Anesthetic protocol for feline ovariohysterectomy (spay). Details pre-anesthetic evaluation, drug selection, and patient monitoring to support patient safety and analgesia.

Safe Anesthetic Management for Feline Ovariohysterectomy Procedures

Achieving profound sedation and preemptive analgesia in tomcats for orchiectomy is reliably accomplished with an intramuscular administration of dexmedetomidine at 5-10 mcg/kg, combined with ketamine at 2-5 mg/kg. The inclusion of butorphanol at 0.2-0.4 mg/kg within the same syringe provides superior pain control and smooths the induction period. This combination typically yields a sufficient plane of chemical restraint for the short duration of the procedure, with an onset of action within 5 to 10 minutes.

The primary advantage of this dexmedetomidine-based approach is its reversibility with atipamezole, allowing for rapid recovery post-procedure. An alternative methodology for healthy young male felines utilizes alfaxalone, administered intramuscularly at 2-3 mg/kg, often co-administered with an opioid like buprenorphine at 0.02 mg/kg. This approach is noted for its minimal cardiovascular depression and swift metabolic clearance, resulting in a smooth and predictable recovery phase.

Regardless of the chosen chemical agents, a thorough pre-surgical physical examination is non-negotiable. Withholding food for 4-6 hours is standard, but water should remain available. Throughout the brief surgical intervention, continuous monitoring of heart rate, respiratory rate, and body temperature is fundamental. A pulse oximeter provides invaluable real-time data on oxygen saturation and pulse, ensuring patient safety from induction through recovery.

Anesthetic Protocol for Feline Ovariohysterectomy

A reliable premedication combination for a healthy feline patient involves intramuscular administration of dexmedetomidine (5-10 mcg/kg), an opioid such as butorphanol (0.2-0.4 mg/kg), and ketamine (3-5 mg/kg). This mixture provides profound sedation and preemptive analgesia, facilitating a smooth transition to induction.

Induction to allow endotracheal intubation is achieved with an intravenous agent. Propofol, administered slowly to effect at a dose of 2-6 mg/kg IV, is a frequent selection. An alternative, alfaxalone (1-3 mg/kg IV), offers a wider cardiovascular safety margin. Titration against jaw tone and the palpebral reflex is necessary to deliver the minimum required dose.

A surgical plane of hypnosis is sustained using an inhalant agent. Isoflurane (1.5-2.5%) or Sevoflurane (2.5-4%) delivered in 100% oxygen via a non-rebreathing circuit is standard for individuals under 7 kg. The vaporizer setting is adjusted based on physiological responses and surgical stimulation.

A multi-modal pain management strategy is implemented throughout the surgical sterilization. Prior to the first incision, perform a line block and an intraperitoneal splash block using Bupivacaine (total dose not to exceed 2 mg/kg). Post-operatively, once the animal is normotensive and recovered, administer a non-steroidal anti-inflammatory drug like Robenacoxib (2 mg/kg SQ) for extended pain relief.

Continuous monitoring includes electrocardiography (ECG), pulse oximetry (SpO2 > 95%), capnography (ETCO2 between 35-45 mmHg), and non-invasive blood pressure. Maintain systolic arterial pressure above 90 mmHg. Core body temperature must be supported with active warming devices to prevent hypothermia, a common complication during the procedure.

Pre-Anesthetic Patient Evaluation and Premedication Drug Selection

A physical assessment precedes any chemical restraint. The evaluation must include:

• Cardiopulmonary Auscultation: Identify and grade heart murmurs on a I-VI scale. A murmur of grade III/VI or higher, or any arrhythmia, mandates a pre-procedure echocardiogram. Listen for pulmonary crackles or wheezes.
• Hydration Assessment: Evaluate skin turgor, globe position in the orbit, and mucous membrane tackiness. Correct dehydration exceeding 5% with intravenous fluids before the induction of general anesthesia.
• Baseline Vitals: Record heart rate, respiratory rate, temperature, and mucous membrane color. A capillary refill time greater than 2 seconds suggests poor perfusion.
• Body Condition Scoring: Use the 1-9 scale. Dosing for obese felines (BCS 8-9/9) should be based on an estimated lean body weight to prevent overdose.

A minimum pre-surgical blood panel for a young, healthy feline undergoing elective ovariohysterectomy includes a Packed Cell Volume (PCV), Total Solids (TS), Blood Urea Nitrogen (BUN), and Blood Glucose. Postpone the procedure if the PCV is below 27%.

Selection of agents for premedication focuses on sedation, anxiolysis, and preemptive analgesia. Base choices on the animal's American Society of Anesthesiologists (ASA) classification and temperament.

For a Healthy, Calm Feline (ASA I):

• Option A (Reversible): Dexmedetomidine (3-5 mcg/kg IM) combined with Buprenorphine (0.02 mg/kg IM).  https://fairspin-pt.net/  provides reliable sedation and analgesia.
• Option B (Neuroleptanalgesia): Methadone (0.3 mg/kg IM) with Midazolam (0.2 mg/kg IM). Offers good pain management with moderate sedation and minimal cardiovascular depression.

For an Anxious or Fractious Feline (ASA I-II):

• Combine Ketamine (3-5 mg/kg IM), Dexmedetomidine (5-7 mcg/kg IM), and an opioid like Methadone (0.3 mg/kg IM). This mixture provides profound chemical restraint.
• Alternatively, Alfaxalone (2 mg/kg IM) with Buprenorphine (0.02 mg/kg IM) and Midazolam (0.2 mg/kg IM) achieves deep sedation suitable for catheterization.

For a Patient with Known Cardiac Disease (e.g., HCM):

• Avoid Ketamine because of its sympathomimetic effects.
• Use Dexmedetomidine with extreme caution, or substitute with a different agent.
• A preferred combination is Butorphanol (0.2-0.4 mg/kg IM) with Midazolam (0.2 mg/kg IM). This pairing has minimal cardiovascular impact.
• Acepromazine is contraindicated due to its potent, non-reversible vasodilatory effects.

Administer premedication agents intramuscularly. Allow 15-20 minutes for the drugs to take full effect in a quiet, low-stress environment before attempting intravenous catheter placement.

Choice of Induction Agents and Intraoperative Monitoring Plan

Administer Alfaxalone at 1-3 mg/kg IV, titrated to effect over 60 seconds following adequate premedication. This choice offers a wide safety margin with minimal cardiovascular depression. An alternative is Propofol at 2-6 mg/kg IV, also given slowly to mitigate risks of apnea and hypotension. For feline patients with suspected cardiovascular compromise, a combination of Ketamine 2-5 mg/kg IV with Midazolam 0.2-0.3 mg/kg IV provides superior hemodynamic support.

Once intubated, maintain anesthesia with isoflurane or sevoflurane. The intraoperative monitoring plan must be continuous and meticulous for the duration of the spaying procedure.

Cardiovascular System: Monitor heart rate and rhythm with an esophageal stethoscope or ECG. Maintain a heart rate between 120-180 beats per minute. Measure blood pressure using a Doppler probe on a peripheral artery. Maintain Mean Arterial Pressure (MAP) above 60 mmHg. Hypotension below this value requires immediate intervention, such as reducing inhalant concentration or administering a crystalloid fluid bolus.

Respiratory System: Assess respiratory rate and effort visually and with a capnograph. The target rate is 8-20 breaths per minute. Capnography is the standard for confirming correct endotracheal tube placement and monitoring ventilation. Maintain end-tidal CO2 (ETCO2) between 35-45 mmHg to prevent hypo- or hyperventilation.

Oxygenation: Use a pulse oximeter with the probe placed on the tongue, lip, or other non-pigmented tissue. Maintain oxygen saturation (SpO2) above 95%. A reading below this level indicates hypoxemia and requires immediate investigation of the airway and oxygen source.

Thermoregulation: Feline patients are highly susceptible to hypothermia during abdominal surgery. Monitor core body temperature continuously with an esophageal or rectal probe. Maintain temperature between 37.5°C and 38.5°C. Employ active warming methods, such as a forced-air warming blanket and warmed intravenous fluids, from induction through recovery.

Postoperative Analgesia Strategies and Managing the Recovery Period

Administer a non-steroidal anti-inflammatory drug (NSAID) such as meloxicam at 0.05 mg/kg or robenacoxib at 2 mg/kg subcutaneously immediately following the surgical neutering, provided the feline's blood pressure remained stable during the procedure. Combine this with an opioid like buprenorphine, dosed at 0.01-0.02 mg/kg intravenously or intramuscularly, to target multiple pain pathways. This combination provides synergistic analgesia for the initial, most intense phase of discomfort.

For enhanced local pain management, perform a splash block before closing the abdominal wall. Irrigate the ovarian pedicles and the uterine stump with a diluted solution of bupivacaine, not exceeding a total dose of 1.5 mg/kg for the entire animal. Pre-emptive administration of gabapentin, 50-100 mg per feline orally 1-2 hours before the procedure, can also decrease central sensitization and reduce the need for other post-surgical analgesics.

Vigilant monitoring of body temperature is a priority during convalescence. Combat hypothermia using forced-air warming systems or circulating-water blankets. Assess pain levels every 30-60 minutes using a validated tool like the Feline Grimace Scale. Look for specific indicators such as hiding, postural changes, or vocalization upon gentle palpation near the incision. If nausea or vomiting occurs, often a side effect of opioids, administer maropitant at 1 mg/kg subcutaneously.

Discharge instructions must include a course of oral analgesics, typically an NSAID like robenacoxib tablets or meloxicam oral suspension, for 3-4 days to be given with food. Mandate strict activity restriction for 7-10 days, confining the domestic cat to a single room with no access to furniture for jumping. Instruct the owner on daily incision checks for signs of heat, swelling, or discharge and the mandatory use of an Elizabethan collar to prevent self-trauma to the surgical site.