Ruminant Anesthesia Flashcards
physiologic consequences of general anesthesia and recumbency in ruminants (5)
-decreased GI motility, regurg
-decreased oxygenation
-decreased alveolar ventilation
-airway obstruction/aspiration
-decreased cardiac output
challenges of ruminant anesthesia (4)
-restraint
-IV access
-airway moderately difficult to intubate
-in mature ruminants, almost always require ventilatory support
aspects of the environment to consider for pre anesthetic prep (5)
-quiet
-safe; fences, rocks, hooks
-clean
-minimal dust/particles (eyes)
-assistance
aspects of the equipment to consider for pre anesthetic prep (5)
-Halter and Rope
-Additional Ropes
-Monitoring equipment
-Pads
-Means to deliver oxygen if warrented; Oxygen tank and regulator, Oxygen tank and demand value, Oxygen tank and machine
-airway equipment
pre anesthetic prep in terms of the animal (7)
-History (pregnancy status)
-PHYSICAL EXAMINATION-including weight estimation or measurement
-Pre-operative Blood Tests if necessary
-Fasting (Food and water)
-Mouth flush
-Concurrent Medications: Antibiotics, Dewormers
-IV Access: jugular, auricular vein
how long to fast cows/bulls, sheep/goat, calves
Cow/Bull=24-48hrs
Sheep/Goat=12-18,
Calf=2-8hrs
what to consider for the anesthetic plan (7)
-Drugs-including top-ups
-Airway Management
-Monitoring
-Supportive Measures: Pads, Oxygen with ventilatory support, Fluids
-Emergency Preparation
-Post operative analgesia
-Drug withdrawal times
pre anesthetic medication options for ruminants, whats the most common
- Alpha-2 Adrenergic Agonists-(most common); Xylazine
- Phenothiazines; Acepromazine
- Benzodiazepines (Unreliable IM); Diazepam, Midazolam
- Opioids
- Combinations
what cant you use for premed in ruminants
anticholinergics
overall benefits of xylazine as a premed
– Excellent quality of sedation: reliable, predictable, dose-dependent
– Reversible
– Analgesic
side effects of xylazine
Hypoxemia (sheep/goats!)
Respiratory Depression
Typany (Ileus)
Bradycardia
Salivation
Hyperglycemia, Diuresis
Increase uterine tone
contraindications of xylazine
Debilitated
Hypoxemic, Hypovolemic
Urinary Obstruction
3rd Trimester of Pregnancy
what species is most susceptible vs most resistant to xylazine
resistant = swine
susceptible = goats
overall features of ace as a premed
– Associated with less profound sedation than xylazine
– No analgesia
– No reversal agent available
side effects of ace as a premed
Hypotension
Regurgitation
when to avoid ace as a premed in ruminants
hypovolemic patients
general features of diazepam/midazolam as a premed, and how to give
- Not routinely used as sedative in adult bovine; Minimal calming, large volume required
- Induces moderate sedation in calves or sick adult ruminants
- Diazepam should not be given IM
- Midazolam can be given IM
anticholinergics as a premed, what its used for
- Not routinely utilized
– Increase viscosity of secretions
– Little efficacy on reducing volume of secretions - Indicated to treat bradycardia
– Glycopyrrolate preferred over atropine - Longer duration of action
- Less placental transfer
options for induction (4)
– Ketamine and Diazepam
– Ketamine
– Guaifenesin (GG) and Ketamine
– Propofol (small ruminants, calves)
IV maintenance options
Intravenous
* Triple Drip – Xylazine/Guaifenesin/Ketamine
* Repeat boluses of injectable agents
general rule for airway management in ruminants
Any domestic ruminant placed under general anesthesia = should have airway protected (even if you are going to maintain with an
injectable anesthetic)
why is it challenging to get an airway in ruminants
Anatomy:
* Tongue
* Jaw mobility
* Larynx position-caudal and sloping
* Goats with horns…sometimes hard to position head
Right main stem bronchus
-Significance: watch endotracheal tube length in calves, sheep and goats
oxygen delivery options for ruminants
- Anesthetic Machine and tank (with
regulator) - Demand valve and tank (with regulator)
- Flow meter and tank (with regulator)
techniques for airway manangement (4)
– Blind Intubation: sheep and calves
– Direct Visualization: sheep and calves
– Palpation: mature bovine
– Fiberoptic intubation
anesthetic drug plans for the healthy cow/bull; plan 1 vs plan 2
Plan 1:
– Premedication: Xylazine
– Induction: GG and Ketamine
– Maintenance: Inhalant or GXK
Plan 2:
– Premedication: Xylazine
– Induction: Diazepam/Ketamine
– Maintenance: Inhalant or GXK
anesthetic drug plans for calf; plan 1 vs plan 2
Plan 1:
– Premedication: Diazepam
– Induction: Ketamine
– Maintenance: Inhalant or GXK or propofol cri or bolus ketamine
Plan 2:
– Premedication: Xylazine
– Induction: Ketamine ± Benzodiazepine
– Maintenance: Inhalant or GXK or propofol cri or bolus ketamine
anesthetic drug plans for sheep; plan 1 vs plan 2
Plan 1:
– Premedication: Xylazine, Acepromazine, Benzodiazepine or
None
– Induction: Ketamine ± Benzodiazepine
– Maintenance: Inhalant
Plan 2:
– Premedication: Xylazine, Acepromazine, Benzodiazepine or
None
– Induction: Propofol ± Benzodiazepine
– Maintenance: Inhalant
how to determine depth of anesthesia (4)
- Eyes; Position, Reflexes, Tearing
- Muscle Tone, Movement
- Respiratory Pattern
- Cardiovascular System
specific features to look at for CV system for monitoring depth of anesthesia
- HR
- Heart Rhythm
- MM Color
- CRT
- Blood Pressure
specific features to look at for respiratory system for monitoring depth of anesthesia
- Rate
- Respiratory Pattern
- MM color
- Hemoglobin Saturation-Pulse Oximeter
- End Tidal CO2
- PaCO2, PaO2
supportive measures for anesthesia
- Padding
- Positioning-raise the occiput, allow drainage of mouth
- Adult cows-consider placing tube into rumen (ororuminal)
- oxygen
- fluids
recovery plan (3)
- Examine Airway: Remove Debris
- Maintain Airway until sternal and strong swallowing reflex
- Extubate with cuff partially inflated
Complications Associated with
Anesthesia in the Ruminant during induction
- Regurgitation
Prevention: Off-feed
Treatment: Position to minimize risk of aspiration - Aspiration
Prevention: Off-feed, Airway protection
Treatment: Suction airway, supportive management
Complications Associated with
Anesthesia in the Ruminant during maintenance
- Hypoventilation (inc PaCO2)
Etiologies: Drugs, Excessive Depth
Treatment: Change Anesthetic Depth, IPPV - Hypoxia (dec PaO2)
Etiologies: dec PAO2, dec Lung Volume- (FRC), dec CO
Treatment: inc FiO2, dec Depth, IPPV, inc CO - Bloat
Prevention: Off-feed
Treatment: Place tube into rumen (ororuminal) after airway secured, Deflate percutaneously
Complications Associated with
Anesthesia in the Ruminant during recovery
- Neuropathy
Etiologies: Drugs, Excessive Depth
Prevent: Positioning, Padding
Treatment: Supportive - Myopathy
Etiologies: Hypotension, Intra-compartmental Pressure, Hypoxemia
Prevent: BP, Position, Padding,
Treatment: Fluids, Anti-inflammatories, Analgesics
local vs systemic analgesia options for ruminants
- Local Analgesia/anesthesia
– Infiltration
– Regional
– Epidural
– IV regional - Systemic Analgesia
– Opioids: Butorphanol, Fentanyl, Hydromorphone
– NSAIDS
