Page 39 - Manual of Equine Field Surgery

Field Anesthesia 35

TABLE 5-1
. .

DrUI!_ Commonly Used for Standing Sedation in Horses

DOSE (IN MG/KG) (ALL CAN

DRUG(s) BE GIVEN IV OR IM) COMMENTS

Single Drugs

Acepromazine 0.04-0.08 1. May cause penile paralysis

2. Variable time to onset

Xylazine 0.3-1 1. Higher doses may cause ataxia

2. Sedation lasts longer than analgesia

3. Approximately 30-minute duration

Detomidine 0.01-0.04 1 . Higher doses may cause ataxia

2. 60- to 90-minute duration

Romifidine 0.04-0.12 1. May cause less ataxia than xylazine or detomidine

2. 60- to 90-minute duration

Drug Combinations"

Acepromazine 0.05 1 . May cause penile paralysis

Morphine 0. 1-0.2 2. Variable time to onset

Acepromazine 0.05 1. May cause penile paralysis

Butorphanol 0.025-0.05 2. Variable time to onset

Xylazine 0.25-1

Butorphanol 0.01-0.05

Detomidine 0.005-0.02

Butorphanol 0.01-0.05

'
Detomidine 0.01

Buprenorphine 0.006

Romifidine 0.04-0.08

Butorphanol 0.01-0.05

"Note: Use of the higher doses of both drugs often results in ataxia.

sedation, respectively. In addition, if a local an- analgesia and sedation, and will slightly prolong

esthetic can be used to desensitize the surgical the anesthesia. A benzodiazepine can also be

site, the general anesthetic requirements are often administered IV prior to ketamine to enhance

decreased. muscle relaxation. Diazepam or midazolam can

be used at the dose of 0.06 mg/kg. In draft horses,

the doses of the drugs are decreased by 10°/o to

200/o.67 If the duration of anesthesia needs to be
ai-Agonist-Dissociative Combinations
extended, one half of the original dose of xylazine

Xylazine and ketamine are commonly used and ketamine can be administered together IV.

together for short general anesthesia. Xylazine Detomidine or romifidine can also be used as a

( 1.1 mg/kg IV) is administered, and then after the preanesthetic prior to ketamine anesthesia.f'"

horse is sedate (usually about 5 minutes), keta- The doses used are detomidine (0.02 mg/kg IV),

or romifidine (0.08 to 0.12 mg/kg IV), followed by
mine is administered (2.2 to 2.75 mg/kg IV).61"64
This will usually provide approximately 10 minutes ketamine (2 to 2.2 mg/kg IV). Because of the

of light general anesthesia. Mules and donkeys do longer duration of action of these drugs, if addi-

not respond adequately to this combination and tional time is 11eeded, a half dose of ketamine

may not even become recumbent if the lower ket- only should be administered. Butorphanol or a

amine dose is used.65'66 Butorphanol (0.02 mg/kg) benzodiazepine could also be used with these

can be administered with xylazine to enhance combinations.