Page 4 - Clinical Connections - Spring 2023
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RVC RESEARCH    STUDY    VETERINARY SERVICES       RVC.AC.UK
         Equine
        OSTEOARTHRITIS IN HORSES –
        IS THERE A NEW OPTION?


        Roger K.W. Smith, Professor of Equine Orthopaedics

             he RVC Equine Referral Hospital   However, the use of autologous stem cells   was recorded for fourteen patients (eg
             had a world-first 20 years ago, when   carries limitations – they require obtaining   figure  2)  at  pre-treatment  and  at  six  and
        T it cultured  mesenchymal stem  cells   the source material to culture the cells from,   twelve weeks after treatment. Unfortunately,
        from the bone marrow of a horse suffering   technical expertise and an element of risk,   two patients could not complete further
        from  an  overstrain  injury  of  its  superficial   particularly for aspiration of bone marrow   assessment – one due to concurrent
        digital flexor tendon. The cultured cells were   from the sternum. Additionally, the second   laminitis and one as it was euthanised due
        implanted into the damaged tendon under   stage in the process requires culture of the   to the severity of their OA.
        ultrasound guidance.                cells in a VMD-licensed laboratory, which is
          While  we  felt  cell  therapy  might  offer   costly. These have limited the use of stem   Figure 2: Scan
        significant  benefits  for  the  treatment  of   cells.                  from a trial patient
        tendon injuries, based on laboratory work,   One way around these limitations is to
        we did not realise how much we didn’t   develop a stem cell product that is allogenic
        know at the time. However, this spawned   – i.e. cells derived from the same species
        significant  interest  from  around  the  world   but  a  different  individual.  This  means
        and the use of autologous mesenchymal   multiple doses can be prepared from the
        stem  cells  became  a  commonly  used   same tissue of origin and supplied to the
        treatment for both tendon and ligament   veterinary  surgeon  ‘off  the  shelf’,  making
        injuries and osteoarthritis.        their use much more convenient. However,
          While the gradually accumulated clinical   because the cells are derived from a different
        outcome  data  from  tendon  injuries  was   individual, they can cause an allergic   Over  the  twelve-week  study,  visual
        generally positive, the evidence for the   reaction when injected into the patient   lameness significantly decreased by a mean
        effectiveness  in  osteoarthritis  was  more   unless  they  are  carefully  characterised  to   of  1.20  units  (p=0.013). The  evaluation  of
        variable. Nevertheless, the use of stem cells   reduce the risk.        the objective gait analysis also showed a
        became keenly adopted as an option for   In  2019,  Boehringer  Ingelheim  obtained   decrease  in  lameness,  although  this  was
        the treatment of inflammatory joint disease,   a European-wide licence for an allogenic   not  statistically  significant  –  most  likely
        especially in the USA.              mesenchymal  stem  cell  line,  derived  from   because  of  the  need  to  separate  analysis
                                            blood and developed by a company in   into forelimb and hindlimb cases, which
                                            Belgium. This cell product has also had the   reduced the statistical power of the study.
                                            cells ‘primed’ to make them more effective   Interestingly, patients with a higher level
                                            for the treatment of osteoarthritis (see     of lameness on presentation responded
                                            figure 1).                          to  the  treatment  to  a  significantly  greater
                                                                                magnitude (p= 0.0156). It was also observed
                                            RVC project                         that the decrease in lameness was greater at
                                            After this product was launched, Boehringer   twelve weeks than six (p=0.0368), showing
                                            asked  our  Equine  Referral  Hospital  to   progressive improvement at a delay post-
                                            undertake a simple case-based ‘trial’. This   injection.
                                            was structured to  allow us  to assess  any   These  results  support  the  concept  that
                                            change in lameness after treatment by re-  stem cells can be beneficial for the treatment
                                            examinations at six and twelve weeks after   of one of the most common orthopaedic
                                            treatment, using both the usual visual scoring   problems in horses, although it also
                                            and objective gait analysis, to minimise   suggests that the treatment does not always
         Figure 1: (A) Left (affected) and (B)   the subjectivity assessment.  This system   result in complete soundness. This may not
         unaffected hip joint from a 17-year-old   of lameness assessment is becoming   be surprising when the cases selected were
         Warmblood gelding, which presented with a
         marked left hindlimb lameness.     mainstream in equine orthopaedics, and   generally  those  more  severely  affected.
                                            we  have  been  using  an  in-house  system,   This simple clinical study also illustrates
         (C) Right (affected) and (D) left (unaffected)   developed by Dr Thilo Pfau of the Structure   the  opportunities  afforded  by  a  university
         hip joints from a 60-year-old male (the
         author!) taken on the same day. While hip   and Motion Laboratory, for about ten years.   equine  hospital,  which  provides  research
         osteoarthritis is very common in humans,   Recently, we concluded this trial and one   opportunities  to  our  talented  veterinary
         it is extremely rare in horses – and yet the   of our students, Daniel Peterson, undertook   students – fostering skills appropriate for
         signs of joint collapse and new bone around
         the joint are remarkably similar. The horse is   assessment of the lameness data as part of   continuing clinical research throughout their
         considered an excellent large animal model   a final year project, with interesting results.   careers.
         of many human musculoskeletal diseases.  Visual and objective lameness assessment
                                                                                       For equine referrals, please call: 01707
                                                                                     666297
                                                                                       Email:
                                                                                     equinehospital@rvc.ac.uk

        4   Spring 2023
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