Founder, or laminitis, is a common condition affecting the feet of horses. An extremely painful condition, founder/laminitis can affect every breed and is a major concern of caring horse owners. Though easy to diagnose and generally treatable, left untreated the condition can result in permanent severe lameness, with euthanasia sometimes the most humane option.
Founder occurs when there is inflammation of the laminae, the folds of tissue connecting the pedal (or coffin) bone to the hoof. When there is subsequent degeneration of the laminae, laminitis results. To properly understand how your horse might be affected it may help to understand what the terms ‘laminitis’ and ‘founder’ mean, and how they interact.
Laminitis is the painful swelling of the laminae, the substances that attach the hoof wall to the pedal bone. There are four stages a horse with laminitis may progress through:
The Developmental Phase is seen for approximately the first 20-72 hours, in the time after the ’cause’ and before the first signs of lameness. There are few clinical signs during this phase and the hoof wall should appear as normal.
This is followed by the Acute Phase, approximately 36-72 hours after the first signs of lameness. Heat will generally be found in the hoof at this point but the hoof wall will still appear as normal.
The Sub-Acute Phase begins some 72 hours after the onset of lameness. This is the recovery stage when proper treatment has been given, pain is receding and proper care must be maintained to prevent any further damage. It may take up to 12-14 months for full recovery. The hoof wall may appear to have a ‘ring’ of protruding hoof growth that will continue to grow downwards from the coronet during this stage.
Chronic Laminitis is the stage that can be avoided if the disease is caught and treated early enough. At this point, the structures inside the hoof have been altered permanently and the pedal bone has rotated downwards in angle, front tip first. This is where the terminology combines and we begin to use the word ‘founder’ to describe the condition.
Founder is the actual misalignment of the bone structures inside the hoof due to destabilisation of the hoof capsule. The inner hoof wall has torn its attachment to the pedal bone, destabilising the bone structures. At this point, the pedal bone is no longer supported within the hoof and rotates toward, sometimes through the sole.
The terminology is used in various ways within the veterinary profession. For simplicity, at Alpine Animal Doctors we will generally use the term ‘founder’ to denote those horses with pedal rotation, and ‘laminitis’ for those horses that suffer from bouts of inflammation with no rotation.
Founder may represent itself on the outside of the hoof wall in the form of ‘rings’ of protruding growth, signs of stress that can occur over time. These rings will grow from the coronet downwards. The hoof wall may begin to curl upwards at the toe, and the sole may become flatter due to the misalignment of the hoof structures.
Although founder is still poorly understood, and the exact mechanisms that cause laminitis are yet to be determined, we do know that there many causes of the condition. Classically, founder would occur in an overweight pony, complete with cresty neck, with a good appetite and access to plenty of lush pasture. In any horse, access to excessive amounts of pasture, hay, grain or pelleted feed is the most common cause of founder.
Other definitively known causes include blood poisoning following a systemic infection, severe cases of colic or enteritis, physical trauma to the soles of the hooves, ingestion of large amounts of cold water, retained placenta following foaling (particularly in shire breeds), and excessive weight bearing on one limb.
A sudden onset of founder is known as acute laminitis, and is considered a potentially life threatening emergency. Ongoing low grade laminitis is often referred to as chronic founder. Any horse that has suffered a previous episode of founder is more susceptible to a future attack.
Although founder can occur in one or all limbs, in most cases it is both forelimbs that are most commonly affected. A foundered horse will be reluctant to move, and will often lean back in an attempt to take weight off the front of the hooves. The pain can be so severe that the horse will often prefer to lay down. There is generally a noticeable increase in the pulse to the hooves, pain on compression of the sole and often the horse’s weight is shifted from one limb to the other.
If you have any suspicions that your horse may have foundered you should call the hospital for advice or seek veterinary attention.
How is founder/laminitis diagnosed?
The condition is relatively easy to define by visual examination. If the laminitis has already progressed to the chronic stage, x-rays may be needed to determine the degree of rotation.
The most important initial treatment is to remove the suspected cause, which may involve restricting and controlling diet and the removal of any other relevant factors.
Ongoing veterinary treatment is most often via the use of anti-inflammatory medication, generally the nonsteroidal antiinflammatory drug (NSAID) phenylbutazone (bute). It is also vital that corrective farriery be employed as specialised trimming and shoeing is almost always necessary. In some cases no shoes and permanent soft footing may also help.
There are many products on the market claiming to assist the foundered horse. Some are useful, just as many not. Before administering any over-the-counter or DIY treatments or supplements please consult us for advice.
How can I prevent founder?
Founder is often a result of ‘killing with kindness.’ A well balanced, appropriate diet with restricted access to excessive feed intake will go a long way to avoid the condition. Commercial vitamin/mineral supplements and some hay should be fed even if strict feed restriction is necessary.
- Regular, controlled exercise is important to keep the animal in good condition.
- Monitor body condition and weight and avoid excess weight gain and obesity.
- If the risk of founder occurring (or recurring) is high, consider adding a founder preventative agent to the feed, but only on veterinary advice.
- Ensure the farrier visits regularly and you provide regular hoof care, including trimming, hoof dressing and feeding supplements to enhance healthy hoof growth.
- Avoid access to unaccustomed pasture, hay, grain or commercial feed pellets and make sure your horse has no chance of ‘binge eating’ of hard feed. Any change in diet should be instituted gradually.