What is laminitis?
This is a common, severely debilitating, painful and potentially life threatening disease of the soft tissue within the hoof capsule, and occurs in ponies and horses of all ages, breeds, and uses.
What are the signs of laminitis?
There are many different ways in which the condition may present, depending on the susceptibility of the animal in question and the severity of the inciting cause. If mild – the signs may be as subtle as choosing to walk on the verge rather than the road when out riding, appearing “pottery” when turned on a hard surface, or walking over to the gate at feeding time as opposed to the usual charge! When more severe the animal will show obvious lameness in the effected feet. The fore feet are most commonly affected however it may occur in the hind feet, all four feet, or just one. Increased heat and a pounding digital pulse may be evident in the effected feet but this is not always obvious. A classic laminitic stance involves both hindlimbs tucked well under the body and the forelimbs stretched out in front. These horses are reluctant to move and when forced appear to be walking on eggshells. When very severe the horse may be sweating, shivering, inappetent or lying down. This can be confused with signs of colic.
What causes laminitis?
At this time we do not fully understand all the mechanisms involved with the development of laminitis, however the underlying problem is an alteration in the blood supply to the effected feet that results in damage to the sensitive tissues (laminae) that form the attachment between the pedal bone and the hoof wall. Once damaged the laminae will swell within a confined area, causing significant pain and some cell death. If enough cells are killed the lamina junction may fail resulting in movement of the pedal bone within the hoof capsule.
Causes that result in laminitis include:
- Digestive upsets due to grain overload or abrupt changes in diet.
- Sudden access to excessive amounts of lush forage before the horse’s system has had time to adapt; this type of laminitis is known as “grass founder”.
- Toxin release within the horse’s system. Any illness that causes high fever or serious metabolic disturbances has the potential to cause laminitis, e.g. Severe colic, Retained placenta in the mare after foaling, pleuropneumonia.
- Excessive concussion to the feet, often referred to as “road founder”.
- Excessive weight bearing on one leg due to injury of another leg (fracture, joint infection) or any other alteration of the normal gait.
- Prolonged use or high doses of corticosteroids.
What factors increase the risk of laminitis?
- Heavy breeds, such as draft horses.
- High nutritional feeds (especially a high in starch content).
- Grass with a high Fructan content.
- Unrestricted binges.
- Previous episodes of laminitis.
- Cushing’s disease or Equine Metabolic Syndrome.
What are Fructans?
These are sugars produced by grass during photosynthesis. They are normally converted to structural components of the plant during the night and will be at their lowest levels early in the morning. However when the days are warm and the night are cold (normally April to June, and September to November) Fructans conversion is reduced and a high percentage of fructans remains as unconverted sugar within the leaf and stem. These levels may accumulate over a number days given the prevailing weather conditions. When consumed by horses fructans will pass rapidly through the small intestine without enzymic breakdown. Subsequent fermentation within the large intestine produces various substances which once absorbed into the blood stream can go on to trigger laminitis.
How is laminitis treated?
In many cases the condition is mild enough for box rest, anti inflammatories such as “bute”, restricted diet, and removal of any inciting cause may be sufficient. Frog supports, acepromazine ( a drug that reduces blood pressure) may also be used depending on the individual case. If there has been significant damage to the join between hoof capsule and pedal bone (as identified on X-rays) remedial foot rimming and shoeing will be required, and recovery may take several months. In cases where the pedal bone has penetrated the sole the prognosis is very poor and euthanasia required. There are a multitude of other treatments that have been put forward for the various forms of laminitis, and a range of opinion concerning what works best still exists amongst vets and farriers. In horses older than fifteen, Cushing’s Syndrome may be a contributing or causative factor, in which case appropriate medication may be recommended.
How do I prevent laminitis?
- Monitor you horse’s condition prevent obesity through control of diet and exercise.
- Restrict grazing when the grass is lush (box rest, grazing muzzles or strip grazing using electric fencing may all be useful).
- Restrict grazing to times of low Fructan level i.e. late at night to early in the morning.
- If supplementary feed is required use high fibre low starch feeds (see nutrition advice) such as hay or haylage (avoid soft haylage), oat straw, high fibre cubes, unmolassed sugar beet (such as Speedibeet) and high fibre chaff products such as Dengie ‘HiFi’, Dodson & Horrell ‘Safe and Sound’ and Spillers ‘Happy Hoof’. Conventional horse and pony nuts, coarse mixes and other starchy feeds or nuts should be avoided.
- If feeding concentrates avoid sudden increases.
- Avoid fast work on hard surfaces.
- Monitor for serious illness such as colic, diarrhoea, and uterine infection following retained placenta. In such cases veterinary help is required as soon as possible.
DISCLAIMER: This advice is intended for use by registered clients of Priors Farm only. The advice offered is general advice only. Priors Farm clients who wish to discuss the individual circumstances of their horse should contact the office. To speak to a vet please phone between 8.30 – 10.00 am on weekday mornings.