Three-dimensional kinematics of the distal forelimb in horses trotting on a treadmill and effects of elevation of heel and toe

REASONS FOR PERFORMING STUDY: Comprehensive understanding of the 3-dimensional (3D) kinematics of the distal forelimb and precise knowledge of alterations induced by dorsopalmar foot imbalance remains incomplete because in vivo studies performed with skin markers do not measure the actual movements of the 3 digital joints. OBJECTIVE: To quantify the effects of 6 degree heel or toe wedges on the 3D movements of the 4 distal segments of the forelimb in horses trotting on a treadmill. METHODS: Three healthy horses were equipped with ultrasonic markers fixed surgically to the 4 distal segments of the left forelimb. The 3D movements of these segments were recorded while horses were trotting on a treadmill. Rotations of the digital joints were calculated by use of a joint coordinate system. Data obtained with 6 degree heel or toe wedges were compared to those obtained with flat standard shoes. RESULTS: Use of heel wedges significantly increased maximal flexion and decreased maximal extension of the proximal (PIPJ) and distal (DIPJ) interphalangeal joints. Inverse effects (except for PIPJ maximal extension) were observed with the toe wedges. In both cases, neither flexion-extension of the metacarpophalangeal joint nor extrasagittal motions of the digital joints were statistically different between conditions. CONCLUSIONS: At a slow trot on a treadmill, heel and toe wedges affect the sagittal plane kinematics of the interphalangeal joints. POTENTIAL RELEVANCE: Better understanding of the actual effects of toe and heel wedges on the 3D kinematics of the 3 digital joints may help to improve clinical use of sagittal alteration of hoof balance in the treatment of distal forelimb injuries.     

Influence of different head‐neck positions on vertical ground reaction forces,linear and time parameters in the unridden horse walking and trotting on a treadmill

Reasons for performing study: It is believed that the head‐neck position (HNP) has specific effects on the loading pattern of the equine locomotor system, but very few quantitative data are available. Objective: To quantify the effects of 6 different HNPs on forelimb‐hindlimb loading and underlying temporal changes. Methods: Vertical ground reaction forces of each limb and interlimb coordination were measured in 7 high level dressage horses walking and trotting on an instrumented treadmill in 6 predetermined HNPs: HNP1 ‐ unrestrained; HNP2 ‐ elevated neck, bridge of the nose in front of the vertical; HNP3 ‐ elevated neck, bridge of the nose behind the vertical; HNP4 ‐ low and flexed neck; HNP5 ‐ head and neck in extreme high position; and HNP6 ‐ forward downward extension of head and neck. HNP1 served as a velocity‐matched control. Results: At the walk, the percentage of vertical stride impulse carried by the forehand (Iz_fore) as well as stride length and overreach distance were decreased in HNP2, HNP3, HNP4 and HNP5 when compared to HNP1. At the trot, Iz_fore was decreased in HNP2, HNP3, HNP4 and HNP5. Peak forces in the forelimbs increased in HNP5 and decreased in HNP6. Stance duration in the forelimbs was decreased in HNP2 and HNP5. Suspension duration was increased in HNP2, HNP3 and HNP5. Overreach distance was shorter in HNP4 and longer in HNP6. Conclusions: In comparison to HNP1 and HNP6, HNPs with elevation of the neck with either flexion or extension at the poll as well as a low and flexed head and neck lead to a weight shift from the forehand to the hindquarters. HNP5 had the biggest effect on limb timing and load distribution. At the trot, shortening of forelimb stance duration in HNP5 increased peak vertical forces although Iz_fore decreased. Potential relevance: Presented results contribute to the understanding of the value of certain HNPs in horse training.     

Use of a pressure plate to analyse the toe-heel load redistribution underneath a normal shoe and a shoe with a wide toe in sound warmblood horses at the walk and trot

The objective of this study was to use a pressure plate to quantify the toe-heel load redistribution in the forelimbs of sound warmblood horses with normal shoes and shoes with a wide toe and narrow branches, used empirically in the treatment of superficial digital flexor tendon or suspensory ligament injuries. In a crossover-design study, six horses, randomly shod with normal shoes and shoes with a wide toe, were led over a dynamically calibrated pressure plate to record data from both forelimbs. There were no significant differences between both shoes in the toe-heel index of stance time, peak vertical force and vertical impulse. For the adapted shoe, the peak vertical pressure was slightly lower and was exerted slightly earlier in the stance phase, albeit not significantly. However, the significantly larger toe contact area of the adapted shoe resulted in a significantly lower total vertical pressure in the toe region. Hence, the pressure plate adequately visualised the individual loading of the toe and heel region, and clearly demonstrated the altered pressure distribution underneath the shoe with a wide toe. Although further research on a deformable surface is needed to confirm this hypothesis, the pressure redistribution from the toe to the heels could promote sinking of the heels in arena footing, thereby mimicking the biomechanical effects of a toe wedge and providing a rationale for its application in the treatment of SDFT or SL injuries. The pressure measuring equipment used in this study can offer to the clinician a diagnostic tool for the evaluation of the load distribution underneath the equine hoof and for the fine-tuning of corrective shoeing.     

Use of a stand-alone pressure plate for the objective evaluation of forelimb symmetry in sound ponies at walk and trot

Subtle lameness in horses may be difficult to diagnose and methods to evaluate lameness objectively are useful when equine clinicians fail to reach a consensus. The aim of this study was to determine whether equine pressure plate measurements are repeatable when used to calculate forelimb loading (peak vertical pressure [PVP], peak vertical force [PVF], vertical impulse [VI]) and symmetry ratios, and to establish if these data are similar to the ‘gold standard’ force plate values. Since plate dimensions are relatively small, ponies were used to enable recordings to be taken from both forelimbs in one trial. Five sound ponies were walked and trotted over a pressure plate which was embedded in a custom-made runway. For each pony, five valid trials were recorded during two different days. A trial was considered valid if complete prints of both fore hooves were recorded consecutively and if velocity was within a preset range.The PVP, PVF and VI values showed an acceptable variability (CV ? 16%), with PVF (130% of bodyweight [BW], n = 5) similar to previously reported force plate data (128% BW, n = 48). Mean symmetry ratios appeared to be high (>95%) and showed a low variability (CV < 5%). The stand-alone pressure plate permitted adequate registration of forelimb PVF, VI and limb symmetry with a high level of precision in sound ponies.     

Use of serum amyloid A and other acute phase reactants to monitor the inflammatory response after castration in horses: a field study

REASONS FOR PERFORMING THE STUDY: Early recognition of excessive inflammation and infectious complications after surgery, leading to early institution of therapy, reduces post operative discomfort and facilitates recovery. Because serum amyloid A (SAA) is a highly sensitive marker of inflammation, measurements of SAA and other acute phase reactants in the equine surgical patient may be valuable in assisting clinical assessment of post operative inflammation. OBJECTIVES: To investigate changes in inflammatory markers after castration and to correlate levels of acute phase reactants with clinical severity of inflammation after castration. METHODS: Leucocyte numbers and blood levels of iron, SAA and fibrinogen were determined before castration and on Days 3 and 8 post operatively in 2 groups of horses; Group 1 (n = 11) had mild post operative inflammation and an uncomplicated recovery and Group 2 (n = 7) had local clinical signs of moderate to severe inflammation. RESULTS: Both groups had elevated serum SAA levels at Day 3 post operatively. In Group 1 concentrations had returned to preoperative levels by Day 8, whereas in Group 2 concentrations remained elevated. Plasma fibrinogen concentrations in serum increased to equal levels in both groups and stayed elevated throughout the study period. Serum iron concentrations of Group 1 did not change in response to castration, whereas concentrations in Group 2 decreased below preoperative levels on Day 8. Leucocyte numbers remained unchanged during the post operative period in both groups. CONCLUSIONS: Serum SAA and iron profiles reflected the course of inflammation and their levels correlated with the clinical severity of inflammation. In contrast, fever and changes in leucocyte numbers, which are usually considered to be hallmarks of inflammation and infection, were not useful for monitoring post operative recovery. POTENTIAL RELEVANCE: Measurements of SAA and iron may improve post operative monitoring. As sustained inflammation may indicate that the surgical wound has become infected, SAA and iron measurements may facilitate early recognition and hence early treatment of infection.     

Use of a blocking ELISA for antibodies to equine influenza virus as a test to distinguish between naturally infected and vaccinated horses: proof of concept studies

An important consideration in the selection of a vaccine during the Australian equine influenza (EI) outbreak in 2007 was the ability to differentiate between infected and vaccinated animals (DIVA). A blocking enzyme-linked immunosorbent assay (bELISA) targeted for the nucleoprotein of influenza A viruses was developed to differentiate between naturally infected horses and horses vaccinated with the ProteqFlu? vaccine, which only induces a response to viral haemagglutinin. This bELISA assay met the DIVA requirements and was used extensively during the EI control and eradication programs and 'proof of freedom' testing.     

Use of an instrument sandwiched between the hoof and shoe to measure vertical ground reaction forces and three-dimensional acceleration at the walk, trot, and canter in horses

OBJECTIVE: To develop an instrument that could be sandwiched between the hoof and shoe of horses and that would reliably measure vertical ground reaction forces and three-dimensional acceleration at the walk, trot, and canter. ANIMALS: 5 clinically sound Thoroughbreds. PROCEDURES: The recording instrument (weight, 350 g) consisted of 2 metal plates, 2 bolts, 4 load cells, and 3 accelerometers. It was mounted to the hoof with a glue-on shoe and devised to support as much load exerted by a limb as possible. The load cells and accelerometers were wired to a 16-channel transmitter, and transmitted signals were received and amplified with a telemetry receiver. RESULTS: The recording instrument could measure in real time the 4 components of the ground reaction force or their resultant force along with acceleration in 3 dimensions as horses walked, trotted, or cantered on a treadmill. Patterns of force-time curves recorded for consecutive strides were similar to each other and to those previously reported, using a force plate. CONCLUSIONS AND CLINICAL RELEVANCE: The recording instrument developed for use in the present study allowed us to record vertical ground reaction force and acceleration in 3 dimensions in horses at the walk, trot, and canter.     

Use of serology and real time PCR to control an outbreak of bovine brucellosis at a dairy cattle farm in the Nile Delta region,Egypt

Background

Bovine brucellosis remains one of the most prevalent zoonotic infections affecting dairy cattle in developing countries where the applied control programs often fail. We analyzed the epidemiologic pattern of bovine brucellosis in a dairy cattle herd that showed several cases of abortions after regular vaccination with RB51 (B. abortus vaccine). In 2013 thirty dairy cows, from a Holstein-Friesian dairy herd with a population of 600 cattle, aborted five months post vaccination by a regular RB51 vaccine. Blood samples were drawn from milking cows and growing heifers, as well as heifers and cows pregnant up to 6 months. These samples were collected in June 2013 (n?=?257) and May 2014 (n?=?263) and were tested by real time (rt)-PCR as well as serological tests, in particular Rose Bengal Test (RBT), Enzyme-Linked Immunosorbent Assays (ELISA) and Fluorescence Polarization Assay. Tissue specimens were also collected from an aborted fetus and cultured. Isolates were subjected to bacteriological typing tests at the genus and species levels.

Results

Five months post vaccination with RB51 vaccine, Brucella (B.) DNA was detected in blood samples of cows by rt-PCR. The serological tests also revealed the spread of Brucella field strains within the herd in 2013. Four Brucella isolates were recovered from specimens collected from the aborted fetus. These isolates were typed as follows: one B. abortus RB51 vaccine strain and three isolates of B. abortus field strain. The seropositive cows with positive rt-PCR might indicate an infection by the Brucella field strain; while the positive rt-PCR results from seronegative animals may either be due to circulating RB51 vaccine DNA in vaccinated animals or to circulating field strain in infected animals before seroconversion.

Conclusion

The results herein suggest that PCR can be a good supplementary tool in an outbreak situation, if an assay is available that can differentiate vaccine and field strains with a high analytical sensitivity. We recommend using RBT and ELISA in parallel in outbreak situations, to identify as many infected animals as possible during the initial screenings. This test procedure should be repeated for at least three successive negative tests, with one month interval.