Equine Anesthesia Flashcards
What are 2 common arrhythmias in horses?
Atrial fibrillation and 2nd degree AV block
Which of the following is a pathologic arrhythmia in a horse?
Atrial fibrillation
2nd degree AV block
Atrial fibrillation
What causes a 2nd degree AV block in a horse?
High vagal tone
What are common respiratory pathologies in horses?
COPD, dorsal displacement of soft palate, laryngeal hemiplegia
How do you dose drugs for obese equine patients?
Based on ideal body condition
What size ET tube is needed for the average equine patient (400-500 kg)?
26 mm (have a 24 mm available as well)
What size ET tube is needed for a large draft horse (>500 kg)?
30 mm
What size ET tube is needed for a donkey?
14-16 mm
True/False: a laryngoscope is needed for equine intubation
False, intubation is blind
What are the possible methods of maintenance for equine anesthesia?
1) Inhalant anesthesia alone; 2) inhalant anesthesia w/ PIVA; 3) TIVA
What is the approximate blood volume of an adult horse? Of a foal?
~8% BW (kg). ~9% BW
Which of the following is the correct mean arterial pressure to maintain in an equine patient?
>25 mmHg >40 mmHg >70 mmHg >80 mmHg >100 mmHg
> 70 mmHg (SAP >90-100 mmHg)
Which of the following is the correct range for ETCO2 and PaCO2 to be maintained in an equine patient?
35-50 mmHg
50-65 mmHg
20-30 mmHg
60-75 mmHg
35-50 mmHg (ETCO2 may be 10-15 mmHg lower)
True/False: if an equine patient is on 100% oxygen, its PaO2 should be at least >200 mmHg
True!
What is an ideal PaO2 for an equine patient on 100% oxygen?
FiO2 x 5 = 500 mmHg
Where do the electrodes go on the horse for the base apex lead system?
Right arm electrode (white) –> cranial to the right scapula in right jugular furrow (“cold shoulder”)
Left arm electrode (black) –> over the apex beat on the left side, level w/ the olecranon (“black heart”)
Left leg electrode (red) –> caudal to black lead
How can you measure anesthetic depth of an equine patient?
Eyes, muscle tightness in shoulders and neck
When at the appropriate depth of anesthesia, what should you see w/ the equine eye?
Ventromedial to central w/ medium sized pupil, minimal to no palpebral reflex, slowed corneal reflex
What do nystagmus and lacrimation indicate about anesthetic depth of an equine patient?
Nystagmus = very, very light Lacrimation = light plane
What are some premeds we can use with an equine patient?
Acepromazine (0.005-0.03 mg/kg) –> as adjunct to other sedatives
Xylazine (0.5-1.0 mg/kg IV; 1-2 mg/kg IM)
Detomidine (5-20 ug/kg IV; 20-40 ug/kg IM)
Romifidine (80-120 ug/kg IV or IM)
Butorphenol (0.01-0.05 mg/kg IV)
Morphine (0.05-0.1 mg/kg IV slowly)
What is a possible complication when using Acepromazine in equine patients?
Potential for penile prolapse –> caution when using w/ breeding stallions
What is a possible complication when using Opioids (Butorphanol/Morphine) in equine patients?
May cause excitement w/o other sedatives
What type of drugs can you use as a premed in foals?
Benzodiazepines
Which of the following is the correct pairing of MAC to gas for an equine patient?
Iso = 1.3, Sevo = 2.3 Iso = 2.3, Sevo = 1.3 Iso = 1.31, Sevo = 2.31 Iso = 2.6, Sevo = 4.6
Iso = 1.31, Sevo = 2.31
True/False: if using TIVA for maintenance anesthetic in an equine patient, you can keep them under indefinitely.
False. Maximum 90 min if using TIVA
What are possible CV complications of anesthesia in a horse?
Hypotension (MAP >70 –> higher mean required to maintain muscle perfusion)
2nd degree AV block
Hemorrhage
How would you resolve hypotension in an equine patient?
Decrease inhalant (vasodilation) --> CRI, local blocks Increase fluids --> isotonic, colloids Positive inotropes --> dobutamine CRI
How would you resolve 2nd degree AV block in an equine patient?
Dobutamine, alpha-2 agonists
What are possible pulmonary complications of anesthesia in a horse?
Hypercapnea, hypoxemia
What affect do inhalants have on hypoxic pulmonary vasoconstriction (HPV)?
They decrease HPV
What are the 4 ways we minimize pulmonary complications in equine anesthesia?
1) Minimize inhalants by using CRI, local blocks, and adequate premeds
2) Provide mechanical ventilation w/ PEEP
3) Provide 100% oxygen even in the field
4) Minimize duration of procedure
What are some complications of recovery in equine anesthesia?
Neuropathy, myopathies, nasal edema, laryngeal dysfunction, dorsal displacement of soft palate, hypoxemia, traumatic injury
How do we treat nasal edema, and why is it a major problem?
Phenylephrine in the nostrils, nasotracheal intubation. Horses are obligate nasal breathers.
What are 2 causes of laryngeal dysfunction?
Preexisting hemiplegia, recurrent laryngeal nerve damage during recumbency
Which of the following is the correct amount of oxygen to give a horse to treat hypoxemia during recovery?
10 L/min
35 L/min
15 L/min
20 L/min
15 L/min. Oxygen should be given with a demand valve via ET tube until the horse is extubated
