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Hoof assessment #1- negative plantar angle (NPA) & associated health risks

Updated: May 5, 2023

This is the first of a number of articles featuring photos of horses hooves and bodies sent to us for review or taken during consultations and to help horse owners and professionals learn to identify and recognise unhealthy hoof morphology, which places horses at increased risk of tissue breakdown, pathology, pain and lameness.


We feel the biggest crisis facing domestic horses in the UK today is lack of awareness of lameness and pain in horses. We believe this is mostly due to unrecognised hoof and body imbalances, and when pain and disease is being recognised, it is treated symptomatically and on the whole, ineffectively, as the root cause isn't typically being addressed. As a result, horses are suffering unnecessarily.


The good news is that one can easily learn to recognise unhealthy hoof morphology and compensatory posture and for the majority of cases, integrative hoof and body rehab done right can be both highly effective and achievable.


In this article you will learn:

  • how we used hoofmApp app and 'healthy ideals' to help recognise unhealthy ideals from a lateral photograph

  • why it is important to rehab the hooves

  • what to do if your horse has similar hoof morphology


What is healthy hoof and posture?
This is the most important question. If you don’t know what healthy looks like, how do you recognise your horse needs support?

We can say with confidence that the following guidelines can help you identify a healthy hoof (although the ideal hoof shape or morphology will change according to the individual horse and even the individual hoof):

  • Straight hoof pastern axis (HPA)

  • Healthy phalangeal alignment and appropriate palmar or plantar P3 angle (as assessed on quality radiographs

  • Appropriate vertical depth, dorsal-palmar and medial-lateral balance.

  • Minimum of 60:40 toe to heel ratio around the centre of rotation of the coffin joint (for the barefoot horse)

  • Maximum of 5 degrees difference between the dorsal wall hoof angle and heel angle

  • Healthy posture and gait with cannon bones perpendicular to the ground (on a level, firm surface)

  • A hoof free from disease, infection, flares, cracks or other signs of distortion and unhealthy growth

  • A hoof score appropriate to the use of the horse, age and health.


You can learn more about these and other articles we have published at the end of this article.


Here is an examples of a hoof which meets minimum health/score as befitting the individual equine in their unique environment:


Healthy hoof on grass kept non-ridden pony in winter (hoof score 6/10)

This is a marked up photo of a hoof in rehab and suggesting the ideal hoof morphology for this horse and his unique conformation in time.


Hoof in rehab (hoof score 5/10) showing ideal hoof shape in 6 months (hoof score 7/10)

It is incredibly useful to learn to document your horses hooves and body, and monitor progress on a regular basis. You can share the photos with your horses team of professionals.


What is unhealthy?

This is easy to answer, and basically, any hoof which doesn’t fit the above considerations, eg:

  • Broken back or broken forward HPA

  • Lack of alignment of the phalangeal bones and unhealthy palmar/plantar P3 angle

  • Lack of depth, and evidence of imbalance on all places of direction

  • Unhealthy toe:heel ratios around the centre of rotation of the coffin joint

  • Unhealthy posture or gait and evidence of lameness

  • Evidence of active or inactive disease processes, infection, inflammation, cracks, hoof distortions and unhealthy growth

  • A hoof score too low for the minimum required for the age, health status and use of the horse


Hoof review

Here is an image of a hind hoof sent by a horse owner seeking advice for their horses hoof care.



We marked up the hoof using HoofmApp app and although the hoof isnt weight bearing, so strictly speaking the HPA cannot be assessed, we can tell by the morphology that the HPA is likely to be broken back and probably NPA (negative plantar P3 angle) and here is our assessment:


1. There is evidence of bull-nosing of the dorsal wall - this is typical where there is low plantar P3 angles. The origin of the outer wall is the coronet band. It is important to asses the dorsal wall angle closest to the coronet band, as this most closely reflects the angle of the pedal bone in horses where acute founder isn't indicated.


2. The coronet band angle is very steep. Angles greater than 28 degrees is associated with low PA. We would suggest a lower angle is indicative of low PA. If you stand the horse square, and the angle of the hind coronet band points to above the knee of the horse, this suggests low PA also.


3. The toe:heel ratio around the center of rotation (COR) is unhealthy, meaning that in a freshly shod horse, with a healthy hoof, it should be close to 50:50. Currently it is 71:29 which informs me there is a low PA and possibly a high toe. During the shoeing cycle, the toe:heel ratio is expected to change and 'creep' is the technical term for this growth, however the current toe:heel ratio tells me the ratio immediately post shoeing was likely to be insufficient for functionality and balance for a horse required to perform, or even for a retired, pasture kept horse


4. Insufficient vertical depth. The curve in the coronet band is typical of horses with unhealthy ideals and potentially also an unhealthy coronet band/extensor process distance - on radiographs, I might expect to see evidence of stretching of the coronet band and CE distance of up to 1 cm. This would suggest there is some distal and caudal collapse, meaning there is insufficient vertical depth, especially in the caudal foot/hoof and weak caudal tissues. There would also be a weak sole and an especially thin sole in the back half of the hoof.


5. Hoof morphology associated with broken back HPA If you were to stand the horse truly square (which the horse might find tricky due to the influence of the hoof on posture, and visa versa), you will most likely see a broken back hoof pastern axis (HPA). This is indicative of low plantar P3 angles. I don't always use HPA as a definitive guide in assessing phalangeal alignment as the connective tissue can accommodate hoof imbalance to an extend and the posture adapts and becomes compensatory (until they cannot and the tissue breaks down). There is also pathology which can cause the hoof pastern to drop and in these instances, you cannot use HPA to assess hoof balance.


5. Collapsed caudal foot and hoof. The heel is non-existent and I cannot actually mark it up. I have made an educated guess as to the angle of growth. The horse is essentially standing on the back of the heel bulb and back of the heel tubules, thus pushing the heel further under. There should be a visible heel, and the ideal length, proportion and angle will vary according to the structural (and to an extend, the postural) conformation of the horse. If it were to grow currently, it would be at around 15 degree initially or less, until it is allowed to restore and become more upright and under the horse. In this breed/type (Dutch warmblood) is should be well developed, possibly around 1.5 to 2:1 toe:heel length ratio, with a high angle (around 55-60 degrees) with a deep digital cushion, upright ungular cartilage and a matching plantar P3 angle. It should be within 5 degrees of the dorsal wall angle, which is currently 48 degrees.


6. The dorsal wall angle and length, its relationship to the heel and the innate ideal static and limb conformation of the horse tells me it is about 8 -10 degrees too low and could possibly be NPA (negative plantar angle).


7. Excessive periople can indicate poor hoof function associated with poor hoof morphology.


In essence, and to summarise, all of the above points leads me to conclude, with confidence, that the horse has low plantar P3 angles, insufficient depth, collapsed and deflated caudal tissues and most importantly, a lack of alignment of the phalanges. This limits its functionality and ability to successfully deal with energy created during the stride.


The tension this places on the tissues on the foot and limb leads to compensatory and pathological limb and body posture and your horse is at risk of tissue breakdown and concomitant lameness in the limb and body.



What's the hoof score?

It is important to recognise the morphology and provide a hoof score to inform and guide the owner and professional team. This helps protect the horse from harm by asking it to perform at a level in excess of what the hoof/body/horse is capable of and what intervention is necessary to improve the score to the desired level required or desired of the horse.


The riders ability, whole horse, history, age, body condition and fitness (which includes soundness, conformation and posture) needs careful consideration. In a consult setting, this is what we assess. In this instance, and for the purpose of this exercise, the hoof morphology alone would lead me to provide a hoof score of 2/10. Given that a minimum hoof score required for a horse simply to be ridden is 5/10, my advice would be to rehab this horse and exercise according to the hoof score.


Below is a chart where I was using a hoof score out of 6, however, we now use a score out of 10 (we are constantly looking to improve and evolve our approach and services). The principles remain the same however:




Why change the hoof care and hoof morphology?

This hoof morphology and resulting (and/or influencing posture) creates significant pressure on the abaxial and axial skeleton, leading to an increased risk of compression of the joints, vertebrae, nerves, blood and lymph in the spine, fascia, muscles, cartilage and connective tissue, placing your horse at risk of a wide range of health issues including but not limited to:

  1. Hoof pathology including navicular disease/syndrome, laminitis, infections, pedal osteitis, side bone, ring bone, flare, cracks, sepsis, and generally poor hoof growth and trauma and evidence of this (flares, rings, cracks,seedy toe, abscesses etc)

  2. Limb pathology including arthritis and injury to the pastern, knee, elbow, hock, stifle and ligament or tendon injury anywhere in the limb

  3. Secondary pathological posture issues in the spine including SI joint issues, kissing spines, wither, neck and poll issues

  4. Secondary pathological posture issues in the body caused by nerve impingement or compression in the spine, fascia, muscles and impacting function of the organs and peripheral limb, including hoof growth issues, digestive issues, malnutrition, colic, ulcers, reproductive organ issues, dental issues, heart and lung issues, hypoxia, etc


Recommendations

I had the opportunity to talk to this horses farrier and he hadn't recognised the poor hoof morphology and welfare and performance risks involved and we discussed the relevance of shoeing to support healthier phalangeal alignment and appropriate PA via a more appropriate shoeing package. I advised that he seek appropriate farriery advice and recommended educational resources and professional support from Yogi Sharp from The Equine Documentalist.


It might be possible to rehab this horse barefoot, however this isn't always appropriate and intervention using shoes can quickly break the posture/hoof morphology cycle and relieve tension on the body quickly and facilitate healthier hoof growth initially, making barefoot rehab more successful once there is improved growth and biomechanics.


Where there is evidence of NPA I recommend properly taken balance podiatry radiographs to confirm PA, help with hoof scoring and recognise the appropriate intervention, which in any case should help promote healthier phalangeal alignment via trimming and/or shoeing. It is worth noting that some horses can be successfully rehabbed using boots/pads which allows for more regular trimming but this depends on the available environment and individual horse.


Below is a photo taken of a clients horse during acquirement of high quality podiatry balance radiographs. This is essential for quality scaled marking up and assessment. Please ensure your team have the correct equipment and metholodogy! Our free online course and blog guides on documenting can assist with this.




It is important to address diet and relieve symptoms associated with compensatory posture, nerve impingement and pain, so it is critical to involve a vet where the horse is unsound or there is evidence of pain and ulcers for instance. I also recommend a holistic rehab programme which will typically also include BTMM (Balanced Through Movement Method) to help address unhealthy limb and body posture and associated issues and specifically, nerve compression and BTMM experts and therapist can help support your horses rehab, hoof and body development, in-person, or where this isn't accessible; on-line. There is currently only one BTMM nerve release therapist in the UK (Yasmin Stuart), however there are 5 new students currently in training in the UK, myself included.



Summary

It is critical for the well-being and lasting longevity of horses to be able to recognise healthy hoof and posture, and monitoring hoof and posture morphology is essential in a PRO-active approach to horse welfare and soundness. HoofmApp and other hoof mapping software such as Metron-Hoof are available to help horse owners and professionals to document hooves and postures and provide effective interventions to correct and maintain healthy hoof ideals.


A holistic and integrative approach to improving and maintaining healthy hoof morphology and posture is essential. In addition, hoof scoring helps identify the usability of a horse to preserve health, identify appropriate and timely interventions and monitor changes. It is therefore also essential that hoof care professionals work together and with other equine professionals to provide appropriate support and referrals.

We all want the same thing - healthy, happy horses and owners. Objective data can inform - but first you have to look!

If you resonate with the information provided here, and believe you can offer horse owners and other professionals much needed holistic support to help horses create and maintain healthy hoof and posture, drop us an email at beccy@holisticreflections.co.uk We are always searching for accessible support and resources for horses owners (and professionals) not just in the UK but internationally too.



Additional resources and assistance

We take an integrative and holistic approach to whole horse hoof and body health. We appreciate the relationship between body, limb and hoof and seek to address imbalances while positively influencing appropriate static and dynamic hoof balance and biomechanics.


If, like our clients, you want to learn a PRO-Active approach to hoof care and wish to prevent lameness in your horse, consider booking us for an Integrative Podiatry Consult, Educational Event, Mentorship, On-line Course or join our new Remote EP mentorship plan where you can learn top tips on how to help rehab your own horses hooves, and have weekly support, tailored to you and your horse!


We also recommend you learn how to document horses hooves and body, whether you trim your own, your clients horses, are an equine professional (in any capacity/field) or simply want to track and monitor progress of your horses hooves and the impact their hoof care has on their posture.


Related articles:

Further information, recommendations and links


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Beccy Smith BSc ADAEP EBW

Diploma in Advanced Applied Equine Podiatry and now an Independent Integrative Equine Podiatrist, Consultant and Therapist

CEO and Founder of 100% Non-Profit Community Interest Company Holistic Reflections CIC

Holistic Reflections CIC – a 100% non-profit organisation promoting wellbeing and resilience in people, horses and the environment - for the benefit of all.

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