1. Dosage
Intravenous — 0.5 mL/20 lb body weight (0.5 mg/lb or 1.1 mg/kg)
Intramuscular or Subcutaneous — 1.0 mL/20 lb body weight (1.0 mg/lb or 2.2 mg/kg)
In large dogs (over 50 lbs) a dosage of 0.5 mg/lb administered intramuscularly may provide sufficient sedation and/or analgesia for most procedures.
Since vomiting may occur (see SIDE EFFECTS), fasting for 6-24 hours prior to the use of xylazine may reduce the incidence; the I.V. route results in the least vomiting.
Following injection of xylazine, the animal should be allowed to rest quietly until the full effect has been reached.
These dosages produce sedation which is usually maintained for 1 to 2 hours and analgesia which lasts for 15 to 30 minutes.
2. Preanesthetic to Local Anesthesia
Xylazine at the recommended dosages can be used in conjunction with local anesthetics, such as procaine or lidocaine.
3. Preanesthetic to General Anesthesia
Xylazine at the recommended dosage rates produces an additive effect to central nervous system depressants such as pentobarbital sodium, thiopental sodium and thiamylal sodium. Therefore, the dosage of such compounds should be reduced and administered to the desired effect. In general, 1/3 to 1/2 of the calculated dosage of the barbiturates will be needed to produce a surgical plane of anesthesia. Postanesthetic or emergence excitement has not been observed in animals preanesthetized with xylazine.
Xylazine has been used successfully as a preanesthetic agent for pentobarbital sodium, thiopental sodium, thiamylal sodium, nitrous oxide, ether, halothane and methoxyflurane anesthesia.
SIDE EFFECTS
Emesis occurs occasionally in dogs, and frequently in cats, soon after the administration of xylazine, but before clinical sedation is evident. When observed, emesis usually occurs only a single time, after which there is no further emetic effect. The use of antiemetics may delay this phenomenon. The occurrence of emesis may be considered a desirable effect when xylazine is administered as a preanesthetic to general anesthesia.
Xylazine used at recommended dosage levels may occasionally cause slight muscle tremors, bradycardia with partial A-V heart block and a reduced respiratory rate. Should excessive respiratory depression or bradycardia occur following the use of AnaSed (xylazine), administer yohimbine to rapidly reverse the xylazine-induced effects.
Gaseous distension of the stomach may occur in dogs treated with xylazine making radiographic interpretation more difficult.3
Movement in response to sharp auditory stimuli may be observed.
Increased urination may occur in cats following the use of xylazine.