Anesthetic Effects of Intramuscular Alfaxalone–Ketamine in Naked Mole Rats (Heterocephalus glaber)

Abstract

In this study, adult intact male and female (n = 10) naked mole rats (Heterocephalus glaber) were anesthetized by using a combination of ketamine (20 mg/kg IM), and alfaxalone (4.0 mg/kg IM). Induction and recovery times were recorded. Vital parameters, including heart rate, respiratory rate, and reflexes, were monitored every 5 min during the anesthetic period. Anesthetic induction was smooth and rapid. Induction time was significantly longer in male rats (median, 325 s; range, 180 to 385 s) than in females (median, 145 s; range, 118 to 180 s). In addition, overall duration of loss of righting reflex was shorter in male mole rats (median, 50 min; range, 36 to 65 min) than females (median, 70 min; range, 60 to 85 min). Males largelyhad intact withdrawal reflexes, whereas females showed variable loss of both forelimb and hindlimb withdrawal reflexes. Neither recovery time (mean ± 1 SD, 16 ± 13 min) nor vital parameters differed between sexes. None of animals showed any anesthesia-related adverse responses. According to these findings, intramuscular AK is a safe and effective protocol that provides brief, light anesthesia in male naked mole rats and deeper anesthesia in females. We recommend adding analgesics when this AK protocol is used for pain-inducing or invasive procedures, and further studies evaluating higher doses anddifferent combinations are indicated.

Anesthetic effects of alfaxalone-ketamine-midazolam and alfaxalone-ketamine-dexmedetomidine administered intramuscularly in black-tailed prairie dogs (Cynomys ludovicianus)

“…The smooth induction quality observed in this study is similar to what has been observed in naked mole rats (Heterocephalus glaber) and fivestriped palm squirrels (Funambulus pennantii) receiving various combinations of alfaxalone with ketamine, dexmedetomidine, butorphanol, or midazolam. [12][13][14][15] In contrast, chinchillas (Chinchilla lanigera) anesthetized with alfaxalone-butorphanol experienced rolling, twitching, and tremors throughout induction of anesthesia, mice given alfaxalone or alfaxalonexylazine experienced erratic jumping and limb jerking during induction, and rats frequently twitched during recovery when given alfaxalone intraperitoneally. 13,18,21,32 This could perhaps be attributed to the use of significantly higher alfaxalone doses in rats and mice; however, the chinchillas in the aforementioned study received comparable alfaxalone doses to the dose evaluated in this study.…”

“…The recovery quality for both studied protocols was smooth with no obvious adverse events, similar to the observed recovery quality of naked mole rats after receiving alfaxalone based anesthetic protocols. 14,15 Prior studies 18,21,32 evaluating alfaxalone in rats and mice or alfaxalone combined with xylazine in mice observed erratic jumping behavior, intense facial scratching, limb jerking, and facial twitching during the recovery period. Five-striped palm squirrels experienced twitching, tail lifting, and vocalization throughout recovery after receiving Body temperature was significantly different between protocols (P < .001), over time (P < .001) (Figure 4), but not with weight (P = .55).…”

“…The alfaxalone dose in the current study was 6 mg/kg, which is much lower than the alfaxalone doses evaluated in rats, mice, and guinea pigs (20 to 80 mg/kg); was similar to the alfaxalone dose evaluated in five-striped palm squirrels (6 mg/kg); and was higher than the alfaxalone dose evaluated in naked mole rats (2 mg/kg). 13,15,[17][18][19] These discrepancies could in part be due to discrepancies in metabolic rates between species or different routes of administration. The current study used intramuscular administration and the prior studies using higher doses of alfaxalone in guinea pigs, rats, and mice used subcutaneous or intraperitoneal administration.…”

“…It has been increasingly investigated as an injectable anesthetic option in a variety of rodent species, particularly via subcutaneous, intramuscular, or intraperitoneal routes. [12][13][14][15][16][17][18][19][20][21][22] Alfaxalone is a neuroactive steroid that produces nonreversible, nonanalgesic anesthesia and muscle relaxation through interaction with the gammaaminobutyric acid (GABA) receptors within the CNS. 22 When used in guinea pigs (Cavia porcellus), rats (Rattus norvegicus), and mice (Mus musculus), alfaxalone as a single agent intraperitoneally, subcutaneously, or intramuscularly, it produces inconsistent planes of anesthesia, generally not reaching a surgical plane of anesthesia regardless of dosage.…”

“…[16][17][18][19][20] The combination of alfaxalone with a dissociative agent or alpha-2 agonist has been documented to provide a deeper, more consistent plane of anesthesia in the rodent species evaluated thus far. [12][13][14][15][16]20,21 Injectable anesthetic protocols that include alfaxalone have not been evaluated in black-tailed prairie dogs previously.…”