COMMON DISEASES OF THE FOOT

Foul In the foot or Interdigital Necrobacillosis

(loor, loo, foul, foot rot, claw ill)

This condition is an acute infection of interdigital skin and adjacent and underlying tissues. It is caused by an infection with Fusobacterium necrophorum and possibly in association Bacteroides melaninogenicus. These two organisms together appear to act synergistically to penetrate the epidermis (or enter through a traumatic skin lesion) and then produce cellulitis which leads to severe lameness.

The milk withdrawal period is often the most important consideration when choosing a treatment for these cases.

Traumatic damage to the interdigital skin may lead to this condition so measures to reduce trauma can often reduce the incidence e.g. avoid stones, stubble, rape and kale, also keep feet as dry as possible improve bedding and remove slurry.

The prognosis for most cases is extremely good.

Interdigital Dermatitis

(scald)

This condition is an inflammation of the interdigital skin without the cracking and fissuring seen in interdigital necrobacillosis. These lesions have a pronounced foetid smell, no fissures and in most cases respond to topical antibiotics.

It is suggested that the lesions are caused by F. necrophorum and Dichelobacter (Bacteroides) nodosua Although there are also now suggestions that it may be related to Digital Dermatitis (see below). The control and treatment of this condition is identical to that for Digital Dermatitis (DD).

Interdigital Skin Hyperplasia

(corn)

The skin adjacent to the lateral digit is most commonly affected. The hyperplasia is thought to be secondary to chronic irritation e.g. low grade interdigital infections. In some instances it may be an inherited condition common in Hereford bulls but also seen in other breeds.

Lameness is caused by the pinching of the interdigital mass or secondary infection leading to Necrobacillosis.

Small lesions will resolve spontaneously if excess horn from the axial wall is removed thus widening the axial space when the cow bears weight. Larger lesions require surgical removal with the application of a dressing. In all cases any secondary infection must be treated.

Digital Dermatitis

Slurry heel 

(heel erosion)

This is a condition of housed cattle standing for long periods of time in corrosive slurry. The normal soft horn of the heel becomes worn away. This is important because it results in rotation of the foot backwards, and may result in a raised toe. Deep erosions may result in infected heels or white line lesions in the axial groove. Control is obtained by attention to the environment especially removing slurry and keeping feet clean and dry.

"Mud Fever"

This is similar to the condition seen in horses, and presents as swelling from the top of the hoof to above the fetlock. Skin becomes inflamed and thickened and hair crusted. Treat by cleaning and drying the area and apply an antiseptic cream.

As Dermatophilus infection is involved systemic antibiotics may also be required.

Laminitis

This condition is currently considered to be extremely important in the aetiology of many claw lesions as well as being a primary cause of lameness in its self.

Laminitis is inflammation of the corium arising from a systemic disorder due to a wide spectrum of largely interdependent aetiological factors. These include metabolic and digestive disorders often seen with rapid changes of diet especially from low energy forage diets to high concentrate diets. There is still much debate as to whether it is excess energy or protein which is the major problem. It is sufficient here simply to advise that cattle always have access to adequate long forage and to avoid sudden dietary changes. Calving or severe inflammatory processes e.g. metritis or mastitis may also lead to laminitis. Local influences within the hoof may also be important such as trauma and overload especially seen in recently housed cattle who do not readily use cubicles and thus have greatly reduced lying times.

Acute laminitis may be caused by one single factor such as acute rumen acidosis with a release of endotoxins. The acute condition is rare but is seen on occasions. Treatment is to remove the underlying cause, place the animal on soft conforming bed and give analgesics. Following an acute attack most cases become chronic, also chronic laminitis often occurs without any history of an acute attack. This "subclinical laminitis" is extremely common. Cows may develop laminitic rings as hoof wall growth is affected. The pedal bone often sinks within the foot resulting in pressure on the corium at the toe. Laminitis can result in any of the following:- Hoof overgrowth, soft horn especially at the white line, yellow discolouration of solar horn, blood in the horn, hardship lines i.e. horizontal grooves on the wall, soft powdery horn, pain and discomfort and gross claw overgrowth.

It can be seen from the above that laminitis is a complex multi-factorial disease which may pre-dispose the cow to many of the common claw lesions.

White line abscess

This is caused by the penetration of the white line by fragments of grit or stones. The white line has often been previously weakened by chronic laminitic changes. If the foreign body tracks to the corium it will form an extremely painful abscess. These can often be diagnosed using hoof testers. Treatment is to provide drainage and to trim away all under run horn. This may require the removal of a large part of the wall or sole. Never leave an area which could become impacted with debris.

Severe deep infections may require antibiotic treatment but this is not common. The prognosis is usually very good however some deep infections may track into joint structures.

The application of a block to the healthy digit will reduce the animals discomfort and also reduce the risk of further trauma to the affected digit.

Foreign body penetration of the sole

Although penetration of the white line is by far the most common site of foot penetration, any part of the sole can be damaged by a sharp object.

It is not sufficient to simply remove the foreign body, all under-run sole must be removed to leave only healthy tissue. The application of a dressing is optional. As a general rule most lesions will heal faster left open, the only real need for dressing is to control haemorrhage.

Solar ulcer

Solar ulcers typically occur on the lateral claw of the hind foot (the pedal bone in this claw rests partly on the sole) or less commonly on the medial claw of the front foot.

The proposed aetiology is that following laminitis the pedal bone drops and later pinches the corium over this site. This results in haemorrhage into the horn or severe impairment of horn production. The resultant horn defect is the ulcer which then becomes plugged with granulation tissue. Over growth of the toe and erosion of the heel will also rotate the pedal bone increasing pinching at this site. The solar ulcer is very often bilateral, it is good practice always to examine the other foot and perform corrective foot trimming when treating solar ulcer cases.

The ulcer is treated by removing all under-run horn and dishing out the sole so that there is no pressure on that site. The application of a block will greatly improve the cows gait and aid recovery.

Sole haemorrhage

(bruising)

Haemorrhagic areas with softening and yellow discolouration of solar horn is all part of the subclinical laminitic syndrome, or may follow acute laminitis. This often does not require specific treatment but should be a warning that laniinitis is a problem within that animal or herd. Steps should then be taken to remove underlying factors leading to laminitis. This should be differentiated from areas of normal healthy pigmented horn when examining the sole.

Severe solar haemorrhage may result in under-running of the sole as the solar horn grows out. If found this should be treated by removing all the "false" sole to leave only healthy solar horn.

Horizontal Fissure

Fracture of the pedal bone

Classically associated with Fluorosis this fracture of the pedal bone can be seen following severe trauma e.g. running on hard ground or oestrus behaviour. Typically the medial claw of the front foot is involved and animals stand with a cross-legged stance. Affected animals show little or no heat or swelling of the foot. X rays can be used to confirm the diagnosis if required, the common fracture site is across the pedal joint to the solar surface of the bone. The hoof horn acts as a good splint and many cases will heal in 2-3 months if a block is placed on the other claw.

The infection can be localised to one structure or involve several e.g. septic pedal arthritis, septic navicular bursitis/osteomyelitis, tenosynovitis of the deep digital flexor tendon sheath or abscess in the heel involving the digital cushion. These lesions usually result in severe lameness, heat and swelling around the coronet and often discharging sinuses at the coronet

Treatment will not respond to antibiotics alone and requires radical drainage and curettage of infected or necrotic tissue. Many require amputation of the digit.

Spastic paresis 

As well as the above causes of foot lameness there are also a number of neurological and orthopaedic conditions which must be considered. For example:

• Joint ill
• Hip dysplasia
• Hypertrophic osteoartbropathy
• Ankylosing spondylosis 
• Hip dislocation
• Osteoporosis
• Sacroiliac luxation or subluxation - post partuxn
• Patellar luxation
• Anterior cruciate rupture
• Contracted tendons
• Calcanean tendon rupture
• Gastrocnemius muscle rupture
• Haematoma
• Tarsal cellulitis
• Carpal hygroma
• Radial paralysis
• Suprascapular paralysis
• Brachial plexus paralysis
• Femoral paralysis
• Obturator paralysis
• Sciatic paralysis
• Tibial paralysis
• Osteochrondrosis

The Prevention of lameness

Routine foot trimming to prevent overgrowth will reduce the incidence of lameness, but beware as poor foot trimming is itself a risk factor. 

Footbaths also have a place in the treatment and control of lameness

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