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Feeding Horses and Ponies Prone to Laminitis

Feeding a horse or pony prone to laminitis is a challenge many owners will face at some time in their horse-keeping career. A huge amount of research has been conducted into this very complex condition and what has become clear is that laminitis is a multi- factorial condition -  meaning that it is unlikely to be caused by one factor alone, but by a combination of several, resulting an increased risk. Some of these factors may be beyond our control, for example certain clinical conditions, or a possible genetic predisposition, but others, such as diet have been identified as key areas in the control, management and prevention of an attack. The severity of an attack can also vary hugely from just the smallest suggestion of lameness through to the horse being in extreme pain as the delicate laminae that attach the pedal bone to the hoof wall starts to fail, causing the pedal bone to rotate and eventually sink, and in the worst cases, actually puncture the sole.

What can cause laminitis?

There are a variety of reasons that can trigger an onset, so whilst dietary control is always going to be foremost in most horse owners’ minds, other risk factors may include:

  • Long term obesity – As well as potentially general health problems, an overweight horse will be putting additional pressure on the delicate structures within the hoof.
  • Clinical conditions such as Equine Metabolic Syndrome (EMS) or Cushings (Pars Pituitary Intermedia Dysfunction PPID)
  • Trauma/Mechanical Damage – This could be from a variety of causes including riding on stony ground, jumping on hard ground, insufficient fitness for workload or poor farriery. Alternatively, if the horse has been lame on one limb for a long period of time, the extra weight and stress the other limbs have had to compensate for may also induce an episode of laminitis.
  • Stress – This could be caused by moving home, the loss of a long term field mate or simply travelling.
  • Toxaemia – This could be as a result of illness or following foaling.
  • Medication – Corticosteroids are known to induce laminitis (although not every time) and can rapidly increase the rate at which the pedal bone starts to rotate.

 

However, diet is often the ‘tipping factor’ in the onset of a case of laminitis and we now know that it is excessive total dietary calories and in particular sugars and starch that frequently cause the problem (NOT protein as has been thought in the past). The main dietary offenders include:

  • Too much grass. Particularly during the spring and autumn when pasture tends to be most abundant.
  • Excessive water soluble carbohydrates. WSC (sugar) levels in grass can be very high in Spring, and to a slightly lesser extent during the Autumn flush. Stressed grass (ie grass that has been over grazed, or frosty grass) is also know to contain high levels of WSC.
  • Certain types of carbohydrates such as the fructans may be pose a greater risk than others.
  • Highly molassed feeds.
  • Large cereal-based meals.

 

When the diet provides very high levels of WSC, the horse’s digestive system is unable to digest and absorb these in the upper gut, so they pass through into the hind gut which contains all the beneficial fibre-digesting bacteria. Although  WSC and starch can be digested here, it will result in a disruption to the normal micro-organisms, resulting in a drop in pH which starts to kill  the beneficial, predominantly fibre-digesting microflora, creating toxins which are thought to initiate a cascade of metabolic changes which ultimately can trigger an attack.

For horses and ponies thought to be prone to laminitis, or after an unexpected episode, ensure all feed provided is very low in WSC and starch (so remove any highly molassed or cereal-based feeds from the diet). Consider using a fibre-based concentrate feed to provide calories from digestible fibre rather than starches and sugar. Ensure correct levels of minerals and vitamins are also provided, either in the high fibre concentrate feed, or as an additional supplement.

It is also vital to accurately assess forage intake. Particularly in the case of horses and ponies prone to laminitis, forage should be the vast majority of the diet so it is important to ensure you are feeding the most suitable forage and at suitable quantities. If the horse or pony needs to be on box rest, in most cases the forage intake should be between 1 and 1.5% of bodyweight, on a dry matter basis, to ensure adequate chewing time and gut motility. However, do check this with the consulting veterinary surgeon. A weigh tape to estimate the horse’s bodyweight and a spring balance to check forage weights are important tools.

Forages selected should be clean (not dusty, as high levels of spores in hay may cause respiratory problems, especially in stabled horses), and generally have a high stalk to leaf ratio – very leafy, green forage will usually have a high level of WSC. Later cut, stalky hay is generally preferable. In order to further reduce the WSC, in hay, one option is to soak the hay to try to leach out some of the sugars, although this is a horrible job in the winter, and not always ideal in summer as warmer weather can cause bacteria levels in the water to rapidly increase.

Haylage products will tend to have a considerably lower WSC level than air-dried hay, as the fermentation process converts those “sugars” to volatile fatty acids. So the overall calorie (energy) level may be the same, but the WSC level will be lower.

Clean oat straw may also be considered as part of the forage allocation, as it too is lower than most grass hays in WSC. Like all feed changes, straw should be carefully introduced into the feed programme, and all feed changes should be discussed with the consulting veterinary surgeon. Always ensure free access to clean, fresh water.

 

Top Tips for feeding horses and ponies prone to laminitis

  • Always avoid high starch and sugar concentrate feeds, use calorie sources such as digestible fibre and oil if extra condition is needed.
  • Ensure your forage is as clean yet low WSC as possible. Either have your hay analysed, or use a good quality bagged forage (haylage) which is guaranteed to fall within certain safe parameters.
  • Keep a close eye on your horse’s weight – an overweight or obese horse is much more likely to suffer from an attack.
  • Be vigilant with your grazing. Try not to use very rich, fertilised grazing and always restrict access at high risk times, such as when the grass is growing fast or there has been a frost.
  • Remember  laminitis is not a condition limited only to small native ponies!

 

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