Ruminants - Anesthesiology

What is the typical ET tube size in small ruminants?

7-10 mmID

What should the MAP be of a cow during anesthesia? Where do you place the arterial catheter?

MAP > 70-80, place in auricular artery

What drug is typically used for sedation in cattle?

SMALL dose of xylazine

What is the difference in cornual blocks in cattle versus goat?

block behind the horn in cattle and in front of horn in goat

What is the issue with administering opioids to ruminants?

causes excitement when given alone

What are the problems with a bloated rumen?

decreased venous return and decreased diaphragmatic movement.

Descibe what eye position tells us during anesthesia in cattle?

eye position is very reliable indicator. ventromedial rotation means surgical plane of anesthesia. central eye position means too deep or too light.

Describe cattle in recovery from anesthesia?

generally uneventful, they don't get up until they are ready. Keep in sternal recumbency to facilitate eructation. Extubate once they are swallowing, but do not deflate the cuff!

ventromedial eye rotation in cattle indicates?

surgical plane of anesthesia

What is unique and significant about the camelid's breathing passage?

they are obligate nasal breathers (just like the horse) and will need to breath through nose before extubation.

What drog combination is used for induction of anesthesia in cattle?

usually ketamine + diazepam + guaifenesin IV.

Which drug causes pulmonary edema and hemorrhage in sheep?

xylazine, an alpha - 2 agonist.

Which alpha - 2 agonist is more potent in ruminants than horses? What is the order of potency in ruminants?

xylazine, goats > cattle > sheep. bulls are more sensitive than cattle

Describe the 4 common drug combinations used for exotic ruminant anesthesia.

1. etorphine + acepromazine 2. xylazine + ketamine 3. xylazine + telazol 4. xylazine + azaperone + carfentanil

What are the 4 major physiological concerns with ruminant anesthesia?

1. hypersalivation 2. regurgitation and aspiration 3. bloat 4. effect of full rumen in dorsal recumbency

What are the effects of a full rumen in dorsal recumbency?

1. rumen can never be fully emptied 2. weight of rumen on abdominal vena cava will decrease venous return and therefore decrease cardiac output. May see tachycardia to compensate 3. rumen will push on diaphragm, decrease diaphragm excursion and cause hypoventilation

What drugs are used for induction in camelids?

1. thiopental - camelids require at higher doses 2. ketamine + alpha 2 agonist 3. ketamine + benzodiazepine 4. telazol - muscle relaxation is poor and intubation is difficult 5. propofol - good choice for alpaca and small llama

What 2 premed combos are used in camelids?

1. xylazine + opioid - camels not as sensitive to alpha2 agonists. 2. ketamine + xylazine + butorphanol - produces predictable recumbency within 10 minutes and lasts about 45 minutes.

How much saliva does a cow produce in 24 hours?

50L

Which drug can NOT be given to ruminants for prevention of saliva? Why?

ATROPINE, because anticholinergics only blocks the watery component of saliva production, causing thick/viscous saliva. This increases the risk of bloat.

What is the issue with administering an anticholinergic to a ruminant?

Do not use as antisialogogue, bradycardia is rarely an issue anyway.

Describe maintenance anesthesia in the small ruminant.

Goat - iso 1.2 - 1.5%, sevo 2.33% Sheep - iso 1.58%, no published sevo. eye position is just as important as with cattle.

How are cattle maintained under anesthesia?

Isoflurane MAC - 1.14%. Hypoventilation and V/Q mismatch are expected, so must provide mechanical ventilation.

What size endotracheal tubes are used in cattle?

adult - 20-30 mmID calf - 8-12 mmID

How long do you fast adult cattle before anesthesia? ruminants under 3 months? small ruminants?

adult cattle: 24-48 hours off food, 12 hours off water ruminants less than 3 months: 12 hours off food, avoid hypoglycemia small ruminants: 12-14 hrs off food, about 2 hours off water

Which arteries are used for direct arterial pressure monitoring in the small ruminant?

auricular artery or median artery

Where is the ECG lead placement for ruminants?

base/apex placement

Why aren't camelids technically ruminants?

because they have a 3 chambered stomach, not 4.

Which premeds are best to use for small ruminants?

benzodiazepines are great sedatives, like midazolam. The animal will go down if given IV. opioids do not cause as much excitement as with cattle. alpha 2 agonists cause PULMONARY edema and hemorrhage in sheep.

What premeds are used in cattle?

can use acepromazine, small dose of xylazine, but opioids can't be used alone, they need adding to neuroleptic drug to achieve neuroleptanalgesia. Don't always need to premed

Describe the routes of venous access and gauge needles you would use in cattle.

jugular vein - 12-14 gauge catheter in adult, 16-18 gauge in calves, may require releasing incision b/c thick skin. coccygeal vein - access for injections/blood draws, impractical for catheterization

Describe the venous access in small ruminants.

jugular vein - 16-18 gauge catheter, do not require releasing incision. difficult to use for drug admin without catheter cephalic vein - 18-20 gauge catheter, can use for off the needle drug admin

Which premed combo causes predictable recumbency within 10 minutes and lasts 45 minutes in the camelid?

ketamine + xylazine + butorphanol

Descibe the recovery in small ruminants. When do you extubate?

maintain in sternal recumbency until awake, do not deflate cuff and do not extubate until chewing.

Describe the venous access of camelids.

no jugular groove, the jugular vein is very close to carotid artery, they have several valves to the jugular vein, thick skin. try high on neck or at 6th cervical vertebrae. Can also try medial saphenous vein, middle coccygeal vein, cephalic vein or auricular vein.

Which drug causes excitement in ruminants when given alone?

opioids

Which induction agent is a good choice for alpaca and small llama?

propofol

What causes bloat in the anesthetized ruminant?

rumen fills with air due to esophageal intubation, air gulping or normal bacterial gas production. The rumen will not explode, the animal will eventually eructate!

What is the mechanical ventilator set to when cattle are under maintenance anesthesia?

set 6-8 breaths per minute and 20-30 cmH2O airway pressure.

What positioning of cattle is most procedure performed in?

standing restraint with LA and +/- sedation

central eye position in cattle indicates?

too deep or too light