Page 5 - Clinical Connections- Summer 2021
P. 5

Equine

        POOR PERFORMANCE

        Andy Fiske-Jackson, Deputy Head of RVC Equine and Senior Lecturer in Equine Surgery

              orses are frequently presented                                    human eye, and those values return to the
              to the RVC Equine Referral                                        normal accepted range following nerve
        H Hospital for investigation of poor                                    or joint blocks, and the rider reports an
        performance. Following acquisition of a                                 improvement, this increases the security
        thorough history, the horse is examined.                                of the diagnosis. OGA gives the user
        Usually this will start with a lameness                                 confidence to embark on a lameness work-
        investigation. The equine industry has                                  up in this situation and adds objectivity to
        seen a surge in interest, availability, and                             the post-block assessment.
        use of objective gait analysis (OGA) for the                             There has been debate about OGA
        detection of lameness in horses and the                                 focusing on the initial assessment –
        RVC continues to be at the forefront of the                             whether the user should rely solely on it to
        field with this technology.                                             detect pain-induced lameness – certainly
          The main advantage of using OGA                                       we should not. However, once lameness
        is the potential to remove bias from                                    has been detected, and a lameness work
        clinical decision-making. At the RVC we                                 up using nerve and joint blocks has started,
        are pursuing its use in measuring back                                  improvements can be confirmed with
        movement and seeking to correlate this                        Figure 2  OGA. Whilst nerve blocks may completely
        with the presence of back pain. Inertial   an owner reports a drop in performance   resolve lameness when the area of
        measurement units are placed on the horse   and the values lie outside the thresholds,   pain is desensitised, joint blocks can be
        (Figure 1 and 2) and the horse is assessed   it is sensible to explore the reason for the   less conclusive. The response to stifle
        both unridden (Figure 3) and under saddle.   asymmetry to establish whether it is linked   blocks in particular can be modest even
                                            to the loss of performance; it certainly   if demonstrable pathology is ultimately
          Figure 1                          demonstrates the limb which is producing   evident on either diagnostic imaging or
                                            less force than the others.         arthroscopy. Improvement well below
                                              Asymmetry can be so mild that it can be   50% can be expected in such cases and
                                            difficult to detect. If this is the case, how   OGA can add reassurance in confirming a
                                            can we ensure it is clinically relevant? It   subjective perception of improvement.
                                            is obvious that its relevance should be   Like all technology, its value is only as
                                            assessed in the context of the horse’s   good as its interpretation. Veterinarians
                                            breed, use, age, history and what the rider   are faced with this scenario every day
                                            reports. As an example, a dressage rider   (e.g. blood results, ultrasound scans,
          Lameness ‘threshold values’ that exist   may notice reduced hindlimb push off   radiographs etc.) and, of course,
        with OGA were derived by comparing   during a canter pirouette in one direction   experience is invaluable.
        OGA measurements with veterinary expert   compared to the other well before it
        assessments following induced lameness.   become visually evident when the horse
        Whilst these thresholds should not be   is trotted in hand. If OGA can detect a
        interpreted as an absolute cut off point, if   subtle lameness, undetectable to the   With the support of the Animal Care
                                                                                 Trust, the Equine Referral Hospital has
                                                                                 recently acquired wireless ultrasound
                                                                                 probes. The probes emit a Wifi
                                                                                 signal that wirelessly connects with
                                                                                 any smartphone, tablet or Windows
                                                                                 operating system laptop, meaning they
                                                                                 can be used in remote areas without
                                                                                 internet connection. These probes are
                                                                                 light and easy to handle and the image
                                                                                 resolution is excellent. The absence of
                                                                                 wires makes them safer to use around
                                                                                 the limbs of horses and also allows the
                                                                                 screen to be placed in a safe location.
                                                                                 It also lends itself well to intraoperative
                                                                                 scanning facilitating maintenance of
                                                                                 sterility.


                                                                                       For equine referrals, please call: 01707
                                                                                     666297
                                                                                       Email:
         Figure 3                                                                    equinehospital@rvc.ac.uk

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