Laminitis in horses and ponies: causes, signs and prevention

Laminitis is an emergency. If your horse is suddenly lame, reluctant to move, or rocking back onto its heels, call your vet straight away. This guide is general information and doesn't replace veterinary diagnosis or treatment.

Laminitis is inflammation and damage to the laminae – the tissue that bonds the hoof wall to the coffin bone (pedal bone) inside the hoof. When those bonds weaken, the bone can rotate or sink inside the hoof. The MSD Veterinary Manual describes laminitis as one of the most important and catastrophic diseases of horses, with outcomes ranging from temporary loss of use to career-ending or life-threatening disease (MSD Veterinary Manual). Agriculture Victoria notes that severe cases can be untreatable and may lead to euthanasia (Agriculture Victoria – basic horse care).

The good news is that many cases are linked to things owners can influence: body weight, diet and grazing.

What causes laminitis?

The MSD Veterinary Manual groups the causes like this (MSD Veterinary Manual):

Endocrine (hormonal) disease – the most common cause today

High insulin levels (hyperinsulinaemia) are thought to be the main predisposing factor. The two key conditions are:

• Equine metabolic syndrome (EMS) – usually in "good doers" that gain weight easily and carry fat on the crest, shoulders and tailhead.
• Pituitary pars intermedia dysfunction (PPID, or Cushing's disease) – more common in older horses.

MSD notes that mild, recurring bouts of laminitis are common in horses with insulin dysregulation or PPID. Your vet can test for both, and our feeding good and poor doers guide covers diet for horses that gain weight easily.

Too much carbohydrate

Eating large amounts of grain, or of pasture rich in sugars and starch, can trigger laminitis. MSD notes that obese and insulin-resistant horses are predisposed to pasture-associated laminitis. Agriculture Victoria lists obesity, too much green pasture and grain as common causes and says ponies are particularly susceptible (Agriculture Victoria).

Serious illness elsewhere in the body

Severe infections and endotoxaemia – for example after a retained placenta, severe colic or diarrhoea – can lead to laminitis (MSD).

Overloading one leg

A horse that can't bear weight on one leg because of an injury may develop laminitis in the opposite, supporting foot (MSD).

Other causes

MSD also lists exposure to black walnut shavings in bedding, and notes anecdotal (not well proven) links with corticosteroids, especially in horses with PPID or EMS. If your horse is at risk, ask your vet before any steroid treatment.

Signs of laminitis

Acute signs

According to MSD and Victoria's Code of Practice, signs can include (MSD; Code of Practice):

• Lameness, usually in both front feet, though any or all feet can be affected
• The classic stance – front feet pushed forward and hind feet brought underneath to take weight off the toes
• Reluctance to walk, turn or lift a foot
• Shifting weight from foot to foot
• A strong, bounding digital pulse at the back of the fetlock
• Hooves that feel warmer than usual (hard to judge in hot weather)
• Lying down more than normal

Agriculture Victoria advises consulting a vet if a horse appears lame, uncomfortable or stands in water for long periods (Agriculture Victoria).

Checking the digital pulse

Learn to find the digital pulse on a healthy day so you know what normal feels like. Run your fingers down either side of the back of the fetlock, just above the joint. In a healthy horse at rest it's faint or hard to feel. In laminitis it can be strong and bounding. Penn State Extension's vital signs guide covers taking a pulse, and our signs of a healthy horse guide shows where to feel.

Chronic signs

Horses that have had laminitis may show (MSD):

• Rings on the hoof wall that are wider at the heel than the toe
• A widened white line
• A dip just above the coronary band
• A flattened or dropped sole

What to do if you suspect laminitis

1. Call your vet immediately. MSD describes the first 72 hours after signs appear as the acute phase, and early treatment matters (MSD).
2. Don't force the horse to walk. Move it only as far as needed to a small, soft-bedded area, if your vet agrees.
3. Remove access to grass and hard feed and offer soaked hay or plain hay as your vet advises.
4. Ask your vet about cold therapy. MSD notes that cooling the feet (cryotherapy) during the developmental and acute stages is currently the most effective treatment for reducing laminar damage. Do this under your vet's direction.
5. Don't give pain relief without your vet's advice.
6. Involve your farrier once your vet has assessed the horse. Victoria's Code says horses with laminitis must receive veterinary or other appropriate treatment (Code of Practice). X-rays guide trimming and shoeing. Find a farrier near you on horse.work.

Prevention

Keep weight in check

Fat horses are at higher risk. Score your horse regularly using our body condition scoring guide, and act early if it is gaining. The University of Minnesota notes that regular exercise and good body condition help lower the risk of pasture-associated laminitis (UMN Extension).

Manage grazing

Plants make sugar in sunlight and use it overnight, so sugar levels are generally higher in the late afternoon and lower in the early morning (UMN Extension; Oregon State University Extension). The University of Minnesota says sugar content tends to be highest:

• In young, fast-growing grass (spring and regrowth)
• When nights are cool and days are warm and sunny
• After frost
• In drought-stressed pasture

In Australia, Agriculture Victoria also warns that rain after a dry spell can produce flushes of new grass that bring a risk of laminitis (Agriculture Victoria – winter care).

Ways to reduce intake for at-risk horses include:

• Limiting grazing time or using a small, sparse "sacrifice" yard with hay
• A well-fitted grazing muzzle
• Avoiding grazing very short, stressed pasture – UMN notes many grasses store sugar in the bottom few inches
• Introducing horses to lush pasture gradually

For extremely sensitive horses, UMN says there is no completely safe time to graze. Talk to your vet before grazing a horse that has had laminitis. See grass sugar and laminitis for more.

Feed for the horse in front of you

Most at-risk horses need forage-based diets, low in sugar and starch, with any concentrate feeds limited. See how much to feed a horse and talk to your vet or a qualified nutritionist about soaking hay or using low-sugar feeds.

Get tested

If your horse is a good doer, is older, or has had laminitis before, ask your vet about testing for EMS and PPID. Managing these conditions is a big part of preventing repeat episodes.

Look after the feet

Regular trimming or shoeing by a qualified farrier (see equine professionals) helps keep feet balanced, and Victoria's Code says hooves must be maintained to allow normal movement and keep hoof shape and function (Code of Practice).

Find an equine vet near you on horse.work.

FAQ

Is laminitis the same as founder?

The terms are often used interchangeably. Some vets use "founder" for chronic cases where the coffin bone has rotated or sunk.

Can a horse recover from laminitis?

Many horses recover well with prompt treatment and good management, but severe cases can end a horse's career or life (MSD; Agriculture Victoria). Your vet can give a prognosis based on X-rays.

What time of day is safest to graze a laminitis-prone horse?

The University of Minnesota suggests early morning (between 3 am and 10 am), when plant sugars are usually lower, but notes there's no guaranteed safe time for very sensitive horses (UMN Extension).

Do only fat ponies get laminitis?

No. Ponies and overweight horses are at higher risk, but laminitis can also follow serious illness, overloading of one leg, or hormonal disease in horses of any size (MSD).

Should I stand my horse in water?

Cold therapy can help in early laminitis, but only under your vet's direction. Agriculture Victoria lists a horse that stands in water for long periods as a reason to call a vet (Agriculture Victoria).