What is Laminitis & How Do We Recognise It?

When we think of laminitis, we often picture an overweight pony knee deep in rich spring grass. Although there are risk factors that make some animals more susceptible, laminitis can occur in any horse, pony or donkey of any age or breed at any time of year.

In the first of a two-part look at this debilitating condition, Sarah Hogg BA VetMB MRCVS from Paragon Equine explains ….

Laminitis is a veterinary emergency, so it’s important to be able to recognise the signs. Quick treatment is essential in stopping this painfully debilitating and potentially fatal condition in its tracks, giving horses the best chance of returning to full health.

We usually see laminitis in two states:

Acute laminitis is the initial stage of the disease. Inflammation within the hoof causes heat and pain, which is often severe. Prompt intervention in this phase can prevent long-term structural damage to the foot.

Chronic laminitis occurs when inflammation is not adequately controlled, causing permanent damage to the foot. The outer hoof shows change and careful long term management is required by vets, farriers and owners. Chronic laminitis is often still very painful.

Even if acute laminitis is managed effectively at the time so the disease doesn’t progress, once a horse has suffered from laminitis he will be more prone to future episodes.

Overweight ponies are not the only equines at risk of laminitis

Signs to watch out for

A range of symptoms are associated with laminitis. Not every horse has all of them and whilst some may show them in a subtle way, others can find themselves completely debilitated in alarmingly little time. Horses may show signs in all four feet, although often only the front feet appear affected or are noticeably worse.

Signs include:

        Lameness – varying from a short, ‘pottery’ gait at trot to an inability to walk

-          More lame on hard or uneven surfaces

-          Sensitive when turning, especially in tight circles

-          Hot feet

-          Increased digital pulses

-          Pain when the toe is squeezed

-          Weight shifting from foot to foot

-          Leaning back with front feet extended to reduce the weight in the toes

-          Change in facial expression – ears back, flat nostrils, a tight jaw

-          Increased periods of time lying down.

-          In severe cases, horses may pant or sweat, which can be confused with colic.

-          Changes to the outer appearance of the hoof, e.g. odd shapes, deep horizontal lines or ‘rings’ or widening/separation of the white line (visible underneath the foot)

-          Visible bruising on the base of the foot when trimmed or soreness after trimming

Know-How: How to take a digital pulse

Finding your horse’s digital pulse is a useful first aid tool in many circumstances, but is particularly useful if you suspect laminitis.

Starting with your horse’s front right foot facing towards the back of your horse, place your right index finger on the inside edge of the lower fetlock. Apply a little pressure and slide your finger over the skin around the base of the fetlock until you feel a cord-like structure ‘ping’ under your finger. This is where the artery lies.

There is a similar cord-like bundle on the outer edge of the lower fetlock, which you may be able to feel with your thumb at the same time.

Apply pressure over the bundle to feel the pulse – this is the tricky bit! Too much pressure can squash the artery, preventing you from feeling the pulse. Too little pressure makes it difficult to feel the blood moving. Practice makes perfect, so don’t be afraid to have a go on your ‘normal’ horse.

It can be difficult to tell if the pulse is normal if you haven’t felt many. A ‘bounding’ or ‘rushing’ feel, or a pulse that is easily found is usually warning sign.
However it presents, laminitis is an emergency and requires immediate veterinary attention. Quick treatment is essential in stopping damage from progressing further and helping horses to return to full health.

What happens inside the foot?

The hoof is made up of a hard, insensitive outer layer (horn) and an inner, sensitive layer of softer tissue called the lamellae. The layers are stuck together in a similar way to ‘Velcro’ and hold the pedal (coffin) bone to the hoof capsule.

In laminitis, inflammation prevents a healthy flow of blood and oxygen to these tissues, which become weakened and damaged. In severe cases, damage is so severe that the tissue is no longer able to support the pedal bone in place – this results in ‘rotation’ and ‘sinking’. In severe cases a horse may ‘founder’. Here the bone presses against or even penetrates the bottom of the sole. As the bone shifts the tissue and blood vessels surrounding it are crushed and the outer hoof begins to show signs of chronic change, such as deep rings running around the hoof. Affected feet require long-term management in order to limit damage and begin to try and restore foot balance.

It’s important to remember that by the time a horse starts showing signs of laminitis, these internal changes are already well underway.

Because horses have evolved to remain standing for the vast majority of time, their feet constantly bear weight and the impact of movement. When the soft inner tissue of the foot becomes inflamed within the rigid hoof capsule, it causes unrelenting pain that quickly becomes debilitating.

An x-ray of a hoof affected by laminitis showing rotation
of the pedal bone. In this case the pony was euthanised.

Confirming a diagnosis of laminitis

Although vets are usually able to diagnose laminitis from a clinical examination, x-rays show the degree of change inside the hoof.

Taking foot x-rays is usually a simple procedure. Painkillers are given beforehand to ensure the horse is as comfortable as possible. A marker is attached to the hoof to show where it meets the skin (the coronary band) and pictures of affected feet are taken from several angles.

The images can then be shared with your farrier, and a detailed plan for corrective trimming made.

Know-How: Obel Grading

Vets often use a system called ‘Obel Grading’ as a guide for classifying the severity of laminitis and monitoring progression.

Grade I – Intermittent weight shifting and lifting of feet. Horses aren’t lame at walk but have a stilted gait at trot.

Grade II – Willing to move, but shortened stride. Able to lift feet.

Grade III - Reluctant to move. Unable or very reluctant to lift affected feet.

Grade IV – Extremely reluctant or unable to move. Frequently lying down.

Grade V – Mostly recumbent. Unable to stand for more than a few minutes.

What next?

It’s very important never to force a horse that may have laminitis to walk or exercise. Suspected cases of laminitis should be box-rested with easy access to hay or water (Remember they may not want to walk across the stable!). Keep any stress to a minimum. Your vet will usually advise you to do this over the phone while you wait for them to arrive, and this will usually continue for 30 days or more. A deep bed – ideally non-edible and dust-free – will support the feet and allow the horse to rest by lying down if needed.

Your vet will be able to provide painkillers and foot supports if needed. Any underlying illnesses can also be treated.

Sadly, despite the best efforts of owners, vets and farriers, the only option left in a minority of cases is euthanasia on welfare grounds.

In the next of our expert veterinary posts, we’ll be looking in more detail at the causes of laminitis and how knowing what type of laminitis a horse has can help us prevent recurrence.