Laminitis
Laminitis
Laminitis is a very common disease traditionally reported in the early grazing season when horses have been turned out to fresh spring grass and show signs of moderate to severe lameness. However, we are now seeing severe cases of laminitis throughout the whole year. Its potential to cause long-term unsoundness is often underestimated and it is not uncommon for severe and uncontrolled cases to require euthanasia on the humane grounds of incurable suffering.
What is laminitis?
Laminitis, in its simplest form, is inflammation of the sensitive layers (laminae) of the hoof. The laminae suspend the pedal bone within the hoof capsule and when the laminae become inflamed this suspension is often lost. This can lead to a rotation and sometimes sinking of the pedal bone within the hoof. In severe cases, the pedal bone may rotate and sink so much as to penetrate the bottom of the sole.
What Causes Laminitis?
Laminitis is caused by interference of the blood supply to the sensitive laminae of the foot. Some of the causes are listed below:
- Diet-related issues, particularly overfeeding or changes in diet are responsible for the majority of cases. Diet change leads to changes in the natural bacterial flora of the hindgut where some bacteria die and release toxins which lead to laminitis. Remember that diet changes include changes in forage as well as hard feed. This includes switching from grass to hay or vice versa. Any changes should be made very gradually.
- Cushing’s disease. This is a disease of older horses (although we have diagnosed it in horses as young as 11). It makes horses more likely to get laminitis and should be considered in older horses that get laminitis for the first time where no apparent cause has been determined.
- Equine metabolic syndrome. This disease is similar to type II diabetes in humans where individuals become insulin resistant. It can affect horses of all ages and is another disease associated with laminitis.
- Toxaemia associated with severe infections can cause laminitis, e.g. mares with retained afterbirths post-foaling.
- Incorrect trimming and shoeing can result in long toe/low heel conformation.
- Excessive concussion due to intense exercise on hard ground e.g. fast road work.
- Excessive weight bearing on one leg due to an injury or pain in the opposite leg. This usually requires the horse to be non-weight-bearing on the injured leg for the other leg to get a traumatic laminitis.
- Horses or ponies with a history of laminitis are susceptible to recurrence.
Sometimes there may be more than one cause, for example, a horse with Cushing’s may then have a sudden change in diet which then ‘tips the horse over the edge’ into having laminitis symptoms.
How can I recognise the early signs of laminitis?
In mild cases of laminitis, the horse or pony may appear slightly ‘pottery’. The forelimbs are most commonly affected although it is possible for the hindlimbs only or all four feet to be affected. The affected foot or feet may appear abnormally warm to the touch and the pulse taken at the heel’s arteries may appear particularly strong.
Laminitic horses sometimes stand with their hindlimbs well under the body and forelimbs stretched out in front, in an effort to keep weight off the painful front feet. This characteristic stance is almost diagnostic of laminitis.
Affected horses will move with their heels landing first to try to avoid concussion to the painful toe region.
If all four feet are affected, they may lie down for long periods and may even look colicy.
More severe cases result in inability or reluctance to move at all and horses with severe rotation and sinking will often be unable to bear any weight on the affected limb or limbs.
What can be done?
Mild cases may respond to box rest, anti-inflammatory medication and a long-term calorie-restricted diet.
More severe cases may also need remedial hoof trimming and shoeing and anti-inflammatory medication for a prolonged period (often many months). Remedial farriery may take several months to return the hoof to being in a more normal position in relation to the pedal bone again.
X-ray images taken of the feet (this can be done at the yard) help us to assess the amount of rotation and sinking of the pedal bone and therefore give us an estimated prognosis. They are also very useful for farriers to produce a remedial farriery plan for an individual.
We may take a blood sample to test for equine metabolic syndrome. We may also test for Cushing’s disease (if the horse is older) as medication is available to try and control the symptoms of these diseases if they are diagnosed. This will hopefully prevent recurrence of laminitis in the future.
Unfortunately some cases worsen despite best efforts from the owner, vet and farrier.
Can it be prevented?
Horses and ponies have evolved in the wild to work hard for poor quality food and any individuals with access to good grazing should be watched carefully for signs of becoming overweight or pottery.
There are several ways of keeping an eye on your horse’s weight:
- Body Condition Scoring (BCS) - This looks at areas of the body such as the ribs, crest and rump and depending on the appearance, a grade (out of 5 or 10) is given. BCS is a good starting point to help you determine whether your horse is overweight, just right or underweight.
- Weighing them on a weigh bridge. This is the gold standard for monitoring weight change.
- Weight tapes- not quite as accurate as weighing but not too far out. What is important is that your horse is measured by the same person in the same area, with the same tape so that weight change can be monitored. Try not to get too hung up about the actual weight as this may not be too accurate.
Once BCS is determined, weigh bridges and tapes are a huge help in ensuring that weight alterations are heading in the right direction.
Tips for preventing a horse from becoming overweight:
Restrict grazing. This can be done by:
- Strip grazing using electric fencing.
- Co-grazing with sheep (good for limiting worm burdens too!)
- Using a grazing muzzle. Horses can still eat and drink through grazing muzzles but they cannot consume as much grass as quickly.
Review your hard feed. Avoid sugary or starchy feed. This includes molassed chop and most mixes and cubes. Look out for feeds approved by the laminitic trust bearing their logo which are low in sugar and starch and tend to be high in fibre and provide your horse with the other essential nutrients to support healthy hoof growth.
When sound, exercise your horse as much as possible. Cases of laminitis are increasing in numbers because we typically have less time to exercise our horses yet more nutritious feed available compared with in the past.
Soak hay/haylage for 12 hours to reduce the sugar content. This means that your horse will be eating the same amount of hay but the calorie content is much lower.
Remember that starving your horse should be avoided; horses are designed to graze throughout the day and consume small quantities often. Dividing hay up into more, smaller nets simulates their natural eating behaviour. Hay can be double netted in nets with small holes and also hung from a beam or the ceiling so that the horse has to work a little harder for his hay. This should help to prevent the boredom and vices associated with having an empty hay net.
