However, founder usually refers to a chronic (long-term) condition associated with rotation of the pedal bone. Acute laminitis refers to symptoms associated with a sudden initial attack, including pain and inflammation of the laminae.
How to recognise laminitis
The ISPCA has issued guidelines for owners on how to recognise laminitic animals. The horse, pony or donkey is extremely lame, reluctant to move, and is perhaps lying down and refusing to get up.
If standing, the front legs are extended, with the weight taken on the back of the heels, rocking backwards and forwards, from side to side, in an effort to relieve the extreme pain of the condition.
The hind legs are placed well forward underneath the body, taking a greater part of the weight of the animal than usual.
In an acute attack, the animal may be sweating, breathing heavily and with a raised temperature. The feet feel hot to the touch, with an elevated pulse rate in the veins on either side of the fetlock and the animal has an expression of pain on its face, ears back, eyes dull, head down, uninterested in its surroundings.
When an animal has recovered from the acute stage of laminitis, there will be major changes to the internal structures of the foot. In time, the external shape of the foot will mirror these internal changes.
The heels become longer than normal, and are often contracted, with a poorly developed frog.
The white line may become wider than normal, leaving the animal prone to seedy toe and abscesses.
The front of the hoof becomes concave. Horizontal ridges appear along the front of the hoof, wider at the heel. Sometimes these ridges can crack open, leaving the foot vulnerable to infections.
The sole becomes flat or convex. Traces of blood can be seen when the sole is trimmed -- this comes from the damaged soft laminae leaking blood and serum into the foot cavity.
In severe cases of founder, there is a distinct hollow above the coronary band, sometimes stretching as far as the heel; these cases indicate that the pedal bone has dropped completely inside the foot cavity.
In some badly neglected cases, the pedal bone can protrude through the sole of the foot or the whole hoof can break off at the coronet, exposing the internal structures. These cases are usually hopeless, and the humane option is put the animal out of its misery.
According to UK-based charity The Laminitis Trust, there are certain circumstances that commonly precede the onset of laminitis:
- Obesity: Overeating on foods rich in carbohydrate or rapidly fermentable fibre such as cereals, coarse mixes, rapidly growing or fertilised grass.
- Any illness that involves toxaemia. This may be a bacterial infection or following the ingestion of plant or chemical toxins.
- Cushing's Disease. This is a condition that follows an abnormality affecting the pituitary gland. It results in the horse failing to shed its winter coat. The coat becomes long and matted and eventually curly. The horse drinks and eats larger amounts of water and food while sweating and losing weight. All Cushing's cases suffer laminitis.
- Weight-bearing laminitis. When the horse is severely lame on one leg and has to put all his weight on the contra-lateral limb, it often suffers from founder in the weight-bearing limb. This is particularly common in hind feet.
- Concussive laminitis (also known as road founder). When horses are subjected to fast or prolonged work on hard surfaces, they may develop laminitis as a result of trauma to the laminae, particularly if their horn quality is poor.
- Hormonal problems. Animals that are 'good doers' may be hypothyroid or have an abnormal peripheral cortisol enzyme system.
The latter condition, recently described, has been called obesity-related laminitis or peripheral Cushing's Disease. Others develop laminitis when they are in season.
- Cold weather. A few horses show laminitis during cold weather. Fitting warm leg wraps during cold snaps prevents the problem in most cases.
- Stress. Worming, vaccination, travelling or separation from a 'friend' can trigger an attack of laminitis.
- Drug-induced laminitis. Although some wormers can precipitate laminitis, the most common group of drugs that cause laminitis are the corticosteroids. Even injecting short-acting corticosteroids into joints can cause severe laminitis.
The Laminitis Trust says overeating and obesity are the most common high-risk situations that lead to laminitis.
The secret to avoiding laminitis in this situation is not to turn the horse out while he/she is fatter than condition score three. This means he should not have a fat deposit along his crest or at the tail head, around the sheath or udder or over the loins. You should be able to easily feel his ribs by running your hand along his side, yet you should not be able to see his ribs.
Limiting the grass intake can be accomplished by using a grazing mask or muzzle, or restricting the area available for grazing.
Acute laminitis should be treated as a veterinary emergency because hours can make a difference in the overall outcome for the animal.
The quicker the treatment begins, the better the chance for recovery.
Your vet will choose the treatment depending on the individual case, but it may include dietary restrictions, fluid therapy if the horse is ill or dehydrated, or other drugs such as antibiotics to fight infection; anti-endotoxins to reduce bacterial toxicity; and anti-coagulants and vasodilators to reduce blood pressure while improving blood flow to the feet.
The vet may recommend stabling the horse on soft bedding, such as sand or shavings, and encouraging the horse to lie down to reduce pressure on the weakened laminae.
Treatment may include opening and draining any abscesses that may develop.
In the longer term, co-operation between your vet and farrier will help to decide on other techniques that may be helpful, including corrective trimming, frog supports, and therapeutic shoes or pads.
Time, patience, good farriery care and hoof hygiene, under supervision of a good equine vet, will allow many laminitic cases to return to sound health according to the ISPCA.
These cases will always be at risk of a laminitic attack, and must have their weight, exercise and foot care carefully monitored for life.
However, some animals will never become sound enough for work, but they can find a comfortable existence as a companion or pet.
These animals are even more vulnerable to future attacks and need very careful management.
Finally, some cases are hopeless. Early in the treatment of a bad laminitic case, the vet and the owner need to assess whether it is fair to put the animal through months of pain, if there is no real prospect of recovery.