L12b: anesthesia in ruminants

MCQ: is ketoprofen FDA-approved for use in cattle?

yes but only SC once daily for up to 3 days

what is the ideal time periodi to allow ruminant to acclimatize to restraint?

3 days

what are common subclinical conditions to consider in small ruminants?

1. pulmonary disease

2. anemia

what common subclinical condition to consider in cattle?

mastitis

what are specific considerations for ruminant anesthesia?

1. eructation

2. saliva

3. regurgitation

4. heavy GI

5. rumen bloating

what leads to a V/Q mismatch in ruminants?

increased rumen content → increased intra-abdominal pressure → hypoventilation and hypotension

why is it important to check for rumen tympany (bloat) in pre-anesthetic exam?

anesthesia reduces rumen motility and airway protection

what position do ruminants tend to assume even with mild sedation?

sternal recumbency

what are the risks associated with general anesthesia in ruminants?

1. bloating

2. aspiration

what is important to know about sedation in ruminants?

much more sensitive to alpha-2 agonists

what alpha-2 agonists can we use for sedation in ruminants?

1. xylazine

2. detomidine

what are signs of alpha-2 agonist sedation in ruminants?

1. head lowers

2. drooping eyes

3. hypersalivation

4. ataxia

5. sternal recumbency

what are the pulmonary complications associated with alpha-2 agonists in ruminants?

pulmonary macrophage activation → alveolar damage → pulmonary edema

what are the clincial signs of pulmonary edema in ruminants?

1. severe and sustained hypoxemia

2. cyanosis

3. fatal respiratory failure

what is the treatment for pulmonary edema in ruminants?

1. oxygen administration

2. atipamezole

what are the indications for an inverted L block or paravertebral block?

1. laparotomy

2. desensitization of nerves supplying surgical field

where is the needle inserted in the proximal paravertebral block?

perpendicular to the skin

what does it mean if there is a pop sensation during a proximal paravertebral block?

you have penetrated the intertransvere ligament → inject

what is the disadvantage of proximal paravertebral block?

higher risk of penetrating aorta and vena cava

where is the needle inserted in a distal paravertebral block?

parallel to the transverse process

what medication do we use to inject for an IVRA block?

lidocaine 2% without epinephrine

what are the indications for an IVRA block?

1. distal limb procedures

2. claw amputation

3. digit surgery

how many nerves are injected for a head block in cattle?

one → cornual nerve

how many nerves are injected for a head block in goat and sheep?

2 → cornual and lacrimal

how many points do we inject for a head block in cattle?

3

how many points do we inject for a head block in goat and sheep?

2

MCQ: Why is withholding feed before general anesthesia in cattle important?

to reduce rumen fill and limit compression of lungs and major blood vessels

what are the key reasons for fasting ruminants?

1. protect breathing

2. reduce bloat

3. reduce regurgitation

4. prevent aspiration

how long do we withhold hay for in fasting adult ruminants?

36 hours

how long do we withhold grain for in fasting adult ruminants?

24 hours

how long do we withhold water for in fasting adult ruminants?

what side recumbency in ruminants has less compression on lungs and major vessels?

left lateral recumbency

what side recumbency in ruminants is it easier to acess the rumen for trocarisation?

right lateral recumbency

what position should ruminants be in for endotracheal intubation?

sternal recumbency

what technique for endotracheal intubation do we use in calves and small ruminants?

direct visualization

what technique for endotracheal intubation do we use in adult/large ruminants?

digital palpation

should you top up drugs if ruminant is light during endotracheal intubation?

no → risk of regurgitation and aspiration

what angle do you want the head of small ruminants to be at during ET tube placement?

orotracheal axis at 180 degrees

when would you use TIVA in ruminants?

1. short procedures

2. field anesthesia

what do we use in bovine to assess anesthetic depth?

eye position (ventral rotation = sx plane)

what do we use in sheep and goats to assess anesthetic depth?

pupil size and shape

when do we extubate a ruminant after general anesthesia?

after laryngeal reflex and chewing/swallowing have returned

how can we reduce the aspiration risk after extubating?

keep head elevated above the larynx

What is the correct order of the phases, from highest to lowest risk of complications in ruminants?

General Anesthesia → Induction/Intubation → Premedication → Recovery