Over the recent years there has been a massive increase in the numbers of horses and ponies seen with laminitis. Most work done has been on the investigation of feeding induced laminitis but it is now recognised that internal factors in the horse are responsible for a lot of the laminitis seen.
The main causes are :
Overeating lush grass or hard feed
Obesity or Equine Metabolic Syndrome
Cushings or Equine PPID
Retained placenta in mares
Direct trauma to the feet
Use of long acting steroid injections
The last ones are not related directly to what the horse has ingested but more to changes occurring in the body.
A few points to remember about grass and laminitis are:
Fructans the grass sugar are the cause of fermentation in the hind gut releasing toxins into the blood which directly affect the laminae.
These are high in grass in spring conditions with cold nights and warm sunny days
They tend to collect in the base of the grass stem so grazing tight is dangerous using a muzzle is much preferred.
If a pony goes down with lamintis on grass it will probably just showing a slight reluctance to walk in tight circles or be a bit ginger on hard surfaces In the worse cases bounding pulses and reluctance to move will be seen. They must be brought in immediately and put in a well bedded stable with deep shavings. Pain relief and possibly ACP (to encourage them to lie down and take pressure off the feet). This will help reduce the risks of rotation or sinking of the pedal bone. The theory on cooling the feet is now again in favour the cooling helps to reduce the damage done by the toxins to the lamellae. Leave the shoes on initially.
If caught in time recovery should occur and with careful work from your farrier in conjunction with X-Rays you should return to work. The use of support shoes is again an area of debate. Thick shavings and restriction to a stable should provide support for the sole. But in severe cases it may take months for recovery.
Equine metabolic syndrome (EMS) is seen increasing now and can affect horses from 6 years old. Certain horses and ponies seem to be more prone. They are typically overweight with a large crest on their necks. Geldings get swollen sheaths. Mare are infertile with irregular cycles. The laminitis is often missed as it is mild and insidious and owner miss the signs in the feet of rings and abnormal growth.
It can be compared to the Type 2 diabetes seen in humans and is the result of OBESITY.
Horses due to their evolution easily lay down fat in the good times to use when feed is scarce. Most horses are overfed and they very rarely have to call on their reserves. Thus fat is laid down in the muscles and around the abdominal organs. Factors released by the fat cells inhibit the action of insulin ( which controls blood sugar levels ) so glucose absorbed from the gut is not removed from the circulation they also convert inactive cortisones into active cortisol.A combination of the cortisol and high glucose level again affects the laminae causing laminitis.
Cushings is seen in the older horse and is caused by an increase in cortisone released from the adrenal gland due to an overproduction of a hormone known as ACTH from the pituitary this is the result of a small growth in the pituitary or due to the reduction in Dopamine production by an area of the brain known as the hypothalamus in old age. Horses affected develop hairy coats lay down abnormal fat pads around the sheath and above the eye they drink more and tend to sweat a lot more. They are also much more prone to infections such as sinusitis.
This cortisone has a direct effect on the laminae breaking down the protein bonds but also causes increased blood glucose which directly affects the blood vessels of the laminae.
The changes in the laminae whatever the cause are much the same but in neither Cushings nor EMS are attributable to intestinally derived factors or changes due to enterotoxaemia
Telling the difference between Cushings and EMS is relatively straight forward. Blood is taken first thing in the morning from an animal starved overnight. Levels of Glucose, Insulin and ACTH can then be analysed to distinguish between the two. Further testing by an overnight Dexamethasone inhibition test can confirm Cushings.
Problems can arise interpreting the results with a pony in the acute stages of laminitis as stress will affect all the levels found.
Pergolide the drug used to treat Cushings has now been released in a Veterinary form known as PRASCEND. It acts by supplementing the bodies Dopamine. Going to the following website will give you a lot more information and enable you to obtain a voucher to help towards the cost of diagnosis.
EMS is much more complex and revolves weight reduction and exercise. This is often difficult and should not be done suddenly. Metformin is a drug available to help address the problem with Insulin resistance. It is not expensive but must be given for life. Its use in horses is still in its early stages but does seem to be effective.
Most horse owners deny their horses are fat or overfed a good website for information on diagnosis of Obesity and its management can be found at
This is run by the Blue Cross and they provide a pack including weight charts and a weight tape.
Do not starve fat horses as this will release fats into the circulation causing a very dangerous syndrome known as lipidosis. Firstly aim to eliminate grain and concentrates over the period of a week.
Feed late cut Meadow hay, soaked in warm water for 30 mins to remove soluble sugars. Aim to feed 1.5 to 2 % target body weight but reduce to this slowly. So a 1000lb horse should be maintained on 15 to 20 lbs of hay per day. Do not starve , if in a stable for a significant part of the day lower the intake of energy but in a group or herd situation feed more. EMS horses do not seem to be able to tolerate alfalfa. Bran with a good supplementation of Vitamins and minerals can also be fed.