Arthritis

Arthritis is inflammation of a joint causing pain and stiffness. The word arthritis is often used to explain a range of conditions including degenerative joint disease, osteoarthritis and synovitis.

How does it occur?

Arthritis often develops following interference with normal joint structure and function of a joint such as damage to the smooth protective cartilage covering the end of each bone or even the bone itself. Damage can occur by:

  • Injury
  • Infection
  • Damage to joint capsule and ligaments
  • Age-related wear and tear

In response to damage to the surface of the joint, new bone is formed, which is rough and not covered by cartilage. This results in reduced joint movement and pain.

Speed of onset

Arthritis can happen very quickly in the case of traumatic injury or infection to the joint when symptoms of pain (lameness) develop very quickly, or it can develop gradually over a longer period of time when associated with age-related wear and tear.

Symptoms

  • Visible swelling of the joint (a result of more joint fluid being produced)
  • Restricted range of joint motion
  • Pain on flexion of the joint
  • Lameness
  • Heat

The symptoms exhibited vary according to the cause of arthritis and joint involved. Not all symptoms will be present in all horses.

Diagnosis

Arthritis can be diagnosed through thorough clinical examination and assessing for lameness. In many cases additional examinations will be required including:

  • Nerve Blocks – injecting local anaesthetic around specific nerves to remove pain from specific parts of the leg.
  • Radiography (x-rays) – to assess bones at the joint surfaces. This is particularly helpful in long term arthritis and will not identify early cartilage damage. (NOTE: A horse can have arthritic changes visible on radiographs but may still move comfortably and compete successfully).
  • Joint Fluid collection – for laboratory analysis to look for signs of infection.
  • Nuclear scintigraphy (bone scan)

Treatment

Treatment is determined by the cause of arthritis and may involve:

  • Flushing the joint with sterile saline and use of antibiotics when the joint is infected
  • Use of oral non-steroidal anti-inflammatory medications which reduce pain and inflammation.
  • Use of injectable medications
  • Medication of the joint itself to reduce inflammation and improve lubrication.
  • Arthroscopy – surgical intervention

Prognosis

In acute cases (e.g. septic joint) complete cure may occur if appropriate and timely treatment is undertaken.

In longer-term arthritis (e.g. age-related wear and tear) ongoing treatment may be required.

Laminitis

With the days getting longer and the grass growing fast, many of us are breathing a sigh of relief. Winter is nearly over. However, as much as we all love spring, the new flush of sugar rich grass can have serious implications for some of our equine friends. 

 Laminitis means ‘inflammation of the laminae’. These are the tubular tissues which support the pedal (coffin) bone within the hoof to the hoof wall. When these laminae become inflamed, the horse, or more commonly pony, can become incredibly painful. Leading to the typical laminitic clinical signs. For example: leaning back to reduce weight load through the front feet, reluctance to move, depression and inappetence, lying down more or a reluctance to pick up feet. Some horses and ponies can be more subtle, simply seeming ‘pottery’ on their front feet and painful to turn tightly. The front feet are more affected as approximately 70% of a horse’s weight is carried through the forelimbs.  But the hind feet will be affected too. 

In this acute phase, it is important to remove the pony from the pasture, put in a stable or restricted area on a deep, preferably shavings bed (shavings pack into the foot better and provide more support) and call your vet. It is important to restrict movement in this acute stage. With the laminae inflamed, there is a possibility the pedal bone may sink and rotate within the hoof capsule, this has more serious long-term implications and a poorer prognosis. 

On clinical examination, your vet will use indicators such as clinical signs, increased pulses to the feet and reaction to gentle pressure to the sole using hoof testers to diagnose laminitis. Anti-inflammatories will be administered to try and counter the changes within the laminae and to provide pain relief. We sometimes dispense acepromazine (ACP) too, mainly to calm ponies that dislike being in and encourage them to lie down. There was a theory that the vasodilation cause by ACP may have a beneficial effect on the laminae but this is unproven. Ice therapy of the feet may be more beneficial. Foot padding and frog supports provide a little elevation of the heel to reduce the pull of the flexor tendon on the pedal bone, which may be applied to reduce the risk of sinking and rotation of the pedal bone. Your vet will advise you on the right treatment.  

We may suggest taking some radiographs of the feet. This will give us an idea whether there has been movement of the pedal bone and give you a better idea of what to expect in terms of rehabilitation and prognosis. These radiographs can also aid your farrier. Once the initial pain has eased, your farrier and vet can work together to discuss trimming the foot as well as specialised shoeing to help your horse or pony feel more comfortable. 

Box rest is important, even if your horse or pony appears better, it is important to be guided by veterinary advice as to when turn out is allowable. Movement increases the risk of the pedal bone rotating and sinking. Feeds must be reduced and adapted to contain low non-structural carbohydrates, look out for the laminitis trust approved sticker on the bag. Access to well soaked hay is important. Although their rations need to be reduced and weight loss is a key factor in recovery and prevention in many cases, starving a horse or pony can lead to other complications. It is about finding a happy balance; your vet can advise you on feeding regimes.  

So why does this happen? Traditionally it was thought of as simply fat ponies having too much good grazing. There is an element of that, but we now know that laminitis is not just a foot issue and it is not that simple! There are three main underlying causes of laminitis. 

  1. Diseases and conditions that lead to systemic (i.e. whole body) inflammatory conditions such as retained placenta, severe diarrhoea and lung infections.
  2. Hormonal disorders like ‘Cushing’s disease’ (more common in older horses and ponies) and Equine Metabolic Syndrome (EMS) and the resultant insulin resistance these conditions create. These horses and ponies cannot control their blood glucose effectively, leading to a range of side effects. Cushing’s also puts horses and ponies in a ‘pro-inflammatory’ state, making secondary infections like foot abscessation a more common sequalae to laminitis.
  3. Uneven weight bearing, after an injury on a different limb for instance, can cause a mechanical laminitis in the supporting limb. 

Prevention is better than cure. Once a horse or pony has had laminitis, they are at a higher risk of being affected in the future. So it is important to remain vigilant. Keep your horses and ponies ‘fit not fat’. Restricted grazing and grass muzzles are good methods of reducing grass intake. Remember, a clever pony can learn to eat as much grass in a few hours as they can eat in a day. So simply reducing grazing hours is often not enough! Winter time is a good time of year to try and get the weight off of the more rotund.  There are some horses and ponies that will be more prone to laminitis and harder to get the weight off. These are your potential EMS ponies. Base line insulin and adiponectin levels in the blood can help determine the risk of laminitis. But the crux of EMS is weight loss. Less sugars and more exercise!  Some advice that I, personally, should heed too!

OCD – Osteochondritis Dissecans

Osteochondritis dissecans (OCD) is a relatively common developmental disease that affects the cartilage and bone in the joints of horses. OCD can occur in all breeds, especially in big size horses, and can show clinical signs in up to 30% of them. Cartilage in joints with OCD doesn’t grow normally causing it and the bone underneath to become irregular in thickness and weaker until they develop into flaps that can either remain partially attached to the bone or break off and float around in the joint. These loose flaps cause inflammation in the joint and predispose it to arthritis.

What causes OCDs?

OCD is a multifactorial disease that can be caused by:

  • Rapid growth
  • Diets very high in energy or have an imbalance in trace minerals
  • Genetics
  • Hormonal imbalances
  • Trauma

How do you spot it?

The most common sign is swelling in the joint of a young horse between 4 months and 2 years of age but may not occur until they are brought into work. The grade of lameness varies with location and severity of the OCD. OCDs can occur in all joints but they occur most frequently in the hock, stifle and fetlock.

How do we diagnose it?

The vet will need to do a physical examination with lameness workup and radiographs. OCD is often bilateral and the vet would suggest taking radiographs of the opposite joint, even if there is little or no swelling in that joint. Sometimes older horses are diagnosed with OCD incidentally without apparent clinical signs. X-rays only show bone clearly and not cartilage so sometimes it is necessary to enter the joint surgically (through an arthroscopy) to assess the degree of damage under general anaesthesia.

How do you treat it?

The best treatment is surgical removal of the abnormal bone and cartilage is through arthroscopy under general anaesthesia. Arthroscopy is performed by making two or more small incisions into the joint through which a small camera called an arthroscope and other specially designed instruments are placed. Aftercare recommendations depends on the location and severity of the OCD but they always require a period of box rest followed by progressive exercise with full return to training in several months.

What’s the prognosis?

Prognosis for athletic function is good to excellent for most OCDs that are treated surgically but depends on the location and the severity of the OCD. In general, if the OCD lesion is not removed the prognosis for future soundness will be decreased.

Navicular Disease

What is Navicular disease?

Navicular disease is a slowly progressive degenrative condition of the navicular bone, causing chronic degeneration of the navicular bone in which there is damage to its flexor surface and the overlying flexor tendon in the front feet. There may be accompanying navicular bursitis (inflammation of the fluid sac around the navicular bone) and osteophyte formation (bony growths). Navicular disease usually causes intermittent lameness and toe pointing when the horse is standing; unfortunately the disease cannot be cured, but a horse suffering from the disease can be treated to relieve any associated pain or discomfort.

Navicular disease should not be confused with navicular syndrome; this is any one of a number of conditions that can cause pain referable to the back of the hoof or navicular area. This can include damage to the navicular tendons and ligaments, inflammation of the navicular bursa and a number of other things.

The navicular bone is located directly behind the coffin bone, held in-between the short pastern and coffin bone by tendons and ligaments.

The navicular bone has two main functions:

  • To protect the joint and tendons from pressure and concussion.
  • To act as a valve for blood flow to the coffin bone and corium in the hoof.
How is navicular disease diagnosed?

Horses with navicular disease will show the following signs:

  • Lameness:
    • A short, choppy foreleg lameness that often shifts from one foot to the other. Affected horses may stumble or resist lengthening their stride because they are reluctant to land and load weight on the heels of their front feet.
  • Sole and toe bruising:
    • This is a result of the inability of the horse to use the cushion of the frog and heels when landing.

Possible causes include:

  • Repetitive trauma to the heels and navicular area.
  • Interruption of circulation to and from the navicular bone.
  • Short, upright pastern conformation.
  • Poor shoeing with long toes and underrun heels.
How is navicular disease treated?

Treatments involved include corrective shoeing – the use of elevated heel shoes may be necessary.

Eggbar shoes may also be used. Although corrective shoeing is a popular choice for treatment of navicular disease, a farrier can’t cure or correct navicular disease, he can only relieve the symptoms to a certain degree.

Your horse may also need to be administered vasodilator drugs, these will help improve the blood supply to the navicular bone. Horses with navicular disease can be kept sound with good shoeing and with vasodilator drugs. As Navicular disease is a bone disease then so called bone remodelling agents (E.g. Tildren or Osphos) can be used which are given by injection. Injection of the navicular or coffin joints with sodium hyaluronate (HA) or corticosteroids has also proven to be very effective for some horses, although long-term soundness is not guaranteed with any of these treatments.

Neurectomy (de-nerving) may be necessary for selected chronic cases. Neurectomy involves sectioning of the nerve supplying the navicular bone, hence providing permanent pain relief.

 

Keratoma

A keratoma is a benign growth between the hoof wall and the pedal bone inside the foot. The growth starts from the horn producing cells, usually originating from the coronary band growing downwards to the toe.
The exact cause is unknown but some cases can be linked to chronic irritation or infection in the shape of slow abscesses or direct hoof injury. Injury to or inflammation of the coronary band is also thought to be a possible cause.

There may not be any visible signs of the keratoma on the outside of the hoof but a bulge on the hoof wall can be present.  There is often an inward deviation of the white line visible on the bottom of the foot. Lameness can develop, due to the pressure of the keratoma. Often this presents as an intermittent lameness. Other clinical signs may involve a foot abscess at the location of the keratoma and possible sensitivity to hoof testers.

Further investigation will include taking X-rays of the foot. This might show the location of the keratoma and how far it has advanced. The keratoma can sometimes be visible as a semicircular defect in the pedal bone. Other options for further diagnosis can be a biopsy of the keratoma to identify the growth and in difficult cases MRI can be a helpful tool.

Surgery is required to remove the keratoma. This can be done either standing or under general anaesthesia. The hoof wall is removed to gain access and the growth is excised. Complete removal is important because the keratoma can return if it is not completely removed. The wound is packed with gauze soaked in iodine and bandaged up completely to keep the wound clean with support of a special shoe. Your horse will require antibiotics and pain relief after the surgery. Further management will include box rest and regular bandage changes. The foot will be bandaged until a hard layer of horn has formed over the area. Following this the horse will have to remain in clean, dry conditions until the wound has completely healed over. The complete process can take many months because the hoof wall grows only about ½ cm each month. With patience and careful management the prognosis is usually good.

Photo source:  “Adams’ Lameness in Horses”, fifth edition, Ted S. Stashak, 2002, 720 – 722

Canker

Canker is a disease affecting the soles characterised by a foul smelling creamy exudate. Canker is similar, but a more serious condition than thrush. Although it is rare, unlike thrush it can be difficult to solve. It is a severe bacterial/fungal infection (proliferative pododermatitis) that generally originates in the frog, and affects the heels, horn and underlying structures of the hoof. The clinical signs are the development of a foul-smelling white/grey pus in and around the frog and the presence of granulation-like tissue which often bleeds. Lameness is often variable depending upon the depth of structures involved.

Quittor

Quittor is a chronic, septic condition of one of the collateral cartilages of the pedal bone 5. Characterized by necrosis of the lateral cartilage of the foot and one or more sinus tracts extending from the diseased cartilage through the skin in the coronary band region. This results in the formulation of purulent fistulas that open above the coronet, usually resulting in lameness. It is seldom encountered today but was common in working draft horses in the past, usually following injury to the area.

Keratoma

A keratoma is a type of benign tumour that grows inside the foot. It originates from the horn producing cells, usually underneath the coronet, and grows down the foot with the normal hoof. When they reach the white line area at the toe, they cause separation of the bond between the hoof wall and sole. Once bacteria penetrate the foot, an abscess forms. The abscess is usually associated with a widening of the white line. An x-ray or MRI scan is needed to confirm the
presence of a Keratoma. An underlying keratoma will always cause the abscess to recur. The cause is unknown but can be associated with chronic irritation or trauma.

Hoof Abscesses

A hoof abscess is a bacterial infection within the sensitive structures of the equine foot. Pus is produced due to the horse’s inflammatory response and, as expansion is not possible within the hoof capsule, the pressure can be extremely painful. The condition is more common in the winter months due to the muddy conditions.

Signs of a foot abscess include:
• Sudden onset and severe lameness usually in one limb, often reluctant to bear weight
• Heat in the affected hoof
• Increased digital pulses (assessed by placing the fingers gently over the inner and outer aspects at the back of the fetlock to feel for the pulse to the foot)
• Possibly swelling of the bottom part of the leg
• May have an increased temperature (normal range 37-38.5 degrees Celsius)

The build-up of pus will eventually break out of the sole of the foot, the coronary band or the heel bulbs however prompt intervention minimises the pain suffered by the horse during the acute stage of the condition. The shoe is removed, hoof testers are used to establish the location of the abscess and the foot is pared, usually following a tract, to allow drainage of the abscess. Once drainage is established the horse will experience significant relief however some residual lameness is to be expected. Following this a period of poulticing may be required to draw out any remaining purulent material. Often if the abscess is deep seated or still developing it may not be found by paring and as excess paring can be detrimental to the horse, the foot should be poulticed to encourage abscess maturation and attempt to ‘draw out’ the abscess. Commercial poulticing material is available from us or most feed shops. The poultice should be trimmed to size and soaked in warm water before applying to the foot over the affected area and fixing in place with bandage material or a purpose bought boot. This poultice should be changed twice daily and the amount of discharge monitored. Some deep seated abscesses can take a significant period of time to develop and rupture, however if you feel your horse has developed an abscess that has taken a prolonged period of time to rupture it is important to seek veterinary advice as potential complications include infection of the deeper structures of the foot such as the pedal bone, requiring far more involved surgery to correct.Treatment of an uncomplicated foot abscess is a procedure that can be performed by your veterinarian or farrier however we stress that if there is any question as to what is causing the pain it is important to consult your veterinarian promptly.

Other conditions that can present in a non-weight bearing lameness include fractures and septic joints, both of which are important to identify quickly!
It is important to monitor your horses feet and pick them out daily in order to minimise the risk of abscess formation and to identify them early if they do occur.

Foot Balance

Hoof imbalance is one of the most common problems associated with lameness in a horse’s foot. It can be attributed to a variety of causes including conformation, the type of shoes fitted and how regularly the horse is shod.

Ideally the horse’s foot should strike the ground as a unit, with the entire weight-bearing surface hitting the ground together. In the case of side-to-side imbalance (lateral-medial imbalance) the outside toe strikes the ground before the heel, with the inside heel landing first. This leads to uneven forces across the hoof and uneven loading of the lower limb joints.

Many horses tolerate a large degree of foot balance, remain sound and are able to compete to a high level. Others are more sensitive, with a minimal discrepancy adversely affecting performance.

X-rays are a tool that we are using more and more in conjunction with farriers to evaluate & correct foot balance….. Essentially a side to side (Lateromedial – side view) and front to back (Dorsopalmar – front/back view) x-ray is taken of each foot to show the position of the pedal bone and the rest of the bony column in relation to the external hoof wall. These images can then be used by the farrier to trim to optimise foot conformation and correct any underlying imbalance. Severe imbalance is often evident without an x-ray but mild to moderate imbalance can be present in a “normal” looking foot.

Foot balance x-rays are particularly useful in horses with poor foot shape or sensitive feet as well as those suffering from foot related lameness. Many elite sports horses have this procedure on a regular basis to pre-empt any problems. The stage of the shoeing cycle must be considered when interpreting the images, it is unreasonable to expect the feet to look as good when they are due for re-shoeing as when they are freshly shod.

Foot balance x-rays can be performed at the clinic or on your yard providing there is an area of level concrete under cover and mains electricity.