Equine Anesthesia Flashcards
What are the problems associated with equine anesthesia?
Prolonged recumbency
Inadequate muscle blood flow and myostitis
Neuropathy due to poor positioning
Detrimental changes in cardiopulmonary function
Poor oxygenation
What makes induction and recovery difficult and potentially dangerous to the animal and other personnel?
The general temperament and size of the horse
Why do horses sometimes colic after anesthesia for elective surgery?
The depressive effects of anesthetic drugs on gastrointestinal motility
Why should an elective surgery be delayed for a horse that has a cough and intermittent nasal discharge?
The oxygenation and ventilation of the horse may be effected
What separates both sides of the lungs?
The mediastinum
Why is airway patency such a big deal in horses?
Horses are obligate nasal breathers
while going under anesthesia or recovering if the air is not provided by an endotracheal tube, or by other means, the horse could be in respiratory trouble
What ECG system (set-up) is used on horses and other large animals during general anesthesia?
The Base-Apex system
What common physiologic cardiac rhythm variations can be detected in horses?
1st degree heart block 2nd degree heart block Sino-atrial block Variably configured P-waves Atrial fibrilation
What is the most common cardiac arrhythmia of clinical significance in the horse?
Atrial Fibrillation
How is atrial fibrillation diagnosed?
Palpation of irregular pulses with varying strengths
Auscultation
Echocardiogram (abscence of P waves)
Why is rinsing out a horse’s mouth a step taken in the pre-anesthetic preparation?
To remove any foreign material to prevent aspiration
What 3 groups of drugs are commonly used for sedation or pre-medication in horses?
Phenothiazines
Alpha-2 agonists
Opiods
List 5 important facts to know about the use of Acepromazine in horses:
It is a major tranquilizer that produces a calm and relaxed state
It does not produce analgesia
Its onset of action is 15 to 20 minutes and the duration is 6 to 10 hours
Causes hypotension
Not reversible
List 5 important facts to know about the use of Alpha-2 Agonists in horses:
Produces a moderate to profound sedation, analgesia, and muscle relaxation
Can induce or exacerbate first and second-degree heart block
Sedation is characterized by a “head down” posture and some ataxia
Used for temporary relief of colic pain
Used for a pre-medication for general anesthesia and for standing chemical restraint
What Alpha-2 agonists are used in horses?
Xylazine and Detomidine
Is Xylaxine or Detomidine more potent?
Detomidine is 80-100 times more potent than xylazine
What does moderate sedation look like in horses?
Head drooping
What does profound sedation look like in horses?
Head goes to the ground
List 2 important facts to know about the use of Opioids in horses
cause nervousness and excitement in horses.
Why is Butorphanol preferred in horses?
it causes less excitement or ileus than the mu-agonists (morphine)
Why are anticholinergics not routinely used as a pre-anesthetic drug in horses?
it can depress gastrointestinal motility.
What breeds of horses are considered lighweights?
Draft horses and Tennessee Walking horses
What drugs are commonly used in horses as induction agents?
Ketamine with Guaifenesin
Ketamine with Diazepam
Thiobarbiturates +/- Guaifenesin
What are the most commonly used drugs for induction?
Ketamine with Diazepam
What are the common endotracheal tube sizes used in horses?
The most common ET tube size is 26 mm
Smaller breeds 16 mm
Ranges 16-30 mm