There are three certainties about laminitis. It a potentially
fatal disease which must never be underestimated, it is 100% preventable, and
any horse or pony that has suffered from it must remain on ‘laminitis
watch’ for the rest if its life.
What causes laminitis?
Once the classical laminitis-risk weather pattern of warm days and cold nights (typical of April to June, and September to November) appears, some restriction of access to grass should be in place. This sort of weather causes the accumulation in grass of sugars known as fructans, which are the main cause of laminitis in grazing horses and ponies. Fructans are made in the plants during the day by a process known as photosynthesis. These are normally converted during the night to structural components (i.e. new leaves and stems) and will be at their lowest levels in the morning. But if the nights are cold this transformation occurs only to a limited extent and although some will be consumed by the plant during the night the level in morning will still be high. Further synthetic activity the next day, and the day after that and so on, will cause very high levels of fructans to accumulate.
An excessive intake of fructans will trigger a cascade of biochemical events in the horse’s large intestine, ultimately resulting in the uptake into the blood of substances which cause constriction of the small blood vessels in the laminae of the feet. Deprived of oxygen and nutrients, these laminae (which are attached to the pedal bone via a Velcro-like system) begin to degenerate resulting in detachment of the pedal bone, which ultimately may start to rotate and sink, with in some cases catastrophic consequences for the horse.
How can we restrict grass intake?
Restriction of grazing time is probably the most effective method but the restriction needs to be severe. Four hours (two hours if the pony has suffered from laminitis before) grazing per day on an unfertilised paddock is the maximum permissible. Fructan levels are lowest from late at night to early in the morning. The pony should therefore be turned as early as possible and then removed from grass by mid-morning. The ‘down time’ can be spent in a loose box or wandering in a pen, with access to some low sugar high fibre feed. The frequent practice of allowing ponies to graze, say, only at night or only during the day, that is for 12-18 hours, is just too long a period for safety.
Alternatively the area of grass available can be restricted using an electric fence. The area of the pen must be so small such that the grass is tightly grazed. If necessary, supplementary feed, such as hay and or oat straw can be provided daily in the pen. If the pony isn’t eating the hay then the pen is too large.
Where a pony is kept as a companion for a bigger horse a pen can be made in the field for the pony, while the horse has unrestricted access to the whole field.
An electric fence tester is a useful device to buy in order regularly to check the output of the fence battery. Hungry ponies will soon discover if the fence is ‘live’ or not. If the pony grazes close to a building with an electricity supply a small mains fencer unit may be more reliable and cheaper in the long term.
Grass grows surprisingly quickly and an apparently bare patch may still generate sufficient grass to trigger laminitis. One option is to measure grass growth by fencing off a small area (say 3ft.x3ft.), and adjust the paddock size appropriately.
Muzzling is an attractive option in that the available grazing area or grazing time can be greater. There are a number of commercially available grazing muzzles available in tack shops and feed stores. Muzzles are however a far from perfect solution. Apart from the fact that some ponies seem to be able to remove them even in spite of exhaustive efforts to keep them in place, they can cause rubs and skin irritation from prolonged wear. They should therefore only be used intermittently.
An alternative approach, which can be combined with the others, is to use a 'boom and bust' approach. In this a mixture of techniques are used. For example the pony might spend several hours at grass one day, followed the next day by keeping the pony off the grass completely and feeding hay, followed the next day by a short period at grass and a longer period indoors etc. The aim is to ensure that the periods of disruption of the gut bacteria by grass intake are short, and are 'settled' by an extended period of hay feeding
Tethering the pony on a long lead can be extremely effective if done with care by ensuring gradual introduction, close supervision, a quick release system, careful selection of the site to avoid hazards and the provision of water and shade. Unfortunately and unjustifiably this method has largely fallen out of use
Laminitis is rare in fit animals. As much exercise as possible to keep the bodyweight down is important. If a child rider is not available (or reluctant!) ponies can be led from a horse while exercising. It can be almost impossible to reduce the weight of a fat native pony without exercising it.
If supplementary feed must be fed then use high fibre low starch feeds for example coarse hay or haylage (avoid soft haylage), oat straw, high fibre cubes, unmolassed sugar beet (such as Speedibeet) and high fibre chaff products such as Dengie 'HiFi', Dodson and Horrell @Safe and Sound' and Spillers 'Happy Hoof'. Conventional horse and pony nuts, coarse mixes and other starchy feeds or nuts must be avoided like the plague.
A product known as Founderguard is a feed supplement from Australia which aims to prevent laminitis by controlling the abnormal fermentative activity in the caecum. It is only available from vets. The evidence so far suggests that it is a useful additional aid to control if used in conjunction with the usual methods.
Look for the early signs
The onset of the disease is slow and often missed. A pony which normally trots to the gate for a titbit when called but which all of a sudden merely walks but is otherwise ‘normal’ may well be in the early stages. When led or ridden a tendency to favour walking on the roadside verge rather than on the hard tarmac, or walking with a stilted ‘straight-legged’ gait, may be a warning sign.
If in any doubt, get the pony indoors immediately and don’t wait for the full-blown signs to appear.
Cushing's Syndrome
Laminitis is one of the symptoms shown by horses with Cushing’s Syndrome.
This condition is caused by an overactive pituitary gland and affects elderly
(usually >20years old) horses. The first sign shown is failure to shed the
winter coat in the summer. A variety of others signs can be seen, such as excessive
drinking, weight loss, a pot-bellied appearance, a long shaggy (rarely curly)
coat, unexplained sweating and bulging of the fat pads in the grooves above
the eyes. Horses showing these symptoms should be examined by a vet both to
confirm the diagnosis and to determine whether, in addition to the usual laminitis
control methods, specific drug therapy is required.
DISCLAIMER
This factsheet is intended for use by registered clients of EqWest only. The advice offered is general advice only. EqWest clients who wish to discuss the individual circumstances of their horse should contact the Clinic.
To speak to a vet please phone between 8.30 - 9.30 am on weekday mornings.
© Copyright EqWest Equine Veterinary Clinic
Click HERE to return to EqWest Home Page