Cardiopulmonary and Thermoregulatory Profile of Xylazine-Ketamine Anesthesia Following Preemptive Administration of Nefopam or Tramadol in Himalayan tom cats

Abstract

Background & aim: This study compared the intra-operative cardiopulmonary and thermoregulatory effects of a xylazine-ketamine anesthetic protocol preceded by preemptive Nefopam or tramadol administration in male Himalayan cats.

Materials and Methods: 24 adult male Himalayan cats were allocated into three groups (n=8): control (xylazine-ketamine alone), tramadol (4 mg/kg preemptive), and Nefopam (2 mg/kg preemptive). Heart rate, systolic/diastolic blood pressure (non-invasively via oscillometry), respiratory rate, peripheral oxygen saturation (SpO₂), and rectal temperature were recorded at 10-minute intervals. Unintubated cats breathed room air spontaneously; anesthetic depth was assessed via pedal withdrawal and palpebral reflexes. No rescue analgesics were administered postoperatively, as preemptive dosing provided sufficient residual analgesia during early recovery, confirmed by stable parameters.

Results: Preemptive analgesia produced distinct cardiopulmonary profiles. The tramadol group developed pronounced bradycardia, with heart rates falling to subnormal levels after 70 minutes. Conversely, the Nefopam group maintained a stable but subnormal heart rate, accompanied by significant hypertension and elevated systolic pressure at multiple time points (P < 0.05). The control group showed initial tachycardia with a gradual decline. Nefopam preserved respiratory rates better than tramadol, though both treatment groups experienced transient SpO₂ reductions versus controls, and significant hypothermia developed by 50 minutes (Nefopam) and 60 minutes (tramadol).

Conclusions: Preemptive Nefopam or tramadol combined with xylazine-ketamine produced predictable yet divergent physiological responses in male Himalayan cats. Clinicians should anticipate tramadol-associated bradycardia/hypothermia and Nefopam-associated systemic hypertension when selecting preemptive analgesics, guiding intra-operative monitoring in feline anesthesia.