Limbs Of Horses Research Articles

In this issue – June 2009

Bandaging and second intention healing in distal limbs of horses ▪ Auricular chondrosis in a horse ▪ National survey of antimicrobials in the Australian pig industry ▪ Analgesia for knife and ring castration in lambs ▪ Incidence of lymphoma in a colony of baboons ▪ Viruses in black tiger prawns from Weipa ▪ Sacral osteochondrosis in German Shepherd Dogs ▪ Congenital pyloric obstruction from a gastric hyperplastic polyp

The effect of different head and neck positions on the caudal back and hindlimb kinematics in the elite dressage horse at trot

Dressage involves training of the horse with the head and neck placed in a position defined by the rider. The best position for dressage training is currently under debate among riders and trainers, but there are few scientific data available to confirm or disprove the different views. To evaluate the kinematic effects of different head and neck positions (HNPs) in elite dressage horses ridden at trot. Seven high-level dressage horses were subjected to kinetic and kinematic measurements when ridden on a treadmill with the head and neck in 5 different positions. Compared to free trot on loose reins the HNP desired for collected trot at dressage competitions increased T6 vertical excursion, increased sacral flexion and decreased limb retraction after lift-off. Further increasing head or head and neck flexion caused few additional changes while an extremely elevated neck position increased hindlimb flexion and lumbar back extension during stance, increased hindlimb flexion during swing and further increased trunk vertical excursion. The movements of the horse are significantly different when ridden on loose reins compared to the position used in collected trot. The exact degree of neck flexion is, however, not consistently correlated to the movements of the horse's limbs and trunk at collected trot. An extremely elevated neck position can produce some effects commonly associated with increased degree of collection, but the increased back extension observed with this position may place the horse at risk of injury if ridden in this position for a prolonged period. Head and neck positions influence significantly the kinematics of the ridden horse. It is important for riders and trainers to be aware of these effects in dressage training.

Effects of platelet-rich plasma on the repair of wounds on the distal aspect of the forelimb in horses

To evaluate the effect of platelet-rich plasma on wounds on the distal aspect of the forelimb in horses. 6 mixed-breed 10- to 15-year-old mares. 3 wounds were created on metacarpal regions in each of 6 horses (n = 36 wounds total). Eighteen wounds were treated with platelet-rich plasma and bandaged, whereas 18 control wounds were similarly bandaged with no prior topical treatment. Decrease in wound surface area and the required number of excisions of exuberant granulation tissue were recorded until complete healing. Tissue specimens were taken from wounds at 1 week for histologic examination and measurement of transforming growth factor-beta1 concentrations and at closure for histologic examination, biomechanical evaluation, and measurement of collagen type I and type III mRNA. Platelet-rich plasma favored excessive development of granulation tissue and significantly slowed wound healing at 1, 2, and 3 weeks after surgery. Transforming growth factor-beta1 had a 1.6-fold higher concentration in treated wounds, compared with untreated wounds. Histologic, biomechanical, and gene expression data did not differ significantly between treated and control wounds. Topical application of autologous platelet-rich plasma did not accelerate or improve the quality of repair of small granulating wounds on limbs of horses. This treatment may better suit wounds with massive tissue loss or, alternatively, chronic wounds that would benefit from a fresh source of mediators to accelerate the healing process.

Laminin receptor 1 is differentially expressed in thoracic and limb wounds in the horse

Healing of wounds located on the distal limbs of horses is often complicated by retarded epithelialization and the development of exuberant granulation tissue (proud flesh). Treatments that definitively resolve this pathological process are still unavailable. Molecular studies of the repair mechanism might contribute to the development of new therapeutic strategies. The study presented herein aimed to clone the full length cDNA and to study the spatio-temporal expression profile of mRNA and protein for LAMR1, previously attributed a role in wound epithelialization, during the repair of body and limb wounds in the horse. Cloning was achieved by screening a cDNA library previously derived from 7-day wound biopsies. Expression was studied in unwounded skin and in samples from 1-, 2-, 3-, 4- and 6-week-old wounds of the body and limb. Temporal gene expression was determined by real time polymerase chain reaction (RT-PCR) while protein expression was mapped immunohistochemically. Full-length cDNA for equine LAMR1 was shown to be highly similar to that of other species. The mRNA expression of LAMR1 was significantly up-regulated only in thoracic wounds, 4 and 6 weeks following wounding (upon epithelialization). Cutaneous wounding induced protein expression at both locations. Our data suggest that up-regulation of LAMR1 protein might favour epithelialization during wound healing. However, its interaction with ligands other than laminin complicates data interpretation. Future studies should quantitatively verify the temporal expression of this protein in order to provide the basis for targeted therapies that might enhance epithelialization.

Effects of extracorporeal shock wave therapy on wounds of the distal portion of the limbs in horses

To evaluate the effects of focused, extracorporeal shock wave therapy (ESWT) on the healing of wounds of the distal portion of the limbs in horses. Randomized controlled trial. 6 healthy adult horses. In each horse, a 4-cm-diameter full-thickness wound that included underlying periosteum was created on the dorsomedial aspect of each metacarpus and two 3-cm-diameter full-thickness wounds that included underlying periosteum were created on the dorsomedial aspect of each metatarsus. One randomly selected metacarpal wound and a randomly selected pair of metatarsal wounds were treated once weekly with ESWT at an energy flux density of 0.11 mJ/mm(2). For metacarpal wounds, swab specimens were collected for bacterial culture on days 1, 2, and 3 and area of epithelialization and extent of wound contraction were measured at 3- to 4-day intervals. Metatarsal wounds were biopsied after 2 and 4 weeks, and immunohistochemical staining for vascular endothelial growth factor, transforming growth factor-beta1, and insulin-like growth factor-1 was performed. Results of bacterial culture, area of epithelialization, and percentage of wound contraction did not differ between treated and untreated wounds; however, healing time for treated wounds (mean, 76 days) was significantly shorter than healing time for untreated wounds (90 days). Staining intensity of growth factors did not differ significantly between treated and untreated wounds. Findings suggested that ESWT may stimulate healing of wounds of the distal portion of the limbs in horses, although the mechanism by which healing was stimulated could not be identified.

Nucleotide structure and expression of equine pigment epithelium-derived factor during repair of experimentally induced wounds in horses

To clone full-length equine pigment epithelium-derived factor (PEDF) complementary DNA (cDNA) and to evaluate its temporal expression during repair of wounds in horses. 4 clinically normal 2-to 3-year-old Standardbred mares. Full-length equine PEDF cDNA was cloned by screening size-selected cDNA libraries derived from biopsy specimens obtained from the wound edge 7 days after experimental creation of a 6.25-cm(2) full-thickness wound in the skin of the lateral thoracic wall. Expression was evaluated in normal skin and in biopsy specimens obtained weekly from experimentally induced wounds on the trunk and limbs of horses. Temporal gene expression was determined by use of reverse transcriptase PCR assay. Equine PEDF shared 87% sequence and 88% peptide homology with human PEDF. Wounding caused upregulation of PEDF mRNA, which did not return to baseline by the end of the study in either anatomic location. Relative overexpression was evident in wounds on the trunk, compared with expression for wounds on the limbs. This study characterized full-length equine cDNA for PEDF and determined that the gene for PEDF appeared to be upregulated in response to dermal wounding. Although the cause of exuberant granulation tissue is probably multifactorial, these data suggested that PEDF, via its potent antiangiogenic capabilities, may contribute to superior healing in wounds on the trunks of horses by protecting such wounds from excessive formation of vascular granulation tissue that characterizes wounds on the limbs of this species.

Cutaneous habronemiasis in a 9‐year‐old Arab gelding in the United Kingdom

SummaryCutaneous habronemiasis causes ulcerative granulating lesions in the skin of equids. Dramatic exuberant tissue may be seen, which becomes traumatised by the horse. To the authors' knowledge, cutaneous habronemiasis has not previously been documented on the distal limb of horses in the UK. Cutaneous habronemiasis should be considered as a potential differential diagnosis for ulcerative granulating skin lesions on the distal limb of the horse.

OB‐cadherin cloning and expression in a model of wound repair in horses

Horses suffer from a debilitating impediment in repairing wounds located on the lower limb that leads to the development of a fibroproliferative disorder (exuberant granulation tissue). This condition is a source of wastage since it often forces retirement from competition. Treatments that resolve or prevent this condition are still lacking, maybe due to deficient knowledge of the underlying molecular mechanisms. Fibroblast-to-myofibroblast conversion is an essential step allowing contraction during wound repair and is accompanied by an increase in OB-cadherin expression. To clone equine cadherin-11 (CDH11) cDNA and to study its spatiotemporal expression profile during the repair of body and limb wounds, thereby contributing to a better understanding of the repair process. Cloning was by a PCR technique. Expression was studied in intact skin and in 1, 2, 3, 4 and 6-week-old wounds of the body and limb. Temporal CDH11 gene expression was determined by RT-PCR while OB-cadherin protein expression was mapped immunohistochemically. Equine CDH11 is a highly conserved gene and protein. mRNA was not expressed in equine skin whereas the wound repair process was characterised by a significantly higher expression in the thorax than in limb samples. mRNA expression pattern was paralleled by protein data as confirmed by immunohistochemistry. The data suggest that deficient OB-cadherin expression in the first phases of wound repair contributes to the excessive proliferative response seen in horse limb wounds. Future studies should verify the quantitative, temporal expression of this protein in order to provide the basis for targeted therapies that might prevent the development of EGT in horse wound repair.

Estimated Influence of Myoglobin on NIRS Signals at Rest and During Exercise

Near infrared spectroscopy is now routinely used to assess tissue (muscle) oxygenation during exercise. While most investigators assume that hemoglobin ([Hb]) is the major contributor to the responses seen during exercise, the relative contribution of [Mb] to the NIRS signals remains controversial. PURPOSE: To calculate the range of light absorbing potential (LAP) of hemoglobin and myoglobin based on analysis of published data in humans and other mammals. METHODS: Information was retrieved from previous studies with regard to capillary density (#caps/mm2) and myoglobin concentration in skeletal muscle of humans and other mammalian species. Preference was given to studies in which both measurements were provided. [Hb] in skeletal muscles was estimated as a function of capillary density, capillary volume, [Hb] in systemic blood, and the ratio of capillary-to-systemic hematocrit at rest and during exercise. RESULTS: Individual group mean values for skeletal muscle [Mb] in the literature ranged from 0.2-0.6 mM in human samples, with a similar range for muscles of the rat hindlimb; horse limb muscles tended to be higher (up to 1.0 mM). Capillary densities ranged from ~200 to 600 caps/mm2 in human and rat muscles, and up to 800 caps/mm2 in horse muscle. Assuming a resting capillary hematocrit of 20% and 4 fold greater LAP for each mole [Hb] vs [Mb], the resulting estimation of capillary LAP-[Hb] ranged from 0.2 to 0.4 mM in human and rat muscles, and up to 0.5 mM in horse muscles. These results suggest that [Mb] could contribute 47-67% of the total LAP at rest. With exercise, total heme with NIRS can increase up to 30% in individual subjects. Assuming this increase reflects only increased [Hb], this fits well with the observed increase in capillary hematocrit of 30% with exercise. CONCLUSIONS: 1) In skeletal muscle at rest, [Mb] is likely to be at least as prevalent a light absorbing heme as is hemoglobin. 2) Observed increases in total heme with NIRS during exercise can be explained by an increase in capillary hematocrit, even in the presence of significant [Mb].

Equine ANXA2 and MMP1 expression analyses in an experimental model of normal and pathological wound repair

Wounds on horse limbs can develop exuberant granulation tissue which resembles the human keloid. Clues gained from the study of over-scarring in horses might help control fibro-proliferative disorders. The aim of the present study was to clone full-length equine ANXA2 cDNA then to study spatio-temporal expression of ANXA2 and MMP1 mRNA and protein, potential contributors to remodeling, during repair of body (normal) and limb (fibro-proliferative) wounds in an established horse wound model. Cloning of ANXA2 was achieved by screening size-selected cDNA libraries. Expression was studied in intact skin and in biopsies of 1, 2, 3, 4 and 6-week-old wounds of the body and limb. Temporal gene expression was determined by semi-quantitative RT-PCR while protein expression was mapped immunohistochemically. ANXA2 mRNA was up-regulated only in body wounds, corroborating the superior and prompt tissue turnover at this location. Immunohistochemistry partially substantiated the mRNA data in that increased staining for ANXA2 protein was detected in neo-epidermis which formed more rapidly and completely in body wounds. MMP1 mRNA levels in body wounds significantly surpassed those of limb wounds in week one biopsies. The protein was abundant in migrating epithelium of limb wounds at weeks two and four; conversely, body wounds in which epithelialization was near complete showed diminished staining of MMP1. We conclude that ANXA2 and MMP1 might participate in remodeling during wound healing in the horse, and that differences in expression may contribute to the excessive proliferative response seen in the limb.

Effect of chiropractic manipulations on the kinematics of back and limbs in horses with clinically diagnosed back problems

Although there is anecdotal evidence of clinical effectiveness of chiropractic in treatment of equine back pain, little scientific work has been reported on the subject. To quantify the effect of chiropractic manipulations on back and limb kinematics in horse locomotion. Kinematics of 10 Warmblood horses were measured over ground at walk and trot at their own, preferred speed before, and one hour and 3 weeks after chiropractic treatment that consisted of manipulations of the back, neck and pelvic area. Speed was the same during all measurements for each horse. Chiropractic manipulations resulted in increased flexion-extension range of motion (ROM) (P<0.05) at trot in the vertebral angular segments: T10-T13-T17 (0.3 degrees ) and T13-T17-L1 (0.8 degrees ) one hour after treatment, but decreased ROM after 3 weeks. The angular motion patterns (AMPs) of the same segments showed increased flexion at both gaits one hour after treatment (both angles 0.2 degrees at walk and 0.3 degrees at trot, P<0.05) and 3 weeks after treatment (1.0 degrees and 2.4 degrees at walk and 1.9 degrees and 2.9 degrees at trot, P<0.05). The lumbar (L3 and L5) area showed increased flexion after one hour (both angles 0.3 degrees at walk and 0.4 degrees at trot P<0.05), but increased extension after 3 weeks (1.4 degrees and 1.2 degrees , at trot only, P<0.05). There were no detectable changes in lateral bending AMPs. The inclination of the pelvis was reduced at trot one hour (1.6 degrees ) and 3 weeks (3 degrees ) after treatment (P<0.05). The mean axial rotation of the pelvis was more symmetrical 3 weeks after the treatment at both gaits (P<0.05). There were no changes in limb angles at walk and almost no changes at trot. The main overall effect of the chiropractic manipulations was a less extended thoracic back, a reduced inclination of the pelvis and improvement of the symmetry of the pelvic motion pattern. Chiropractic manipulations elicit slight but significant changes in thoracolumbar and pelvic kinematics. Some of the changes are likely to be beneficial, but clinical trials with increased numbers of horses and longer follow-up are needed.

Equine CTNNB1 and PECAM1 nucleotide structure and expression analyses in an experimental model of normal and pathological wound repair.

BackgroundWound healing in horses is fraught with complications. Specifically, wounds on horse limbs often develop exuberant granulation tissue which behaves clinically like a benign tumor and resembles the human keloid in that the evolving scar is trapped in the proliferative phase of repair, leading to fibrosis. Clues gained from the study of over-scarring in horses should eventually lead to new insights into how to prevent unwanted scar formation in humans. cDNA fragments corresponding to CTNNB1 (coding for β-catenin) and PECAM1, genes potentially contributing to the proliferative phase of repair, were previously identified in a mRNA expression study as being up-regulated in 7 day wound biopsies from horses. The aim of the present study was to clone full-length equine CTNNB1 and PECAM1 cDNAs and to study the spatio-temporal expression of mRNAs and corresponding proteins during repair of body and limb wounds in a horse model.ResultsThe temporal pattern of the two genes was similar; except for CTNNB1 in limb wounds, wounding caused up-regulation of mRNA which did not return to baseline by the end of the study. Relative over-expression of both CTNNB1 and PECAM1 mRNA was noted in body wounds compared to limb wounds. Immunostaining for both β-catenin and PECAM1 was principally observed in endothelial cells and fibroblasts and was especially pronounced in wounds having developed exuberant granulation tissue.ConclusionThis study is the first to characterize equine cDNA for CTNNB1 and PECAM1 and to document that these genes are expressed during wound repair in horses. It appears that β-catenin may be regulated in a post-transcriptional manner while PECAM1 might help thoracic wounds mount an efficient inflammatory response in contrast to what is observed in limb wounds. Furthermore, data from this study suggest that β-catenin and PECAM1 might interact to modulate endothelial cell and fibroblast proliferation during wound repair in the horse.

Factors affecting outcome of extensor tendon lacerations in the distal limb of horses

Distal limb lacerations are common injuries in horses, with a better prognosis reported for extensor tendons lacerations compared to flexor tendons lacerations. The objective of the present study was to determine the influence of type and location of injury, modalities of treatment and post surgical complications on the outcome of extensor tendon lacerations. The medical records of 156 horses surgically treated for extensor tendon lacerations over a 10-year period were analysed retrospectively. Information was obtained for 124 horses with a minimum of 18 months follow-up. Statistical analysis was performed on 129 horses (five horses were euthanatized during hospitalization) in order to determine factors affecting outcome. Seventy-four percent of the horses returned to soundness, 17% had moderate gait impairment and 9% remained lame. Approximately 60% of the sports horses returned to an equal or higher level of performance, and 17.5% returned to a lower level. In the multivariate statistical analysis, the only significant factor that favourably influenced outcome was complete suture of the wound. A significant association could not be detected between outcome and absence of a functional extensor tendon, The most important post-surgical complication was extensive scarring of the wound. The present results report outcome of extensor tendon lacerations in a large number of horses and outline the importance of primary wound healing in order to avoid major scarring with potential functional consequences.

Local analgesic techniques for the equine head

Horses are excitable animals by nature and are often particularly sensitive to and intolerant of palpation around their head and ears. However, it is frequently necessary to perform procedures around the head, during routine veterinary examination and treatments, and prophylactic dental procedures. Such procedures are often poorly tolerated by the horse and may result in potentially violent avoidance behaviour, preventing safe completion of the procedure. In addition, due to the high cost of general anaesthesia, and its reported risks of morbidity and mortality, and due to the high demands on time and personnel, the ability to perform many investigative, surgical and dental procedures safely in the conscious, sedated horse is attractive. Regional and local nerve blocks are commonly used to enhance the analgesia achieved under general anaesthesia, for oral surgical procedures in other species, including dogs (Beckman and Legende 2002; Lantz 2003) and man (Reiter 1980; Johnson 1982; Lefevre 1991), and for surgical procedures on the distal limbs in horses. Traditionally, restraint of horses for procedures on the head has been achieved with the assistance of an experienced handler, nose twitches and administration of sedatives, especially α-2 agonist drugs. The α-2 agonists produce a satisfactory level of sedation and analgesia, particularly when used in combination with opiates including butorphanol (Torbugesic)1, methadone (Physeptone)2 and morphine (Morphine Sulphate)3. Although adequate, chemically-assisted restraint can be achieved using these techniques in many horses and for many minor procedures, the horse undoubtedly still experiences considerable pain, which is both noxious and undesirable. Therefore, from a welfare perspective, with respect to the horse, and from an efficacy and safety perspective with respect to the veterinarian, it is highly desirable to achieve a greater degree of regional analgesia and muscle relaxation than is possible using sedatives alone, particularly when doing invasive procedures requiring a high degree of precision. The use of regional or local anaesthetic techniques produces superior analgesia resulting in better compliance, safer restraint, reduced doses of sedative drugs and greater duration of sedation, and consequently facilitates shorter operating times. In addition, head-shy behaviour, which can be learned as a consequence of noxious veterinary procedures on the head, is less likely to be reinforced.

Antibodies to elastin peptides in sera of Belgian Draught horses with chronic progressive lymphoedema

Chronic progressive lymphoedema (CPL) is a recently recognised disease of the lymphatic system characterised by lesions in the skin of the lower legs in several draught horse breeds, including the Belgian Draught hourse. Clinical signs slowly progress and result in severe disfigurement of the limbs. Ideally, supportive treatment should be started early in the disease process. However early diagnosis and monitoring progression of CPL is still a challenge. Elastin changes, characterised by morphological alterations as well as increased desmosine levels, in the skin of the distal limbs of horses affected with CPL are probably associated with a marked release of elastin degradation products, which elicit production of circulating anti-elastin antibodies (AEAbs) in the serum. An enzyme-linked immunosorbent assay (ELISA) for detection of serum AEAbs may document elastin breakdown. An ELISA technique was used to evaluate levels of AEAbs in sera of 97 affected Belgian Draught horses that were clinically healthy except for possible skin lesions, associated with CPL in their distal limbs. The horses were divided into 5 groups according to the severity of these skin lesions: normal horses (Group 1, n = 36), horses with mild lesions (Group 2, n = 43), horses with moderate lesions (Group 3, n = 8), horses with severe lesions (Group 4, n = 10) and, as a control, healthy Warmblood horses, unaffected by the disease (Group 5, n = 83). Horses with clinical signs of CPL had significantly higher AEAb levels compared to clinically normal Belgian Draught horses and to healthy Warmblood horses. These levels correlated with severity of lesions. CPL in draught horses is associated with an increase of serum AEAbs. Evaluation of serum levels of AEAbs by ELISA might be a useful diagnostic aid for CPL. Pathological degradation of elastic fibres, resulting in deficient support of the distal lymphatics, is proposed as a contributing factor for CPL in Belgian Draught horses.

Three-dimensional kinematic analysis of head and limb movements of lame and non-lame colts

AbstractLameness manifests itself during the movement of the animal or at rest, indicating a structural or functional disturbance in one or more limbs. Videographic analyses allow the qualitative and quantitative investigation of the movement, reducing the subjectivity of evaluations. The objective was to record the alterations in the movement of the head and limbs of horses in a lame and non-lame condition. Video cameras (60 Hz) and computational methods were used. Six Purebred Arabian colts were filmed on a treadmill, at walk and at trot, before and after induction of lameness. Lameness was induced in the left forelimb utilizing a transient lameness model. Markers were placed on the zygomatic process of the temporal bone, spiny process of the sixth thoracic and first lumbar vertebrae and on the proximal phalange. Nine strides were analysed. At walk and at trot, the animals demonstrated two vertical head movements per stride, while after induction of lameness only one head movement was observed per stride, where this movement was of greater amplitude. The head was shown to be in a more elevated position when the lame limb made first contact with the treadmill belt, which was not observed in the case of the healthy limbs. Only with trotting did the lame animals manifest a prolonged duration of the stance phase for all limbs. The lame animals had a longer support time, lifted the non-lame limbs and showed a shorter stride. Videographic analyses offered details of the alterations in the movement of horses, which are important in the diagnosis of lameness.

Desmitis of the suspensory ligament in fore- and hind limb of horses - a retrospective study of the results of various treatments in practice.

Desmitis of the suspensory ligament in fore- and hind limb of horses - a retrospective study of the results of various treatments in practice.

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.

Influence of exercise on thermographically determined surface temperatures of thoracic and pelvic limbs in horses

To determine the amount of time required for surface temperatures of thoracic and pelvic limbs in horses to return to pre-exercise temperatures after high-speed treadmill exercise, as detected via infrared thermographic imaging. Prospective study. 6 Thoroughbreds. All horses had been trained on and conditioned to use of a high-speed treadmill. Baseline thermographic images were obtained 3 days prior to exercise (baseline). Horses were exercised on a treadmill at a walk for 5 minutes, a slow trot (3 m/s) for 5 minutes, a trot (5 to 6 m/s) for 5 minutes, and a slow gallop (6 to 8 m/s) for 5 minutes, then back to a trot for 3 minutes, a slow trot for 3 minutes, and a walk for 3 minutes prior to stopping. Thermal images were obtained immediately after stopping exercise (0 minutes) and 5, 15, 45, and 60 minutes and 6 hours after stopping exercise. Ambient temperature surrounding each horse was recorded. In all regions, significant differences in surface temperatures were detected between thermograms obtained before exercise and those obtained immediately after, 5 minutes after, and 15 minutes after exercise was stopped. There were no significant differences in surface temperatures between thermograms obtained before exercise and those obtained > or = 45 minutes after exercise was stopped. In horses, images generated via infrared thermography are not influenced by exercise-generated heat > or = 45 minutes after exercise is stopped.

Ground reaction force and hoof deceleration patterns on two different surfaces at the trot

AbstractThe objective of the present study was to compare the hoof deceleration and ground reaction forces following impact on two different surfaces. Seven unshod Standardbreds were trotted by hand at 3.0–5.7 m s− 1over a force plate covered by either of the two surfaces, sandpaper or a 1 cm layer of sand. Impact deceleration data were recorded from one triaxial accelerometer mounted on the fore- and hind hooves, respectively. Ground reaction force data were obtained synchronously from a force plate, sampled at 4.8 kHz. The differences between the two surfaces were studied by analysing representative deceleration and force variables for individual horses. The maximum horizontal peak deceleration and the loading rates of the vertical and the horizontal forces were significantly higher on sandpaper compared with the sand surface (P &lt; 0.001). In addition, the initial vertical deceleration was significantly higher on sandpaper in the forelimb (P &lt; 0.001). In conclusion, it was shown that the different qualities of the ground surface result in differences in the hoof-braking pattern, which may be of great importance for the strength of the distal horse limb also at slow speeds.