Laminitis

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April 14, 2011
Skin Eruptions in Horses
April 14, 2011
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Laminitis

Laminitis is an inflammation in the feet and there are many different causes.

What happens? Hooves grow downwards from the coronet. The hoof wall is attached to the coffin/pedal bone by way of finger-like projections called laminae. There are two types of laminae in the hoof. The “dermal” laminae is attached to the pedal/coffin bone and stays still whilst the hoof is growing downwards. The other laminae are attached to hoof wall “epidermal” laminae and that has to grow downwards past the dermal laminae. This movement is regulated by specialised enzymes, enzyme activators and enzyme inhibitors and they interact to disconnect and reconnect the dermal and epidermal allowing only a few disconnections within a small area so as not to weaken the overall hoof structure. This is very similar to how our finger and toenails grow.

Laminitis occurs when these finger-like laminae stop suspending the bone and this natural process is halted.

An overabundance of activated enzyme may overwhelm the inhibitors resulting in too many disconnects in a particular lamella region. This can threaten the entire hoof structure. These substances are produced elsewhere in the body and can be made available to the lamella tissues by the circulatory system (blood flow) So several factors can disrupt the laminae process and cause laminitis.

So without proper attachment to the inner hoof wall, the weight of the horse and the forces of movement drive the coffin/pedal bone down, damaging arteries and veins and crushing the living tissues of the coronary band and sole. This causes terrible pain and lameness.

When this happens to a horse or pony they suffer a great deal of shock brought on by this sudden very acute pain and this can cause sweating, laboured breathing and in extreme cases actually threaten the life of the animal, so it must never be disregarded. No one wants their horse or pony to die in agony or shock. I’ve never seen a pony die from an attack but it could happen. You must call your vet at once.

Some causes of laminitis are well known but there is still a lot of research into why these breakdowns occur. Grass founder or alimentary (to do with feeding or digestion) laminitis is when the grass is very rich and probably one of the most common types but we are not sure, some grass induced laminitis might not be, we might just think it is. If your horse or pony is susceptible to laminitis then it is better to be careful to restrict grazing in the Spring and Autumn when there is a flush of fresh, very rich grass. Then again, with global warming we are seeing rich grass growing at some very odd times so this has to be watched too. Weather as well can affect the grass. On cold nights and sunny days, grass can produce high enough concentrations of sugar to cause gut fermentation. Some people believe that by fertilising your fields with rich fertiliser this can affect the grass that the ponies are eating. In fact, there is a special “horse” fertiliser out now so there may be something in this.

Rich hard food – grains/ oats etc can cause an imbalance and are believed to be a cause.

Concussion laminitis caused by unshod ponies running on hard ground has been thought of as a cause and certainly a pony recovering from laminitis or has suffered pedal/coffin bone damage in the past can become very lame again after exercise.

Stress induced laminitis is a cause not often referred to, but stress can cause imbalances in the system so should be considered too. We have known laminitic ponies come down with it after they have been moved from their home paddocks for what seems like no other reason than stress caused by the move.

A mare can get laminitis after foaling believed to be caused by retained placenta, if she has not discharged all her placenta there are many dangers and laminitis is one.

I think body weight could play a part in this too because small ponies such as Shetlands and Dartmoor ponies seem more prone to it than larger horses. Although of course any sized horse of pony can suffer.

It can affect any hoof but is more usually seen in the front feet. There is a particular stance that is common when a pony develops laminitis. He will stand with his front feet out and stand back on his heels in an effort to reduce the terrible pain in fore part of the hoof. He looks a bit like a rocking horse.

Laminitis can permanently damage the feet, if there is any rotation of the pedal/coffin bone. What happens here is that the laminae in the front of the hoof which bears most of the weight of the horse could tear and stretch and all the front part of the coffin/pedal bone pull away from the hoof wall allowing it to drop. This is called rotation and in severe cases all the laminae will die allowing the pedal/coffin bone to drop right through the bottom of the hoof, because there is nothing to hold it in place.

However, if you manage to catch laminitis in the early stages or in mild cases the pony can recover quite well.

Most people believe there are three stages of laminitis: developing, acute and chronic. Laminitis starts developing before the pain occurs. Zodiac is a good example of this, she seems to know when an attack is starting and if she is a bit off colour, she is brought in straight away. If the signs are not understood, she could become lame within a day.

Developing is after they have become lame, and merges into the acute, changes are taking place and it should be noted that some ponies go straight into that situation. In an acute stage there is damage to the laminae and the coffin/pedal bone could have moved. At this stage an X-ray will tell you how the bone is affected. If the horse does not die of the disease process that caused the laminitis, it can make a complete recovery or become chronic.

Treating the laminitic is not by starving him. We once found a pony with colic because his feed rota had been changed suddenly, so watch out for this, reduce hard feed if he is having any and bring his feed down as quickly as you can but by doing it slowly or as the vet advises. Having seen ponies left for months even years starved because they once suffered an attack of laminitis is downright cruel. Monitoring feed is important and there are many medications, homeopathic and otherwise than can help restore the balance. My favourite is “Farriers Formula” although expensive it has worked wonders to restore a healthy regrowth of the hoof, inside and out.

Your vet will have seen many cases and he will be informed so please take his advice carefully. Don’t do what one person, we knew did to his cat though. “The cat had severe diarrhoea and the vet suggested that it was given a little white fish to help out, four years later I spoke to her about the cat’s diet because he looked so tired and thin. I found out that she was still only giving this poor cat a small portion of white fish. This diet of course did not have all the vitamins and elements in it that cats need to stay healthy.

If you think at any time, your horse or pony has laminitis then please call your vet at once. It is a life threatening condition and it is extremely painful, painful enough for strong horses to beat their heads against the sides of their boxes, break out into a sweat and develop breathing problems. It can be fatal and it must be taken seriously.

Many can recover and we have several here with rotated coffin/pedal bones who are carefully monitored and watched. Billy2 is a good example of a miniature Shetland who canters out each morning happy and pain free although he has a displaced coffin/pedal bone.