Ron Mandsager, DVM, DACVA
3/25/03

New Notes

• Many surgical procedures can be accomplished in cattle using local anesthetics combined with chemical restraint either standing or restrained on a tilt table
• Violent recovery usually do not occur with ruminants
• Inhalant anesthesia is a better choice over intravenous injection technique for a long or complicated surgical procedure
• Similar to horses, proper position and protective padding are necessary when perform general anesthesia in ruminants
• Endotracheal intubation is essential to maintain a patent airway, and provides a rapid and safe means for controlling or assisting ventilation, and a route for delivery of oxygen and/or inhalant anesthetic
• Ruminants should be fasted for 24-48 hours and water for 12-24 hours.

• Regurgitation/aspiration
• Active regurgitation or vomiting: occurs in a lighter plan of anesthesia.  It is a complicated and coordinated series of unsuppressed reflex mechanisms intent on rejecting unwanted material from the pharynx and other upper digestive tract.
• Passive regurgitation or silent regurgitation: occurs in a deeper plan of anesthesia through relaxation of the esophageal sphincter and an increased transruminal pressure gradient.
• Bloat : fermentation continues and eructation stopped during for a period of time after general anesthesia
• Respiratory complications due to weight & abdominal viscera
• Large ruminal contents and bloat will severely compress the diaphragm and impair pulmonary ventilation and venous return.
• Hypoventilation due to anesthetic effect
• Nerve paralysis
• Malposition
• Poor padding, hard floor
• Hypotension

• Use of anticholinergics to prevent salivation in ruminants is controversial.
  • Ruminants produce large quantities of saliva (sheep: 6-16 liters/24 hr; cattle 50 liters/24 hr) that continue to flow even after induction of anesthesia (at which time they lose their swallowing reflex).  It has been suggested that use of atropine as an antisialagogue is of little value because it does not reduce the amount of saliva secreted. Rather, atropine causes an increase in saliva viscosity, rendering it more difficult to remove from the respiratory passages if inhaled.
• Use of anticholinergics to treat or prevent bradycardia is effective.
  • Dosage: atropine 0.1 mg/kg, IV or IM 

• phenothiazines: produce mild to moderate tranquilization
  • acepromazine: 0.02-0.05 mg/kg, IV or 0.03 – 0.1 mg/kg, IM
  • Slow onset and mild to moderate tranquilization
• Alpha-2 agonists: Effective sedatives that may produce a wide range of effects from mild sedation to lateral recumbency (almost like general anesthesia)
  • xylazine: 0.1 mg/kg, IV and 0.2 mg/kg, IM,
    • Ruminant are the most sensitive species to xylazine.
    • Use of 2% (20 mg/ml) solution is recommended
  • detomidine: species dependent 10-20 µg/kg, IM
  • medetomidine: species dependent, 10-20 µg/kg, IM
• benzodiazepines: producing mild sedation when using alone
  • diazepam: 0.2 mg/kg IV
    • Poor absorption if IM due to propylene glycol preparation
  • midazolam: 0.2 mg/kg, IV
    • Water-soluble therefore it can be used IM with good absorption. More expensive than diazepam.

• xylazine: 0.1-0.2 mg/kg IM or IV combined with one of the opioids and local anesthetic technique
• butorphanol: 0.02 mg/kg - 0.03 mg/kg, IM or IV
• morphine: 0.02 mg/kg – 0.04 mg/kg, IM or IV
• Adding 0.5-1 mg/kg of pentobarbital tends to enhance the standing sedation seen with above combinations.

• Premedication with a tranquilizer or sedative IM or IV 15-20 min before induction
• Induction agents:
• Infuse to effect method
  • GG (guaifenesin) and thiopental
    • Add 50 gram of guaifenesin to 1 liter of 5% dextrose in warm water
    • Add 3 gram of thiopental to one liter 5% guaifenesin in 5% dextrose solution
    • Administer IV as a fast infusion to effect
  • GKX (guaifenesin-ketamine-xylazine)
    • Add 1000 mg of ketamine and 100 mg of xylazine to every one liter of 5% GG
    • Give this mixture IV to effect or you can give it as a bolus injection (0.5 ml/kg)
• Bolus induction method
  • You do not have to give any premedication if you use these combinations. If you want to use xylazine or diazepam as a premedication, it will be safe if you just give the induction dose of these two drugs as premedication
  • xylazine and ketamine
    • xylazine (0.2 mg/kg, IM or IV) follow by ketamine 2-3 mg/kg, IV in approximately 5 minute
    • Or mix these two drugs in the same syringe and give it a single IV bolus injection
  • diazepam with ketamine
• diazepam 0.2 mg/kg, IV follow by ketamine 2 mg/kg, IV in approximately 5 minutes.
• Or mix these two drugs in the same syringe and give it a single IV bolus injection.

• Intubation
• Monitoring:
• Heart rate, respiratory rate,
• Blood pressure and hemoglobin saturation for oxygen
• Body temperature
• Eye signs for cattle

• Place animal in sternal recumbency position
• Extubate only when animal actively swallow
• Minimal stimulation to the animal (yelling, poking the animal)
• Wash the regurgitant out of the mouth and nostril with endotracheal tube in place and inflated
• Reverse Alpha-2 agents, such as xylazine or detomidine with Tolzaline (2.2 mg/kg, IV) if necessary

• Difficult to restrain in large size pigs.
• Lack of accessible superficial veins and arteries
• Endotracheal intubation relatively difficult due to anatomic peculiarity
  • Inability to open mouth widely
  • Limited visibility of the larynx due to long distance between the snout and the larynx
  • Endotracheal tube tend to enter the middle ventricle in the floor of the larynx
  • Laryngospasm is easily induced. (similar to the cat)
• Will require longer needle (1.5-2”) for IM injection.  This is especially true for the large domestic pigs and potbellied pigs.

• Use of anticholinergics to prevent salivation and bradycardia is appropriate.
• Dosage: atropine 0.06-0.08 mg/kg, IV or IM 

• In contrast to the ruminant, the pig is the least sensitive to xylazine in the domestic animals.
• Use IM injection is usually a better approach than IV. For general anesthesia one may use IM follow by face masking induction (to achieve adequate depth of anesthesia for endotracheal intubation).
  • Xylazine-telazol
  • Xylazine-ketamine
  • Medetomidine-ketamine
  • telazol alone

• Type and Positioning
• Limb Support
• Post Operative Myositis
• Causes - the three “P” rule.  The following three “P's” (poor pressure, poor position and poor padding) predispose horses and adult cattle to postoperative myositis and nerve paralysis
  • Pressure: hypotension (mean blood pressure lower than 60 mmHg for an extensive period of time)
  • Positioning:  Animal is placed in an improper position, e.g., down front limb not pulling forward, or upper limbs are not properly supported.
  • Padding: Poor, thin or no padding on a hard surface.  The down side of the animal’s body laying against the hard surface for extensive period of time prevents proper circulation and create local ischemia of the muscles.  An other situation is leaving the halter in place and damaged the facial nerves.
• Nerve Paralysis
  • Facial
  • Radial
  • Femoral
  • Peroneal
• Treatment
  • Analgesics
  • Steroids
   

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© 1996-2003, Oklahoma State University College of Veterinary Medicine, all rights reserved Last modified October 19, 2007 by Ron Mandsager, DVM, DACVA Questions? Comments? Contact me at aerrane@okstate.edu

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