Lecture 15.1 10/29/24

Question 1

What are the goals of general anesthesia in horses?

Answer 1

-unconsciousness
-muscle relaxation
-analgesia
-amnesia

Question 2

Which aspects of history and physical exam are important prior to general anesthesia in horses?

Answer 2

-age
-size and body condition
-CRT
-heart and lung sounds
-drug sensitivities
-concurrent diseases

Question 3

Which blood tests are useful prior to GA in horses?

Answer 3

-PCV
-TP
-CBC
-chem
-blood gas

Question 4

Which drugs are used for GA premedication in horses?

Answer 4

-phenothiazines
-alpha2 agonists
-opioids
-benzos

Question 5

What are the goals of anesthesia induction?

Answer 5

-provide analgesia and muscle relaxation
-have minimal risk of apnea

Question 6

What factors impact the surgical anesthesia time provided by induction medications?

Answer 6

-premedications
-environmental factors
-extent of stimulation
-use of adjunct analgesic techniques

Question 7

What are the characteristics of guaifenesin?

Answer 7

-muscle relaxant
-minimal or no anesthetic properties
-no sedative or analgesic effect
-high doses may cause muscle rigidity
-minimal resp. and CV effects
-clinical conc. of 5%; higher conc. can cause significant hemolysis
-perivascular admin. causes tissue sloughing

Question 8

Why is TIVA limited to around an hour?

Answer 8

increased time can lead to drug accumulation, CV and resp depression, and prolonged recovery

Question 9

What are the complications associated with inhalational anesthesia in horses?

Answer 9

-requires appropriate equipment
-CV and resp. depression

Question 10

What are the characteristics of equine intubation?

Answer 10

-done blind
-cuffed tube used
-need a large animal anesthesia circuit
-sevoflurane/isoflurane used for inhalant maintenance

Question 11

What are the characteristics of PIVA?

Answer 11

-combines sevo/iso with lidocaine, ketamine, or xylazine
-can provide analgesia with sedation
-better cardiovascular and resp. stability
-comparable costs

Question 12

What is monitored during anesthesia?

Answer 12

-pulse rate and rhythm
-resp. rate
-ECG
-blood pressure
-arterial blood gas
-anesthetic agent conc.
-EtCO2

Question 13

What are the characteristics of cardiovascular depression under anesthesia?

Answer 13

-MAP less than 70 mmHg
-higher risk of myopathy
-treated/prevented by using lower doses of depressant drugs, using PIVA, and using positive inotropes

Question 14

What are the characteristics of resp. depression under anesthesia?

Answer 14

-hypoxemia due to physical compression of lower lungs
-exacerbated by hypoventilation and V/Q mismatch
-treated by using less depressant drugs, providing flow-by O2, and assisting ventilation

Question 15

Which complications can occur during recovery?

Answer 15

-cardiovascular accidents
-physical/musculoskeletal injury
-nerve damage (radial and facial nerve)

Question 16

What are the characteristics of foal anesthesia?

Answer 16

-don’t fast for long periods or at all
-don’t separate foal and dam until foal is asleep
-sedate mare following separation
-avoid prolonged procedures
-avoid hypoglycemia and hypothermia
-provide analgesia

Question 17

What are the characteristics of donkey and mule anesthesia?

Answer 17

-depends on size and age
-often require higher dose/kg than horses
-narrow airway
-thick skin over jugular

Question 18

What are the concerns regarding anesthesia in pregnant mares?

Answer 18

early pregnancy:
-may affect fetal development
late pregnancy:
-may induce parturition
c-section:
-resp. depression in foal