Lecture 11 Ruminant and Camelid Anesthesia

Question 1

What are some indications for doing general anesthesia in ruminants

Answer 1

1. umbilical surg.,
2. penile surgery,
3. cryptorchidism,
4. fractures,
5. septic joints,
6. tube cystotomy,
7. research

Question 2

What are some risks ruminants have when undergoing general anesthesia

Answer 2

1. ruminal reflux,
2. bloat etc.

Question 3

What are the 4 special concerns of ruminants

Answer 3

1. Salivation throughout anesthesia
   
   • Fluid loss, risk of airway occlusion & aspiration
2. Rumen
3. Airway protection
   
   • ET intubation recommended, usually easy but can be challenging
4. Hypoventilation under general anesth.
   
   • Mechanical ventilator

Question 4

Why is the rumen a special concern in anesthesia

Answer 4

1. Never completely empty
   
   • Passive reflux and aspiration pneumonia
2. No eructation under anesthesia
   
   • Bloat & pressure on lungs ® hypoxemia
   • Stomach tube to decompress/trochar
3. Large & heavy
   
   • Pressure on lungs when recumbent

Question 5

Why fast ruminents?

Answer 5

–Reduces rumen size

–Decreases microbial activity/gas production

Question 6

Patient Preparation in:

1. Adult cattle
2. Sheep, goats, camelids
3. Calves, lambs, kids, crias

Answer 6

1. Adult cattle
   
   • Withhold food for 24-48 hrs & water 8-12 hrs
2. Sheep, goats, camelids
   
   • Withhold food for 24 hrs & water 12 hrs
3. Calves, lambs, kids, crias
   
   • Withhold food 2-4 hrs (age?)

Question 7

Side effect of fasting

Answer 7

metabolic alkalosis

Question 8

1. Premedication advantages
2. Disadvantages

Answer 8

1. Advantages
   
   • Preemptive analgesia, reduces induction/maintenance doses
2. Disadvantages
   
   • May increase risk of ruminal reflux once recumbent

Question 9

1. Are premedications necessary for ruminents?
2. Why or why not?

Answer 9

1. Often unnecessary
2. Reasons:
   
   • Calm animals accept restraint for IV catheter & induction
   • Cattle can be strapped to tilt table

Question 10

• What are 2 options for IV access in cattle
• What are special considerations for using each

Answer 10

1. Jugular vein
   
   • Thick skin: pilot hole with needle or blade to insert catheter
2. Auricular vein
   
   • Can’t inject large volumes e.g. guaifenesin

Question 11

IV Access – Sheep & Goats

Answer 11

1. Jugular vein
2. Cephalic vein

Question 12

1. Are anticholinergics used as premedications?
2. Why or why not?

Answer 12

1. NOT used
2. Salivation does not stop & saliva gets thicker

Question 13

What are premedication options in ruminants

Answer 13

1. Acepromazine ± opioid (butorphanol) IV or IM
2. Acepromazine + diazepam IV – sheep & goats
3. Midazolam + butorphanol IV or IM – sheep & goats
4. Xylazine IV or IM

Question 14

What are considerations when using xylazine in ruminants

Answer 14

1. Hypoxemia in all ruminants
   
   • Sheep can develop pulmonary edema because of their types of macrophages
2. Increases myometrial contractions
   
   • Better avoid in last trimester of pregnancy (cattle)
3. Breeds sensitivity
   
   • Hereford and Brahman anecdotally more sensitive
   • Breed sensitivity also for sheep and goats?

Question 15

How much smaller of a dose of xylazine do you use in ruminants compared to horses

Answer 15

use 1/10th the equine dose

Question 16

1. What % of xylazine do you use in ruminants?
2. Why?

Answer 16

1. Best to use 2% xylazine
2. Extremely sensitive compared to horses

Question 17

What are the 4 induction protocols for cattle

Answer 17

1. Guaifenesin (GG) + Xylazine + Ketamine (large volume)
2. Ketamine + Xylazine IV (bolus induction)
3. GG + Ketamine IV
4. Ketamine + benzodiazepine IV (small volume)
   
   • 50:50 mix by volume, approx. 1 mL/20 kg
     
     • Small ruminants & calves primarily

Question 18

3 Small ruminant induction protocols

Answer 18

1. Ketamine + benzodiazepine IV
2. Ketamine + propofol
3. Propofol ($$)
   
   • Cheaper when using on small animals

Question 19

Why can endotracheal intubation be hard in ruminants

Answer 19

1. Narrow mouth & sharp teeth
2. Larynx can be difficult to visualize
3. Profuse salivation & risk of reflux
   
   • Adequate anesthetic plane to avoid regurgitation
   • Quick ET tube insertion & cuff inflation

Question 20

What are the 2 methods of endotracheal intubation and which animals do you do each one on

Answer 20

1. Manual palpation
   
   • Larynx relatively insensitive vs other species
   • Adult cattle only
2. Visual
   
   • Long laryngoscope blade & stylet
   • Small ruminants & camelids
   • Can do in Adult cattle

Question 21

Endotracheal Intubation Equipment

Answer 21

1. Mouth gag/speculum
2. Roll gauze
3. Laryngoscope – lung blade
4. Stylet
5. Selection of ET tubes

Question 22

How to do Endotracheal Intubation by Palpation

Answer 22

1. Adult cattle only
2. Mouth gag or speculum
3. Direct insertion or with stylet
   
   • Reflect epiglottis & palpate arytenoids
4. Ideally mouth lower than poll
   
   • Drain saliva and reflux

Question 23

How to do Endotracheal Intubation by Visualization

Answer 23

Small ruminants & camelids

1. Keep sternal for intubation after induction
2. Visualize larynx with laryngoscope
3. Camelid: lidocaine spray on aritenoids
4. Insert small diameter stiff stylet
5. Tube over stylet into trachea, inflate cuff, tie tube to mandible
6. Position on the surgery table

Adult cattle

1. Usually strapped to tilt table – lateral recumbency
2. Very long laryngoscope blade

Question 24

What is special about camelid endotracheal intubation

Answer 24

–lidocaine spray on aritenoids

Question 25

Positioning

Answer 25

1. Head elevated and mouth below poll * Saliva & passive reflux drain downwards and out 2. Considerations for large, heavy animals as for horses * Myopathy and neuropathy * Padding, limb position

Question 26

What drugs do you use for Anesthetic Maintenance by IV only

Answer 26

1. “Double drip” * GG + Ketamine * Shorter procedures \< 20 minutes 2. “Triple drip” * GG + Ketamine + Xylazine 3. ET tube and O2 supplementation

Question 27

What is important to know about using guaifenesin in cattle

Answer 27

* 5% GG preferred in cattle * Hemolysis at higher %

Question 28

1. What gas inhalents do you use on ruminants 2. What is special about the anesthetic machine vs small animals

Answer 28

1. Isoflurane or $evoflurane 2. With mechanical ventilator

Question 29

1. What is the minimum flow rate for ruminants? 2. Why is IPPV required?

Answer 29

1. Minimum O2 flow 5 mL kg-1min-1 2. Usually IPPV required because: * High respiration rate & low tidal vol. --\> * Hypercapnia & hypoxemia and Poor alveolar absorption of anesth --\> * Light anesthetic plane

Question 30

* What happens to eye position and palpebral reflex in light, moderate, and deep planes of anesthesia * Also include if they respond to painful stimuli

Answer 30

1. Light: eye central & palpebral reflex present * responds to painful stimuli 2. Moderate: eye rotated ventrally & palpebral reflex absent * does not respond to usual surgical stimuli 3. Deep: eye central & palpebral reflex absent * may be necessary for very painful procedures, e.g. fracture repair

Question 31

Shoud jaw be taught or relaxed in a good anethestic plane

Answer 31

•Jaw should be relaxed

Question 32

1. Expected heart rate in ruminants 2. At what HR do you treat for bradycardia? * How to treat?

Answer 32

1. Expected heart rate: * 70-80 bpm 2. Treat bradycardia if \< 60 bpm * Isoproterenol CRI (beta agonist)

Question 33

1. How do you monitor blood pressure in ruminants? 2. What should the MAP be? 3. How to treat hypotension? 4. Another benefit of using invasive blood pressure monitoring

Answer 33

1. Catheter in auricular artery 2. MAP \> 60 mm Hg 3. Dobutamine CRI for hypotension 4. Arterial samples for blood gas analysis

Question 34

How do you recover a ruminant

Answer 34

1. Extubate when animal chews, swallowing or coughs * Leave ET tube cuff inflated 2. Place in sternal recumbency, nose down, well supported – allows eructation 3. Leave the stall when animal can lie sternal without support

Question 35

Why do you leave ET tube cuff inflated when extubating a ruminant?

Answer 35

just in case there is any fluid or food particles sitting on it

Question 36

1. Can food reflux from stomach in camelids? 2. How long do you fast? 3. Water with held?

Answer 36

1. Content of compartment 1 of the stomach may reflux 2. Fast for 24 hours, * Do not fast cria if \< 1 month old 3. withhold water for up to 12 hours

Question 37

1. What is special about IV catheterization in camelids 2. Are they sensative to xylazine? 3. Are they normal breathers, semi-obligate nasal breathers or obligate nasal breathers?

Answer 37

1. IV catheterization * No jugular furrow * Valves along jugular veins may impede catheter advancement 2. Less sensitive to xylazine than ruminants 3. Semi-obligate nasal breathers

Question 38

Explain why jugular vein IV access is hard to obtain (check notes)

Answer 38

Question 39

What are different vein options in camelids

Answer 39

1. Jugular commonly used but has valves * 16 – 18 G x 5” catheter * 14 G x 1.5” needle or scalpel for pilot hole 2. Auricular 3. Cephalic 4. Saphenous

Question 40

Why would you use nasotracheal intubation in camelids

Answer 40

1. Are semi obligate nasal breathers 2. For oral cavity/dental surgery 3. Post recovery if nasal congestion impairs breathing * If head is low there would be edema

Question 41

How do you do Anesthesia Recovery in camelids

Answer 41

* Semi-obligate nasal breathers * Risk of airway obstruction * Naso-tracheal intubation possible * Position in sternal recumbency, nose down * Extubate when able to lift head and swallow