ARCHIVE - ARTICLES 2008

February 2008 - Thoughts about 'jarred up' horses
Suggested involvement of top line, shoulders, knees and feet

 

Archive - Forge Magazine - February 2008
Thoughts about 'jarred up' horses
Suggested involvement of top line, shoulders, knees and feet

 

Peter Baker, AWCF, is an experienced farrier based in Marlborough, Wiltshire.
He sits on the FRC Council as an elected member (Southern area) employee farrier

Physical condition
At the height of the flat racing season, how many terms, along the lines of ‘jarred up’, are used to describe horses that lose their action and have become ‘scratchy’ and non-free-flowing in their movement? The description depends upon those that are explaining the condition, and what is perceived to be the cause and the effect. However, being ‘jarred up’ offers no observable foot-specific condition.
Horizontal striation of the dorsal wall [Fig 1] is rarely present in two-year-olds [Figs 2 and 3], but is fairly common in the three-year-old plus groups [Figs 4 and 5], specifically when the animals have raced on firm ground the previous season.
There are several diagnostic constants that mix the primary causes of being ‘jarred up’ with the secondary effects, to form the source of the discomfort. The primary cause of loss of action relates to horses’ feet suffering acute inflammatory changes. The conclusions are drawn from physiological changes noticed recently, now considered relevant to the loss of action during the previous racing season, some six to 10 months after the physiological insult occurred.
Early foot changes are demonstrated by irregular growth patterns in the development of the dorsal surface of the hoof wall that relate to voids within the structure of the hoof, [Fig 3]. The features progress downwards locked in the structure of the hoof wall during normal growth, and descend from the area of formation, initially located within the tissues of the coronary crown. In time the horn tissue grows/develops down towards the weightbearing surface. The voids are revealed, physically and visually, when the attendant ridging and grooving reaches ground level [Fig 3].
Without doubt, the observations so far as flat racehorses are concerned, relate to an incident or repeated incidents of athletic output during the previous race season, on ground conditions unsuitable for the animal or its physiology [Figs 4 and 5]. The horse often presents as not being free moving, without any observable unilateral lameness. Often a few days on ‘the walker’ at rest and medication with an anti-inflammatory drug will enable the animal to continue racing throughout the season, without any apparent loss of form. The animal’s action, however, has changed and varies from slightly off to quite uncomfortable. To continue to race demonstrates how adaptable a racehorse is, which probably is related to its natural resolve to survive predation.
...when moving at speed, horses prepare to land using lateral and medial adduction and abduction prior to foot planting...
Landing
Colleagues have long since suggested that, when moving at speed, horses prepare to land using lateral and medial adduction and abduction prior to foot planting, a flaccid lower limb flight state. They are probably assessing the nature of the ground surface and what adjustment to make to avoid injury. Chris Pardoe demonstrated this using high-speed video at a seminar earlier this year.
The landing preparation aspect of the stride of sore or jarred up horses is dramatically visually bilaterally exaggerated. Instead of abducting/adducting its feet, the horse assumes a base-wide flight where, prior to landing, its feet describe circular movements. The movement is bilaterally matched and symmetrical, but such motion is felt to be abnormal as the forwards-progress is mechanical (not free flowing), yet the animal does not exhibit single leg lameness.
What is happening in the foot?
There is strong evidence of coronary shunting, affected by concussive forces transmitted through the dorsal wall of the hoof into the sensitive tissues of the coronary cushion, because of a firm racing surface or unsuitable training surface. It is these concussive forces that cause the coronary corium to lay down a protective fluid barrier, a ‘coronary seroma’ (blister) or, in the most severe insults, a ‘haematoma’ (blood blister). These fluids protect and buffer the vital horn growth area, and become locked within the growing structures of the dorsal wall. The lymphatic system mops up the fluid fairly rapidly but a cellular, sometimes bloodstained, void remains within the structure of the wall that, coincidentally, functions as nature’s shear line, causing the defective horn to snap off. The severity of the initial physiological insult determines the extent of the fluid, seroma/haematoma, and the resultant cavity or void.
The weakened, cellular or hollow area locked up within the horn and below the coronary crown initially dissipates shock by way of a hydraulic, damping, action. Later the cavity buffers further insult, a near perfect way of reducing collateral damage, however, further concussive injuries compound the syndrome. The repetitive nature excites the formation of the insecure and defective horny structure found in broken down (abraded) feet.
The problems of shoe attachment to this defective horn are effectively still latent as it is above the area used for shoe attachment.
Abraded feet
‘Abraded’ feet, is a fairly loose term to describe the ultimate nightmare for the farrier offering racetrack support. The distal edge of the hoof capsule is flaky, cracked, under-run with cavities and, to a greater degree, is loose from its supporting structures [Fig 8]. The sole is often found to be thickened, one of nature’s processes to protect the solar surface of the distal phalanx (P3) and its related soft tissues. This thickened sole is often not sufficiently mature to be mechanically exfoliated and has to be physically sculpted, a somewhat delicate process. This sole commonly hangs down below the level of the hoof wall; sadly nature takes no account of the need for a farrier to attach a shoe! The act of reducing the double sole remains the decision and control of a farrier.
The increased thickness of the sole appears to create stressing forces of its own, demonstrated by the sideways loading on the weakened wall that accelerates the natural separation of the defective superficial structures. This is probably a necessary, normal stage prior to nature’s rebuilding of the hoof. Another feature often seen is the presence of a dorsal depression in the wall (Bailey, Newmarket Seminar, 1989) [Figs 2, 3 and 8]. The inflexible nature of the thickened sole constricts the natural processes of the connective tissues. In the wild state this horse would be in a recovery state and acutely in danger of predation.
These feet seldom support a shoe satisfactorily. Racing plates tend to become detached easily, especially during transit. This is a headache for the racetrack farrier, as in order to reattach a shoe, the loose unviable horn and great deal of the remaining poorly integrated glue has to be removed [Fig 8]. This is required in order to achieve a satisfactory layer onto which a shoe could be loaded and to re-attach or nail the plate into. The problem is that often after the defective horn is removed there is insufficient wall horn left, both quantity and quality into which a nail can be driven. Nails can often only be placed in the toe area and, perhaps, one nail in each heel because no other viable nail-supporting wall horn remains. The thickened, solar plate can, in the short term, be used to assist with a semi-secure nailed shoe attachment. This is demonstrated by the system of low nailing and close shoe fitting sometimes seen in US imported stock.
With ingenuity, stealth, a great deal of luck and some skill, a failure to reattach a shoe for the purpose of a single race is extremely rare. In my experience, this has occurred twice in 26 years, once due to the stroppy nature of the patient (who immediately struck the replaced shoe off again); on the other occasion, the animal was as lame after re-attachment as it had been with the shoe absent when it arrived at the track.
For interest’s sake, occasions have arisen when horses have gone to post where the nailing was supported by electrical insulating tape. At other times the shoe and nailing was supported using layers of Vetwrap (3M). Both are useful tools to have in the van. What happens after the animal returns to the care of its yard technicians is fortunately another’s worry.
Voids within the horn represent wall detachment and the formation of ‘locked up’ cavities, so that when the affected area reaches the level of bearing, there is a loss of integrity with the underlying and surrounding horny tissue. The remaining wall structure gradually fractures away from the defective basal connection, and further disintegrates under the loading associated with the stresses of athletic performance, and when any attempt is made to nail into it.
...when the farrier’s nails penetrate into the cavity in order to attach a racing plate...
Seedy toe, yeast infections and white line problems
There is a complicating factor in feet containing dry seroma cavities. The integrity of feet affected in this way remain fine, and seem to remain so until the separated area grows down to a level of the white zone junction, when the farrier’s nails penetrate into the cavity in order to attach a racing plate. The action of nail penetration seems to trigger a secondary effect, by, perhaps, introducing bacteria and yeast infection, associated with loose wall, seedy toe and or white line disease. These conditions assist the weakened foot and separation of the hoof wall from its junction with the solar plate. The author feels that infection is an induced condition, secondary to the original insult.
Further breakdowns of the wall sole junction are without doubt related to environmental influences, concussion, and compaction by the racing/training surfaces.
To identify the onset of these syndromes requires close observation as the initial indication is masked by the racing shoe and is not unusually seen as an extremely thin linear fissure, on many occasions detected by little more than a gut feeling. If the fissure is missed at an early stage, then during the course of a full shoeing cycle, horn destruction will take place in the area of the white zone. A seedy toe, yeast-induced wall separation will occur and, unless effectively dealt with, will migrate up the bisulphide junction more quickly than the wall can grow downwards, creating a chronic and accelerating condition.
This horn decay is something that can be easily controlled and/or reversed, with recently and specifically developed products that toughen and condition hoof horn and destroy hoof related infection. My own trials using Equitech Hoof Hardening Gel over the past two years have yielded good results.
‘Bandaids’, acrylics and polymers, glue-on shoes, panic fixes versus diet, environment and hoof conditioning
When problem feet are being addressed there is a distinct move towards the early use of hoof rebuilding materials, and the attachment of alloy plates using glue. This is the equivalent of a ‘Bandaid’ exercise. [Figs, 10 to 13]. Undoubtedly, glue destroys the integrity of some viable and healthy hoof horn. This rebuild/attachment method is a nightmare to the racecourse support farrier, rebuilt feet and the shoes attached with glue seem to be easily rejected. During the course of a year, several reinforced feet/glue-on shoes are lost at the racecourse prior to racing. In fact, the majority of front feet presented for shoe re-attachment have evidence of glue/rebuild materials. When this happens most of the lower hoof wall falls away with the polymer and/or the acrylic. There is never sufficient time for the racecourse farrier to re-glue or re-build a foot. The retained farrier has to find a way to replace the glue reinforced/attached shoe using the traditional nailing method.
Once a horse is at the racecourse, there is little more critical than getting a horse to the starting gate sound. It is a stressful time for everybody, and damaged feet are best avoided.
How can feet be made to regenerate sufficiently after having been subject to treatment with re-enforcing material? The basic conclusion seems to be, getting back to common sense methods, good diet, working on suitable surfaces, [sea sand is not one of these], good husbandry, a regular shoeing cycle, sufficient hygiene, suitable bedding, pre-racing foot conditioning and an observant farrier. A most important aspect is conditioning of the animal and its limbs, in a way to assist sufficient horn keratinisation, which possibly can be effected by training on suitable surfaces and the use of suitable bedding. National hunt horses subjected to an element of road work in their preparation seem to have less hoof problems, yet this may simply be that they do not race on very firm ground, a seasonal influence.
Looking ahead
In the future should we consider fitting a rolled toe shoe when animals are going to be asked to perform on really hard ground? There seems to be no place for the general use of the square toe shoe on the racehorse due to a lack of traction during the acceleration phases, but a very light roll, as was recommended in the paper, ‘The rolled toe shoe and its dynamic effect on the front foot of the racehorse’ (1990). I believe there will be a niche for the rolled toe during the recovery stage from this condition, but how about as a preventative measure? I will undertake such a study now it has been suggested!

 

 

Top L-R
Fig 1. A normal foot of a hunting horse [Irish Sport]. One can see the striation rings growing down the hoof wall in a symmetrical fashion. Each ring represents a Saturday hunt. Just above clench level, a clear unmarked area can be seen. This represents three weeks when the hounds had kennel cough and hunting did not take place
Figs 2 and 3. The feet of a late broken, May born, two-year-old Thoroughbred. This animal was reared on the Irish bogs and taken into a deep litter cattle barn in the latter part of 2006. The animal was imported into the UK in April 2007 (it had a rough journey). Notice the absence of close work associated rings demonstrated by the horse in Fig 1. It is interesting to note the two stress trauma rings on this horse. The lower ring could be associated with its being bought into the deep litter barn. The higher ring was effected due to transit trauma. With pronounced rings like these it would not be surprising to find cavities within the wall’s structure. The rings have already started to function as shear lines (Fig 3). This animal at first had a thickened sole and later a distinct toe solar callous, which can be seen in Fig 2
Figs 4 and 5 (See below). The foot of an older horse. Each ring, ridge and groove represents a traumatic event. This animal has also developed a bulge in the heel wall, which is commonly associated with change in the structure of the animal’s lateral cartilages. Such deviation of the heel may simply be due to heel contraction. Time and the change of shoeing regimen will demonstrate if the heel wall bulging outwards can be expanded to a normal hoof cone
Bottom L-R:
Figs 6 and 7. The front feet of an un-raced three-year-old that box walks (left handed). This horse is kept tied up most of the time, yet its feet have still developed divergent rings closer together on the left side, indicative of compression during the act of inscribing tight left hand circles. Minor left side wings are also present but these will disappear at the next shoeing
Fig 8. A seriously abraded right fore foot that resulted from the impact forces of racing and training abroad, on sea sand. This foot suffered dramatic inflammatory changes that caused an almost total detachment of P3 from the forward capsule; the lateral cartilages were still integrated with their overlying rearwards hoof capsule. This animal had a bilateral doubled sole [both fore feet], the leading edge of which can be seen behind the clip in this picture. Thankfully it had good strong well-developed frogs, which sufficiently supported frog support shoes. Extensive evidence of coronary and subsolar seroma cavities were seen [right fore]. On this occasion, the condition required the use of a hoof rebuilding adhesive compound [Imprint; Poynton] to affect a horn restructuring process by re-gluing the hoof capsule to its base structure, the whole exercise required eight months in light work before the living and horny structures reunited. The animal is presently in full work, but is proving delicate to train.

 

 

L-R:
Fig 9, The rings around the foot function perfectly as shear lines to detach overgrowth of horny wall as nature intended
Fig 10. A fissure at the toe of the hoof capsule, which was present before the shoes were stripped off and the horse turned out to grass. This fissure would have been barely visible until impacted with debris
Fig 11. A left fore foot with compound material in order to veil defective areas. It is difficult to understand why. The compound hides low, weak nailing into an area of extremely weak hoof quarter horn

 

 

L-R:
Fig 12. When dressed back, sufficient horn is present in the toe and heel area to safely attach a shoe, without the need to use of a horn repair compound, or the weakened area at the widest point of the foot. The rebuilding compound is associated with horn destruction following cosmetic applications
Fig 13. The right fore foot of horse with a similar weak foot at widest part; again the foot has evidence of re-build material.
Fig 14. The front feet of the horse, standing. Once the loose material and horn was removed, re-shoeing should be straightforward. It would need some boxing off of both shoes at their widest parts

 

This article first appeared in Trainer magazine. To learn more about Trainer magazine please visit
www.trainermagazine.com