What are laminitis and founder?
The terms laminitis and founder are often used interchangeably. This is incorrect, although laminitis frequently leads to founder. Laminitis is an infection of the laminae, or tissue that connects the coffin bone to the hoof wall. It is a debilitating disease that causes the delamination of a horse’s hoof. As the layers of the hoof wall delaminate (separate) they cause extreme pain in the sensitive tissues underneath the hoof wall. (The sensitive laminae are living tissues that connect with the insensitive laminae to form a strong and durable bond between the hoof wall and the coffin bone.)
Founder occurs when the bond between the sensitive and insensitive laminae completely fails, as the laminae die. This causes the attachment of the coffin bone to the hoof to break down, damaging arteries and veins and crushing the remaining living tissues around the coffin bone. In extreme cases, as the whole weight of the horse bears down on the coffin bone, it will rotate downwards and through the sole of the hood to the ground. (The term “to founder” is a maritime expression meaning to sink.)
Usually the horse’s front feet are affected, although laminitis can affect the back feet as well. (The front feet are usually affected because they support close to 60 percent of the body weight.)
Fig. 1 Laminitis and Founder
Laminitis Hoof Structure Changes
What are the signs of laminitis and founder?
It is far easier to prevent laminitis and founder than it is to treat these conditions. Treatment can be difficult, expensive and time consuming. Worse, even the most aggressive treatment may end in failure, requiring the horse to be euthanized.
Early symptoms of laminitis are often subtle. The horse may be slightly stiff, particularly the forelegs. Always check with your veterinarian if your horse appears stiff as it is better to be safe than sorry.
When laminitis has set in to the forefeet, the horse will typically stand in the "founder stance" with his hind legs well up under the body carrying as much weight as possible, and the front legs placed forward with the weight on the heel. He will be reluctant to walk, due to the intense pain (known as “walking on eggshells”), and will turn round by leaning back and pivoting around on the rear legs. (Some horses have a high pain tolerance and will not develop this stance until laminitis is well advanced.)
If all four of the horse’s feet are affected, he may lie down and not want to get up. If forced to stand however, he will pull his forelegs and hindlegs in towards each other under the centre of his body, in an attempt to reduce pressure on the hooves.
Other symptoms include heavy breathing and glazed eyes due to pain. The feet will feel hot and the digital artery, located over the fetlock joint, will have a pounding pulse.
Each attack of acute laminitis can leave a ring formation on the hoof. A horse suffering from chronic founder will often have multiple rings on his hooves.
He may also have “seedy toe,” a separation of the hoof wall from the sensitive laminae in the toe area. If left untrimmed, the hoof wall will overgrow to form a "slipper foot". In advanced stages of laminitis, the coronary band may ooze blood or serum.
Is my horse at risk for laminitis and founder?
The precise mechanisms by which the lamellae are affected remains unknown, although several causal factors have been identified. Although laminitis occurs in the horse's feet, the underlying cause is usually a disturbance elsewhere in the horse’s body. Occasionally, there will be no apparent cause for the condition.
Numerous causes of laminitis and founder have been identified. These include:
- The over consumption of carbohydrate-rich grain, lush pasture, or lawn grass clippings, which causes changes in the microbial climate of the intestines. (“Grass founder” is the term often given to founder that develops after lush pasture has been ingested.) These changes lead to the release of bacterial toxins into the bloodstream. These toxins disrupt normal blood flow to the hoof, causing laminitis. (This is the most common cause of laminitis.)
- Drinking copious amounts of water when overheated.
- Reproductive difficulties in mares including abortion and retained placenta.
- Excessive concussion of the feet (sometimes referred to as “road founder”).
- Having insulin resistance (also called Equine Metabolic Syndrome or, inappropriately, Peripheral Cushing's) as a predisposing condition. Horses with this condition can get laminitis with exposure to grass at virtually any time of year, even though the grass may be far from lush. This is because the fructan levels in grass can shoot up from many stress factors, including drought and cold. Grass that looks virtually dead can therefore be sky high in sugar, which insulin reistance horses can't handle. They also can't handle such things as grain (in any amount), or treats like carrots and apples. If you are interested, you can get further information on insulin resistance from SaferGrass.org
- Exposure to black walnut shavings (usually in bedding).
- Prolonged use of high doses of corticosteroids.
- Any stressful condition, including colic.
- High fever or illness. Any disease that causes a high
fever or serious metabolic disturbances has the potential to
cause laminitis, e.g. Potomac horse fever.
What causes laminitis and founder?
The following are risk factors for laminitis and founder.
- Heavier breeds of horse, such as draft horses.
- Horses that are overweight.
- Horses on a high grain diet.
- Unrestricted grain binges such as when a horse breaks into the feed room or overfeeds on lush pasture. (If this happens, do not wait until symptoms develop to call your veterinarian. Call immediately so that corrective action may be taken before tissue damage progresses.)
- Horses that have had previous episodes of laminitis.
Helping the horse with laminitis and founder
If you suspect that your horse is developing laminitis, it is important to act immediately. Even a few hours can make an enormous difference in the outcome of laminitis and founder treatment.
First, call the veterinarian and follow his/her instructions. Take your horse off the pasture immediately and make sure he does not have access to any grass.
Even if your horse shows only mild symptoms, such as slight stiffness in the forelegs, you should make sure he is taken off grass as even a small amount will pose great danger to a horse with laminitis.
Feel for heat in your horse’s feet. If possible, direct a spray of cold water from a garden hose over the affected feet to reduce inflammation. (Inflammation contributes towards separation of the laminae.)
When the veterinarian arrives, he/she will be able to assess
the situation and start treatment to relieve pain and reduce
swelling, if necessary.
Treatment for laminitis and founder
The earlier treatment for laminitis begins, the better. With early diagnosis and treatment, your horse can go on to live a happy and useful life.
Treatments for laminitis vary according to the severity of the condition but include:
- Encouraging the horse to lie down to relieve pressure on the hoof/hooves.
- Imposing dietary restrictions to prevent overeating and obesity.
- Treating with mineral oil via a nasogastric tube to purge the horse’s digestive tract. This will limit the absorption of bacterial toxins, especially if the horse has overeaten.
- Administering fluids if the horse is ill or dehydrated.
- Administering natural medicines and/or drugs, such as antibiotics to fight infection, anti-endotoxins to reduce bacterial toxicity, anticoagulants and vasodilators to improve blood flow to the feet. (Corticosteroids are contraindicated for laminitis as they can cause it to worsen.)
- Administration of painkillers. Since moderate to intense pain often accompanies laminitis and founder, the veterinarian will likely prescribe painkillers and/or anti-inflammatories for your horse. These may include NSAIDs.
- Use of a magnetic hoof pad. This recently introduced treatment is said to increase local circulation and help relieve pain.
- Stabling the horse on soft ground, such as sand or shavings.
- Opening and draining of any abscesses that may develop.
- Co-operation between your veterinarian and farrier. (Corrective shoeing is often very effective, particularly in preventing founder.
- Treatment of the primary problem by your veterinarian.
(A delay of even a few hours can literally be the difference
between continued healthy living and euthanasia.)
Preventing laminitis and founder
Laminitis is a disease that is avoidable when proper horse management is practised consistently.
The following points are important to preventing the condition:
- Avoid feeding excesses and keep your horse at a reasonable weight.
- Watch for and avoid grass blooms on pastures. Pull your horse off the fields and onto a dry lot if necessary. Feed hay in the morning and turn the horse out after dew has evaporated from the grass.
- Keep grain in closed bins and the door to the feed room closed.
- Give your horse unlimited access to fresh, clean water, except immediately after exercise, when the amount should be regulated.
- Make changes to routines slowly and progressively, to avoid stress.
- Some breeds and body types are more likely to founder
than others. Be particularly careful with horses that have
thick, cresty necks and with ponies. If you have a horse or
pony that has previously foundered, be extra careful to
avoid a recurrence.