Acepromazine – “ace” – is a muscle relaxant that is commonly used alone or in combination with other sedatives in horses. Ace can be given IV, IM or orally for mild tranquilization. However, ace has no pain relieving qualities, it is not analgesic.
Although ace is commonly available in the horse world, ace is a prescription medication and it should always be used under veterinary guidance only.
Ace is often used (or misused) to accomplish various tasks including minor medical procedures or hoof trimming. While it is useful in certain circumstances, ace should not be used as a substitute for good horsemanship.
Ace is often used as a pre-operative tranquilizer. It is thought to relax horses, making them more susceptible to other sedatives and anesthetics. Ace lowers blood pressure by dilating (opening) small blood vessels in the limbs, muscles, and skin.
Historically, it has been thought that ace improves circulation in the hoof. For this reason it is used by some vets in treating laminitis, although its effectiveness in these cases is unclear.
Ace is also sometimes used in combination with intravenous fluids in cases of tying-up (exertional rhabdomyolysis). The rationale is that ace relaxes the horse and increases blood flow to muscles.
Related DiagnosesThis Treatment Might Be Used for these Diagnoses
Consider Potential Side Effects & Complications
As a muscle relaxant and tranquilizer, ace may cause a horse to become mildly wobbly and uncoordinated.
Ace is not recommended for stallions because it can cause a permanent erection (priapism) or penile paralysis (paraphymosis). This reaction can also occur in geldings, and needs to be considered as a risk in using this medication.
Ace does not work well on horses that are excited and is not a suitable drug to achieve profound sedation.
Consider Reasons Not To Use This Treatment
Ace lowers blood pressure, and in most cases, it should not be given to horses experiencing colic, shock, anemia or dehydration. It is used with caution in older horses and horses with liver or heart disease.
Ace is a prohibited class drug in most competitions. It is not used in stallions. It is not used in horses that are at risk for or exhibiting seizures.
Is It working? Timeframe for effect
Whenever using this drug, the recommended dose must be given well in advance of the desired time for tranquilization; 15-30 minutes IV, 30-45 minutes IM, and 30 minutes to 1 hour orally.
Individual response to ace varies widely, and its effects may range from 1-4 hours.
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