Understanding sedation

Patience, correct handling and well-maintained equipment usually makes clipping a snip. However, some horses can be so nervous that it becomes potentially dangerous for them and their owners. In such cases, sedating the animal can be the safest bet.

Dr Polly Taylor, a specialist in anaesthesia, says that sedation can be safely used in the short term to build long-term confidence in processes that the horse may associate with discomfort, such as clipping and shoeing. It also plays a valuable role in surgical procedures where the horse remains standing.

“You can do a better job of stitching a leg wound, for example, if the horse is standing calmly and not trying to kick you,” she points out.

“Sedation can also be a nice way to show a horse that something isn’t as bad as he thinks. Sedating a horse who has been made uncomfortable by overheating or blunt clipper blades may help to show him it won’t happen again: you often only need to do it a few times.”

How does it work?

There are several commonly used sedatives, which work by slowing down or blocking a number of nerve transmissions in the brain, so the processes normally required for alertness are suppressed.

Many owners are familiar with Acepromazine (ACP), but Dr Taylor warns this is actually a tranquilliser, rather than a true sedative.

“ACP will stop a nervous horse being worried about something, but it won’t help if it’s trying to kill you!”

Common sedatives come from a group called alpha-2 agonists. Dr Taylor says that in many cases the best results come from using an alpha-2 agonist in combination with one of the common opiate drugs, such as morphine or Torbugesic.

Used alone, alpha-2 agonists produce a heavily sedated horse, but he may be hypersensitive to sound and touch. This, says Dr Taylor, is when you are more likely to get injured.

All the drugs mentioned here, including ACP, are prescription only and should only be administered under the direct supervision of a vet. A vet may allow an owner to give ACP in a tablet or paste form, but it should not be given to a different horse without the vet’s consent.

Alpha-2 agonists and opiate-type drugs are commonly injected intravenously, a procedure normally only carried out by a vet.

“You’re producing a central nervous depression,” she says, “and although the way they’re used is pretty safe, no drug is without side-effects. When half a millilitre can sedate a 500kg horse, you want it to be administered by a vet.”

Side effects of sedation are uncommon and those which occur are more usually connected with large and intravenous doses. There is the slight risk with any injection into the jugular vein that it will accidentally go into the carotid artery and thus directly into the brain.

• This article was published in full in the 20 November 2003 issue of Horse & Hound. To purchase a back issue contact (tel: 020 8532 3628).