First aid: dealing with diarrhoea

The amount of water in a horse’s droppings determines how loose they are, and mild cases of diarrhoea are usually nothing to worry about. Such episodes are frequently seen if a horse is upset or stressed – for instance, when it is off to a show.

If an adult horse with diarrhoea is bright, well, eating and drinking, diarrhoea is unlikely to be an immediate emergency, but your vet should be contacted if it persists for more than 48 hours. However, if an adult horse with diarrhoea is ill – particularly if it shows signs of colic or laminitis, or has a raised temperature – you should consult your vet immediately. Any form of diarrhoea in a foal justifies contacting your vet the same day.

What to look for

If diarrhoea appears suddenly, with copious amounts of loose droppings being produced very frequently, a lot of fluids can be quickly be lost from the body. With profuse diarrhoea, a horse can rapidly become dehydrated and may lose more than 40 litres (10 gallons) of water and electrolytes in a single day.

A horse can become very ill as a result of such rapid dehydration — with potentially fatal complications ranging from laminitis to kidney failure. Such acute diarrhoea is properly called ‘enterocolitis’, as it causes severe gut inflammation and acute pain and distress.

Watch out for signs of dehydration, which include:

• Skin tenting – when you pinch the skin, it does not spring back to its normal position but remains pinched
• Sunken eyes
• Dry, tacky mucus membranes
• Reduced urine output

Any of these are indicators of significant dehydration. Offer plenty of fluids to the affected horse and encourage it to drink, and contact your vet. If a horse is dehydrated, your vet may administer fluids and electrolytes by stomach tube or, in a severe case, an intravenous drip may be required. A sick horse with severe diarrhoea may need 50-80 litres of intravenous fluids daily, which usually requires intensive nursing in an equine hospital. It will need to be kept in isolation to minimise the risk of infection to other animals and people, in case a virus has caused the condition.

What you should do

To treat an adult horse suffering from diarrhoea, you should:

• Stable the horse. Keep it away from other animals in case it is contagious.
• Feed good hay but no lush grass, which may exacerbate the problem, and provide plenty of water.
• Avoid feeding concentrates and consider the use of probiotics to encourage the growth of healthy gut flora.
• As well as plain water, offer separate buckets of water containing electrolytes.
• Check the horse’s temperature. If it is elevated and the horse appears dehydrated and ill, contact your vet.
• Look for oedema (accumulation of fluid) under the belly and on the lower limbs. Severe diarrhoea cases may have reduced blood protein levels, resulting in oedema. This is a serious sign, and if you notice it, you should talk to your vet.
• Check your worming regime, as diarrhoea may be due to parasites and proper worm control will reduce the risk of problems.
• There is always a risk that diarrhoea can spread to other horses or people. For this reason, it is sensible to be particularly careful with hygiene yourself and keep the affected horse in, away from all other animals.
• Clean the horse’s dock area and buttocks and applying petroleum jelly to reduce skin damage.
• Bandage the tail to keep it clean.

What causes diarrhoea?

Causes of equine diarrhoea are many and varied. It may not be possible for the vet to tell why a horse is suffering simply from a clinical examination – samples often have to be taken for diagnostic tests. It can be difficult to pinpoint a specific cause, and repeated tests may be required.

Some potentially serious causes of diarrhoea include:

• Infections such as salmonella that can spread to other horses and people
• Intestinal worms – particularly cyathostomes
• Dietary disruption following change of feed – for example, sudden access to lush grass or overfeeding concentrates
• Use of antibiotics, which can disrupt the normal healthy bacteria in the bowel and produce diarrhoea
• Internal tumours within the bowel, preventing normal gut function
• Sand colic, where hungry horses on poor grazing eat sand that damages their gut
• Internal organ malfunction, such as liver disease or heart failure
• Hyperlipaemia, in which the body’s fat metabolism goes wrong; most commonly seen in ponies and donkeys
• Peritonitis or inflammatory bowel disease
• Reaction to certain medications, including ‘bute’

This first aid feature was first published in HORSE magazine (November ’04)