Poisoning is often suspected as a cause of unexplained illness in an equine. Although it is an unusual cause of sudden illness requiring first aid, it is important to be able to recognise and respond to the symptoms.

Poisoning may be suspected if:

  • many horses are ill at once with no known infectious cause
  • the affected individual(s) have been exposed to a new environment, such as new grazing
  • there has been a recent change in feed
  • the affected horses have insufficient grazing or feed so are more likely to nibble on somethingpoisonous
  • very unusual clinical signs are seen that cannot otherwise be explained
  • an unexplained death has occurred.

If you suspect poisoning, your vet should be contacted. Immediate action should include preventing further exposure to the poison, for example withdrawing a suspected feed.

Your vet will have access to specialist advice from the National Poisons Unit, which can advise on the correct antidote for a particular poison, if there is one available.

First aid may include reducing absorption of poison by:

  • keeping the horse calm and quiet
  • feeding a bran mash and Epsom salts
  • administration by your vet of activated charcoal or liquid paraffin, as well as fluids.

Preventing poisoning

Check pasture regularly: there are many potentially poisonous plants in the UK, but most are not palatable to horses. They will only eat them if there is nothing else available or if they are cut and wilted.

Ragwort is a good example – it is rarely eaten on the pasture, but will be consumed in hay.

Be aware that yew is highly poisonous but also very palatable. Horses are extremely susceptible to the toxin. Around 150g of the leaves is sufficient to kill a horse, which is roughly one horse-sized mouthful.

As yew is a well-recognised poisonous plant, it is rarely found bordering pastures, but horses may grab some when out at exercise;if your horse does this you should immediately pull the leaves out of his mouth.

There is no antidote, so avoidance is the only safe approach.

For more expert advice on horse care, see the April issue of HORSE magazine, on sale now.

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