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1Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Ruminant and Swine Anesthesia
Chapter 10
2Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Ruminant Anesthesia
Temperament and economics Ruminants don’t undergo general anesthesia as
often as horses and small animals Don’t require general anesthesia because of their
calm nature Many surgeries are performed using local or
regional anesthetic techniques and physical restraint
Must consider drug withdrawal times in food and milk-producing animals
General anesthesia in production animals is not often economical
3Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Ruminant Anesthesia (Cont’d)
Equipment Special equipment is needed because of their size Tilt tables, head gates, hoists, transporters Small animal equipment can be used for small
ruminants (lambs and kids) Anatomy and physiology
Ruminants produce more saliva, which can be aspirated during anesthesia
Ruminants are prone to regurgitation and bloat during general anesthesia
4Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Patient Preparation
Use the same principles as with small animals Assess, prepare, and weigh the patient Make sure the patient is fasted to prevent bloat Prepare equipment for and place IV catheter Calculate the volume of each agent to give including fluid
administration rates Review the oxygen flow rates Prepare equipment required to administer drugs and fluids,
equipment for endotracheal intubation, and monitoring equipment
Assemble and test the anesthetic machine and ventilator
5Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Selecting an Anesthetic Protocol
Factors to consider Minimum patient database Patient physical status class Type and duration of procedure
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Ruminant General Anesthesia
Equipment preparation Make sure all equipment is present before
induction begins Check circle system and ventilator of the
anesthetic machine Make warming equipment available for small
ruminants and calves Crash cart for emergency drugs and equipment
7Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Ruminant General Anesthesia (Cont’d)
Premedication or sedation Tranquilizers are generally not needed prior to IV
catheterization and induction in calm and tractable animals
May need tranquilizers for aggressive, excited, or stressed animals
Anticholinergic drugs cause saliva to become thick and ropy
8Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
IV Induction
In a special padded area, in a transporter, on a tilt table
Goal Get to unconsciousness rapidly with minimal injury Get immediate control of the airway
Administration Double drip: ketamine and guaifenesin IV to effect Larger ruminants: IV agent bolus Smaller or compromised ruminants: IV agent to
effect
9Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
IV Induction (Cont’d)
Position Sternal recumbency for intubation Watch for regurgitation to prevent aspiration
Check vital signs and intubate
10Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Equipment for Endotracheal Intubation
Appropriately sized endotracheal tubes (22-mm, 26-mm, or 30-mm tube)
Stylette (small ruminants and calves only) Mouth gag to hold the jaws apart
(adult cattle only) Laryngoscope (small ruminants and calves) Gauze sponge to grasp the tongue (optional) A syringe to inflate the cuff
10 mL for small ruminants and calves 60 mL for adult cattle
11Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Intubation of Small Ruminants and Calves
Small oral opening and thick caudal tongue make visualization of larynx challenging
Use of a stylette protruding beyond the end of the tube results in better visualization of the larynx
Head extended, tongue gently pulled forward, laryngoscope is placed to visualize the larynx
Pass stylette into airway Pass endotracheal tube over stylette and into the
larynx Inflate the cuff
12Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Intubation of a Calf
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Intubation of Adult Cattle
Intubation is done blindly Mouth gag is placed and head is extended by the
assistant Anesthetist protects endotracheal tube cuff with
nondominant hand Using nondominant hand, the anesthetist palpates
the larynx with the fingers and directs the endotracheal tube into the larynx, while advancing the tube with the dominant hand
Inflate the cuff and remove the mouth gag
14Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Maintenance of Anesthesia with Inhalant Agent
Small ruminants and calves Similar to small animals
Adult cattle Similar to horses
Ruminants tend to hypoventilate Place on ventilator if necessary
15Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Intravenous Maintenance of Anesthesia
Reserved for short (<20 minute) procedures in healthy patients
Can also be used to extend anesthesia in intubated patient
Double drip commonly used
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Patient Positioning, Comfort, and Safety
Use same principles as for small animals Additional concerns
Position ruminants with mouth lower than pharynx Provide padding to prevent neuropathy and
myopathy as in horses
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Ruminant Anesthetic Recovery
Ruminants tend to have a smooth recovery Patient transferred to padded recovery stall Place in sternal recumbency Make sure mouth is lower than pharynx Monitor for signs of excessive bloating Keep cuff inflated or partially inflated to prevent
aspiration Extubate when strong swallowing movements or
coughing appear
18Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Ruminant Anesthetic Recovery (Cont’d)
Ruminants tend to have smooth recovery (Cont’d) Remove more air from the cuff if extubation is
difficult Leave unattended after patient is lying in sternal
recumbency without support Don’t need to withhold food or water
19Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Positioning a Ruminant for Recovery
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Swine Anesthesia
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Physical Examination of Swine
General observation Assess respiratory rate and character Observe obvious problems
Swine are difficult to restrain for a more involved physical examination
Rely on patient history to determine health status
Assessing cardiovascular status and drawing blood samples are difficult to impossible
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Sedation of Swine
Sedatives administered IM No readily available peripheral veins Thick layer of subcutaneous fat
• Must use at least 1.5-inch needle Inject muscles of neck caudal to ear and 3-5 cm
lateral to dorsal midline
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Sedation of Swine (Cont’d)
Swine are resistant to sedative drugs Use a combination of tranquilizer or sedative, an
opioid, and a dissociative May produce sedation enough for short surgical or
nonsurgical procedures TKX: Telazol®, ketamine, and xylazine
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Pig Sedated with TKX
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IM Injection in Swine
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Anesthetic Induction
TKX often induces anesthesia Eyes are not suitable for information
regarding depth of anesthesia Relaxation of mouth muscles (so mouth can
be opened without resistance) is best indicator
If patient isn’t deep enough more anesthetic must be administered IV catheter in aural vein and administer IV
induction drug in small increments Administer inhalant anesthetic via a face mask
27Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Aural Vein Catheter Placement
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Use of a Face Mask in a Pig
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Swine Intubation
Challenging because of poor visualization Small mouth opening Narrow dental arcade Anatomy of larynx: ventral laryngeal diverticulum Proximal trachea Laryngotracheal junction at angle Laryngospasm
30Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Swine Intubation (Cont’d)
Methods Patient in sternal or dorsal recumbency Using a straight stylette and laryngoscope Using a curved stylette
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Swine Intubation (Cont’d)
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Maintenance of and Monitoring Swine Anesthesia
Use small animal anesthetic machine and circle system
Can use large animal machine on very large pigs Monitoring
Palpate pulse in the ear or on inside of the carpus Brachial artery in smaller pigs Doppler signal from tail artery Pulse oximeter transmission probes on tongue or snout and
ears of pink pigs Respiratory monitoring with breathing bag and capnometry
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Doppler Probe and Blood Pressure Cuff
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Pulse Oximetry Probe Placement
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Porcine Stress Syndrome
Malignant hyperthermia Can be associated with inhalant anesthesia Mutation in one gene that controls calcium
metabolism in muscle Symptoms
Muscle rigidity Rapid rise in body temperature Hypercapnia and hyperkalemia Death
Treatment Terminate anesthesia, deliver oxygen, dantrolene
36Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Anesthetic Recovery
General principles for extubation and recovery are the same as for small animals
Leave IV catheter in place if pig is to be hospitalized