Neonatal Puppy Anesthesia for Umbilical Hernia Repair

Neonatal puppies (≤8 weeks) have unique physiology: immature hepatic and renal function, low glycogen stores, high body surface area to weight ratio (rapid heat loss), limited cardiovascular reserve, and increased sensitivity to anesthetics. Risks: (1) Hypoglycemia: fasting for 6 hours is excessive; neonates should not be fasted longer than 2–4 hours. Glucose 85 mg/dL is low-normal; monitor and supplement with dextrose. (2) Hypothermia: no active warming is dangerous; use forced-air warming, warm water blanket, and warm fluids. (3) Hypotension: acepromazine causes vasodilation and hypotension; avoid. Propofol at 6 mg/kg is a high dose and can cause apnea and cardiovascular depression; reduce to 2–3 mg/kg IV titrated or use alfaxalone 1–2 mg/kg IV. (4) Mask induction with isoflurane is stressful and can cause airway irritation and breath-holding; consider preoxygenation and induction with injectable agents, then intubate with a small uncuffed tube (e.g., 3.0–3.5 mm). (5) Fluids: 0.9% NaCl at 10 mL/kg/h may be too high and lacks potassium; use a balanced solution (e.g., lactated Ringer's) at 3–5 mL/kg/h, and consider adding dextrose (2.5–5%) if hypoglycemic. (6) Buprenorphine at 0.01 mg/kg is a low dose; use 0.02 mg/kg IM or IV. (7) Monitoring: use Doppler blood pressure, pulse oximetry, capnography, and temperature. (8) Postoperative: monitor for hypoglycemia and hypothermia; provide warmth and early feeding. Modified plan: premedicate with buprenorphine 0.02 mg/kg IM (no acepromazine); induce with alfaxalone 1–2 mg/kg IV or propofol 2–3 mg/kg IV; intubate and maintain with isoflurane at lowest effective concentration; provide active warming; administer warmed lactated Ringer's at 5 mL/kg/h with 2.5% dextrose if glucose <100 mg/dL; monitor blood pressure and glucose; keep surgery short.

Intraoperative monitoring: (1) Heart rate and rhythm (ECG or auscultation); (2) respiratory rate and effort, SpO2 via pulse oximetry (use a reflectance probe on the tongue or a clip on the ear/paw); (3) end-tidal CO2 via capnography to confirm intubation and ventilation; (4) blood pressure via Doppler (target systolic ≥80 mm Hg) or oscillometric; (5) temperature (rectal or esophageal) every 15 minutes-maintain >36.5°C; (6) blood glucose every 30–60 minutes-treat if <80 mg/dL with 0.5–1 mL/kg of 10% dextrose IV slowly; (7) assess anesthetic depth (jaw tone, palpebral reflex, HR response to surgery). Management: active warming (forced-air blanket, warm water blanket, warm fluids), limit surgical time, use local anesthetic (e.g., bupivacaine 1 mg/kg incisional block) to reduce volatile requirement. Postoperative: (1) Continue warming until normothermic; (2) monitor glucose and provide early feeding (within 1–2 hours of recovery) or dextrose supplementation; (3) monitor for pain using a neonatal pain scale (e.g., UNESP-Botucatu) and provide buprenorphine 0.02 mg/kg IV/IM q6–8h; (4) monitor for hypotension and bradycardia; (5) ensure adequate hydration and urine output; (6) keep the puppy with its littermates for warmth and social comfort if possible; (7) discharge with instructions to monitor for lethargy, hypothermia, and hypoglycemia. Avoid acepromazine and excessive fasting. Educate the owner on neonatal care.