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Ridden Evaluation – The Aid of Objective Measures

By Christina Frigast Christina Frigast, MRCVS, CERP, ECP | Updated on | C Frigast, ridden evaluation


Ridden Evaluation – The Aid of Objective Measures
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Have you ever had a client say:

“Something about my horse
just isn’t right”?

It is not uncommon for me to hear clients say that something about their horse isn’t right. They can’t say if the horse is lame or if another medical condition is the reason for the change. All they can say is that the horse is not performing at its usual level or has experienced a sudden change in behaviour when ridden. Cases of poor performance can be difficult and time consuming. Utilising the rider module with the Equinosis Q enables me to objectively assess asymmetry when the horse is ridden. Currently a feature of the system that not many veterinary surgeons are taking advantage of – are you?

With the use of the Equinosis Q, I save time and feel more confident that I get to the root of the problem. I always perform a ridden evaluation in cases of:

  • Poor performance
  • Suspicion of back pain and/or sacroiliac pain
  • Subtle/mild (multiple) limb lameness
  • Monitoring competition horses

In many cases of poor performance, I neither visualise nor measure a lameness in a straight line. Working the horse on the lunge might raise suspicion of a lameness but often so mild I wouldn’t feel confident without objective measures. In those cases, I see the horse ridden. This often exacerbates the asymmetry making it easier to visualise and increases confidence that this could cause poor performance.

Observing the behaviour of the horse when ridden adds useful information to the lameness assessment. Experiencing an improvement in behaviour and attitude supported by an improvement in asymmetry subjectively as well as objectively measured on the Q is what I aim to achieve not only in cases of poor performance but any lameness evaluation where the horse is being assessed ridden either following diagnostic anaesthesia or following a period of treatment. 

It is important to consider the impact and activity of the rider as well as the saddle fit when assessing a horse ridden regardless of whether objective measures are being used. A poor fitting saddle or an inexperienced rider can cause asymmetry to show only when the horse is ridden. Assessing the saddle or have a more experienced rider on the horse for comparison might help rule these scenarios in or out. Should the rider be causing an asymmetry due to inexperience or riding style, I find it important to make them aware as the asymmetry is likely to cause soreness and lameness over time if left untreated. In those cases where the horse is already lame and required treatment, your treatment is unlikely to be successful in the long run unless the impact of the rider is addressed too. I am not telling them that they are bad riders. I am advising them on how best to avoid the asymmetry causing future problems for the horse. This could be regular assessments performed by paraprofessionals or simply advice on changes to the exercise program. Re-evaluations with the Equinosis Q can then be performed to monitor progress over time.    

Personally, I find the Equinosis Q invaluable in the management of competition horses. Monitoring mild asymmetry over time can help decide on adjustments in training and treatment strategies - hopefully avoiding substantial time off work during competition times. I prefer to assess whether asymmetries are significant or changing over time by watching these horses perform according to their particular discipline. Ridden exams are only relevant for sports horses whereas carriage horses or standardbred trotters should be evaluated pulling the carriage or sulky. It is another service you can offer your clients from which I have had very positive feedback. After all prevention is better than cure!

The rider module for the Equinosis Q consists of a rider sensor and a rider belt which is placed around the waist of the rider. It must be fastened properly to ensure it doesn’t move independently but instead follows the movement (acceleration) of the rider. We are still measuring and evaluating the vertical movement of the torso of the horse but also how the rider impacts this movement. The rider sensor then measures the activity (acceleration) of the rider differentiating posting trot from sit trot so that they can be evaluated separately. This is necessary since posting trot will create an artefact in normal horses. As a rule of thumb, in normal horses posting will cause a push off lameness on the inside hindlimb – meaning a left hindlimb push off asymmetry on the left rein and a right hindlimb push off asymmetry on the right rein.

Sit trot should mimic the asymmetry observed on the lunge. However, it will depend on whether the horse is ridden on a circle or following the ménage around (which is mostly riding in straight lines) where the torso is tilted less causing smaller amplitude of ‘normal’ asymmetry compared to on the lunge. Evaluating the ridden Q reports is complex as more graphs are shown and more factors (horse, surface, tack and rider) can affect the results. However, with experience it can become an invaluable aid to your subjective assessment.

Case 1:

Red was a 14 yo Appaloosa gelding used for pleasure riding. He came to me for a poor performance assessment as he had gradually become more reluctant to go forward when ridden. The clinical exam had no significant findings. The straight line showed a mild left forelimb and right hindlimb impact asymmetry which doesn’t follow the ‘law of sides’ for compensatory lameness so a primary limb couldn’t be determined.

Straight line

A mild left forelimb impact lameness and mild right hindlimb impact lameness are seen. A primary limb cannot be determined (fig. 1).

Fig. 1 Results of initial straight line trial. A mild FL impact lameness and mild right HL impact lameness are revealed.

Fig. 1 Results of initial straight line trial. A mild FL impact lameness and mild right HL impact lameness are revealed.

Lunge comparison

The left forelimb asymmetry seen on the lunge to the left is slightly worse than the right forelimb asymmetry on the lunge to the right (fig. 2). The hindlimbs are difficult to interpret as the pattern to the right is an expected pattern of asymmetry for a soft surface and there is no significant asymmetry circling to the left.  Because the lunge didn’t help differentiate the limbs any further, a ridden exam was performed.

Fig. 2 Lunging results revealed a left forelimb asymmetry on the lunge to the left that is slightly worse than the right forelimb asymmetry on the lunge to the right.

Fig. 2 Lunging results revealed a left forelimb asymmetry on the lunge to the left that is slightly worse than the right forelimb asymmetry on the lunge to the right. 

Ridden exam

A left forelimb lameness is only seen when ridden on the left rein. A significant right hindlimb lameness is seen on both reins. Furthermore, this pattern circling to the left is particularly abnormal as lack of impact on the outside hindlimb is unexpected in any surface. Notice the lack of pushoff in the inside hind limb each direction when the rider is posting (rising trot). This is likely an induced rider effect.  It is now possible to determine that the primary limb is the right hindlimb and not the left forelimb. Following a full lameness work up with ridden evaluations before and after diagnostic nerve and joint blocks, the diagnosis was made - bilateral hindlimb proximal suspensory desmitis. Red was successfully managed conservatively. This is likely due to the mild degree of lameness detected at an early stage in a ridden assessment.

Without performing a ridden evaluation, I wouldn’t have been confident blocking the very subtle right hindlimb lameness seen on the straight line. The left forelimb lameness on the straight line and left rein lunge was also more obvious than the right hindlimb lameness so I would likely have started blocking the forelimb – unsuccessfully.

Fig. 3 The ridden evaluation comparison report reveals a left forelimb lameness that is only seen when ridden on the left rein. A significant right hindlimb lameness is seen on both reins. This pattern circling to the left is particularly abnormal as lack of impact on the outside hindlimb is unexpected in any surface.

Fig. 3 The ridden evaluation comparison report reveals a left forelimb lameness that is only seen when ridden on the left rein. A significant right hindlimb lameness is seen on both reins. This pattern circling to the left is particularly abnormal as lack of impact on the outside hindlimb is unexpected in any surface.

Case 2:

Fiona was an 8 yo warmblood mare used for low-level dressage. She had experienced poor performance issues for several months and was referred to me by the physiotherapist who felt something wasn’t right with her movement behind. The clinical exam revealed soreness on palpation of the thoraco-lumbar and sacro-iliac area. No lameness was seen on the straight line and lunge.

Straight line

No lameness seen (fig. 4).

Fig. 4 Results of initial straight line trial reveal no evidence of lameness.

Fig. 4 Results of initial straight line trial reveal no evidence of lameness.

Lunge comparison

No significant asymmetry seen in forelimbs or hindlimbs (fig. 5).

Fig. 5 Lunging exam results show no significant asymmetry seen in forelimbs or hindlimbs.

Fig. 5 Lunging exam results show no significant asymmetry seen in forelimbs or hindlimbs.

Ridden exam

A mild left hindlimb asymmetry was observed on both reins when ridden. Furthermore, Fiona was unable to canter and very short gaited behind, so I decided to perform a sacro-iliac joint block. I must say this is a diagnostic block that I use fairly often although rarely as my first initial block. In this case, it proved very useful as the block made the left hindlimb lameness worse and easier to visualise. Fiona was still short gaited behind but able to canter on both reins. 

Diagnostic block comparison ridden on the right rein (using the ‘general comparison’ option in the drop-down menu) (fig. 6): An SI-joint block was performed, which worsened the left hindlimb push off lameness significantly from 3.1 mm to 7.4 mm. Fiona was now able to canter both reins and the left hindlimb push off lameness was visual.

Fig. 6 Diagnostic block comparison ridden on the right rein. An SI-joint block was performed, which worsened the left hindlimb push off lameness significantly from 3.1 mm to 7.4 mm.

Fig. 6 Diagnostic block comparison ridden on the right rein. An SI-joint block was performed, which worsened the left hindlimb push off lameness significantly from 3.1 mm to 7.4 mm.

I then performed a tarsometatarsal joint block which was positive without a switch to the right hindlimb.

Diagnostic block comparison ridden on the right rein (fig. 7): A tarsometatarsal joint block was performed and improved the left hindlimb push off lameness significantly from 7.4 mm after the SI-joint block to 3.3 mm after the TMTJ block. Only mild degenerative changes were seen on the radiographs and Fiona responded well to intra-articular treatment with hyaluronic acid and triamcinolone.

Fig. 7 Diagnostic block comparison ridden on the right rein.  A tarsometatarsal joint block was performed and improved the left hindlimb push off lameness significantly from 7.4 mm after the SI-joint block to 3.3 mm after the TMTJ block.

Fig. 7 Diagnostic block comparison ridden on the right rein.  A tarsometatarsal joint block was performed and improved the left hindlimb push off lameness significantly from 7.4 mm after the SI-joint block to 3.3 mm after the TMTJ block.
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