5-Hoof

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HOOF AFFECTIONS

1-Ringbone or phalangeal exostosis: -

Definition:

Bony exostosis (new bone growth), at the lower half of the 1st phalanx and down ward, ensues as a result of periostitis and may lead to osteoarthritis or ankylosis of the pastern or coffin joints. It is common in the forefeet than hind feet.

Classification:

A-High and low ringbone

High ringbone is a new bone growth at the distal end of the 1st phalanx and/or proximal end of the 2nd phalanx, and low ringbone is the same at the proximal end of the 2nd phalanx and/or the proximal end of the 3rd phalanx

B-Articular and periarticular ringbone

Articular ringbone is a new bone growth involving the joint surface of the pastern or coffin joint, and periarticular ringbone is a new bone growth around the joint but doesn’t involve the articular surface (common in high ringbone)

Etiology:

1-Direct trauma like blows or wire cutting

2-Periostitis as a result of pulling collateral ligament of the joint, joints capsule attachment to the bone, or common extensor tendon attachment to the phalanx.

3-Fracture of phalanx and if it involves the joint, ankylosis will ensue

4-Tension on the common extensor tendon that either causes fracture or periostitis of extensor process of the 3rd phalanx after (buttress foot).

5-Poor conformation (base narrow, base wide, or short upright pastern)

6-Uneven spacing of the articular surface

Signs:

1-Lameness in all gaits and on turning the animal, but sometimes it is asymptomatic especially if it is periarticular (even no heat or pain can be detected if it is chronic).

2-Heat, swelling and pain during active ringbone

3-If it is buttress foot, the hair on the coronary band will stand erected at the front of the foot and when it is chronic, shape of the foot changes (V-shaped foot).

4-Bilateral low articular ringbone is characterized by pointing of the feet, short anterior phase of stride (similar to navicular), and exaggerated landing on the heel.

5-Early high ringbone may show periodic swelling and lameness that disappear with corticoid and reappear with work, and gait of these animals resembles that of laminitis. 

6-Osteoarthritis and ankylosis if it is articular ringbone (ankylosis of the pastern of the hind limb may show no lameness).

Diagnosis:

1-Signs                       

2-Clinical examination                   

3-Radiography (the most important point)

Treatment:

A-Recent cases (no bone growth)

Local injection of corticoid, application of plaster cast (4 weeks), and rest (4 months)

B-Chronic cases

1-Blistering, firing, or arthrodesis in case of pastern ringbone for induction of ankylosis followed by plaster cast for 8 weeks 

2-Ringbone of the coffin joint can be treated either by volar neurectomy or neurectomy of the anterior and posterior digital nerve

3-Surgical removal of the periarticular bone exostosis, if it encroaching adjacent structures (50% success)

4-Corrective shoeing with full roller motion shoe in case of articular ringbone or ankylosis

Prognosis:

*Guarded if it is periarticular                                                    

*Unfavorable if it is articular

2-Pyramidal disease or Buttress foot: -

Definition:

New bone growth on the extensor process of the 3rd phalanx (low ringbone) either as a result of fracture of the extensor process or periostitis, leading to an enlargement at the coronary band at the center of the toe.

Etiology:

Excessive strain on the insertion of the long or common digital extensor at the extensor process of the 3rd phalanx leading to its fracture or periostitis.

Signs:

1-Non-specific signs of lameness, pointing with the foot, short anterior phase of stride, and tendency to land heavily on the heels.

2-Early stages show lameness in all gaits; heat, pain and swelling at the coronary band at the center of the toe with erected hair.

3-Chronic osteoarthritis of the coffin joint

4-After long period, shape of the wall at the toe changes (V-shape foot), as the wall of the toe bulges from the coronary band to the bearing surface of the toe.

Diagnosis:

1-Signs           

2-Clinical examination              

3-Radiography (the most important diagnostic point)

Treatment:

1-No treatment is of particular value for such disease

2-Injection of corticoid and immobilization within a plaster cast in recent cases 

3-Blistering or firing in old cases                                   

4-Anterior digital neurectomy in old cases

5-Corrective shoeing by full roller motion shoe to take motion from the coffin

Prognosis:

*Unfavorable in all cases

3-Fracture of the extensor process of the 3rd phalanx: -

Etiology:

1-Pressure or strain on the common digital extensor tendon       

2-Over extension of the coffin joint

Signs:

1-Relatively obscure lameness          

2-Pain on palpation over the center of toe at the coronary band

3-Short anterior phase of stride (like navicular disease but with no reaction to hoof tester over the middle 3rd of the frog)

4-Change in the shape of the foot (V-shaped foot) and if it present for more than year, the shape of the wall changes over the full length of the wall

5-Typical buttress foot if much periostitis ensue at the fractured area

Diagnosis:

1-Signs of pain on palpation (may or not be present) and shape of the foot            

2-Radiographes

Treatment:

1-Surgical removal of small fragment, followed by plaster cast (changed after week), supporting bandage (for month), and rest for 6 months

2-Surgical fixation with bone screw for large fragment, followed by plaster cast (for month), confinement in the stall (for month), and rest (6 months)

Prognosis:

*Guarded as a result of osteoarthritis of the coffin

*Unfavorable of articular ringbone involves the coffin

4-Quittor: -

Definition:

Common affection of the forelimbs that is characterized by chronic purulent inflammation and necrosis of the collateral cartilage, of the 3rd phalanx, with one or two recurrent sinuses that drainage at the coronary band

Etiology:

1-Interfering ad damage of the medial collateral cartilage                  

2-Puncture wounds of the sole

3-Injury over the cartilage near the coronary band with formation of sub-coronary abscess 

4-Trauma or bruising of the cartilage with reduction of circulation

Signs:

1-Lameness during acute stage

2-Swelling, heat, and pain; and chronic suppurative sinus tract over the affected cartilage at the coronary band. The sinus has intermittent nature

3-Sidebone may develop, and permanent swelling over the region may be formed

4-Permanent damage and deformity of the foot with persistent lameness may ensue

Diagnosis:

1-Signs   

2-Differential diagnosis from gravel, other foot infections, and shallow abscess (probing)

Treatment:

1-Early cases can be treated by daily irrigation with escharotic agents (20%silver nitrate followed by saline) till all necrotic tissue is removed, followed by use of enzymes.

2-Chronic cases can be treated by surgical removal of the cartilage, via elliptical excision  (5 cm long and 1 5 cm wide) parallel to the coronary band. The dark-blue necrotic cartilage and tissues should be removed and the tract is followed to its origin then the foot is bandaged without suturing. This technique causes no cracks in the hoof wall at the coronary band.

Prognosis:

*Guarded to unfavorable according to duration

5-Sidebone: -

Definition:

Ossification of the collateral cartilage, most commonly affecting forefeet in horses with base narrow or base wide. Lameness is clear only during active stage but later on it disappears, and fracture of the ossified cartilage can occur either at its proximal end (small fracture) or through the wing of the 3rd phalanx.

Etiology:

1-Concussion of the quarters leading to trauma of the cartilage

2-Mal conformation like base wide or base narrow, predispose to trauma of the cartilage

3-Improper shoeing like shoe with heel calks or shoeing a horse off level may predispose to traumatization of the cartilage

4-Direct trauma of the cartilage by wire cuts

Signs:

1-Lameness can be observed only during ossification and inflammation of the cartilage and can be observed on turning the animal, but the lameness is mild in general, and when it is associated with massive bone formation, it causes mechanical interference with foot action

2-Heat, pain, and hardening over the affected cartilage during inflammation

3-Visible bulging of the quarter at coronary band 

4-Partial or complete ossification radiographically

Diagnosis:

1-Signs and examination during active stage                                

2-Volar nerve block

3-Radiographically (ossification doesn’t mean that sidebone is the cause of lameness)

Treatment:

1-Rest, firing and blistering during active phase

2-Thinning and grooving of the wall at the quarter to permit foot expansion and relief of pain

3-Full roller shoe to decrease stress on coffin joint

4-Proximal small fractures can be removed surgically controversial to fractures through the wing of the 3rd phalanx. The later can be treated only by immobilization shoe

5-Posterior digital neurectomy in chronic cases with evident lameness

Prognosis

*Guarded to favorable   

*Unfavorable if extensive exostosis is present

6-Laminitis or Founder disease: -

Definition:

Acute or chronic, infectious or non-infectious, inflammation of the laminae of the foot, characterized by passive congestion of the laminae, leading to severe pain as a result of pressure on the sensitive laminae. Usually it affects the forefeet but it can affect the four feet. The name founder means changes in the hoof wall as a result of inflammation of the coronary band. Its common sequelae include rotation and osteitis of the 3rd phalanx

Etiology:

1-Ingestion of toxic amount of grains (Grain founder), like wheat, barely, or corn but oats is uncommon cause, and signs of laminitis appear 12-8 hours post ingestion with gastro-intestinal disturbances. The signs ensue either as a result of formation of great amount of histamine, or absorption of endotoxins

2-Ingestion of large amount of cold water after racing (Water founder) leading to gastroenteritis and histamine release

3-Concussion (Road founder) as a result of hard work on hard surface, especially in horses with thin wall and thin sole, and these animals may have bruising sole and pedal osteitis at the same time

4-Endometritis (post-parturient laminitis) or systemic infection (pneumonia)

5-Ingestion of Lush grass (Grass founder)

Pathogenesis:

Separation between the sensitive and insensitive laminae (junction of stratum germinativum and stratum corneum) ensues as a result of inflammation and edema. Once separation occurs, the 3rd phalanx rotate within 3 days (as a result of pulling by the deep digital flexor tendon, pushing by the digital cushion, and the weight on the phalanx), and penetration of the sole by the 3rd phalanx may ensue within 10 days, leading to flat or dropped sole. In chronic cases (persistent inflammation), pedal osteitis ensues

Signs:

A-Acute laminitis

1-Systemic reaction like congestion of the mucous membranes (toxemia), anxiety, and increased respiration

2-If the four feet are affected, the horse stands under in front in the forefeet and under behind in the hind feet, leading to short base of support, or lie down and refuse to stand

3-If the forefeet only affected, the horse standing camped in front in the forefeet with the weight on the heels and under behind in the hind feet, and the horse reluctant to move

4-Heat over the wall, sole, and coronary band, and increased pulsation of the digital artery behind the fetlock joint. Rotation of the 3rd phalanx or penetration of the sole and separation of the hoof may occur

B-Chronic laminitis

1-Exaggerated motion with landing on the heel (long toe and low heel), with rapid growth of the wall leading to curling of the toe and heavy rings formation on the wall

2-Rotation of the 3rd phalanx or penetration of the sole, and seedy toe formation (separation of the sensitive and insensitive laminae)

3-Formation excessive flaky materials (flat and dropped sole) that may be invaded by infection similar to thrush leading to destruction of protection of the 3rd phalanx. The separation at the white line may predispose to infection of the sensitive laminae

4-Bleeding at the sole on trimming, even months after the attack, as a result of congestion 

Diagnosis:

1-Signs                                         

2-Hoof tester reveals diffuse pain and tenderness over the sole

3-Radiographs (the 3rd phalanx rotates within 3 days and penetrates the sole within 10 days)

Treatment:

A-Acute laminitis

1-Treatment of the primary cause

2-Promoting venous blood flow either by forced exercise (even by nerve block), or by hot soaking

3-Anti-inflammatory and anti-histaminic

4-Prevention of rotation of the 3rd phalanx because of the difficulty of correcting rotation once I it has occurred. Prevention of rotation can be achieved in early stages by lowering the heel, exercise, and standing the horse in sand.

B-Chronic laminitis

1-If the sensitive tissue is infected as a result of separation of the white line the defect should be opened for drainage and swapped with tincture of iodine, and then bandaged.

2-Grooving or rasping the quarters of the hoof wall and corrective showing. The heels and the wall of the toe should be trimmed to make the 3rd phalanx in normal position. Then the wall and the sole of the hoof are covered with plastic that is held by toe and quarter clips, and plastic pad is inserted under the toe to force the 3rd phalanx to its normal position. This treatment is repeated every 6 weeks till it is evident that the 3rd phalanx returned back to its normal position (may last a year). 

3-Volar neurectomy

Prognosis:

*Guarded in all cases             

*The acute phase may be fatal

*Unfavorable when; rotation occurs, there is crack at the coronary band indicating sloughing of the hoof, the disease lasts more than 10 days, or infection of the pododerm ensues via seedy toe or sole

7-Navicular disease, navicular bursitis, or podotrochleitis: -

It is one of the most important causes of lameness in the forefeet (affect forefeet only), and it has insidious nature that shows improvement at rest (in early stages) but reappears when the horse is put back to work. The disease starts as inflammation of navicular bursa between deep flexor tendon and navicular bone. As the disease progresses, pathological changes appear at the tendinous surface of the bone, the adjacent deep flexor tendon, and bone substance

Degenerative and erosive changes of the fibrocartilage ensue, at the tendinous surface of the bone, making it more frayed and pitted near the sagittal ridge. Fibrils of the tendon are torn near the distal edge of the bone, the surface of the tendon progressively destroyed and may rupture spontaneously or after neurectomy, and adhesion between the tendon and the bone may ensue even before extensive radiographs are shown. The bone affected with hyperemia and osteoporosis (decalcification or rarefaction), and fracture may ensue. Calcification of the suspensory ligament of navicular bone may ensue. Affection may extend to the coffin joint leading to arthritis 

Etiology:

1-Hereditary (up right pastern and weak navicular bone)        

2-Concussion (work on hard surfaces)

3-Increased pressure of the deep flexor tendon on the navicular bone as a result of improper trimming (low heel)

4-Infections of the bursa by puncture wounds (fore or hind foot)

5-Irregular blood supply to the navicular bone (hard work with long period of rest)

Signs:

1-History of intermittent lameness that decreases with rest and the lameness is worse the morning after heavy work. Usually both forefeet are affected and sometimes one of them is more affected than the other 

2-During rest, the horse points alternately with one foot then the other or may show camped in front, and the toe excessively worn (landing on toe). Chronic cases and prolonged protection of the frog from pressure predispose to contraction of the foot, the heels contract and rise, the sole become more concave, and the hoof becomes narrow at the quarters. If up right pastern is present, osselets may be found along with navicular disease

3-During motion, the horse has shuffling gait on walking, and during walking and trotting, he tends to land on the toe to protect the navicular bone (under the middle 3rd of the frog) from concussion, and the anterior phase of the stride is reduced. Lameness increases on irregular ground (frog pressure by irregular ground), or on turning the horse in the direction of the affected foot

4-Pain over the middle 3rd of the frog on using hoof tester

5-Sole bruising in chronic cases, so it must be detected if it is primary or it is secondary to navicular disease, and nerve block and radiographs can detect whither it is primary or secondary

Differential diagnosis:

1-Early bilateral ring bone has signs similar to navicular disease, but typical findings of hoof tester and posterior nerve block are not obtained

2-The shuffling gait and the short anterior phase of stride give false impression that the horse has shoulder lameness, however, posterior nerve block can differentiate the two cases

3-Arthritis of the coffin joint ensues either primarily or secondary to navicular disease, however, articular analgesia of the coffin joint and reaction to hoof tester differentiate the two cases

4-Laminitis (shoulder action is the same but animal lands on heel)              

5-Fractured 3rd phalanx

6-Puncture wounds of sole and frog          

7-Fractured navicular bone                     

8-Pedal osteitis

Diagnosis:

1-Signs                                 

2-Reaction to hoof tester

3-Posterior digital nerve block (2 ml, 2%, 5-10 minutes), it is also an indication of the degree of improvement after neurectomy. However, the horse may not response completely to the nerve block as a result of;

a-Fibrous adhesion of the bone to deep flexor tendon (mechanical interference)

b-Arthritis of the coffin joint (articular analgesia)

c-Accessory nerve supply from the anterior digital nerve or posterior digital nerve

d-Sole bruising           

e-Osselets (local analgesia of the volar pouch fetlock joint)

4-Local analgesia of the navicular bursa (5 cm, 2%) through the fossa of the heel, but it is ineffective if adhesion is present 

5-One can’t relay on radiographs, as 50% of the affected horses show normal radiographs, and adhesion of the tendon to the navicular bone show no extensive radiographic changes. When the disease is well established, the radiographic changes include; osteoporosis, exostosis, enlarged vascular channels, narrowing of articular space, sclerosis, and osteolysis 

Treatment:

1-Injection of the bursa with steroids, but it is of little value as a permanent cure, and can’t be used if adhesion is present

2-Injection of the burse with irritants (Lugol’s iodine), but it is no longer recommended, and can’t be used if adhesion is present

3-Corrective trimming without adversely affecting the angle between the hoof and the pastern 

4-Proper shoeing consists of;

a-Raising the heels by building them up (brings the hoof to proper angulation) 

b-Permitting expansion of the foot to counteract foot contraction, either by using slippery shoe (tapering the branches out ward from the quarter through the heels) leading to out ward sliding of the wall; or by rasping quarters of the hoof wall, or putting vertical or parallel groves on the quarters 

c-Rolling the toe, which in combination with raised heels, permitting quick break over 

d-Using a bar across the middle 3rd of the frog, which in combination with the raised heels, protect the frog from pressure, other wise, soft padding of the sole can be performed  

5-Posterior digital neurectomy is the best method of treatment if preceded by nerve block and showed efficacy, although it has some complications like;

a-Neuroma it can be prevented by; injection of anesthesia at a level higher than neurectomy site, minimal trauma, epineural capping with ligation of the distal nerve end, pressure bandage post surgically, post operative anti-inflammatory, local injection of anti-inflammatory every 3 days, and rest for 6 weeks

b-Rupture of the deep digital flexor tendon even after several weeks following the surgery, indicated by raised toe from the ground, and it has no treatment

c-Loss of hoof wall as a result of fibrosis around the artery

d-Regeneration of the posterior digital nerve after 6 months                 

e-Accessory nerve supply

Prognosis:

*Unfavorable in all cases and although neurectomy can aid in providing years useful service, but the high incidence of complications, the possibility of picked up nail, and the restricted use of it in racing horse, make the prognosis unfavorable 

8-Fracture of the navicular bone: -

Definition:

It is rare and ensues following navicular disease or trauma to the foot

Etiology:

1-Violent concussion to the foot                      

2-Neurectomy after chronic navicular disease (chronic inflammation causes demineralization of the bone and adhesion between the bone and deep flexor tendon). The bone may be fractured, as a result of stress from adhesion, after neurectomy when the horse starts to use the foot normally

Signs:

1-Sings are identical to those of navicular disease but they are more acute 

2-Unilateral contraction of the foot                   

3-Radiographs will reveal the fracture

Treatment:

Posterior digital neurectomy is the only treatment

Prognosis:

*Unfavorable

9-Fracture of the 3rd phalanx: -

It is more common affection in the forefoot than the hind one

Etiology:

1-Trauma with twisting action as the foot lands

2-Penetration of the sole by foreign body (picked up nail)

3-Trauma to a large side bone leading to fracture of the wings of the 3rd phalanx

Signs:

A-Recent fracture involves the center of the bone and extends to the articular surface

Acute supporting-leg lameness will be detected, the horse may refuse to place the foot on the ground for 72 hours, and examination will reveal increased pulsation and heat of the foot, and uniform pain over the sole area with hoof tester. If the fracture involves one wing of the bone, the lameness will not be so severe, less pain can be detected over the entire sole, and more severe pain can be detected over one quarter

B-Chronic fracture

Lameness will not be as evident and history, hoof tester, and radiographs are necessary for diagnosis. Radiographs detect the presence of fracture and its site

Diagnosis:

1-History                                  

2-Examination with hoof tester                                  

3-Radiographs

Treatment:

1-Immobilization of the hoof by full bar shoe with quarter clips. The bar of the shoe should be recessed from the frog (to prevent frog pressure), and the quarter clips should be placed near the junction of the heel and quarter (to prevent expansion of the quarters). This will finally immobilize the 3rd phalanx. The shoe should be used for 3-6 months and reset every 4-6 weeks, and after relief of the symptoms, the horse should be shoed with either quarter clips or full bar for a time before both are removed. The horse shouldn’t be used for work for 6-12 months after removal of the shoe with bar and quarter clips, if the symptoms don’t disappear after the end of the 6 months

2-If the fracture ensued as a result of puncture of the sole with foreign body, the wound should be treated and tetanus antitoxin should be administered, but bone abscess or demineralization should be expected

3-Fixation of the fracture by bone screws                       

4-Neurectomy of the posterior digital nerve

Prognosis:

*Guarded although most horses return sound if treatment instituted soon after the fracture 

*Fractures of the wing are favorable than center fractures involving the articulation surface, as the later has greater chance for chronic lameness

*Small separated splinters cause sequestrum and prolonged lameness even after being removed

10-Pedal osteitis: -

Definition:

Demineralization (rarefaction or osteophytic development) of the 3rd phalanx as a result of inflammation and manifest it self as roughness of the borders of 3rd phalanx especially lateral wing

Etiology:

1-Persistent inflammation of the foot like; persistent corns, chronic bruising of the sole, navicular disease, laminitis (especially from concussion), puncture wounds of the foot, and local periostitis due to detachment of few sensitive laminae (osteophytic development with no signs of lameness)

2-It may be associated with infection (infected corn or puncture wound), or without infection (laminitis or sole bruising)

Signs:

1-Lameness in all gaits               

2-Diffuse or localized pain at the bottom of the foot by hoof tester

3-It may be only a sign of the mentioned causes       

4- 3rd phalanx demineralization by radiographs

Treatment:

1-Treatment depends upon the cause

2-Proper shoeing to prevent pressure over the sole by leather pads

3-Neurectomy if the lateral wing of the distal border of the 3rd phalanx is affected

Prognosis:

*Unfavorable as it is a chronic disease

11-Puncture wounds of the foot, or Picked-up nail: -

Definition:

Supporting-leg lameness as a result of nails or sharp foreign bodies that treaded over by the horse leading to puncturing or penetrating wounds of the foot   Some of these wounds are difficult to be located if the nail is missed and the frog is the affected area (as the spongy frog closes over the wound). The most serious puncture wounds are those of the middle 3rd of the frog (navicular bursa, deep flexor tendon, or lateral cartilage), the anterior 3rd (osteitis, fracture, and necrosis of 3rd phalanx), and finally the posterior 3rd (digital cushion) 

Signs: Vary greatly according to;

1-The involved area                                                                      

2-Direction and length of the nail                      

3-Severity of injury                                                                        

4- Presence and nature of infection 

If the causative agents still in the foot, the diagnosis will be more simple and degree of injury to underlying structures should be determined, but if the nail is not present; attitude, hoof tester, and paring the sole will be helpful. Attitude of the gait is helpful for determination of the location of the foreign body (the horse will land on heel if the toe is affected and vise verse), hoof tester also helps detection of the location of wound, and on paring the sole, punctures will appear as black spots that should be probed for determination of its depth and weather they lead to sensitive tissue or not

3-Lameness may be not evident until infection of the foot causes pododermatitis. If the infection of the foot is associated with no drainage of the wound puncture the infection will force drainage at the coronary band (quittor) 

4-Distension of the flexor tendon sheath above the fetlock joint in some cases (with heat but with no pain on palpation) 

5-Puncture wound of the hind limb may cause stringhalt attitude to the gait, and the horse will move the limb in hyper flexed manner

Complications:

1-Infectious laminitis           

2-Necrosis or fracture of the 3rd phalanx                       

3-Tetanus

4-Infection of navicular bursa or digital cushion                 

5-Fracture of navicular bone 

6-Phlegmon of the limb, septicemia, and systemic reaction in severe cases

Diagnosis:

1-History                                          

2-Signs and examination                                     

3-Radiographs

Treatment:

1-Removal of the nail                                                        

2-Establishing drainage by wide opening to the sensitive tissue. If navicular bursa is penetrated, drainage should be established at the center third of the frog under volar nerve block with formation of a window through the aponeurosis of the deep flexor tendon

3-Control and prevention of infection, till healing, by cleaning of the wound with hydrogen peroxide, dressing with tincture of iodine, application of foot bandage, rest in dry area, and systemic administration of antibiotic. If the wound drains via a sinus at the coronary band, it is advised to make magnesium sulfate bath daily and interval of bath and bandage increases once healing begins (every three days)             

4-Administration of tetanus antitoxin

Prognosis:

*Favorable in early case with no damage to the underlying structures

*Guarded to unfavorable if the navicular bursa or the 3rd phalanx are damaged

12-Corn and Bruised sole: -

Definition:

A-Corn Affection of the sensitive and insensitive tissues of the sole by the shoe at the inner angle between the wall and the bar of the forefeet (as the forelimbs carry most of the weight)

B-Bruised sole The same affection of barefooted horses anywhere of the sole (toe or quarter) and caused by rocks and may be predisposed by flat foot

Etiology:

1-Shoe left for long period (heel of the shoe will be forced into the angle between the wall and bar) 

2-Improper trimming of foot (too low heel)                  

3-Horse with thin sole or previous laminitis

Types:

A-Dry corn

Red stains on the inner surface of the horn due to hemorrhage and bruising of sensitive tissues

B-Moist corn

Accumulation of serum beneath the horn due to more severe injury to sensitive tissues

C-Suppurating corn

Infection of the corn area with necrosis of sensitive tissues and planter cushion

Signs:

1-Varying degrees of lameness according to severity of the injury

2-Varying attitudes of lameness according to location of the injury

3-Pain or flinching as a reaction to hoof tester

4-Paring with hoof knife reveals presence of red-stained area or bluish discoloration (if sole abscess is developing)

5-If the horse has corn, he will try not to land on the affected area during motion, while during rest, he will bear most the weight on the toe, rises the heels, and the knee is forward. If he has bruised toe, he will make exaggerated effort to land on the heel during motion, and will bear most the weight on heels during rest.

6-Short anterior phase stride if the animal has bruised sole and long anterior phase stride if the animal has corn.

Treatment:

1-Removal of the shoe with rest of the animal if the shoe is the main cause, and the animal shouldn’t be reshod till subsidence of signs

2-Paring horny materials over the corn (don’t exposing sensitive tissues) to relieve pressure

3-In case of suppurating corn or bruised sole 

a-The entire horny layer should be removed for drainage of the sensitive tissue 

b-Warm bath of magnesium sulfate solution or antiseptic       

c-Application of tincture iodine

d-Bandaging and protection from contamination 

e-Application of antiphlogistic paste under the bandage for drawing out infected fluids 

f-Administration of tetanus antitoxin

Prognosis:

*It is always guarded, as some cases tend to be chronic with osteitis of the 3rd phalanx

13-Rachitic ring bone: -

Definition:

It is not a true ring bone, or arthritis, but it is merely fibrous tissue swelling at pastern region in foals and horses up to 2 year-old

Etiology: Nutritional

Signs:

1-More than one foot involvement (both fore or hind, or both fore and hind)

2-Lameness and joint soreness 

3-Presence of bog spavin, enlarged carpal joint, or contracted flexors

4-No bony growth on radiographic investigation of the firm swelling

Treatment:

Correction of diet, and response can be observed 4 weeks later

Prognosis:

*Guarded                                             

*Unfavorable if it is old

14-Sand crack: -

Definition:

Crack of the hoof wall, either originating from the bearing surface of the wall and extends up the wall to variable distance, or originating at coronary band due to defect of the coronary band and extends downward. It may present at toe, quarter, or heel

Etiology:

1-Excessive growth of wall as a result of lack of trimming, leading to splitting of the wall

2-Injury to coronary bands leading to weakness and deformity of the wall

3-Weakening of the wall due to excessive dryness of wall

Signs:

1-Presence of splitting in the wall

2-Lameness when crack extends to sensitive tissues with infection

3-exudate that differs in nature according to elapsed time and depth

4-Variable lesions above coronary band (lacerated wounds) when the crack started at it

Diagnosis:

1-Signs                           

2-Examination

Treatment: According to location

A-Toe cracks

1-Lowering the toe 2 cm on either side of the crack (should be cleaned daily) at bearing surface and shoeing with toe clips to prevent expansion. Burning or grooving of triangle (base toward coronary band) and bar to prevent upward expansion .The crack is dressed with tincture of iodine

2-Strippiong out or undermining the crack 0.5 cm in triangular manner with the base of the triangle next to sensitive tissue. Drilling of holes on either side of the crack and threading the holes with umbilical tape or stainless steel wire. Filling the defect with plastic. Corrective shoeing by toe clips and lowering the toe on either side of crack

B-Quarter cracks

1-Lowering of bearing surface posterior to the crack. Application of half bar shoe with the bar at the heel of affected side. Application of pattern (triangle with bar) at the tip of the crack to prevent expansion. Application of quarter clips

2-Stripping out as mentioned

C-Heel cracks

Treated as quarter cracks with lowering the heel posterior to the crack, and with no need for half bar shoe at the heel

Prognosis:

*Favorable when it originates from bearing surface and has no infection

*Guarded to unfavorable when it started at the coronary band as it will persist for life and need permanent corrective shoeing

15-Thrush: -

Definition:

Degenerative changes of the central and lateral sulci of the frog characterized by black necrotic materials, and infection may penetrate as deep as sensitive tissues

Etiology:

A-Predisposing

1-Unhygienic conditions                               

2-Dirty unclean feet, poor shoeing, and poor trimming

B-Exciting

Spherophorus necrophorus

Signs:

1-High moisture and black discharge of variable quantity and foetid odor in the frog sulci.

2-After cleaning of the sulci, it seems painful as deep as the sensitive tissues

3-Large area of the frog may require to be undermined due to loss of continuity with the underlying of frog

4-Lameness with same signs of foot infection encountered in puncture wounds

Diagnosis: Signs

Treatment:

1-Removal of the cause

2-Cleaning by phenol and tincture of iodine, 10% formalin, or 10% sodium sulfa pyridine 

3-Blistering the heel to stimulate frog growth  

4-Lowering the wall  

5-Protection of frog by leather

Prognosis:

*Favorable                                       

*Guarded when sensitive tissues are involved

16-Canker: -

Definition:

Chronic hypertrophy or chronic vegetative growth of horn-producing tissues of foot, commonly affects the hind feet

Etiology:

1-Unhygeinic stabling (mud or bedding soaked in urine and feces)              

2-Lake of frog pressure

Signs:

1-Lameness can be detected only in late stages                               

2-Ragged appearance of the frog

3-Foul smelling of the foot                                                              

4-Horn tissues loosen easily

5-Corium is swollen, covered with white caseous exudates, has little tendency for healing, and easily bleed. It may extend to the sole or the wall

Diagnosis:

1-Signs and examination                                          

2-Differential diagnosis from thrush

Treatment: 

Slow improvement and low healing (10 days- 40 days)

1-Remove the cause and apply dry bedding

2-Removal of loose horn with application of bandage with;

a-Astringent antiseptic (5% picric acid solution)         

b-Caustic (copper and zinc sulfate crystals)

3-Systemic penicillin

4-After improvement, apply sulfa pyridine powder dressing and bandage

Prognosis:

*Guarded to unfavorable