lameness (equine hoof affections) Dr. Alaa Ghazy

lameness

عالء . دغازي

مدرس الجراحهالبيطريهكلية الطب البيطريجامعة كفر الشيخ

دكتوراه من الواليات المتحده االمريكيه

Equine Hoof Affections

LaminitisINTRODUCTION

o Laminitis is a painful condition of the sensitive laminae which attach the hoof wall to the pedal (coffin) bone.

o It can affect one foot or more and most commonly affects the front feet as they bear more weight than the hind feet.

LaminitisINTRODUCTION

o Laminitis occurs or progresses in three phases: Acute laminitis: initial phase of laminitis accompanied by severe pain

(acute phase may recur during sub-acute or chronic phases) Sub-acute laminitis: follows after acute phase subsides, it is a less painful

phase which involves either the repair of or progressive damage to the sensitive laminae (depending upon the severity of the acute phase)

Chronic laminitis: follows incomplete resolution of laminitis, where the feet must accommodate to the rotation or sinking of the pedal bone (pain is variable)

Laminitis is a potentially-life threatening condition and requires an urgent attention from a veterinarian.

LaminitisCAUSATIVE DISEASES OR CONDITIONS

o The primary diseases which can eventually cause laminitis are usually systemic abnormalities.

o The disease process causes toxins to be released into the blood stream, producing toxemia and, eventually, laminitis.

o Primary conditions or diseases associated with laminitis:

Excessive Lush Grass Intake Generalized Toxemia

Excessive Carbohydrate Intake Retained Placenta

Excessive Weight Bearing on Leg Thyroid Hormone Imbalance

Excessive Work on Hard Ground Pituitary Gland Tumors

Long Toe Conformation Adverse Reaction to Corticosteroids

LaminitisDEVELOPMENT OF LAMINITIS

o The primary disease process results in the release of toxins into the blood stream causing toxemia.

o Toxemia produces spasm in the muscular walls of the blood vessels supplying the hoof laminae and as a result the blood supply to the hoof laminae is restricted or abolished and its cells begin to die.

o Cell death releases biochemical mediators (body chemicals) into the surrounding tissues, causing inflammation, fluid swelling and pain (acute laminitis).

LaminitisDEVELOPMENT OF LAMINITIS

o Severe or persistent cases of laminitis:

Damaged laminae fail to support the pedal bone correctly and it rotates ('founder') or sinks within the hoof ('sinker')

Pedal bone separates uniformly around the hoof wall (sinking)

Pedal bone only separates at the front of the hoof wall (Rotation)

If not corrected, the tip (toe) of the pedal bone will rotate down through the sole of the foot, which often requires euthanasia of the horse on humane grounds

o Less severe, chronic cases of laminitis:

If neglected, these cases result in a misshapen ‘Chinese slipper’ foot

LaminitisDIAGNOSES / CLINICAL EXAMINATION

o Signs include an increased heart rate, depressed appetite, sweating, trembling and rapid, shallow breathing.

o The acutely laminitis horse stands and walks with its weight shifted onto its heels and hind limbs with a typical stance or gait

LaminitisDIAGNOSES / CLINICAL EXAMINATION

o The horse is reluctant to move, feeling footy (prefer soft ground) and may prefer to lie down to keep weight off the feet.

o Affected feet are often warm to the touch

LaminitisDIAGNOSES / CLINICAL EXAMINATIONo In chronic laminitis

Abnormal hoof growth

long curled-up toes and collapsed heels

Hoof rings (laminitic rings) sometimes thickened sole

Gas shadows at the toe may signify infection.

LaminitisDIAGNOSES / CLINICAL EXAMINATIONo In chronic laminitis

Wall cracks

Changing in hoof angle

Bruising (red) on the wall

LaminitisDIAGNOSIS / CLINICAL EXAMINATION

o The sole, particularly at the toe, is painful to examination with hoof testers

o A palpable depression at the coronary band at the front of the hoof and a convex and painful sole ('dropped sole') suggests rotation of the pedal bone and the risk of sole penetration by the tip of the pedal bone

LaminitisDIAGNOSIS / RADIOGRAPHY

o Used to determine whether the pedal bone has rotated or not, and to what degree it has rotated.

o A wire taped to the front of the hoof helps to clarify the relationship between the hoof wall and the pedal bone.

In normal hoof anatomy, the hoof wall is parallel to that of the pedal bone

Pedal bone rotation with < 5.5° between the hoof wall and pedal bone

favorable prognosis for athletic use, if the horse responds well to treatment

Pedal bone rotation with > 11.5° between the hoof wall and pedal bone

poor prognosis

LaminitisDIAGNOSIS / RADIOGRAPHY

Gas shadows at the toe may signify infection.

LaminitisTREATMENTo Complete stable rest is required in acute laminitis to prevent further damage to the

laminar support structures.o Radiographs:

Radiographic examinations of the feet will determine to what degree the pedal bones have rotated and, therefore, guide treatment

Follow-up radiographic examinations of the feet will assess the response to treatment and determine requirements for further treatment

o Euthanasia

may be indicated in the following instances:

Severe, acute cases where the horse is suffering uncontrollable pain

Severe, chronic cases where the horse is suffering incurably

Cases where the pedal bone has penetrated the sole of the foot or where the hoof wall completely separates from the foot (sloughing, exungulation, shedding or casting of the hoof)

LaminitisTREATMENTo Primary Goals of Treatment are:

Eliminate the initiating cause

Relieve the pain

Improve the blood circulation in the foot

Provide support for the foot through

trimming and shoeing and corrective surgery



Excessive lush grass or grain intake: Horse is removed from grass or grain source and laxatives (liquid paraffin, mineral oil) are administered to remove intestinal toxins. Small quantities of hay and plenty of drinking water are provided

Excessive weight bearing on leg: Lameness affecting other leg is treated.

Long toe conformation: Feet are trimmed and shod correctly

Generalized toxaemia, pituitary gland tumours: Diarrhoea, liver disease, or other initiating cause of toxin production are treated

Retained placenta: Retained placenta and associated inflammatory uterine fluids are removed and uterine infection is treated



Relieve the pain

Non-steroidal anti-inflammatory and anti-endotoxic drugs (i.e. phenylbutazone, flunixin, ketoprofen) provide humane relief and inhibit the inflammatory process

heart bar shoes can be fitted to remove pressure on the toes and hoof wall



Relieve the pain

DMSO 20-100 mg/kg bw IV

Local anaesthetic blocks of the heel nerves will abolish the pain but will encourage rotation of the pedal bone as the horse takes more exercise, and are therefore best avoided



Relieve the pain


Vasodilators (i.e. acetylpromazine, isoxsuprine) may help by relieving the vasoconstriction which occurs in the arteries of the laminae of the hoof

Nitroglycerine ointment 10-15 mg per foot, applied locally, improves blood vessels repair through cutaneous absorption



Relieve the pain


Hot or cold hydrotherapy use is controversial

Cold water cools the feet and reduces the inflammation but increases vasoconstriction

Hot water warms the feet and amplifies the inflammation but decreases vasoconstriction

Both hot and cold hydrotherapy have beneficial and detrimental effects and must be used with caution (depends upon each individual case)



Relieve the pain



Horse should be bedded on wet sand or wood shavings (these materials pack up into the foot supporting the sole)

Frog support pads, taped to the feet, will transfer weight bearing from the walls to the sole and frog, reducing the stress on the weakened laminae of the hoof wall

Feed intake should be reduced to lower body weight,

maintaining mineral, vitamin and trace element supplementation, especially biotin, methionine, and amino acids which help encourage the growth of good quality hoof.



Relieve the pain



trimming and shoeing and corrective surgery

Expert trimming and shoeing should be performed

Corrective Surgery may be helpful in some cases (dorsal hoof wall resection DHR)

LaminitisTRIMMING & SHOEING

o During the trimming and shoeing process the foot is gradually re-structured to accommodate the effects of the pedal bone rotation

o Expert trimming progressively reduces the length of the toes and lowers the heels to improve the angle between the pedal bone, hoof wall and sole and to allow new shoes to seat further back under the weight of the foot at a better angle to the pedal bone

o Heart bar shoes or other shoes designed to support the frog, transfer weight from the damaged hoof walls and encourage blood circulation in the foot

LaminitisTRIMMING & SHOEING

o Shoes which support the frog must be expertly and individually made and fitted or their use may be counter-productive (can act as a fulcrum over which the pedal bone will be encouraged to rotate further):

o Apex of the 'V' is positioned in front of the attachment of the deep digital flexor tendon to the pedal bone (by approximately 2 cm)

o Bar should not extend beyond the limits of the frog or damage to blood vessels may occur

LaminitisCORRECTIVE SURGERYo Deep digital flexor tenotomy:

The surgical section of the deep digital flexor tendon has been suggested as a therapeutic option, but results have been variable

o Dorsal wall resection:

In appropriate cases, a partial or complete surgical removal of the front hoof wall is performed under local anaesthesia

Requires expert farriery with veterinary help and supervision

May help by initially relieving pain and pressure and allowing treatment of infection

If successful, the hoof re-grows intimately with the pedal bone, creating a better angle between the pedal bone, hoof wall and sole

LaminitisAFTER-CARE

o Varies in each case depending upon severity

o Clinical condition must be carefully monitored

o Analgesic and vasodilator medication is carefully reduced over a 2 to 4 week period

o Horse should have box rest until off all medication

o Heart bar shoeing and foot trimming should be continued as determined by the veterinarian and farrier

o Once off medication and clinical condition allows, there should be a gradual return to walking exercise

LaminitisPREVENTION

o Keep horses (especially small ponies) in fit and healthy body condition, avoiding obesity and sudden access to lush grass or a high grain diet

o attention without delay for lameness, diarrhea, retained placenta and generalised illnesses

o Maintain correctly conformed and balanced feet by regular hoof trimming and shoeing (especially to prevent the development of long toe conformation)

LaminitisCAUTION

o The symptoms associated with laminitis are sometimes misinterpreted as signs of colic, muscle pain or back pain

o Laminitis is a very painful, debilitating and potentially life-threatening disease, for which veterinary attention should be sought without delay

Nail Bind & Nail PrickINTRODUCTION

o Accurate placement, by the farrier, of each nail through the insensitive epidermal laminae of the hoof is essential

o Nails must penetrate deeply enough to hold the shoe firmly, but without penetrating the sensitive laminae of the hoof

o If the nail does penetrate the sensitive laminae, pain, infection and lameness can result

Nail 'bind'

is the term used when the nail has been driven too close to the sensitive laminae.

Nail 'prick'

is used when the nail has been driven through the sensitive laminae.

Nail Bind & Nail PrickCAUSE

o Nail bind and nail prick are caused by the direct penetration of a nail through the sensitive laminae of the hoof, or close enough to impinge upon the laminae.

DIAGNOSIS: CLINICAL EXAMINATION

o Horse becomes lame, often not immediately, but usually the next day or within the first week after shoeing

o Increased digital pulse

o Pain on percussion of the hoof, or application of hoof testers, directly over the head of the nail

Nail Bind & Nail PrickTREATMENT

o The shoe should be removed, any pus drained, and the nail hole flushed with antiseptic solution

o Politic ( antibiotic ointment + MgSo4 ) and hoof bandage should be applied

o Tetanus antitoxin injection given for prophylactic issue.

o In severe cases, infection may track under the sole, or even track up to and burst out from the coronary band, in which case local resection of the necrotic sole and/or hoof wall, and a course of antibiotic treatment may be necessary

AFTER-CARE

o Once the horse is sound, with no discharge from the nail hole, careful re-shoeing may be recommended

Penetrating foot woundsINTRODUCTION

o Any penetrating injury to the horse foot is potentially serious

o Can cause physical damage to the important anatomical structures within the hoof and, more seriously, may introduce infection

o Identifying the site of injury, the direction of injury, and the depth of penetration enables the veterinarian to establish which structures of the hoof may be damaged and potentially infected

Penetrating foot woundsINTRODUCTION

o Site of Injury

To explain the correlation between the site of injury and the seriousness of the injury, the hoof is divided into 3 regions: dorsal third, mid third and palmar third

Deep penetration into the dorsal third of the hoof may involve the pedal bone

Penetration into the mid third of the hoof is potentially the most serious as it can involve the navicular bone, navicular bursa, deep digital flexor tendon and the distal interphalangeal (DIP, coffin) joint

Penetration into the palmar third of the hoof is most likely to involve the digital cushion

Penetrating foot woundsCAUSE

o Penetrating injuries to the horse foot are most commonly caused by

nails,

screws and

pieces of wire.

Penetrating foot woundsDIAGNOSIS: CLINICAL EXAMINATION

o In all cases, lameness is the clinical sign which alerts an owner to a penetrating injury.

o Where synovial structure penetration has occurred the following may be noted:

Straw-coloured, yellowish synovial fluid discharging through the tract or hole

Very severe lameness with a sudden onset (up to l2 hours after the injury), sometimes to the point where the horse will not bear weight on the injured foot

Penetrating foot wouundsDIAGNOSIS: RADIOGRAPHY

o If the penetrating object remains in the foot, the temptation to immediately withdraw it should be resisted (during radiographic examination it helps identify affected hoof structures).

o If the penetrating object is no longer present in the foot:

A sterile probe is carefully inserted into hole or tract and a radiograph is taken to determine the direction and depth of the injury

Injury is filled with radio-opaque dye and a radiograph is taken to determine the extent of injury

Penetrating foot wouundsDIAGNOSIS: SYNOVIAL PENETRATION

o The most serious penetrating injuries are those which enter synovial structures such as the navicular bursa or DIP joint

o Infection within these closed cavities is extremely difficult to treat, often leading to a fatal outcome

Penetrating foot wouundsTREATMENT

o Non-synovial Penetrating Injuries

Tract or cavity is opened with a hoof knife to establish good drainage and then flushed with hydrogen peroxide and/or antibiotic solution or spray

Antiseptics and astringents (i.e. dilute povidone iodine) or antibiotic wound spray should be applied to the wound daily

May need to be treated with antibiotics, active against both aerobic and anaerobic bacterial infections

Penetrating foot wouundsTREATMENT

o Synovial Penetrating Injuries

Require treatment similar to that described for non-synovial injuries

In addition, synovial injuries require repeated lavage (flushing with large volumes of sterile saline solution) of the affected joint and/or bursa to remove inflammatory chemicals and to reduce the numbers of infecting bacteria.

Penetrating foot wouundsAFTER-CARE

o Antiseptics and astringents (i.e. dilute povidone iodine) or antibiotic wound spray should be applied to the wound daily

o Tetanus antitoxin injection given if necessary

o Horse should be kept in a clean, dry environment

Penetrating foot wouundsCAUTION

o Prognosis for synovial penetrating injuries is always guarded

o Even the smallest penetrating foot injury may be very serious, introducing infection deep within the foot, so always treat such injuries as potentially serious until proven otherwise

o If the degree of lameness seems to exceed the severity of the visible injury, synovial penetration should be suspected and immediate investigation is justified

CornsINTRODUCTION

o Important cause of lameness in shod horses

o A corn is a specific bruise of the sole, found in the 'seat of corn (angle between the hoof wall and bars)

o Caused by an injury which results in hemorrhage into the sensitive tissues of the sole, increasing pressure and causing pain and discoloration

o Most commonly affects the medial side of the front feet and may be either acute or chronic

o Three types of corns

1. dry corns, 2. moist corns, 3. suppurating corns

CornsCAUSE

o Almost invariably caused by shoes which fit improperly (fitted short and tight at the heels) and traumatize the seat of corn

o Corns are also caused by:

Shoes left for long period (as the hoof grows the shoe is carried forward causing the heel branches of the shoe to traumatize the seat of corn)

Stones or other debris becoming lodged between the shoe and the seat of corn, resulting in bruising

Excessive weight bearing at the heels (seen in horses with low heels or where heel calks or heel studs have been used, traumatizing the seat of corn)

CornsDIAGNOSIS

o Severity of lameness depends upon the degree of bruising)

o Affected horse may have shortened cranial phase of stride with toes contacting the ground, saving the heels

o Lameness is usually increased on hard ground, when circling, or when shoes are removed and

o Lameness decreased on soft ground

o feet may feel warm to the touch

o After sole paring, a dry, moist or suppurating bruise can be seen at the seat of corn

o There is pain response to hoof testers specifically over the seat of corn rather than all over the sole.

o Radiographs may be used to rule out other causes of lameness

CornsTREATMENT

o Horse shoes are removed.

o In dry or moist corns the sole is pared out to relieve pressure (sole should not be pared excessively in horses with thin soles as this may worsen the condition).

Paring out a dry corn

CornsTREATMENT

o Suppurating corns are opened and drained:

Infected corn is located with a hoof knife

Sole opened over the corn to allow pus to drain

Hole is flushed with hydrogen peroxide and/or antiseptic foot spray

Poultice is applied to the foot to encourage drainage of pus

Poultice is removed 24 to 48 hours later and hole treated with antiseptic foot spray

Foot is dry bandaged for a further 24 to 48 hours

o Horse is rested until it is better.

CornsPREVENTION

o Regularly trim and shoe the horse's feet

o Make sure that shoes are fitted correctly to the horse's feet (not too short at the heels)

o Avoid excessive trauma on hard ground

o Horses with thin soles often have poorly balanced feet (usually with long toes and low heels) and this should be corrected if possible with egg-bar shoes fitted when needed

o Hoof pads, which remain very popular with some owners and trainers, are often fitted in an attempt to prevent bruising of the sole, however they must be used with care since they are often ineffective and sometimes even detrimental

ThrushINTRODUCTION

o Thrush is an unpleasant infection of the frog

o Thrush is predisposed by moist, damp, dirty ground or stable conditions

ThrushCAUSE

o Thrush is an infection of the central and lateral sulci of the frog.

o Bacterial infection is most often involved in the development of thrush:

One species of bacterium, Fusobacterium necrophorum, is particularly aggressive and it invades and destroys the frog, sometimes exposing the deeper sensitive tissues

o Occasionally a fungal infection can lead to thrush as well.

o Long heel conformation encourages the development of deep narrow frog sulci which, under appropriate environmental conditions, become more prone to the development of thrush.

ThrushDIAGNOSIS: CLINICAL EXAMINATION

o A foul smelling, black discharge is found in the affected sulci of the frog

o Horse demonstrates pain when pressure is applied to the affected area

o Infection may result in a general swelling of the distal limb

ThrushTREATMENT

o Horse should be moved into a dry, clean environment

o Foot should be thoroughly cleaned and the necrotic debris within the affected frog sulci removed

o Sulci should then be pared to reveal the healthy tissue beneath and allow air to reach any remaining damaged tissue

o Frog should be scrubbed daily with a dilute iodine solution

o Any remaining areas of unhealthy tissue should be regularly plugged with cotton wool soaked in antiseptic (e.g. povidone iodine)

o Two weeks of treatment is usually effective

o Tetanus antitoxin injection given, if necessary

ThrushAFTER-CARE

o Horse should be kept in clean, dry stable conditions

o The frog should be cleaned and trimmed regularly until the infection is controlled and the tissues heel

ThrushPREVENTION

o Preventing thrush is better than curing thrush

o Thrush can be avoided by good stable management, and regular foot care and inspection

o Stable horse in clean dry conditions

o Have horses' feet regularly trimmed and shod by a competent farrier to avoid the development of long heel conformation and to keep the frog healthy

ThrushCAUTION

o With early treatment and good stable and environmental management, the prognosis for complete recovery is good (treatment will usually be required for 7 - 14 days)

o Prognosis for complete resolution is good unless the infection has been allowed to become chronic and/or there is extensive involvement of the deeper tissues (even then, diligent draining and plugging every two days for two weeks is usually effective)

CankerINTRODUCTION

o A rare condition which more commonly affects the hind feet

o Most often seen in horse kept in wet topical climate

o It is a proliferative, foul smelling infection which usually starts at the frog and may spread to the adjacent sole and hoof wall

o Results In formation of characteristic hoof growth, which are fragile (brittle, and weak) and wart- like.

o If left untreated , canker will result in a progressive destruction of the hoof

CankerCAUSES

o Mixed infection with aerobic and anaerobic bacteria and fungi

o Predisposed by wet, unhygienic stable condition

o Infection starts around the frog and then extends to the sole and hoof wall

o In advanced cases, infection may inter the underlying sensitive lamillae

CankerDIAGNOSIS

o Canker in early stage:

Foul smelling, moist, vegetative mass is seen

Lameness is rarely encountered

Cheesy foul smelling discharges

o Canker in advanced stage:

A cauliflower-like, proliferative growth along the heel, bars, sole and wall

Lameness may seen

Swelling in the pastern and lower limb

CankerTREATMENT

o Removal of all abnormal, dead and infected tissue under general anesthesia

o Packing with sterile gauze socked in antiseptic solution,

o Foot bandage

o Antibiotic

o Tetanus toxoid

CankerAFTERCARE

o Clean dry stable

o Change bandage every 2-3 days

o Keep the horse out of wet and muddy conditions until the wound is completely healed

CankerPREVENTION

o Clean and dry stable

o Regular exercise

o Regular trimming

Navicular SyndromeINTRODUCTION

o Recognized as an important cause of lameness in the horse since the middle of the nineteenth century.

o Despite considerable research it remains a poorly understood condition, which may be attributable to the following:

Traditionally viewed as a single condition, it is now recognized to be a complex, multi-factorial disease

In the past, diagnosis was often imprecise and not based upon thorough veterinary examination

It involves other structures within the foot in addition to the navicular bone

It is a dynamic and not a static disease (anatomical structures of the foot all move in relation to one another as the horse exercises)

It is a progressive disease with clinical signs changing according to the stage at which the horse is examined

Navicular SyndromeINTRODUCTIONo Navicular syndrome is most commonly diagnosed as a cause of chronic forelimb

lameness in middle aged (6 - 12 years old) performance horses but, with detailed investigation, is probably a much less common condition.

o Hunters and show horses are more commonly affected.

o A thorough knowledge of the normal anatomy of the horse foot is essential in understanding navicular syndrome.

Navicular SyndromeCAUSES

o The causes of navicular syndrome are poorly understood, however current theories include:

Abnormal foot conformation and foot imbalance predisposes the horse to navicular syndrome

Repeated trauma to and wear and tear of the deep digital flexor tendon, navicular bone and navicular bursa causes pain

Poor blood supply to the navicular bone, associated with thrombosis and pressure from the deep digital flexor tendon on the damaged bone, causes pain (this theory is less favored)


o Once navicular syndrome has been initiated the resultant pathology includes

bone changes,

cartilage changes,

tendon changes and

ligament changes.



bone changes,

Micro fractures and thickening of the palmar cortex of the navicular bone occur

Lysis of the navicular bone occurs (destruction or decomposition of bone cells)

Lysis results in holes developing in the bone (these holes are sometimes called synovial fossae)



bone changes,

cartilage changes,

Partial and full thickness erosions of cartilage on the palmar surface of the bone

These erosions result in ulceration and exposure of the sensitive bone on the surface where the deep digital flexor tendon moves over it



bone changes,

cartilage changes,

tendon changes and

Damage to the deep digital flexor tendon may occur, leading to fibrous adhesions (scar tissue) forming between the tendon and the ulcerated navicular bone



bone changes,

cartilage changes,

tendon changes and

ligament changes.

Small areas of new bone, sometimes called entheseophytes, may form at the insertion point of the collateral (suspensory) ligaments of the navicular bone


o It is important to note that navicular syndrome is a dynamic problem:

During each stride the horse lifts up the leg, moves it and then lowers the leg to bear weight

All of the structures of the foot are loaded and unloaded, stretched and relaxed, time after time

Navicular SyndromeDIAGNOSIS: CLINICAL EXAMINATIONS

o History of intermittent forelimb lameness of variable degree, which may shift from one leg to another or involve both legs simultaneously

o Lameness develops insidiously over a period of weeks or months

o Horse may have a tendency to point one foot forward and then the other while at rest

o Horse has a short forelimb gait with a tendency to stumble (worsens on hard ground)

Navicular SyndromeDIAGNOSIS: CLINICAL EXAMINATIONS

o Toes of shoes show excessive damage and at the toe the sole may be bruised (caused by stubbing)

o In some chronic cases, abnormal gait causes the feet to become small, narrow and high at the heels (one foot will often have poorer shape and be more painful than the other)

o In rare cases, pressure with hoof testers across the heels or diagonally across the frog to the opposite heel causes pain (not a reliable guide in the diagnosis of navicular syndrome)

Navicular SyndromeDIAGNOSIS: NERVE BLOCKS

o A local anaesthetic nerve block of the palmar digital nerves, the distal interphalangeal (coffin) joint and/or the navicular bursa results in an improvement or abolition of lameness.

Navicular SyndromeDIAGNOSIS: RADIOGRAPHY

o Specific radiographic views may reveal:

Micro fractures or thickening of the palmar cortex of the navicular bone

Chip fractures of the distal (bottom) edge of the navicular bone

An increase in the number of holes normally seen at the bottom edge of the navicular bone (synovial fossae) or a change in their shape (mushroom-shaped or rounded)


o Specific radiographic views may reveal:

Holes in the wings or proximal (upper) edge of the navicular bone (cyst)

Areas of abnormal density or pattern in the navicular bone (lollipopos)

Formation of new bone (entheseophytes) at the proximal border or wings of the navicular bone


o Many of these radiographic abnormalities may be found during a routine or pre-purchase examination of normal horses:

May be argued that some of these horses are in the early stages of developing the condition, however, navicular syndrome should not be diagnosed on the basis of radiographic findings alone

Confirmatory clinical examination and nerve block results help ascribe significance to radiographic examination

Navicular SyndromeTREATMENT

o Navicular syndrome is a progressive and irreversible syndrome which cannot be truly cured.

o Treatment of the condition is designed to slow its inevitable progression and to relieve pain through

corrective trimming and shoeing,

drug therapy and

corrective surgery.

Navicular SyndromeTREATMENT: CORRECTIVE TRIMMING & SHOEING

o Aim of trimming and shoeing is to correct foot abnormalities or imbalances.

o For a broken backwards hoof pastern axis which leads to a long toe/low heel conformation or in cases where the heels have collapsed badly:

Toe is trimmed back as much as possible from the ground surface

Heels are trimmed only if they are overgrown

Horse is shod every 4 - 6 weeks with a rolled toe, egg bar shoe, fitted full at the quarters and extending well back at the heels to provide support

Navicular SyndromeTREATMENT: CORRECTIVE TRIMMING & SHOEING

o Aim of trimming and shoeing is to correct foot abnormalities or imbalances.

o For chronic cases where the feet are small and upright:

Horse is shod with a wide webbed, rolled toe bar shoe, fitted well back at the heels to provide support

Navicular SyndromeTREATMENT: DRUG THERAPY

o Vasodilator drugs

Drugs (i.e. isoxuprine, papaverine) which cause blood vessels to dilate

May improve the blood supply to the navicular bone

o Thrombolytic drugs

Drugs (i.e. warfarin, streptokinase, alteplase, reteplase, and tenecteplase) which dissolve blood clots

May help remove blood clots and improve blood circulation to the navicular bone

Dosage must be carefully monitored through regular blood clotting tests to prevent life-threatening internal haemorrhage

Warfarin must not be used in combination with other drugs, especially phenylbutazone, where there is the risk of a potentially fatal drug interaction

Navicular SyndromeTREATMENT: DRUG THERAPY

o Non-steroidal anti-inflammatory and anti-endotoxic drugs

Drugs (i.e. flunixin, phenylbutazone) which counteract inflammation or bacterial toxins

Will help relieve pain but will not treat the cause

Must not be used with warfarin because of the risk of a potentially fatal drug interaction

o Long-acting anti-inflammatory or lubricating drugs

Injections of long-acting anti-inflammatory (i.e. corticosteroids) or lubricating (i.e. sodium hyaluronate) drugs may help alleviate pain in some cases but response is variable.

Navicular SyndromeTREATMENT: CORRECTIVE SURGERY

o Desmotomy

Surgical section of the medial and lateral collateral (suspensory) ligaments of the navicular bone under general anaesthesia

May relieve pressure on the damaged navicular bone and relieve the lameness

o Surgical section of heel nerves

Will prevent the horse from feeling pain in the heel area

Should only be used as a last resort for horses which are not used for demanding athletic work

Horse will no longer have sensation in the heel, therefore the foot requires careful supervision to avoid heel injuries and infections

Navicular SyndromeAFTER-CARE

o Good foot shape and foot balance should be maintained through regular trimming and shoeing by an experienced farrier

o A controlled exercise programme, whilst the horse is receiving non-steroidal anti-inflammatory medication, is often helpful

o Feeding the horse supplements which include glucosamine and polysulphated glycosaminoglycans may help cartilage repair

Navicular SyndromePREVENTION

o Maintaining good foot shape and foot balance through regular trimming and shoeing by an experienced farrier

o As not all the inciting causes of navicular syndrome are known the condition is not always specifically preventable

Navicular SyndromeCAUTION

o Navicular syndrome is a complex problem which may end the working life of a performance horse

o An accurate diagnosis as well as the elimination of other causes of heel pain is a pre-requisite for successful management

o The most common factors predisposing a horse to navicular syndrome are an abnormal foot shape and hoof imbalance caused by inadequate or improper hoof trimming and shoeing, therefore use a properly qualified farrier regularly

o Corrective trimming and shoeing should be performed by a specifically-experienced farrier

o If a horse shows signs of lameness a veterinarian should be contacted to accurately diagnose the cause of the lameness

SidebonesINTRODUCTION

o Sidebone is a term that describes the ossification of the collateral cartilages of the foot and results in the cartilages becoming no longer flexible

o Collateral cartilages are found on the inside and outside of the foot, and can be palpated just above the level of the coronary band as flexible projections on either side of the pastern

SidebonesINTRODUCTION

o The cartilages are important in the shock absorbing mechanism of the foot .

o The front feet are more commonly affected than the hind feet

o The condition is more frequently seen in the heavy breeds of horses (especially draft horses) than the lighter breeds and ponies

SidebonesCAUSE

o Ossification, which begins at the junction between the collateral cartilage and the pedal bone, is believed to be part of the horse's normal ageing process.

o Mild sidebone formation, unassociated with lameness, is sometimes seen in radiographs taken from older horses and young heavy horses.

o Excessive, abnormal or premature sidebone formation (i.e. bone change resulting from undue loading and concussion of the cartilages) may be predisposed by:

Poor foot conformation, especially chronic imbalance, associated with incorrect hoof trimming and/or shoeing

Abnormal limb conformation (may cause uneven forces on the cartilages)

Direct trauma to the cartilage

Infection (i.e. Quittor)

SidebonesDIAGNOSIS

o Clinical Examination

Lameness is rarely seen and, if present, is usually associated with complications due to advanced ossification

The coronary band may bulge over the affected cartilage

o Radiography

Ossification of the cartilages is confirmed by radiographic examination of the foot (normal cartilage cannot be seen, whereas bony cartilages can), comparing one with another, to aid interpretation

SidebonesTREATMENT

o No treatment is required for uncomplicated, normal, progressive ossification of the collateral cartilages which are not causing clinical problems.

o Where clinical problems occur, the complicating or predisposing problems may require treatment:

Foot imbalance should be corrected by proper trimming and shoeing

Horse may require an extended period of stable rest (6 - 8 weeks)

A course of non-steroidal, anti-inflammatory drugs may be given if the horse is lame

Sidebones

PREVENTION

o Horses feet should be regularly trimmed and shod by a competent farrier, to prevent imbalance, uneven weight-bearing and excessive concussion.

SidebonesCAUTION

o Prognosis is poor for cases where sidebone is causing lameness, especially those with extensive cartilage ossification and hoof deformity

QuittorINTRODUCTION

o Quittor is an old term for a septic condition which involves the necrosis of the collateral cartilages of the pedal bone following an infection in the foot.

o Quittor more commonly affects the front feet rather than the hind feet and was more frequently seen in the heavy breeds of horses rather than in the lighter breeds or ponies

o uncommon

QuittorCAUSE

o The collateral cartilages of the pedal bone have a poor blood supply and so they respond poorly when infected and consequently infections can become chronic and damaging.

o Quittor can be caused by the following:

A condition known as 'treads':

Draft horses which pulled loads in teams would tread on the feet of the horse in front

if they stood on another horse, resulted in damage to the skin over the coronary band and introduced infection into the cartilages

Occasionally occurs following external trauma or interference injuries to the pastern and coronary band.

May occur, very rarely, extending from a sub-solar abscess (see Pus in the Foot).

QuittorDIAGNOSIS

o Once the collateral cartilage of the pedal bone is damaged and infection established, bacteria converge on the area of dead tissue to live and multiply. The infection results in an intermittently discharging wound on the inside or outside of the hoof over the collateral cartilages.

o Clinical Examination

Wound area is frequently warm, swollen, painful and multiple sinuses (holes) may appear above the coronary band (over the infected cartilage)

Purulent discharge erupts out of the sinuses

Horse may exhibit mild to very severe lameness (lameness usually subsides after the infection discharges or 'breaks out')

Long term cases of quittor may result in deformity of the hoof wall

QuittorDIAGNOSIS

o Radiography

Radiographic examination of the foot may reveal necrosis and/or gas shadows which confirm the presence of infection or ossification of the cartilages (see Sidebones), depending on the stage of the condition

May be confused with an abscess (see Pus in the Foot)

QuittorTREATMENT

o Cases of Quittor often respond to topical and systemic antimicrobials (antibiotics) active against both aerobic and anaerobic infections.

o If infection 'breaks out', due to the build up of pus within the foot, the dead and infected material must be surgically trimmed away (often more effective to anaesthetize the horse and then thoroughly investigate and trim the affected area as any remaining infected or dead tissue will encourage the problem to recur).

o In some cases it is necessary to either remove a section of the hoof wall or drill holes in the hoof to allow the infected area to drain.

o Wound is packed with sterile gauze soaked in antiseptic solution (i.e. dilute povidone iodine) and the foot is bandaged until it has completely healed.

o tetanus antitoxin injection given if necessary.

QuittorCAUTION

o Prognosis for complete resolution and a return to soundness is poor for long-standing cases of true quittor, especially those with hoof deformity

o Horses should always be fully vaccinated against tetanus, an invariably fatal infection, which can gain access through hoof injuries

Hoof Wall CracksINTRODUCTION

o Many factors can result in hoof wall damage: poor hoof quality, overgrowth, poor foot/limb balance, poor nailing and shoe fit, trauma, disease and environmental conditions

o Hoof cracks are referred to by their type, location and depth

o Cracks are either complete (extend the entire length of the hoof wall) or incomplete (extend part-way up or down the hoof wall)

Hoof Wall CracksTYPES OF HOOF CRACKSo Grass Cracks

Vertical cracks originating at the ground surface of the hoof

May extend partially or completely up the hoof wall (to the coronary band)

Considered a split in the hoof wall o Sand Cracks

Vertical cracks originating at the coronary band

May extend partially or completely down the hoof wall (to the ground surface)

Considered a fracture of the hoof wallo Horizontal Cracks

Run parallel to the coronary band

Hoof Wall CracksLOCATIONS OF HOOF CRACKS

o Wall Cracks

Cracks which appear in the wall of the hoof, such as toe cracks, quarter cracks or heel cracks

o Solar Cracks

Cracks which appear in the sole of the hoof, such as sole cracks or bar cracks

Sole cracks are often superficial and usually radiate out from the apex of the frog, however they can also be deep and occasionally infected

Bar cracks are often deep

Hoof Wall CracksDEPTHS OF HOOF CRACKS

o Superficial

Penetrate only the outer insensitive horn of the foot

If neglected they can become deep cracks

o Deep Cracks

Penetrate the sensitive laminae of the foot

Often bleed during exercise and may become infected

Hoof Wall CracksCAUSE:

GRASS CRACKS

o In general, hoof wall cracks, including grass cracks, are the caused by:

Poor hoof quality: hooves of a brittle or 'shelly' consistency which are easily split

Environmental conditions: hooves are weakened in either extreme wet or dry conditions

Incorrect nailing: hooves can be split by the use of over-large nails and nailing too superficially ('fine') into the hoof wall


SAND CRACKS

o Caused by uneven stress to the hoof capsule, arising from a foot-limb imbalance.

o Sand cracks can occur following a traumatic injury or after excessive and repeated concussive stress

o Additional causative factors include poor hoof quality, environmental conditions, type of exercise surface and speed at exercise

o Although coronary band treads were often considered to be a cause of sand cracks in working horses of the past, direct trauma to the coronary band is unlikely to cause sand cracks in modern athletic horses.


HORIZONTAL CRACKS

o Caused from an injury to the coronary band which results in the temporary cessation of healthy horn growth


SOLAR CRACKS

o Sole Cracks

Most commonly seen in horses with chronic laminitis Caused by the direct pressure from a rotating pedal bone

and in young horses with upright or 'clubby' feet

In a young horse solar cracks are temporary, but in the laminitic foot they can be persistent

o Bar Cracks

Can be caused by some cases of low grade, chronic laminitis and in horses with a long toe/low heel syndrome

Hoof Wall CracksDIAGNOSIS

o Hoof wall cracks are visibly obvious, but their significance is determined by the extent of coronary band involvement and whether or not infection is present

o In lame horses, a crack through the coronary band may be painful to palpate and the edges of the crack may move apart when the horse bears weight (signifies instability, pinching and inflammation of the sensitive laminae)

o In lame horses, a crack through the ground surface of the hoof may be associated with a localized area of pain on palpation (signifies infection and abscess formation)

o In chronic cases of hoof wall cracks, radiographic examination may reveal secondary changes to the pedal bone.

Hoof Wall CracksTREATMENT

o Crack is trimmed out to debride the cavity and hoof wall, exposing the area to air

o If a solar abscess is present, it should be located, trimmed and treated

o Infected crack is flushed with a topical antibiotic

o Proper shoe (i.e. full-bar shoe) is applied to stabilize the foot (nails should not intrude into crack)

o If required, toe or quarter clips are fitted on either side of the crack (clips should not intrude into crack)

Hoof Wall CracksTREATMENT

o If crack is recent and uncomplicated it is wired or laced together (using horizontal holes drilled through the hoof wall)

o If crack is long-standing and complicated it is filled with an acrylic hoof repair material to hold the edges of the crack

o Bar and sole cracks should not be covered by any repair material

o Hoof hardener can be applied

Hoof Wall CracksAFTER-CARE

o Stable rest is required until the hoof wall crack is stabilized and healing

o The hoof should be trimmed and the stabilization components (i.e. wires or laces, patch, shoe, clips) reapplied as the hoof grows and the crack changes position

o Note: The hoof wall grows approximately 0.6 cm every month

Hoof Wall CracksPREVENTION

o Maintain regular hoof trimming and shoeing at all times but especially during times of dry weather

o Feed supplements containing biotin and methionine to aid good quality hoof growth, especially for horses with naturally brittle feet

Bruised SoleINTRODUCTION

o Important cause of lameness in shod or unshod horses

o It is an injury which results in hemorrhage into the sensitive tissues of the sole

o Hemorrhage increases pressure in the sensitive tissues of the sole which results in pain

o Hemorrhage also causes discoloration in the typical manner of a bruise

Bruised SoleCAUSE

o A bruised sole is caused by trauma resulting from the following:

Treading on a stone or another hard object

Poorly fitting shoe

Excessive work on hard ground

Bruised SoleDIAGNOSIS

o Horse may become suddenly lame and then appear to recover but will often be lame the next day

o Pain is located when pressure is applied with hoof testers

o Sole paring at the area of pain reveals a visible bruise

Bruised SoleTREATMENT

o Steps in the treatment of a bruised sole include:

Trimming the overlying solar horn may relieve the painful pressure of haemorrhage

Applying an antiseptic spray to help keep the damaged horn clean

Applying a poultice and bandage

Applying a shoe with a pad

Bruised SoleAFTER-CARE

o The poultice should be removed after 24 hours but the protective bandage can be left on for a further 48 hours

o The foot is trimmed and shod when it is no longer painful

o The horse may remain lame until it is reshod

Bruised SolePREVENTION

o Pick and thoroughly clean out the horse's feet before exercise

o Avoid exercise on stony ground

o Maintain regular hoof trimming and shoeing

o Consider the use of pads to protect the sole if the horse is prone to bruising

Bruised SoleCAUTION

o A foot abscess can cause a similar type of sudden lameness with focal pain

o Abscesses must be found, drained and poulticed without delay

Education

lameness (equine hoof affections) Dr. Alaa Ghazy