Frederik Pille

Accuracy of pressure plate kinetic asymmetry indices and their correlation with visual gait assessment scores in lame and nonlame dogs

OBJECTIVE To determine the accuracy of pressure plate kinetic asymmetry indices (ASIs) for diagnosis of unilateral hind limb lameness in dogs and their correlation with visual gait assessment (VGA) scores. ANIMALS 9 healthy dogs and 16 dogs with previously diagnosed unilateral rupture of the cranial cruciate ligament and concurrent unilateral hind limb lameness. PROCEDURES Dogs were walked over a pressure plate to determine paw contact area (PCA), peak vertical pressure (PVP), peak vertical force (PVF), and vertical impulse (VI) of both hind limbs. An ASI was calculated for each gait variable. Simultaneously, gait was assessed visually and scored by use of a numeric rating scale (0 to 10). The ASI of each variable was tested for its usefulness in discrimination between lame and nonlame dogs and for correlation with VGA scores. RESULTS Sensitivity and specificity of ASIs to discriminate between lame and nonlame dogs were excellent for PVF, VI, and PCA; these values were substantially lower for ASI of PVP. Cutoff values to discriminate between lame and nonlame dogs were determined by use of ASIs for PVF, VI, and PCA; however, this could not be done for ASI of PVP. Correlations between ASIs of PVF, VI, and PCA and VGA scores were higher than correlation between the ASIs of PVP and VGA scores. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that ASIs of PVF and VI determined via analysis of pressure plate measurements were reliable indicators of clinical lameness in dogs, but the ASI of PVP was not. The ASI of PCA is an interesting new variable for assessment of limb loading symmetry.

A pressure plate study on fore and hindlimb loading and the association with hoof contact area in sound ponies at the walk and trot

The aim of this study was to evaluate the association between fore- and hind-hoof contact area and limb loading. Data from a previous study on forelimb loading and symmetry were compared with data on hindlimb kinetics, and the fore- and hind-hoof contact area at the walk and trot was evaluated. Five sound ponies, selected for symmetrical feet, were walked and trotted over a pressure plate embedded in a custom-made runway. The hindlimb peak vertical force (PVF) and vertical impulse (VI) were found to be significantly lower than in the forelimb, whereas their high symmetry ratios (>95%) did not show a significant difference from forelimb data. Hindlimb PVF in ponies was found to be slightly higher when compared to data reported for horses even though the ponies moved at a similar or lower relative velocity. The contact area had low intra-individual variability and was significantly smaller in the hind- than in the fore-hooves. A larger contact area was significantly associated with lower peak vertical pressure (PVP) but higher PVF and VI. No significant differences between left and right sides were found for contact area or loading variables. Pressure plate measurements demonstrated a significant association between hoof contact area and limb loading, in addition to intrinsic differences between fore and hindlimb locomotor function. The pressure plate provides the clinician with a tool to quantify simultaneously contralateral differences in hoof contact area and limb loading.

Comparison of pressure plate and force plate gait kinetics in sound Warmbloods at walk and trot

Modern pressure plates (PP) could be an alternative to traditional force plates (FP) for quantitative equine gait analysis, thereby providing the clinician with objective data on the horses gait while unravelling the loading of different regions of the hoof during the stance phase. The aim of this study was to determine whether a stand-alone PP allows reliable measurement of gait kinetics, compared to simultaneously recorded FP variables. Six sound Warmblood horses were walked and trotted over a combined PP and FP system for collection of a set of five valid kinetic measurements for each forelimb. A measurement was considered valid if the horse was moving in a straight line at a constant pace while gait velocity was within a preset range and the hoof fully contacted the plate surface. Significant differences between FP and PP data were seen for peak vertical force (PVF), vertical impulse (VI), time at which the PVF occurs (tPVF) and forelimb symmetry ratios (SymPVF and SymVI) (P < 0.05), but not for stance phase duration (ST). Nevertheless, mean agreement indices (AIs) of ST, tPVF and SymPVF and SymVI were excellent (≥ 0.92), whereas AIs of PVF and VI were moderate (≥ 0.70). The excellent agreement between PP and FP symmetry ratios confirms that observed differences between PP and FP in symmetry ratios are small (2-7%), especially when compared to the expected decrease in symmetry associated with mild lameness (> 20%). The results indicate that a stand-alone pressure plate can be used to measure absolute (ST) and relative (tPVF) temporal variables and loading symmetry ratios and offers equine veterinarians a mobile, cost-efficient and quick gait evaluation method for routine clinical use. However, the system cannot be used interchangeably with a force plate to measure absolute values of limb loading.

Use of blood culture medium enrichment for synovial fluid culture in horses: a comparison of different culture methods.

REASONS FOR PERFORMING STUDY Standard methods for culturing equine synovial fluid (SF) are often unrewarding. Evidence-based information on the relative efficiency of different systems used for optimisation of isolation of microorganisms from equine SF is lacking. OBJECTIVES To compare the results of different culture systems performed in parallel on SF samples from horses clinically diagnosed with synovial sepsis. METHODS Synovial fluid specimens were collected between February 2007 and October 2008 from all horses admitted to a referral hospital that were clinically diagnosed with synovial sepsis and from control horses. Synovial fluid samples were cultured in parallel by: 1) direct agar culture (DA); agar culture after: 2) lysis-centrifugation pretreatment (LC); 3) conventional enrichment (CE); 4) combined LC/CE; or 5) blood culture medium enrichment using an automated system (BACTEC 9050). RESULTS Ninety SF samples from 82 horses were included, together with 40 control samples. Seventy-one of 90 samples (79%) were culture-positive by using blood culture medium enrichment (BACTEC), which was significantly higher compared to all other methods. BACTEC enrichment was never negative while any of the other methods was positive. Although agar culture following LC and/or CE resulted in a slightly higher number of positive samples compared to DA, this difference was not significant. All control samples were culture negative by the 5 different techniques. Although the majority of samples containing isolates recovered without enrichment, culture results after BACTEC enrichment were available on the same day as for agar culture with or without LC (19/23 samples), while CE postponed recovery by at least one day in 20/23 samples. CONCLUSION Blood culture medium enrichment is superior to other techniques for isolation of bacteria from SF of horses. The use of an automated system allows enrichment without substantially postponing recovery of microorganisms. POTENTIAL RELEVANCE The efficient and fast isolation of microorganisms from infected SF by the BACTEC system allows for rapid susceptibility testing and a more appropriate antibiotic treatment.

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.

Do developmental orthopaedic disorders influence future jumping performances in Warmblood stallions

REASONS FOR PERFORMING THE STUDY Few reports are available on the relationship between developmental orthopaedic diseases (DOD) and future performances in Warmblood horses. OBJECTIVES To investigate the relationship between performance and the presence of DOD lesions. METHODS Records of Warmblood stallions for which radiographic and performance data were available were collected. Showjumping performances were expressed as scores derived from the final ranking of horses in each competition. These scores are available in an established performance database. The relationship between radiographic findings and both performance scores and number of performances was analysed using a linear regression model. RESULTS Two hundred and fifteen horses met the inclusion criteria. There was no difference in either the number of performances or performance score between horses categorised as affected with DOD lesions (independent of joint location) compared with controls. Significantly lower numbers of performances were recorded for horses with osteochondral fragments (OCD) located at the dorsal aspect of the sagittal ridge of the metacarpo/metatarsophalangeal bone. No significant difference was found between horses affected with DOD lesions of the tarsocrural joint and controls. Horses with osteochondrosis of the lateral trochlear ridge of the femur had both significantly lower performance scores and numbers of performances compared with controls. CONCLUSION This study demonstrated that specific DOD location and site within the joint have an influence on performance. Osteochondral fragments in the femoropatellar and at the dorsal aspect of the sagittal ridge of the metacarpo/metatarsophalangeal joint resulted in lowered performance. Fragmentation in the tarsocrural joint had no influence on performance. POTENTIAL RELEVANCE The future athletic performance of Warmblood jumping horses may be limited as a result of OCD in the femoropatellar joint and to a certain extent the metacarpo/metatarsophalangeal joint.

Pressure plate analysis of toe-heel and medio-lateral hoof balance at the walk and trot in sound sport horses.

Empirically, equine distal limb lameness is often linked to hoof imbalance. To objectively quantify dynamic toe-heel and medio-lateral hoof balance of the vertical ground reaction force in sound sport horses, seven Royal Dutch Sport Horses were led at the walk and trot over a dynamically calibrated pressure plate. Forelimb hoof prints were divided into a toe and heel region and a medial and lateral zone. Toe-heel and medio-lateral hoof balance of the vertical ground reaction force were calculated throughout the stance. Toe-heel balance was highly symmetrical between contralateral limbs at both gaits. At the walk, medio-lateral balance of both forelimbs presented higher loading in the lateral part of the hoof throughout the stance. However, at the trot, left medio-lateral balance presented higher loading of the medial part of the hoof at impact, whereas the right limb showed higher loading of the lateral part of the hoof in all horses, and both limbs presented increased lateral loading at the end of the stance. This study provides objective data for toe-heel and medio-lateral hoof balance in sound sport horses.

Ultrasonographic findings in 100 horses with tarsal region disorders.

Ultrasonographic findings from 100 horses (103 joints) diagnosed with tarsal region pathology are described. Results of standard orthopaedic, radiographic and ultrasonographic examination of the tarsal region were analysed retrospectively. Periarticular swelling and/or synovial effusion was present in 100% of the joints, a wound was observed in 14.5% and 76.7% of the horses that were lame. Abnormalities were detected in 69.7% of joints using radiography and in 100% with ultrasonography. Our results show that the main disease process can affect all aspects of the tarsus. The most common ultrasonographic findings were synovitis of the tarso-crural joint (n=52) at the dorsal aspect, collateral ligament injury (n=23) at the lateral/medial aspect, and superficial digital flexor tendon injury (n=15) at the plantar aspect. Multiple ultrasonographic abnormalities were detected in 60 joints (58.3%) indicating that a complete and systematic ultrasonographic examination is mandatory when investigating the tarsal region.

Evaluation of an automated blood culture system for the isolation of bacteria from equine synovial fluid

The objective of this study was to evaluate an automated blood culture system for the isolation of microorganisms from infected equine synovial fluid (SF). Samples were collected from 220 severely inflamed synovial joints and classified as either presumably infected (group A: n=149) or not infected (group B: n=71), based on a combination of clinical history, clinical signs and cytological analysis of the SF. Samples were inoculated into blood culture bottles and after incubation were subcultured onto agar media to confirm the results and to facilitate full bacterial identification. Microorganisms were isolated from 107 group A samples (71.8%) and from three group B samples (4.2%). Overall, the detection system identified 117 bottles as positive and 103 as negative, including nine instrument-false-positives and two instrument-false-negatives. The median time-to-detection for Gram-positive bacteria, Gram-negative bacteria, and for fungi was 14.3 (interquartile range [I.R.] 10.0) h, 8.8 (I.R. 12.8) h, and 72.0 (range 60.8-74.8) h, respectively. It was concluded that culture of infected SF using the automated system combines the advantages of enrichment in specialised medium with the rapid detection of bacterial growth.

Distal limb desensitisation following analgesia of the digital flexor tendon sheath in horses using four different techniques

REASONS FOR PERFORMING STUDY Controversy exists about the desensitisation obtained after diagnostic analgesia of the digital flexor tendon sheath (DFTS) during lameness examinations. OBJECTIVES To determine whether DFTS analgesia results in inadvertent desensitisation of the palmar/plantar digital nerves and whether this depends on the injection technique used. STUDY DESIGN Crossover experimental study. METHODS The DFTS of 9 horses were injected with local anaesthetic solution and radiodense contrast medium using one of the following techniques: Proximal (at lateral proximal recess of the DFTS), Axial (axial to the lateral proximal sesamoid bone), Base (at base of the lateral proximal sesamoid bone), and Distal (at palmar/plantar mid-pastern). In total, 72 injections were performed. Skin desensitisation at the heel bulbs was tested with a dynamometer before and at 15, 30, 90 and 120 min after injection. RESULTS Overall, complete desensitisation of a heel bulb at one or more time points after injection occurred in 22 limbs (30.6%). An additional 7 limbs were partially desensitised. Complete skin desensitisation occurred in 10, 3, 4 and 5 limbs using the Proximal, Axial, Base and Distal techniques respectively. Significant differences between techniques were only found at T30. The probability of skin desensitisation at the heel bulbs was 4 times higher when using the Proximal compared with the Axial and Base techniques in the forelimbs, and 3 times higher compared with the Axial and Distal techniques in the hindlimbs. Skin desensitisation nearly always occurred exclusively on the lateral heel bulb. Bilateral desensitisation only occurred in 5 limbs. CONCLUSIONS Anaesthesia of the palmar/plantar digital nerves with distal limb desensitisation often occurs after DFTS analgesia. A higher chance of desensitisation exists when injecting the proximal DFTS recess. It is advisable to verify skin sensitivity at the heel bulbs after DFTS analgesia to avoid false interpretations about the origin of pain causing lameness.