Ruminants & Swine

Ruminant Anesthesia

  • Overview

    • Ruminant anesthesia involves techniques tailored for ruminant animals, primarily cattle and small ruminants (e.g., sheep, goats).

Standing Restraint

  • Standing Restraint

    • Preferred method when possible due to the calm nature of ruminants.

    • Ideal for surgical procedures that allow for it.

    • Often used in conjunction with local anesthesia or epidural anesthesia to enhance comfort during procedures.

Equine Anesthesia

  • General Anesthesia

    • Administered intravenously (IV) for short procedures (duration 20-30 minutes).

    • Inhalant anesthesia preferred for longer surgical procedures.

    • Safeguard Measures

    • Intubation is essential with general anesthesia to protect the airway from aspiration of saliva or regurgitated rumen contents.

Ruminant Anesthesia - Medications

Drugs Used in Ruminant Anesthesia

  • Anticholinergics

    • Not commonly used as pre-medications.

    • Atropine may be used specifically for managing cardiac arrhythmias or during cardiopulmonary resuscitation (CPR).

  • Sedatives/Tranquilizers

    • Generally not needed for calming animals but can be employed to reduce the required dosage for induction or to provide analgesia.

    • Common medications include:

      • Xylazine

      • Acepromazine

      • Butorphanol

  • Induction Agents

    • Administered as a bolus for rapid induction of anesthesia and can be used as a constant rate infusion (CRI) to maintain anesthesia.

    • Examples include:

      • Ketamine

      • Ketamine combined with guaifenesin

      • Ketamine combined with diazepam

      • Telazol

      • Propofol

      • Used as an induction agent for small ruminants, following similar protocols as in canines.

Preparation for Anesthesia

  • Fasting Protocols Pre-Anesthesia

    • Cattle should have food withheld for 24-48 hours prior to surgery.

    • Small ruminants and calves should have food withheld for 12-18 hours.

    • Water should be withheld for 8-12 hours.

  • Pre-Anesthetic Preparation

    • Ensure all equipment and materials are prepared before administering anesthesia.

    • Flush the animal's mouth with water using a dosing syringe to clear any debris.

    • Use an IV catheter for rapid medication administration:

    • Recommended catheter size: 4-6 inches, 14-18 gauge, placed in the jugular vein.

Induction Process

  • IV Induction

    • Involves a rapid bolus of the anesthetic agent.

    • Position the ruminant in sternal recumbency to facilitate breathing.

    • Entubation Process

    • Perform intubation promptly following induction

    • Recommended endotracheal tube size: 22-30mm for adult cattle.

    • Use a mouth gag and a stylet for smaller ruminants or calves.

    • Palpate to locate the epiglottis during intubation for adult cattle.

    • Secure the tube in place and overinflate the cuff to ensure a proper seal.

Maintenance of Anesthesia

  • Short Procedures

    • Use IV anesthetic agents for maintenance of anesthesia.

    • A “double drip” method utilizing Ketamine and Guaifenesin.

  • Longer Procedures

    • Use inhalant agents such as isoflurane or sevoflurane.

    • Utilize a large animal anesthetic machine for animals larger than 150 kg.

    • A small animal anesthetic machine should be used for animals weighing less than 150 kg.

Potential Complications

  • Main Complication

    • Bloat, the primary concern due to the inability to eructate under general anesthesia.

    • Risk of aspiration of saliva or regurgitated rumen contents, leading to aspiration pneumonia.

    • Possible effects of hypoventilation, which may result in:

    • Hypercarbia

    • Hypoxia

    • Difficulty maintaining adequate surgical anesthesia.

Monitoring and Support

  • Observational Monitoring

    • Monitor for distention of the abdomen, especially since this may be hard to detect in smaller patients under surgical drapes.

    • Recognize that bloat can compromise respiratory and cardiovascular function:

    • Pressure on the diaphragm or the caudal vena cava can reduce preload and impair respiratory function.

  • Aspiration Prevention Measures

    • Use an endotracheal tube with an inflated cuff to prevent aspiration risks.

    • Ensure that the mouth is positioned lower than the pharynx to allow drainage of saliva and rumen contents.

    • Utilize an orogastric tube to alleviate the risk of regurgitation of rumen contents during the procedure.

    • Flush the mouth with water at the end of surgery to remove any remaining rumen contents before extubation.

  • Respiratory Monitoring

    • Carefully observe the respiratory pattern post-anesthesia.

    • For patients exhibiting shallow respirations, mechanical ventilation may be required.

    • Use pulse oximetry (SpO2), end-tidal CO2 (ETCO2), or blood gas analysis to monitor levels of hypoxemia and hypercarbia.

Recovery Protocol

  • Recovery Positioning

    • Position the animal in sternal recumbency with the mouth lower than the pharynx during recovery.

    • Proceed with extubation cautiously:

    • Wait for clear signs of swallowing or coughing before complete extubation.

    • Keep the endotracheal tube partially inflated during the extubation process to prevent aspiration.

    • Ruminants typically rest quietly after surgery in sternal recumbency, but monitoring for bloat is essential.

    • Once stable, offer food and water to facilitate recovery.

Swine Anesthesia

  • Overview of Swine Anesthesia

    • Restraint can be particularly stressful for pigs and veterinary technicians (LVTs).

    • Preferred for induction: IM administration to reduce handling before sedation/anesthesia.

    • TKX Mixture: telazol, ketamine, and xylazine.

    • Longer surgical procedures require maintenance via gas anesthesia, administered through a face mask or via endotracheal tube.

Monitoring in Swine Anesthesia

  • Key Monitoring Parameters

    • Hypothermia, hypoventilation, hypoxemia, hypovolemia, and hypotension are critical concerns.

    • Monitor with:

    • SpO2 and ETCO2 measurements.

    • Doppler ultrasound can also be used to monitor pulse rate and blood pressure.

  • IV Catheterization

    • Swine have limited peripheral veins, commonly accessed sites include:

    • Ear vein

    • Medial saphenous vein

    • Administering IV fluids can help prevent postoperative complications.

  • Considerations of Porcine Stress Syndrome

    • Associated with hyperthermia, particularly during gas anesthesia.

    • Special considerations must be made for pot-bellied pigs during anesthesia protocols.

Conclusion

  • Wrapping up, the study of anesthesia in ruminants and swine requires careful consideration of the unique physiological characteristics and monitoring requirements of these species to ensure their safety and effective surgical outcomes.