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Talking Horse Care - Racing

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Most equestrian horse owners respect the many challenges that are faced by race horse trainers when it comes to feed, fitness, care of joints that facilitate continuity of training for the horses in their stable. The success of the trainer's business is closely aligned with the success of their horses ... and horses that are not fit and well, cannot race and cannot win. A successful trainer will have many"secrets" and you can find many of them in this article.

Expert Equine Vet, nutrition and horse care specialist Dr John Kohnke has written this excellent article and all horse owners will find it very helpful.

Kohnke's Own products are available at your local Saddleworld Store.

Talking Horse Care - Racing
By Dr John Kohnke BVSc

Handy Hint 1
Maintaining Cannon Bone Strength
When a young galloper is turned out for a spell after its first preparation, even if it does not develop shin soreness, the bone on the inside edge of the front cannon bones will start to model back to a ‘resting’ diameter, strength and thickness.  Rest periods greater than 4 weeks can trigger calcium loss from the bone shaft, resulting in weakened bone. Remodelled has a greater risk of fracturing if suddenly overloaded by repeated all-out galloping on return to training.  The bone ‘weakening’ effect can be minimised by saddling up and galloping the horse over 200-400 metres once a week during the rest or spelling period in the paddock.   This will allow the cyclic loading to help maintain bone strength for return to race training and help avoid catastrophic race day failure or bone fracture.  This is especially recommended for horses resting for 4-6 weeks between hard racing campaigns.  A daily maintenance supplement of bone minerals, such as in Kohnke’s Own® Cell-Osteo® (Supplet® pellet calcium which does not sift-out or blow away from paddock feeders, or Kohnke’s Own® Cal-Xtra™ powder in a damp feed), should be maintained during the rest period to help ensure normal bone repair.

Handy Hint 2
Change Working Surfaces Regularly
In both galloping and pacing/trotting horses, high speed exercise on a dry or compacted track surface can lead to bone concussion and damage to bone. The internal scaffolding structure, referred to as cross bridging or bone trabeculae, may not be able to adapt to loading or repair itself naturally between repeated high speed cyclic loading. Although exercise stimulates new bone at the sites of compression, concussive effects can reverse this adaptation process. Repeated compression and high concussion can also deform and reduce the nutrition to joint cartilage, resulting in joint disease and osteo-arthritis.  It is important to vary the training surface, especially for gallopers, to help minimise cyclic concussion on the lower limb bone structures, being trained on dry or compacted track surfaces.  Working a horse out from the rail, or a less compacted surface, or including gallops on a synthetic or sand/sawdust track surface, can reduce the damage caused by repeated concussion on the rail.  In harness horses, where tracks are generally firmer to facilitate the lower resistance rolling of tyres on the sulky, hoppling-up and working on a dampened or lightly harrowed track surface, will help to reduce front hoof concussion, in particular, within the hooves of horses which hit the ground hard during high speed work-outs in the hobbles.

Handy Hint 3
Avoid Long Term High Dosing of Anti-Ulcer Medications
In horses with Grade 3-4 gastric ulceration or EGUS, the initial form of therapy prescribed is anti-ulcer drug medication to suppress gastric acid production to reduce its irritating effect on the unprotected stomach lining. Some medications, such as those containing Omeprazole® provide a healing benefit to the eroded gastric lining, as well as suppressing gastric acid secretion. However, suppressing gastric acid secretion by maintaining high 2000mg daily doses of Omeprazole®, can reduce the normal overflow of gastric acid into the small intestine which is important for the uptake of calcium into the body. In time (6-8 weeks or more), especially if horses are already on a diet inadequate in calcium, or when blood calcium is drained daily in those horses which sweat heavily (300mg calcium lost per litre of sweat, such as 10-20 litres lost daily by harness horses or gallopers working under hot or tropical conditions), can result in bone demineralisation of the pedal bone, cannon bones and pelvic/spinal column bones, increasing the risk of fracture. Phasing out the medication by reducing it to a maintenance dose after 10-14 days, and offering a daily pre-exercise meal of 4 litres of lucerne chaff, 4 scoopsful of Kohnke’s Own® Gastro-Coat® and 40g (2 tablespoonsful) of fine limestone (Ag-Lime™) as a small feed 30 minutes before training each day, has a role in providing natural saliva–like gastric acid buffering. Kohnke’s Own® Cal-Xtra™ is a calcium supplement which forms an acid salt during digestion in the small intestine, providing a role in calcium uptake in horses on long term gastric ulcer medication.

Pedal Osteitis - a result of concussion
The internal pedal (coffin) bone is encased in the hoof wall and protected on its under-surface by the sole and frog and the bulbs of the heels to the rear.  However, repeated jarring and concussion in both gallopers and harness horses, especially those worked on a hard track surface, such as next to the rails and particularly on parched, dry summer tracks, can act to reduce the blood supply and deoxygenated blood drainage, as well as the normal vital under-sole shock absorbing action. This can lead to devitalisation and inflammation of the pedal bone, with fluid collection (oedema) of the lower borders and under the base of the pedal bone. Often the bone itself becomes inflamed, starved of oxygen and nutrients, resulting in an increased rate of bone mineral loss (demineralisation). The ‘honeycombing-like effect’ eventually results in enlarged vascular channels and loss of strength of the outer edges of the wedge-shaped flare or rear wing of the pedal bone. There is a link between grain overload, hind gut acidosis and low grade laminitis in race horses, with loss of mineral density of the pedal bone surface as the lamellae become chronically inflamed. The combination of chronic bruised soles and loss of bone density, particularly in heavily shouldered horses, especially those which gallop on the forehand on hard tracks, causes an increased risk of pedal osteitis and pedal bone weakness leading to fracture of bone segments or the wings.
There is also a possible heritable link associated with pedal osteitis in bloodlines of Thoroughbreds with larger hooves, thin or flat soles and low heel conformation which can pass on a higher risk to their progeny, especially when they are worked on compacted surfaces.

Symptoms
Some horses, in my experience, such as large chested and heavy shouldered fillies and mares which develop a shortened stride and obvious foot soreness with symptoms of a ‘shuffling’ or ‘scratchy’ gait at the trot, usually in the leading forelimbs, are likely to develop underlying pedal osteitis as they age. Many only initially display signs of hoof pain and tenderness when galloped on sand.  Tapping the soles on the affected hoof/hooves, and firm pressure exerted by hoof testers over the whole sole, will usually result in a withdrawal reaction and increased lameness for 7-10 strides on trot-out.  Horses with chronic pedal osteitis exhibit foot soreness when walking on soft sandy surfaces, which compact under the soles with the under surface of the pedal bone bears more direct weight. In horses on high grain diets, low grade laminitis should always be considered as a cause of foot soreness and ‘scratchy’ gait on the trot out. Studies in the USA in the late 1980’s indicated that 46% of foot-sore gallopers developed grain starch overload induced hindgut acidosis, often with ‘cow pat ‘droppings and low grade laminitis.

Diagnosis of Pedal Osteitis
Pedal osteitis is most common in the Thoroughbreds with ‘boxy hooves’, ‘flat feet’ and soft soles. Any 3-4 year old horse with heavy front shoulders, low heels, and a hard hitting hoof fall, which exhibits pain reaction to hoof testers pressed around the edges of the sole, is likely to be developing pedal bone erosion. Diagnosis can be confirmed by X-ray to identify demineralisation and the ‘rat-eaten’ edges of the pedal bone characteristic of pedal osteitis in horses with a history of ‘sore feet’, especially when galloped on a soft, sandy surface. However, more accurate diagnosis is now available using Magnetic Resonance Imaging (MRI) and even Nuclear Scintigraphy, both of which are useful to pin-point inflammation, inflammatory fluid collection and swelling around the pedal bone. Consult your vet for advice.
Radiographs taken from a front 45o angle show the edges of the pedal bone to help determine demineralisation, widened and increased vascular channels and uneven, eroded edges of the pedal bone. This is necessary to differentiate between pedal osteitis, with and without fracture of the pedal bone. In harness horses which ‘hit the ground hard’ when pacing, the demineralised, weakened channelled bone edges can break away on the sides of the pedal bone by fracturing across the inwardly radiating eroded vascular channels around the borders of the pedal bone.  X-rays will also help to differentiate navicular syndrome or fractured side-bone in older campaigners, which may have similar symptoms, especially if they also exhibit caudal (rear) heel pain.

Handy Hint 4
Check for Corns and Bruised Soles
Many horses with pedal osteitis (coffin bone inflammation) and sore feet syndrome will exhibit a painful reaction when pressed firmly with the hoof testers around the edge, over the central sole area in front of the frog and around the quarters. However, it is important to check for specific sore spots in the rear quarters of the hoofs for deep bruising or a corn.  Deep seated corns can cause local bruising around the edge of the pedal bone. Your farrier or vet will pare away the sole over a painful focal area to check for tell-tale discoloured areas in the sole which can indicate deep bruising and hard pea-like dry, corn tissue.  It is also a good idea to carefully remove excess sole growth to check for discolouration due to chronic sole bruising in horses with a ‘stilted’ or ‘scratchy’ trot-out on a hard surface.  Some horses with pedal osteitis will also show increased ‘ouchiness’ for a few days following a trim back on the walls and after being shod with wide shoes which overlap onto the sole around the inside of the white line, especially on the borders of the quarters. Consult your vet or farrier for specific advice.

Handy Hint 5
Consider Bevelled Shoes and Aluminium Sole Protection Plates
The usual treatment for early pedal osteitis is a prolonged rest and turn out for 4-6 months in an attempt to allow remineralisation of the bone. Although for many years, anabolic steroids were prescribed, combined with a calcium supplement to help the remineralisation process within the pedal bone, the long withdrawal times and the banned use of anabolics prevents this time-honoured therapy.
Initially for the first 2-3 weeks, under-sole pain and the pedal bone inflammation may be controlled by anti-inflammatories at a dose to maintain comfort, rather than to achieve total pain relief.  Shoeing with leather pads or anti-concussion shoes is often advocated, but in chronic cases, relieving sole-ground contact and concussion is essential.  This can be assisted by fitting bevelled or ‘sole-relief’ shoes (Mustad Horse Shoes™) to minimise the contact pressure on the inside of the white line around the quarters and toes of the front hooves. It is important to prevent sand compacting between the sole and shoe along the sole relief edge or gap over the white line. This can be prevented by wiping the sole and bevelled gap with liberal amounts of methylated spirits to remove grease and contamination and then packing the gap with a bead of silastic window or bathroom sealant. Then smooth it off onto the sole to provide increased shock-absorbing function from the layer of silastic filler. Many ‘shuffly’ horses will trot off and work sound after being fitted with bevelled cushioned shoes. If you would like more practical guidelines.

Please email Gary at newsletters@kohnkesown.com to request a copy of Fact Sheet C16 - Hoof Angles and Anti-Concussion Shoeing. It provides step by step instructions on fitting sole-relief/bevelled shoes, including filling the gap with a bead of replaceable silastic sealant.

Aluminium sole protection underplates, cut out from 2mm thick aluminium sheet, trimmed to the shape of the shoe, with rounded off edges and then nailed between the shoe and hoof wall, can provide additional under-sole protection for horses with pedal osteitis. A 13mm hole can be drilled at the toe inside the white line before the under-plates are nailed in place to allow a hose nozzle to be used to flush out sand under pressure after each training workout. A strip of wide duct tape can be stuck over the hole to prevent contamination entering the under-sole space. The gap between the under-plate and sole can be dried using a warm stream of air from a hair drier directed at the heels to avoid softening of the sole and fungal build-up. After drying, the plate-sole space can be flushed with a mix of 80% methylated spirits and 20% Betadine® or Vetadine® to aid drying and control fungal infections.

Handy Hint 6
Consider Magnetic Bell Boots to Promote Hoof Circulation
Studies in humans have indicated that the drug Tildren® is helpful to promote remineralisation of osteoporotic bone.  However, the drug is not approved for use in horses in Australia and it is expensive, costing over $1,000 per single dose.  Over recent years, magnetic bell boots with at least 3,000 gauss magnetic strength, which is sufficient magnetic field power to attach and hold their own weight on a steel fence, have been used to normalise blood circulation and hence nutrient supply to the porous pedal bone.  Any less magnetic strength and hence tissue penetration, is considered to be of little benefit in aiding blood circulation.  Magnetic fields also attract calcium into the bone within the magnetic field area and are promoted as an aid to remineralisation of the pedal bone and callous formation of pedal bone fractures.  Magnetic bell boots are also claimed to be of benefit in promoting hoof growth in horses with slow growing or ‘shelly’ hooves, as well as an adjunct to therapy for pedal osteitis and pedal bone fractures. The bell boots should only be applied for 12 hours per day, usually overnight when a horse is confined to a stable.  Magnetic Pastern Bands (e.g. Dick Witt®) are also claimed to improve hoof circulation.  The magnetic strips can be glued to conventional ‘velcro’ bell boots around the mid-section of the bell boot to focus the magnetic field within the hoof and pedal bone.  A calcium supplement, such as Kohnke’s Own® Cell-Osteo® Supplet® pellets, or Kohnke’s Own® Cal-XTRA™ can be fed daily as directed to provide calcium and bone minerals, with Vitamin A and D. A daily supplement of Bonefide® containing a patented Vitamin K blend which is claimed to assist bone deposition,  may be also be prescribed. Consult your vet for advice.

Stone Bruises -‘ouchy’ lameness
Bruised soles and heels are a common problem in horses worked on hard, dry home training track surfaces containing small stones, or those conditioned by paddock work on rough ground, especially unshod horses and those with already collapsed or ‘dropped’ soles and ‘flat feet’ on the front hooves.
Lameness caused by a stone bruise is a common reason for downtime from training or for being scratched from a race.  The direct pressure causes under-sole deformation, rupturing of sub-sole micro-blood vessels, with discolouration due to blood seepage and local clotting of blood trapped in the bruised tissue within the sole lamellae and corium tissue.  Because of the interruption of the sole integrity by a stone, the damage to the under-sole barrier membrane may allow entry of bacteria from ground contamination through the sole tubules, with the likelihood of abscess formation, resulting in intense pain, inflammation and lameness.
In cases where a shoe has been made to be turned in at the heels for horses with contracted heels, the shoe can effectively block the clearing of sand from the grooves (‘sulci’) around the frog. The sand may compact to form a stone-like mass which is packed even harder by rapid acceleration when galloping off. The sand is forced back in the frog grooves towards the bulbs of the heel where it collects and compacts. Some researchers consider this to be the most common cause of heel bruising of the medial (inside) heel of the hoof in a race horse.
Stone bruises are best carefully pared out to allow drainage. In some cases, a warm damp poultice may be necessary to soften the sole or mature an abscess to allow it to be drawn out. The crater left may be covered with an antibiotic preparation and bandaged to allow healing of the sole for a week or so before the horse is returned to work. Where horses are prone to repeated under-sole hoof infections, stone bruises are the common underlying cause if a horse is worked on rough or stony surfaces, especially during wet weather.

Corns - Pain in the Quarters
A corn is a localised sole bruise in the rear of the hoof where the quarters narrow towards the heel and the grooves of the frog (sulci). 
A corn forms most commonly when a shoe is loose or the side walls at the buttress overgrow the outer edge of shoes, allowing the shoe to move inwards off the wall supporting edge onto the sole as the quarters expand outwards as the hoof lands heel first onto the track surface. Shoes which are placed tightly on the quarters to restrict their expansion during the weight bearing phase of the stride, can also bruise the sole and result in a corn. A ‘dry corn’ is a thickened and often bruised area of hardened sole which can cause pain and discomfort. A ‘soft’ or ‘moist’ corn is an infected stone bruise or shoe pressure point in the heel area, often weeping serum and pus when opened. Excess trimming to thin the sole along the sides of the quarters can also lead to increased shoe-sole contact and internal bruising to form a corn.
Diagnosis
Most trainers are familiar with the heel lameness associated with a corn(s), which with careful scraping of the sole, can reveal it as a discoloured hard, horny area within the lower layers of the sole. A corn is most commonly caused by deformation and bruising of the sole by an ill-fitting or loose shoe. The bruised, blood filled area may become infected during wet conditions by soil microbes. An infected, soft corn will discharge smelly pus and blood tinged serum when it is opened by your farrier or vet. If left untreated, an infected corn can migrate as a tract of infection upwards under the internal wall of the heel to the coronary band, bursting out as an abscess and causing separation of the hoof wall and coronet at the heel.
Management
This is a job for your farrier or vet as the corn will need to be either cut out or opened and pus drained out to relieve the pressure and pain, aided in deep corns by a drawing poultice, such as an Animalintex® pad bandaged onto the hoof overnight.  An antibiotic infusion into the crater left after the corn is pared out, with bandaging and box rest to keep it dry for a few days, may be necessary.

Handy Hint 7
Avoid Glue Lumps When Fitting Glue-on Horse Shoes
An ill-fitting shoe, a loose shoe on an over-grown hoof wall which exerts pressure on the inside of the white line and outer sole edge, can also cause sub-solar bruising.  Where glue-on shoes are fitted for racing or for therapeutic or shock absorbing benefit, it is important to avoid dropping beads of glue on the sole or using excessive amounts of acrylic glue which sets hard and acts as a ‘lump’ on the inside edge of the shoe or on the sole itself. It is important to scrape off any excess glue before it sets, especially around the bulbs of the heels where hardened glue can form a sharp edge and pinch or bruise the bulbs of the heels to cause extreme pain and lameness.

Handy Hint 8
Managing Dry, Non-Infected Corns
If the corn is dry, hard and sensitive, acting as a small lump in the heel area, then paring it out and packing the hole with gauze soaked in 80% honey (Manuka® or Tasmanian Leatherwood® honey) mixed with 20% PVP iodine as Betadine® or Vetadine® by volume, and bandaged daily for a few days during stable rest, may minimise infection and allow the sole corium to regenerate protective horn tissue.  A bar shoe with a leather pad to support the heel and keep the bruised area dry with silastic window sealant smeared over the crater (after cleaning with methylated spirits to remove fat and oils) will provide a waterproof compressible and flexible barrier under the pad.  This can be removed and replaced every 5-7 days until the corn area heals. Consult your vet for more specific advice.

Pedal (Coffin) Bone Fractures
Although a pedal or ‘coffin’ bone fracture is a rare occurrence in a young horse, older race horses, particularly harness horses, can fracture a segment along the edge of the pedal bone, or the outer flat side of the flared-out wing along the rear edge of the pedal bone.  Most gallopers land on the outer edge of their heels at the point of ground contact at the gallop, placing high loading forces on the thin pedal bone wing.  In many cases, the horse may be lame off and on for some time, with acute lameness becoming apparent when the fracture becomes inflamed or spreads upwards into the coffin joint.
Surgical stabilisation of the fracture by inserting a bone screw to unite the fracture or floating section of bone if a large section is separated from the pedal bone, with stable confinement and a stabilising bar shoe, may be recommended to help the fracture repair. However, where the bone is severely eroded or the fractured portion is demineralised, then there is less chance of long term stable healing or callous formation. Magnetic field therapy and calcium supplementation may be also useful to repair the fracture. (refer to Handy Hint #6)
Consult your vet for advice, as retirement to breeding may be the best option in an older well performed mare or stallion.

Handy Hint 9
Check for Pedal Osteitis as a Cause of a Pedal Bone Fracture
A developing pedal osteitis within the pedal bone, with demineralisation at the rear of the pedal bone, or around the borders, increases the risk of an edge or wedge segment fracture.  The widened vascular channels join to form a weakened focus point within the demineralised internal honeycomb-like bone structure.  In an older harness horse, an X-ray may reveal a bone cyst or an internal cavity which has developed within the devitalised pedal bone, most commonly within a hind limb pedal bone.  The weakened bone area can result in a secondary fracture, especially if the horse is a ‘hard hitter’ and hoppled up and worked or raced on a dry, compacted track surface. Consult your vet for advice.

Did you know that...
Bone is an adaptable, living tissue which can react to the demands of weight and momentum loading during exercise.
It is light weight and structurally reinforced internally with cross bridging (trabeculae) enabling it to withstand high compressive loading of up to 5,000 kg in a galloping horse.
However, bone has a low sideways strength, with only a 45 kg force from the side being enough to break a front cannon bone.
The front cannon bones in particular, have to adapt to the repetitive cyclic loading of fast exercise. Bones will become more dense, increase their circumference and thicken along the stress lines (loading pathways) to withstand high speed momentum weight loading.  They are also able to decrease in density or mass and surface strength in the shaft cylinder wall (cortex) when loads are reduced during a rest or spelling period out of work. The cylinder wall can increase in thickness by 2-3 times as it reacts to high speed cyclic loading when galloping. 
All bones have an important role as a calcium storage depot (‘bone bank’ of calcium) and calcium can be either stored in the bone tissue or ‘mined’ to top–up blood calcium, relative to blood calcium levels from hour to hour. 
Calcium has a vital role in muscle contraction and tone, and bone provides the ‘bank’ to maintain blood calcium and normal muscle function. 
Bone also has a hollow ‘medullary’ cavity where red and white blood cells are synthesised, as well as stem cells which can differentiate into other tissue cells as a basis of healing.  The race horse in training produces around 7 million red blood cells per second in its bone marrow to replace dying cells and to increase cell count to carry oxygen as the demand increases due to anaerobic fast work.
The race horse in training relies on skeletal adaptation to withstand the high loading, but it takes time to model and strengthen bone.  Overloading of the front cannon bones in particular must be avoided in the immature skeleton as it adapts over a 6-8 week period to carry the increased loading of momentum at fast speeds. 
Reference:  Dr Larry Bramlage DUM (2013) AAEP Proc 59:412-422

Did you know that...
The hoof structures, especially the front hooves of galloping horses, withstand high loading and shear forces.  It is estimated that the hooves bear up to twice the horse’s body weight during a straight gallop, and up to 5-10 times the body weight (up to 5000kg for a 500kg horse) when cornering on a sharp bend on a race track.  The hooves must be shod so that hoof wall, rather than the sole carries the weigh, which is important to avoid sole concussion, stone bruises, and corns.
Ideally, the hoof should be trimmed so that it lands in a balanced and symmetrical pattern that ensures an even weight distribution onto the hoof wall.  It is important to realise that the symmetry of the hoof should match the limb conformation, so that the hoof lands in a flat strike pattern.In other words, if there is a natural deviation of the pastern that influences the way the hoof lands, it is important to evaluate the individual horse’s strike pattern when trimming the hooves.  The way the hoof lands at working speeds when maximum loading is imposed, may improve the long term soundness of a horse if the hooves are properly balanced.

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