New therapies for the treatment of tendonitis in horses


Introduction 

  • tendon disorders: 

– common in racehorses and sport horses 

– overload due to hyperextension of the fetlock during the stance phase  

 (Genovese et al. 1990) 

  • consequences : 

– temporary cessation of sports operations for 9 to 15 months 

– possibly permanent cessation in case of recurrence 

  • scarring: 

– repair according to the fibrositis process 

– tissue obtained that is functionally deficient compared to the initial tissue 

 (Crevier-Denoix et al. 1997) 

– tendon generally stiffer than initially 

– predisposes to the creation of a new lesion above or below 

 of the initial lesion = recurrence

  • New therapeutic approaches: 

– originate from regenerative medicine 

– aim to obtain a fabric very similar to the original fabric 

– stimulus provided by PRP, stem cells or other substances 

  • Validation of treatments: 

– numerous treatments 

– some relatively empirical 

– scientific validation: 

  • experimental in vitro studies (on an isolated tendon) 
  • experimental in vivo studies (on lesions created experimentally on live horses) • clinical studies 


Basic treatments 

  • Ultrasound examination: 

– between 3 and 10 days after the accident 

– choice of treatments to be carried out and convalescence 

– to give a prediction 

– assistance with monitoring and changing activity levels 

  • Inflammation management: 

– anti-inflammatory treatment as soon as it appears 

- ice 

  • Immobilization : 

– natural enlargement of the lesion during the first two weeks 

– Proper immobilization during the first 10 days significantly limited this increase in lesion size (David et al. 2011) 

– Robert-Jones dressing at a minimum, or even with a plaster cast, particularly if the fetlock has descended – splint limiting hyperextension of the fetlock (Equistride) 

  • Hardware: 

– fitting with a covered clamp and narrow sponges: 

  • superficial flexor tendon 
  • suspensory ligament of the fetlock 

– inverted shoeing or shoeing with a narrow clamp and enlarged sponges: 

  • deep flexor tendon of the finger. 

– shoe both front hooves or both hind hooves with the same shoe 

  • Convalescence: 

– 75 % of horses put out to pasture show a relapse (Gillis 1997) 

– 50 % of horses receiving controlled convalescence develop a recurrence following superficial digital flexor tendonitis in steeplechase horses (Dyson 1994, OMeara 2010) 

  • Duration : 

– well-defined protocol for managing tendinitis of the superficial digital flexor tendon in thoroughbreds (Godwin et al. 2012) – Thoroughbred: 11 months 

– walker: 9 months? 

– sport horse: 9 months? 

– reducing this period increases the risk of relapse 

Platelet-rich plasma 

(PRP = platelet-rich plasma) 

  • Definition : 

– blood = several cell lines diluted in blood plasma 

– Platelets: numerous growth factors that aid in the healing of various tissues 

  • Platelet isolation: 

– centrifugation techniques 

– platelet-rich plasma 

  • Results : 

– In vitro: 

  • Effects of PRP on the superficial flexor tendon of the digit and on the suspensory ligament of the fetlock: increased production of COMP and type 1 collagen, thus a significantly higher increase in a growth factor (Schnabel et al. 2007, McCarrel et al. 2009) 

– In vivo: 

  • experimental model of superficial flexor tendonitis of the finger performed seven days after the onset of the lesion 
  • higher cellularity, higher collagen and glucosaminoglycan content, better histological organization and more developed neovascularization than in the control group 
  • tendons stronger than in the control group (Bosch et al. 2010) 

– Clinical study: 

  • severe desmitis of the suspensory ligament of the fetlock in 9 trotters 
  • All the horses returned to racing 8 months after the accident and raced for at least two years; they had the same number of starts as the 9 uninjured horses. 
  • lack of real control and a small number of cases 
  • a single injection of PRP (Waselau et al. 2008) 
  • Advantage : a single session 
  • Injection administered 7 and 10 days after the accident 

• Summary : TVALIDATED TECHNIQUE


Stem cells 

  • Definition : 

– cells capable of differentiating into different cell lineages: 

  • embryonic stem cells 
  • mesenchymal stem cells 

– in horses, studies are mainly carried out on stem cells of mesenchymal origin: • bone marrow 

  • adipose tissue (fat) 
  • umbilical vein (taken from the fetus immediately after birth) 
  • Origins: 

– adipose tissue: appear to differentiate less well than cells from bone marrow (Toupadakis et al. 2007, Im et al. 2005, Vidal et al. 2007) 

– few studies on the umbilical cord (Guest et al. 2010, Bi et al. 2007) 

– more knowledge of bone marrow 

  • Results : 
  • In vitro: 

– stem cells injected into sections of tendon 

– survive, proliferate and migrate into the matrix to express several extracellular matrix genes (Stewart et al. 2009, Richardson et al. 2007) 

  • In vivo: 

– survival in the tendon for up to four months after implantation (Guest et al. 2008) 

– tendinitis experimentally induced with collagenases 

– significant improvements in tendon healing (Schnabel et al. 2009, Nixon et al. 2008) for bone marrow and adipose tissue 

  • Recent clinical study (Godwin et al. 2011): 

– 141 horses treated with follow-up for 113 horses 

– Recurrence rate: 27.4% (%) 

– 25.7 % for steeplechase horses (105 horses) 

– 50 % for flat racing horses (8 horses) 

– significantly lower than with conservative treatment alone 

– no relationship with age, discipline, number of stem cells injected, or time of implantation after the accident 

  • Inconvenience : two visits 

– bone marrow sampling 

– injection of the prepared stem cells into the lesion 

  • Injection within 6 weeks of the accident 

• summary : VALIDATED TECHNIQUE

  • Definition : 

– bone marrow: 

  • produces the majority of blood cells 
  • stem cells capable of differentiating into different lineages 

 cellular (but only from 0.01 % to 0.01 %) 

  • numerous growth factors 
  • Bone marrow sampling: 

– on the sternum 

– on the ilium (pelvis) 

  • Centrifugation: 

– bone marrow concentrate 

– contains up to 15 % stem cells (Nixon, 2010) 

  • Administration of bone marrow concentrate and PRP. 
  • Clinical study: 

– PRP and bone marrow concentrate 

– Tendinitis and desmitis of the superficial flexor tendon of the finger 

 and the suspensory ligament of the fetlock 

– 13 sport horses 

– controlled convalescence 

– 85% of horses returned to competition (Torricelli et al. 2011) 

  • Advantage : a single session 
  • summary : VALIDATED TECHNIQUE


IRAP (=ACS) 


Definition : 

– culturing blood on syringes containing glass beads marketed by the companies Orthokine and Arthrex 

– IRAP-enriched serum: anti-inflammatory properties, used for the treatment of numerous joint problems 


Results : 

– not recommended for the treatment of tendinitis 

– studies are underway to verify its potential effectiveness 


Shock waves 

  • tendon and ligament insertions with interesting clinical effects 
  • Use on the tendon alone is a subject of controversy: 

 – adverse effects on tendon repair in the medium term (Bosch et al. 2007) 

  • Summary : not recommended 


Nuclear medicine« 

  • No studies conducted 
  • Effective on bone lesions, but not on tendinitis. 
  • Summary : not recommended 


Conclusion 

  • Satisfactory results but 25% recurrence rate (%) 
  • Do not neglect the basic principles: 

 - immobilization 

 – convalescence 

  • maintain a critical perspective on some currently proposed treatments: 

 – some have no proven effectiveness 

By Dr. Matthieu COUSTY, ECVS Diplomate

Specialist in equine surgery 

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