribution and manifestation of osteochondrotic lesions in the Warmblood foal.

Osteochondrosis (OC) in the horse has been defined as a disturbance in the process of endochondral ossification which is of multifactorial origin, becoming evident in a large number of joints. Exercise is one of the environmental factors that may influence the clinical manifestation of the disorder, but has never been thoroughly investigated. In this study we investigated the influence of exercise during the first 5 months on the development and distribution of OC lesions in foals of age 5 and 11 months. Forty-three foals, all from sires having OC in either the femoropatellar or tibiotarsal joint, were reared to weaning at 5 months under similar conditions except for the type and amount of exercise. Fifteen foals remained at pasture, 14 were kept in box stalls and 14 foals were kept in the same box stalls but daily given an increasing number of gallop sprints. After weaning, 8 foals from each group were subjected to euthanasia. The remaining 19 animals were given identical light exercise regimen for an additional 6 months to euthanasia at 11 months. After euthanasia all major diarthrodial joints were inspected for macroscopic lesions. Histological sections were made from the lesions and from all distal tibial sagittal ridges. Lesions were scored according to severity on a scale of 0 to 4, and a total OC score per joint was calculated. In the 5 month group, lesions were found in all foals (mean number of lesions 5.5, range 1-14). Frequency was highest in the tibiotarsal (1.9 lesions/foal), the femoropatellar/femorotibial (1.0), the cervical intervertebral (1.0), and the metatarsophalangeal joints (0.6). At 11 months the prevalence of lesions had significantly decreased (mean number of lesions 3.1, range 0-7). This decrease was most evident in the femoropatellar/femorotibial joint, but was negligible in the tibiotarsal joint. Exercise did not significantly influence numbers of lesions, but at 5 months there was a tendency towards more severe lesions in the box-rested foals. In the femoropatellar/femorotibial joint, lesions were found mainly in the femoral condyles of the box-rested foals and at the lateral trochlear ridge of the femur in the trained foals. It is concluded that OC may become manifest in many joints. Many lesions regress and do not become clinically evident, making the number of horses with lesions at mature age into an underestimation of the total amount of animals that have suffered from the condition. The period during which a lesion develops and possibly regresses is limited and variable per site. Exercise at the level given in this study may have some influence on the appearance and the distribution of the lesions, but did not appear to have an aetiological role.

Animals↗
PubMed1999

The influence of birth weight, rate of weight gain and final achieved height and sex on the development of osteochondrotic lesions in a population of genetically predisposed Warmblood foals.

The influence of inherent variables (sex, birth weight, final achieved height, monthly weight gain rates and osteochondrosis (OC) status of the parents) on the occurrence of osteochondrotic lesions in the femoropatellar and tarsocrural joints in a group of foals was investigated as part of a research project aimed at the study of the development of osteochondrosis and the influence of exercise on the development of the musculoskeletal system in Warmbloods. The foals were genetically predisposed to develop OC, being offspring of sires that all had radiographically proven OC in either the femoropatellar or the tarsocrural joint. In the mare population the incidence of femoropatellar OC was 16% and of OC in the tarsocrural joint 7%. Foals (n = 43) were weighed at birth, and thence every second week until euthanasia at 5 (n = 24) or 11 (n = 19) months. Height at the withers was taken twice, at birth and at euthanasia. Weight gain rates were calculated for months 1, 2, 3, 4, 5, 7, 9 and 11 and for the entire 5 or 11 month period. Osteochondrosis status of the parents in the 2 joints with respect to the distal tibial sagittal and lateral femoral trochlear ridges was determined radiographically. In all foals, radiographs were taken from the same sites prior to euthanasia. After euthanasia the joints were examined macroscopically and histologically for the presence of osteochondrotic lesions and classified as OC positive (OC+) or negative (OC-). No influence of sex on the prevalence of OC in either of the joints could be established. Also, no relationship between the prevalence of tarsocrural OC and any of the growth variables was found. Foals positive for femoropatellar OC had a significantly higher weight gain rate in the third and fifth month. Animals killed at 11 months that were OC+ in the femoropatellar joint had a significantly higher weight gain rate over the 11 month period, weighed more at 11 months, and were taller at the withers and at the croup than non affected animals. Offspring of tarsocrural OC- parents did not have a lower number of lesions in this joint than foals of which at least one of the parents was affected, but no foals that were offspring of femoropatellar OC- parents themselves showed lesions. It was concluded that, in this selected group, sex had no influence on the occurrence of OC lesions. Even in this relatively homogenous group weight gain rate affected the occurrence of lesions in the femoropatellar joint, but not in the tarsocrural joint. This corresponds with the different time-frames in which the lesions develop in the various joints and with the existence of windows of 'susceptibility'.

Animals↗
PubMed1999

Changes in bone morphogenic enzymes and lipid composition of equine osteochondrotic subchondral bone.

Osteochondrosis (OC) is a disturbance in the process of endochondral ossification, a process in which cartilage is mineralised and transformed into bone. In this process different biochemical events occur, of which the cartilage component has been studied so far almost exclusively. In this study we concentrated on the biochemical characterisation of normal and osteochondrotic subchondral bone, by analysis of enzyme activities, DNA content and phospholipids (PL). In subchondral bone, lysyl oxidase and both total and bone alkaline phosphatase activity were significantly increased in all degrees of OC. DNA content was increased only in the most established grade of OC investigated (grade 4). Furthermore, lactate dehydrogenase activity was significantly lower in grades 2 and 3 OC, but was normal in grade 4 OC, indicating that severe cell damage is not probable. Nonbuffer extractable PL content was substantially higher in osteochondrotic subchondral bone. The phosphatidylethanolamine (PE) to phosphatidylcholine (PC) ratio in both normal and OC subchondral bone was very low (typically 0.21 w/w, PE/PC), which indicates that these PLs were not from cellular origin and could be important in the maturation process of mineralised cartilage into bone and hence in the pathogenesis of OC.

Alkaline Phosphatase↗
PubMed1999

Changes in proteoglycan metabolism in osteochondrotic articular cartilage of growing foals.

In osteochondrosis (OC) the process of endochondral ossification is impaired. Proteoglycans form one of the major components of the extracellular matrix of cartilage and are able to bind calcium. For this reason, proteoglycans are thought to play an important role early in the mineralisation process and may, therefore, be important in the pathogenesis of OC. To investigate possible differences in proteoglycan metabolism, normal and osteochondrotic articular-epiphyseal cartilage was harvested from the hock and stifle joints of 43 foals age 5 and 11 months. The samples were cultured as explants in which 35S-[sulphate]-incorporation, release of newly synthesised and endogenous proteoglycans and content of DNA and proteoglycans were measured ex vivo and after a 4 day period of serum stimulation. In osteochondrotic cartilage of foals age both 5 and 11 months synthesis of proteoglycans was less stimulated by serum than in normal cartilage. Furthermore, only in the foals age 11 months, ex vivo proteoglycan production was decreased and an increase in the turnover of newly synthesised proteoglycans was detected in osteochondrotic cartilage, without a change in release of endogenous proteoglycans. The reduced response to serum stimulation in osteochondrotic cartilage indicates that osteochondrotic chondrocytes are less vital. The increase in turnover of newly synthesised proteoglycans reflects a change in composition of the proteoglycan pool. Considering the late changes in proteoglycan synthesis, an aberrant proteoglycan synthesis pattern is more likely to be a sequence than a primary cause of the impaired endochondral ossification of osteochondrotic lesions.

Animals↗
PubMed1999

Hormones, growth factors and other plasma variables in relation to osteochondrosis.

Osteochondrosis (OC) is a multifactorial disorder with endocrinological dysfunction and mineral imbalance having a role in pathogenesis. The present study focused on a possible relationship between insulin-like growth factor I (IGF-I), insulin-like growth factor II (IGF-II), parathyroid hormone (PTH), 1,25-dihydroxy-vitamin D (1,25(OH)2D), cortisol, copper, zinc, calcium, ionised calcium, magnesium and phosphorus and 5 different postmortem and radiographical osteochondrosis scores of hock and stifle joints in foals age 0-11 months. Osteochondrosis-positive foals showed a significantly lower IGF-I activity than osteochondrosis-negative foals. PTH, 1,25(OH)2D, cortisol, copper, zinc and calcium also showed significant differences between osteochondrosis-positive and osteochondrosis-negative foals.

Animals↗
PubMed1999

Influence of different exercise levels and age on the biochemical characteristics of immature equine articular cartilage.

This study aimed to examine whether biochemical characteristics of juvenile articular cartilage are changing during the first year post partum and whether they can be influenced by exercise at young age. Water, glycosaminoglycan (GAG), DNA, total collagen, hydroxylysine and hydroxylysylpyridinoline (HP) content were measured in articular cartilage of 43 foals that were subdivided into 3 groups (n = 15, 14 and 14) which were subjected to different exercise regimens from one week after birth to age 5 months. At the age of 5 months all foals were weaned and 8 foals were selected randomly from each exercise group and subjected to euthanasia. The remaining foals (n = 19) were grouped and subjected to a similar exercise regimen for an additional 6 months. Differences were tested by student's t test (P<0.01). No effect of exercise on the water or DNA content was found. GAG content increased with increasing exercise in the 5 months group. These differences had disappeared after 6 months of similar exercise. No influence of exercise could be demonstrated on any of the collagen parameters. When comparing 5 months with 11 months group, all parameters except hydroxylysine changed significantly during these 6 months. Water, DNA and GAG content decreased during maturation. Collagen and HP content increased. It is hypothesised that juvenile equine articular cartilage may be seen as a dynamic, continuously remodelling tissue that is gradually taking on the biochemical characteristics it will have during the rest of the life of the animal. Moderate exercise does not influence the collagen component of the extracellular matrix. It has a beneficial, but reversible, effect on the glycosaminoglycan component.

Aging↗
PubMed1999

Effect of exercise on the proteoglycan metabolism of articular cartilage in growing foals.

In this study, the effect of different exercise regimens on proteoglycan metabolism of articular cartilage was examined in 43 newborn foals randomly divided into 3 groups: a) box-rest, b) box-rest with training and c) free pasture exercise. They were subjected to these exercise regimens from ages 1 week to 5 months and at 5 months, 24 foals (8 from each group) were sacrificed to assess short-term exercise effects. The remaining 19 foals were subjected to the same regimen of light exercise for an additional 6 months before being sacrificed to evaluate possible long-term effects. Articular cartilage explants were cultured and proteoglycan synthesis, both ex vivo and after 4 days of serum stimulation, release of endogenous and newly synthesised proteoglycans, and DNA- and GAG contents were measured to determine the metabolic state of the cartilage. Cartilage metabolic parameters in the box-rest group at 5 months indicated a retardation in development of the cartilage but, after an additional 6 months, this retardation had almost completely disappeared. The training regimen induced an increase in proteoglycan synthesis at 5 months in cartilage that was, however, accompanied by an increase in proteoglycan release. In the training group at the long-term, the ability of cartilage to increase proteoglycan synthesis when stimulated was severely reduced. We consider this extra proteoglycan synthesis capacity of great importance to repair small injuries and hence as essential to prevent an early onset of degenerative disorders such as osteoarthritis. Therefore, although extrapolation of in vitro data to the in vivo situation always should be done with the utmost care, it is concluded that pasture exercise is best for the development of healthy cartilage resistant to injury and other exercise protocols may carry harmful long-term effects.

Animals↗
PubMed1999

Early changes in the distal intertarsal joint of Dutch Warmblood foals and the influence of exercise on bone density in the third tarsal bone.

It was hypothesised that imposition of different exercise levels at a young age would lead to differences in bone density in the third tarsal bone and to difference in the prevalence of pathological lesions that might contribute to the development of bone spavin later in life. Furthermore, based on earlier literature, it was hypothesised that such lesions could be classified as a manifestation of osteochondrosis. Changes in bone density in the third tarsal bone and early pathological changes in the articular cartilage of the distal intertarsal joint were studied in the offspring of sires with radiographic evidence of osteochondrosis in either stifle or hock. Twenty-four foals were studied at age 5 months after having been subjected to different exercise programmes (box-rest, box-rest with sprint training, pasture exercise) from age one week. Nineteen other foals that originally belonged to the same exercise groups were studied at age 11 months, after they had been weaned, housed together and subjected to an identical low level exercise regimen for an additional 6 months. Bone density was quantified using a microscopic technique. Histomorphological analysis was performed semiquantitatively and using high detail radiography techniques. At age 5 months, mean +/- s.d. bone density in the compact bone of the third tarsal bone was significantly lower in the box-rested foals (37 +/- 4%) than in both the trained and pastured foals (48 +/- 7% and 52 +/- 11%, respectively). After 6 months of identical exercise the previously box-rested foals showed an increase in bone density (53 +/- 12%) which became similar to the value found in the formerly pastured foals (52 +/- 8%). Major pathological lesions (chondrocyte necrosis, fragmentation and chondrone formation) of the articular cartilage of the third and central tarsal bones were already present at age 5 months, but were significantly more numerous at 11 months. There was no relation between the number of cartilage lesions and the osteochondrosis status of the foals. Only 2 lesions in 11-month-old foals had histological characteristics compatible with osteochondrosis, all other lesions were degenerative in nature. It is concluded that bone density of the compact bone of the subchondral bone plate in the third tarsal bone reacts strongly to variations in exercise at a very young age. Low bone density, caused by lack of exercise, can be compensated for when exercise is later increased. Pathological changes in the distal intertarsal joint are common at 5 months and increase to 11 months. These lesions are degenerative in nature and seem not to be related to osteochondrosis. Although the clinical relevance of these abnormalities is uncertain, they may be relevant for the development of osteoarthritic processes in this region later in life.

Animals↗
PubMed1999

Effect of age, exercise and growth rate on bone mineral density (BMD) in third carpal bone and distal radius of Dutch Warmblood foals with osteochondrosis.

This study aimed a the determining bone mineral density (BMD) in the 3rd carpal bone and distal radius of foals age 5 and 11 months that had been subjected to different exercise regimens from birth until age 5 months. It was hypothesised that BMD would be greater in older animals, and that differences in exercise regimens before age 5 months would be associated with differences in BMD at both age 5 and 11 months. Epiphyseal bone tissue was available from 5 and 11 month old Warmblood foals bred from sires known to have radiographic evidence of osteochondrosis (OC). The foals were in a clinical trial which assessed the effect of exercise up to age 5 months on osteochondrosis (OC). Until age 5 months, foals were either box confined, box confined and sprint trained daily, or kept at pasture. Half the horses in each group were then confined together in a large stall, with access to pasture for 2 h daily, from age 6 to 11 months. BMD was assessed by dual x-ray absorptiometry in 4 areas of interest (AOIs) of excised third carpal bone (C3) and 5 in the distal radius. Volumetric BMD was determined in C3, only surface BMD was analysed in the radius. Across age groups, exercise had an effect on BMD in the mediodorsal and mediopalmar areas of C3. In the 5-month-old animals, the training exercise had similar effect to constant pasture exercise. In all AOIs, BMD was significantly greater in 11-month than in 5-month-old animals. Between age groups there was a difference in effect of exercise regimen before 5 months, in mediodorsal C3 and medial aspect of the radius, and the difference observed between exercise groups at age 5 months was no longer present in horses age 11 months, indicating no residual effect of early exercise. BMD was lower in the group with high OC scores. In the group of horses with the most severe OC, monthly growth rate did not fall uniformly with age over the first 5 months, as it did in groups with lower OC scores. It was concluded that exercise influenced significantly BMD at 5 months, suggesting that carefully designed training programmes to increase bone mineral could be employed in young animals. There was no residual effect at 11 months.

Absorptiometry, Photon↗
PubMed1999

Influence of exercise on bone mineral density of immature cortical and trabecular bone of the equine metacarpus and proximal sesamoid bone.

Bone mineral density (BMD) and cross-sectional area (CSA), measured using peripheral quantitative computed tomography, were determined in the left third metacarpal bone (MCIII) and left medial proximal sesamoid bone (psb) in 3 differently exercised groups of foals. Group(box) (n = 14) was confined to a box stall from birth to age 5 months, Group(training) (n = 14) was kept in similar box stalls but additionally given a daily exercise programme consisting of an increasing number of gallop sprints and Group(pasture) (n = 15) remained at pasture. At 5 months of age, 8 foals from each group were randomly selected and subjected to euthanasia, the remaining 19 foals were given an identical light exercise regimen for an additional 6 months and were killed at age 11 months. In MCIII CSA increased with age and was also significantly (P<0.05) larger in Group(pasture) compared to Group(box) at age 5 months. At 11 months this difference had disappeared. In the dorsal cortex, BMD was significantly (P<0.05) higher in Group(box) than in both other groups. At age 11 months all significant differences had disappeared. In the psb, CSA increased with age, but there were no differences between the exercise groups. At the apical level, trabecular BMD was higher in Group(training) than in Group(box) and Group(pasture) (P<0.001 and P<0.01, respectively). At 11 months, trabecular BMD in the foals that had belonged to Group(training) was less than in the foals that had belonged to Group(box) (P<0.05). It is concluded that box-rest during the first months of life results in a retardation of normal development which is compensated for when the restriction on exercise is lifted. Exercise during the first months of life induces an increase in CSA in the third metacarpal bone. In the psb exercise increases BMD, principally in trabecular bone. There is an indication that the specific training regimen used in this study led to an overstimulation of the bone resulting in less active mineral deposition in the longer term.

Animals↗
PubMed1999

Age-related changes and effect of exercise on the molecular composition of immature equine superficial digital flexor tendons.

To test the hypothesis that exercise at very young age may influence the eventual molecular composition (and hence the biomechanical properties) of tendon tissue in the horse, 43 Dutch Warmblood foals were allotted to 3 differently exercised groups (box-rest, box-rest with training and pasture exercise). Twenty-four superficial digital flexor tendons (SDFTs) were collected at age 5 months (8 from each exercise group) and the others were obtained at 11 months after an additional period of light exercise that was equal for all remaining foals and was intended to see if any induced changes would be reversible or not. Significant changes in DNA content (cellularity), hyaluronic acid (HA) and polysulphated glycosaminoglycans (PSGAGs) were found after the 5 month period of different exercise regimens. There was a tendency towards an exercise-related effect on hydroxylysine content and number of hydroxylysylpyridinoline (HP) crosslinks. Levels of Cartilage Oligomeric Matrix Protein (COMP), measured by homologous inhibition ELISA, showed significant differences at 5 months and were highest in foals kept at pasture and lowest in foals maintained in a box but given enforced exercise. At 11 months, the biochemical parameters of the tendons from the foals of the former box-rest and pasture groups became similar, indicating the capacity of the immature tendon to recover from a retarded development. However, the ratio of PSGAGs per unit of DNA of the former training group was significantly lower than those from the other groups, suggesting that the training regimen in this study had a lasting negative effect on the tenocytes resulting in a decrease of the production of PSGAGs. Therefore, inappropriate or excessive exercise may damage developing tendon, with limited recovery after normalising the exercise level. These possibly deleterious effects of a training regimen on tendon development may be important for the management of young would-be equine athletes.

Analysis of Variance↗
PubMed1999

The influence of different exercise regimens on the development of locomotion in the foal.

To study the influence of different exercise regimens on the development of locomotion, 40 Warmblood foals aged 1 week were subdivided into 3 groups: box-rest, training and pasture exercise. The box-rest group remained for 24 h a day in a box stall while the training group was housed similarly, but additionally received a 30 min workout with gallop sprints 6 times a week. The pasture group served as a control group and was kept at pasture for 24 h a day. After 5 months, the locomotion pattern at the trot of every foal was recorded overground with a 2-D MacReflex gait analysis system. A randomly selected group of 19 foals was recorded again at age 11 months after they had been kept in an open loose box with access to a small paddock without any specific training for 6 months duration. At 5 months of age the box-rest group moved with a more protracted forelimb, and more extended shoulder and elbow joints than the pasture group. Carpal and fetlock joint kinematics were rather similar in all groups. In the hindlimb, the box-rest foals were significantly different from the other 2 groups, reflected in a more retracted hindlimb, more hip extension, more flexed stifle and tarsal joints, and a larger maximal flexion of hip, stifle, tarsal and fetlock joints. In the simultaneous video recordings this locomotion pattern was visible as a hypermetric movement. The larger protraction in the forelimb and retraction in the hindlimb, as seen in the box-rest group, is opposite to the interlimb coordination of a superior moving horse. The pastured foals had a smaller range of motion of the shoulder and hip joint and less maximal step height of both fore and hind hooves, while the velocity and step length were similar between the 3 groups. Pastured foals could trot the same distance with less joint motion and therefore had a more efficient intralimb coordination. The training group moved in a way comparable with the box-rest group in the similar velocity box-rest foals trot with an abnormal, hypermetric and therefore inefficient and poorer locomotion pattern. When, superimposed on box-rest, exercise is provided in the form of gallop sprints, this will mainly improve the hindlimb locomotion. These induced differences in locomotion pattern of foals can be reversed when the foals afterwards are subjected to the same exercise regimen again.

Animals↗
PubMed1999

Conclusions regarding the influence of exercise on the development of the equine musculoskeletal system with special reference to osteochondrosis.

This paper summarises and interrelates the findings of a large-scale multidisciplinary investigation to assess the influence of exercise on the development of the equine musculoskeletal system in general and of osteochondrosis in particular, up to age 5 months. Forty-three foals, genetically predisposed to develop OC, were divided into 3 exercise groups: box-rest, box-rest with training and free pasture exercise. At 5 months, all foals were weaned and 8 foals per group were subjected to euthanasia for postmortem examination. The remaining 19 foals were placed together and subjected to euthanasia at age 11 months. Foals were clinically and radiographically monitored during life, muscle and tendon biopsies were taken and gait analysed kinematically. After euthanasia, all major musculoskeletal tissue components (bone, articular cartilage, tendon and muscle) were analysed extensively using a wide variety of techniques. Radiographic monitoring of the stifle and hock joints and postmortem analysis of all diarthrodial joints led to the conclusion that osteochondrosis is a dynamic and very common process in which lesions cannot only develop, but may regress spontaneously during the 'windows of susceptibility' of the various joints, making the clinically diagnosed forms of osteochondrosis into the tip of an iceberg. Closure of the 'window of susceptibility' may be determined by the metabolic status of the chondrocyte which was shown to be inferior in older lesions. Exercise had no influence on the number of lesions, but was related to the distribution of lesions within the joint. There was some evidence that growth rate may be one of the most important intrinsic factors that determine the occurrence of OC. Lack of exercise (box-rest) generally delayed the development of the tissues that make up the equine musculoskeletal system. This was evident in bone mineral density (BMD) at various sites, chemical composition of tendon and of articular cartilage, and in the development of gait. In most cases, this delay was compensated for when box confinement was lifted after 5 months. However, there were indications that this was not true for some collagen characteristics of articular cartilage where the withholding of exercise at early age may therefore have a lifelong effect. The training protocol used (rather high-intensity exercise superimposed on a basic box-rest regimen) appeared to have long lasting negative effects, affecting chondrocyte viability long after the training protocol had ended. A same tendency was seen in bone (decrease in BMD) and tendons (decreases in proteoglycan and hyaluronic acid content). It is concluded that, during the first months postpartum, the equine musculoskeletal system passes through a very dynamic period of growth-related development and intense alteration. In this period, the system is vulnerable to adverse influences that may result in developmental orthopaedic disease. However, regenerative capacity is still high, also in those tissues that are notorious for their lack of repair capacity in the mature individual, such as articular cartilage and tendon. Exercise seems to be an important factor in the determination of the final make-up (and hence biomechanical strength) of these tissues and, therefore, is a potentially powerful tool for the enhancement of injury resistance.

Animals↗
PubMed1999

Influence of site and age on biochemical characteristics of the collagen network of equine articular cartilage.

OBJECTIVE: To determine variations in biochemical characteristics of equine articular cartilage in relation to age and the degree of predisposition for osteochondral disease at a specific site. SAMPLE POPULATION: Articular cartilage specimens from 53 horses 4 to 30 years old. PROCEDURE: Healthy specimens were obtained from 2 locations on the proximal articular surface of the first phalanx that had different disease prevalences (site 1 at the mediodorsal margin and site 2 at the center of the medial cavity). Water, total collagen, and hydroxylysine contents and enzymatic (hydroxylysylpyridinoline [HP]) and nonenzymatic (pentosidine) crosslinking were determined at both sites. Differences between sites were analyzed by ANOVA (factors, site, and age), and age correlation was tested by Pearson's product-moment correlation analysis. Significance was set at P< 0.01. RESULTS: Correlation with age was not found for water, collagen, hydroxylysine contents, and enzymatic cross-linking. Nonenzymatic crosslinking was higher in older horses and was linearly related to age (r = 0.94). Water and collagen contents and HP and pentosidine crosslinks were significantly higher at site 1. Hydroxylysine content was significantly lower at site 1. CONCLUSIONS: Except for nonenzymatic glycation, the composition of articular cartilage collagen does not change significantly in adult horses. A significant topographic variation exists in biochemical characteristics of the articular cartilage collagen network in equine metacarpophalangeal joints. These differences may influence local biomechanical properties and, hence, susceptibility to osteochondral disease, as will greater pentosidine crosslinks in older horses that are likely to cause stiffer and more brittle cartilage.

Aging↗