Laminitis (also known as "founder") is inflammation of the laminae of the foot - the soft tissue structures that attach the coffin, or pedal bone, of the foot to the hoof wall.
The inflammation and damage to the laminae causes extreme pain and leads to instability of the coffin bone in the hoof.
In more severe cases it can lead to complete separation of and rotation of the pedal bone within the hoof wall.
Laminitis is a crippling condition which can be fatal in severe cases.
Once a horse has had an episode of laminitis, they are particularly susceptible to future episodes.
Laminitis can be managed, but not cured, which is why prevention is so important.
Initial (acute) symptoms
- Although all four feet can be affected, the forelimbs are more frequently and more severely affected than the hindlimbs.
- Affected horses are reluctant to move and adopt a 'sawhorse' stance where they rock their weight back off the more badly affected forelimbs.
- Laminitic horses will often lie down.
- It will be difficult for you to pick up one forelimb due to the severe pain of the other supporting forelimb.
- The hoof wall and coronary band (the soft tissue around the top of the hoof) are often warm to touch.
- There is often pain on application of hoof testers (a tool your vet or farrier uses to assess hoof pain), particularly over the toe area.
- Digital pulses are strong and rapid (the digital pulse is found at the back of your horse's fetlock).
Chronic symptoms
These are found in cases where the inflammation has existed for some time and structural changes are now evident.
- There are laminitic "rings" on the surface of affected hooves which correspond to previous episodes of laminitis.
- The hoof wall takes on a dish/slipper shape with long toes.
- Where the pedal bone has rotated in the hoof, there is a bulge in the sole corresponding to the rotated bone.
- The horse has restricted movement in its front legs and will tend to place more weight on its back legs, often described as a 'laminitic stance'.
Causes
Over-feeding fat ponies is a very common cause, particularly during spring after recent rain.
The soluble carbohydrate content increases in grasses and clovers after rain. When ingested, this causes metabolic changes that result in altered blood flow to the laminae of the foot.
Other causes include:
- Over-feeding grain or grain engorgement when a horse gets into a feed shed/bin.
- Retained placenta in post-foaling mares.
- Septicaemic conditions.
- Obesity (a common predisposing factor in laminitic ponies).
- Lameness which prevents weight bearing in one leg leading to laminitis in another supporting limb.
- Trauma resulting from excess work in unshod horses on hard ground, or from over-enthusiastic hoof trimming.
Risk Groups
Fat ponies and their cross-breeds are most predisposed to laminitis.
However, any horse suffering a condition mentioned above may also be affected.
Horses which show signs of previous episodes of laminitis (eg. hoof rings or slipper-shaped feet) are predisposed to future episodes because they have fewer healthy laminae remaining to support the pedal bone.
Spring is when most episodes of laminitis due to over-feeding occur
Diagnosis
If you suspect your horse has laminitis, seek veterinary attention immediately.
Depending on the severity of the clinical signs, your veterinarian will probably wish to take some X-rays of your horse's feet.
This will provide your veterinarian with a benchmark against which to assess response to treatment.
Management
The key to a successful outcome is early diagnosis and an aggressive approach to treatment, together with a good relationship between you, your vet and your farrier.
- First, remove the cause. Horses which have developed laminitis as a result of over-feeding need to be removed from the food source immediately. Mares with retained placenta constitute a medical emergency - your veterinarian will need to remove any remaining placenta, flush the uterus with saline and start appropriate medical treatment. Horses with a septicaemic condition will similarly need aggressive medical treatment by your veterinarian.
- Anti-inflammatories are the cornerstone of therapy. Consult with your veterinarian regarding the appropriate drug and dose rate depending on the cause/severity/stage of laminitis.
- Affected horses need to be stabled in deep shavings so they can dig their hooves into a comfortable position. Alternatively a sand yard can be used, however it is crucial that you use a hoof pick twice daily to prevent sand packing up in the sole. In the early stages exercise should be avoided as it may result in further rotation of the pedal bone.
- Hoof care is vital. Your farrier should consult with your vet and trim the hoof according to the degree of rotation of the pedal bone.
- Ongoing dietary management is crucial. Consult with your vet on the most appropriate feeding regime. Many feeds promoted as being safe for laminitic horses are not appropriate if your horse is also receiving other feed sources high in soluble carbohydrate. Until you are able to get veterinary attention/advice, feed hay only.
- Horses need company. You should ensure that horses confined during laminitis treatment are able to interact with other horses.
Prevention
- Ensure your horse or pony is fed a balanced ration appropriate for their type, age and activity level.
- Restrict access to lush pasture.
- Seek veterinary attention immediately if you suspect your mare has retained placenta (12 hours later can be too late) or if your horse is otherwise unwell.
- Ensure your horse receives regular hoof care from a reputable farrier.
