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  • Laminitis in horses

With the days getting longer and the grass growing fast, many of us are breathing a sigh of relief. Winter is nearly over. However, as much as we all love spring, the new flush of sugar rich grass can have serious implications for some of our equine friends. 

Laminitis means ‘inflammation of the laminae’. These are the tubular tissues which support the pedal (coffin) bone within the hoof to the hoof wall. When these laminae become inflamed, the horse, or more commonly pony, can become incredibly painful. Leading to the typical laminitic clinical signs. For example: leaning back to reduce weight load through the front feet, reluctance to move, depression and inappetence, lying down more or a reluctance to pick up feet. Some horses and ponies can be more subtle, simply seeming ‘pottery’ on their front feet and painful to turn tightly. The front feet are more affected as approximately 70% of a horse’s weight is carried through the forelimbs.  But the hind feet will be affected too. 

In this acute phase, it is important to remove the pony from the pasture, put in a stable or restricted area on a deep, preferably shavings bed (shavings pack into the foot better and provide more support) and call your vet. It is important to restrict movement in this acute stage. With the laminae inflamed, there is a possibility the pedal bone may sink and rotate within the hoof capsule, this has more serious long-term implications and a poorer prognosis. 

On clinical examination, your vet will use indicators such as clinical signs, increased pulses to the feet and reaction to gentle pressure to the sole using hoof testers to diagnose laminitis. Anti-inflammatories will be administered to try and counter the changes within the laminae and to provide pain relief. We sometimes dispense acepromazine (ACP) too, mainly to calm ponies that dislike being in and encourage them to lie down. There was a theory that the vasodilation cause by ACP may have a beneficial effect on the laminae but this is unproven. Ice therapy of the feet may be more beneficial. Foot padding and frog supports provide a little elevation of the heel to reduce the pull of the flexor tendon on the pedal bone, which may be applied to reduce the risk of sinking and rotation of the pedal bone. Your vet will advise you on the right treatment.  

We may suggest taking some radiographs of the feet. This will give us an idea whether there has been movement of the pedal bone and give you a better idea of what to expect in terms of rehabilitation and prognosis. These radiographs can also aid your farrier. Once the initial pain has eased, your farrier and vet can work together to discuss trimming the foot as well as specialised shoeing to help your horse or pony feel more comfortable. 

Box rest is important, even if your horse or pony appears better, it is important to be guided by veterinary advice as to when turn out is allowable. Movement increases the risk of the pedal bone rotating and sinking. Feeds must be reduced and adapted to contain low non-structural carbohydrates, look out for the laminitis trust approved sticker on the bag. Access to well soaked hay is important. Although their rations need to be reduced and weight loss is a key factor in recovery and prevention in many cases, starving a horse or pony can lead to other complications. It is about finding a happy balance; your vet can advise you on feeding regimes.  

So why does this happen? Traditionally it was thought of as simply fat ponies having too much good grazing. There is an element of that, but we now know that laminitis is not just a foot issue and it is not that simple! There are three main underlying causes of laminitis. 

  1. Diseases and conditions that lead to systemic (i.e. whole body) inflammatory conditions such as retained placenta, severe diarrhoea and lung infections.
  2. Hormonal disorders like ‘Cushing’s disease’ (more common in older horses and ponies) and Equine Metabolic Syndrome (EMS) and the resultant insulin resistance these conditions create. These horses and ponies cannot control their blood glucose effectively, leading to a range of side effects. Cushing’s also puts horses and ponies in a ‘pro-inflammatory’ state, making secondary infections like foot abscessation a more common sequalae to laminitis.
  3. Uneven weight bearing, after an injury on a different limb for instance, can cause a mechanical laminitis in the supporting limb. 

Prevention is better than cure. Once a horse or pony has had laminitis, they are at a higher risk of being affected in the future. So it is important to remain vigilant. Keep your horses and ponies ‘fit not fat’. Restricted grazing and grass muzzles are good methods of reducing grass intake. Remember, a clever pony can learn to eat as much grass in a few hours as they can eat in a day. So simply reducing grazing hours is often not enough! Winter time is a good time of year to try and get the weight off of the more rotund.  There are some horses and ponies that will be more prone to laminitis and harder to get the weight off. These are your potential EMS ponies. Base line insulin and adiponectin levels in the blood can help determine the risk of laminitis. But the crux of EMS is weight loss. Less sugars and more exercise!  Some advice that I, personally, should heed too!