Evaluation of anaesthetic and cardiorespiratory effects after intramuscular administration of alfaxalone alone, alfaxalone-ketamine and alfaxalone-butorphanol-medetomidine in common marmosets (Callithrix jacchus)

Evaluation of Anesthetic and Cardiorespiratory Effects after Intramuscular Administration of Three Different Doses of Telazol® in Common Marmosets (Callithrix jacchus)

Marmosets' small body size makes anesthesia challenging. Ideally, small volumes of drugs should be administered intramuscularly (i.m.). In addition, dose-dependent sedation and anesthesia are desirable properties for sedatives and anesthetics in marmosets. Telazol® (tiletamine and zolazepam) is highly concentrated, allowing the use of small injection volumes and dose-dependent sedation and anesthesia. A randomized, blinded study with crossover design in ten healthy adult common marmosets (Callithrix jacchus) was performed to evaluate the anesthetic and cardiorespiratory effects of three doses of i.m. Telazol® (respectively, 5, 10, and 15 mg/kg). Depth of anesthesia, cardiorespiratory effects, and induction, immobilization, and recovery times were determined. A significant difference was observed in immobilization time between 5 and 15 mg/kg of Telazol®. In addition, 15 mg/kg of Telazol® resulted in increased recovery times compared to 5 mg/kg. The cardiorespiratory effects during the first 45 min of immobilization were within clinically acceptable limits. The pedal withdrawal reflex was the best indicator of the anesthetic depth.

Comparison between three dosages of intramuscular alfaxalone and a ketamine-dexmedetomidine-midazolam-tramadol combination in golden-headed lion tamarins (Leontopithecus chrysomelas)

OBJECTIVES

To characterize the cardiopulmonary and anesthetic effects of alfaxalone at three dose rates in comparison with a ketamine-dexmedetomidine-midazolam-tramadol combination (KDMT) for immobilization of golden-headed lion tamarins (GHLTs) (Leontopithecus chrysomelas) undergoing vasectomy.

STUDY DESIGN

Prospective clinical trial.

ANIMALS

A total of 19 healthy, male, wild-caught GHLTs.

METHODS

Tamarins were administered alfaxalone intramuscularly (IM) at 6, 12 or 15 mg kg^-1, or KDMT, ketamine (15 mg kg^-1), dexmedetomidine (0.015 mg kg^-1), midazolam (0.5 mg kg^-1) and tramadol (4 mg kg^-1) IM. Immediately after immobilization, lidocaine (8 mg kg^-1) was infiltrated subcutaneously (SC) at the incision site in all animals. Physiologic variables, anesthetic depth and quality of immobilization were assessed. At the end of the procedure, atipamezole (0.15 mg kg^-1) was administered IM to group KDMT and tramadol (4 mg kg^-1) SC to the other groups; all animals were injected with ketoprofen (2 mg kg^-1) SC.

RESULTS

A dose-dependent increase in sedation, muscle relaxation and immobilization time was noted in the alfaxalone groups. Despite the administration of atipamezole, the recovery time was longer for KDMT than all other groups. Muscle tremors were noted in some animals during induction and recovery with alfaxalone. No significant differences were observed for cardiovascular variables among the alfaxalone groups, whereas an initial decrease in heart rate and systolic arterial blood pressure was recorded in KDMT, which increased after atipamezole administration.

CONCLUSIONS AND CLINICAL RELEVANCE

Alfaxalone dose rates of 12 or 15 mg kg^-1 IM with local anesthesia provided good sedation and subjectively adequate pain control for vasectomies in GHLTs. KDMT induced a deeper plane of anesthesia and should be considered for more invasive or painful procedures. All study groups experienced mild to moderate hypothermia and hypoxemia; therefore, the use of more efficient heating devices and oxygen supplementation is strongly recommended when using these protocols.

Current Topics in Marmoset Anesthesia and Analgesia

Anesthetic and analgesics are essential components of both clinical and research procedures completed in marmosets. A review of current anesthetic and analgesic regimens for marmosets has been complied to provide a concise reference for veterinarians and investigator teams. Published dose regimens for injectable and inhalant anesthetic drugs and analgesic drugs are included. Appropriate physiological monitoring is key to the success of the procedure and perianesthetic options are provided. Although recent publications have refined anesthesia and analgesia practices, our review demonstrates the continued need for evidence-based resources specific to marmosets.