Research, facts, evidence and reasons for blogging

My post last week about the latest set of follow-up x-rays which have been done on a rehab horse seemed to be a popular one and has also generated some debate on the HHO forum so I thought today's blog could usefully be used to clarify some issues, though it is a bit long - apologies!

Project Dexter

For those who are interested, the synopsis for Project Dexter, our research programme (for want of a better word), is below (and has been available for years to anyone who asked for it!). It was devised in, as I recall, 2009 with the help of Prof. Peter Clegg at Liverpool University.

"Project Dexter is a proposal for research into the rehabilitation of horses who are included in one of two categories:

1  horses where magnetic resonance imaging (“MRI”) of the affected limb has indicated lesions to the deep digital flexor tendon (“DDFT”) proximal to the navicular bone; or

2  horses with a clinical history of lameness over at least [3-6 months] where lameness is abolished or significantly improved (more than 50%) by perineural analgesia of the palmar or plantar (abaxial sesamoid) nerves.

These criteria will be demonstrated by the referring veterinary surgeon’s diagnosis, local analgesia, radiography and MRI.

The horses in the study will have received a variety of treatment prior to entering the study, but none will have returned to full work as a result of that treatment.  This will be demonstrated by a questionnaire to be completed by the horses’ owners, in the form attached. 

Background

In a recent study (Dyson et al, EVJ (2005) 37 (2) 113-121), horses diagnosed with lesions  to the DDFT or damage to the navicular bone or distal interphalangeal joint (“DIP”) had a guarded to poor prognosis for return to full competitive work, with the majority (72-95%) failing to return to full work after treatment.  The prognosis for horses with injuries to both DDFT and navicular bone was extremely poor, with 95% failing to return to full work.

Experience at Rockley Farm has indicated that very often it is possible to achieve significant improvements in soundness in horses showing similar patterns of lameness using the rehabilitation programme set out in section 2 (“RP”).

1            Research Question

Can the RP deliver a significant improvement on the previously poor prognosis for horses with these two types of lameness?

2            Methodology and rehabilitation

RP will be carried out at Rockley Farm.  Horses within the RP will have their shoes removed and will be kept on supportive surfaces to maximise comfort levels and encourage movement.

All horses included in the RP will be fed a low fructans, high mineral diet and ad lib forage.

Horses within the RP will be exercised only on surfaces on which they are able to move soundly, but provided this criteria is met, exercise will be used as an important part of the RP.

3            Assessment criteria during and after the study

Before entering the RP, each horse will be assessed by his or her referring veterinary surgeon using the baseline lameness assessment protocol and using the information provided by owners, both in the form attached. 

To provide a consistent comparable, each horse will be assessed by the same vet, in the same location, using the same protocol, at the beginning, end and, if possible, during participation in the RP.  Owners will also be asked to provided feedback replicating the original questionnaire to document the horse’s return to work, or otherwise.

For horses in the first group, repeat MRI will be undertaken to assess whether previous DDFT lesions have improved.  For horses in the second group, the referring veterinary surgeon will be asked to repeat the lameness assessment as far as possible in the same location and conditions as the original lameness assessment.

Each horse will be filmed using high definition frame by frame footage, to assess footfall (ie toe first/flat/heel first) and limb loading on the date of entry into the RP.  This footage will be replicated on a monthly basis for each horse.

Still photographs of each hoof will also be taken, with external measurements,showing lateral, dorsal, solar and palmar views, to allow for assessment of hoof capsule changes throughout the RP and will be replicated on a monthly basis for each horse.

Follow-up information will be gathered from owners as to how horses that have responded well to the RP continue to perform.

4            Case control study

A control group of horses will be selected on the basis of case control study, using horses referred to the Unversity of Liverpool’s Equine Clinic at Leahurst, who fall into one of the two selection categories above, on the basis of the clinical assessment at Leahurst.

Control group horses will receive a range of treatments, but none will be included in the RP.  Treatment outcomes will be monitored using the veterinary and owners questionnaires attached, supported by photographic and video footage as for the RP."

Rehab and research results

To date there have been over 70 rehab horses included in Project Dexter (I have no details of the control group at this stage). The last update on our results was done in February 2012 (full text below) and a new update will, I hope, be available later this year. 

The 2012 update was compiled with the help of Emma Watts, an owner who also has a background in veterinary research, and was submitted to the BEVA congress last year in their required form (a 300 word abstract of preliminary findings). The full blog on that update is here but for whatever reason, it wasn't accepted by BEVA.

"Palmar hoof rehabilitation: a means of increasing soundness in horses with DDFT/collateral ligament injuries within the hoof. 

Aims: To assess whether a specific rehabilitation protocol which improves palmar hoof development and medio-lateral balance provides a comparable/better prognosis for long-term soundness than current treatments. Methods: Forty-four horses with a history of more than 12 weeks forelimb lameness that was abolished/significantly improved by palmar digital nerve block were rehabilitated over approximately 12 weeks. Shoes were removed and horses kept on surfaces which maximised comfort and encouraged movement (including shingle and sand). Free movement on these surfaces was encouraged. Diets were low in sugar/starch with balanced minerals and adlib forage. In-hand and ridden exercise on varied surfaces formed an important element of rehabilitation. Palmar hoof development and medio-lateral balance were regularly monitored with photography, using video footage to assess foot placement (toe-first/heel-first). After ~12 weeks, horses returned home to continue a normal exercise programme. Results: Forty-four horses (aged 5-19yrs) were enrolled with 35 programmes completed and 9 still ongoing.  Of the 35 horses who completed, 30 have since been maintained at the same level of work or higher than before their diagnosis, 4 improved but did not return to full work, 1 had rehab interrupted by colic surgery and is in light work. Improvements in palmar hoof development occurred relatively rapidly, with most horses’ landing changing from toe-first to heel-first within 2-6 weeks.  Soundness on hard surfaces and on circles typically improved once this landing was established and palmar hoof development also improved with exercise on varied surfaces once horses were landing correctly. Conclusions: Horses with palmar foot pain may benefit from therapeutic rehabilitation which  improves palmar hoof strength and medio-lateral hoof balance.  Practical Significance: This type of rehabilitation may improve the prognosis for long-term soundness in horses with similar diagnoses. Acknowledgments: Constructive advice from Prof. Peter Clegg; Jeremy Hyde BVetMed MRCVS."

Assessing the effect of rehab

The only way to truly assess what is happening inside the hooves of the rehab horses is with MRI. If money were no object then every horse could undergo MRI before and after rehab; the reality is that to do this would cost £2000-3000 per horse - which is way more than rehab here costs.  Naturally, no insurance company will fund MRI on a sound horse so without research funding we won't get follow-up MRI.

Its a problem that faces conventional therapies and remedial farriery as well, of course. There is as little research to support these as there is for barefoot rehab and I am not aware of any studies into palmar hoof pain where horses have routinely had follow-up MRIs even though this would be the veterinary "gold standard".

The veterinary profession is required to practice evidence-based medicine - something I blogged about in detail last year - but this is a broad onus.  A famous article (Sackett, D.L. et al (1996). Evidence based medicine: what it is and what it isn't. BMJ, 312, 71-72) on evidence-based medicine makes this clear:

"Evidence based medicine is not restricted to randomised trials and meta-analyses. It involves tracking down the best external evidence with which to answer our clinical questions. 

...Because the randomised trial, and especially the systematic review of several randomised trials, is so much more likely to inform us and so much less likely to mislead us, it has become the “gold standard” for judging whether a treatment does more good than harm.

However, some questions about therapy do not require randomised trials (successful interventions for otherwise fatal conditions) or cannot wait for the trials to be conducted. And if no randomised trial has been carried out for our patient's predicament, we must follow the trail to the next best external evidence and work from there."

Last year my own vet and I spent some considerable time (and quite a lot of my business' money) on using ultrasound on rehab horses in an attempt to identify a way of measuring soft tissue changes in a reasonably cost-effective way. We were unsuccessful, as its just not possible to get clear enough ultrasound of the DDFT within the hoof without some pretty drastic cutting of frogs, which would clearly be counter-productive for the soundness of our rehab horses. 

Facts, evidence and reasons for blogging

I've talked to dozens of vets (including the referring vet for each horse who has come here whom I also update about the progress of the horse) and I've found most of them to be both interested and supportive even though, as I've blogged before, many have a curious view that shoes are "normal" and barefoot is not!

Meanwhile, I continue to find rehab horses and their hooves endlessly fascinating and I will continue to post blog updates so you and everyone else can draw your own conclusions.

The blog isn't an attempt to take the place of research, its just a factual record of how hooves are changing, how horses are moving and the work they are able to achieve, often despite being given poor prognoses for recovery. Its evidence, not research - but then I'm a lawyer, not a scientist ;-)