Exam 2: Anesthetic Consideration in the horse, ruminants, and exotic species Flashcards
What are considerations of anesthesia in the horse when it comes to size, behavior, cardiovascular function, and GI? How does recumbency and recovery affect them?
Horses are big and more prone to ventilation/perfusion mismatch.
they are also self destrcutive in behavior.
their CO decreases by more than 40% due to a decrease in contractility so inotropes are very important as an inhlant in anesthesia
their GI not only affects ventilation but the cardivascular system by inhibiting venous return. traditiuonally, fasting was recommended but some research hows horses do better not fasted. anesthesia also increases the risk of ileus in general.
horses are not made for laying down as it increases chance of myopathies and neuropathies. They MUST stand after anesthesia. Extubate when horse is up, typically give small doses of alpha 2 so they can sleep longer and breathe out inhalant.
What are contraindications and indications with common anesthesia drugs in the horse?
horses get excited with opioids.
sedation involves an alpha 2 agonist (xylazine (shortwer duration of action), detomidine, romifidine (longest acting), and dexmedetomidine (shorter DOA))
Can add acepromazine (slow onset, give 10 minutes ahead of induction) and can combine alpha 2s with acepromazine and opioid for deeper sedation. butorphanol is a good choice. if painful, may be better off with pure agonist like hydromorphone or morphine.
opioids do not decrease MAC in horses
opioids can go in joints or epidural space
what is the drug of choice for anesthesia equine?
alone?
Ketamine
Usually don’t use alone. Alpha 2 to help for muscle relaxant. Midazolam and diazepam are classic combinations.
Guafenesin is also a good combo
Propofol is a new addition (in combination!), works well with ketamine.
What is a typical anesthetic cocktail in the horse?
guafenesin (midazolam) for muscle relaxant, ketamine for induction and xylazine for analgesia and extra muscle relaxation.
What are some consideration in the horse for anesthesia? How long is a horse safe under anesthesia? What should you monitor? What about pain management?
Should they have reflexes on ketamine?
Horses should have a palpebral reflex on ketamine but also ensure anesthesia is not too light
for total intrabenous anesthesia, keep it five minutes to an hour. you want to avoid drug accumulation. Inhal;ants can extend anesthesia 2-3 hours dafely.
will need oxygen supplementation to prevent hypoxia if procedure runs long.
Monitor blood pressure and MAP should be >70 mmHg at all times.
Horses have a lot of limitations, NSAIDs are most typical. Alpha 2s are not good for post op. Lidocaine is goood in that it improves GI motility, has anti-inflammatory effects, improves health of gut, nd decreases anesthtetic requirement but does not improve CO.
Are anticholinergic anti-saliva properties helpful in the ruminant?
One of the major considerations for anesthesia in the ruminant is around the amount of saliva that a ruminant produces. Suctioning or lowering the head to allow the saliva to drain can be helpful. There is some controversy around anticholinergics and saliva production: the dose you would need to actually affect salivation is higher than the doses you would use for cardiac correction. The saliva may also simply become more viscous and harder to manage. So, use to decrease heart rate, not salivation.
keep tube inflated
True or false: Fasting is helpful when it comes to regurgitaiton in the ruminant during anesthesia.
False
Regurgitation can happen at any time and passively but can also be active if stimulated. After anesthetizing, do not move them until you have secured an airway to prevent regurgitation and position so larynx is higher than rumen. Fasting is one preventional method but does not entirely eliminate, should still count on regurgitation being possible. Restrict water for 8-12 hours max but be cognizant of hot weather. The main benefit from fasting is decreasing bloat (which affect ventilation and venous return, will be more prone to VQ mismatch and hypoxemia). Also be aware that fasting animals have a lower heart rate*
What is the best method of intubation in a ruminant?
CAUTION: do not intubate a ruminant under too light anesthesia. Larynx should be highest point (even over mouth) putting a towel or pillow under neck is helpful. When extubating, keep tube inflated so feed material does not fall in.
True or false: bloat is not an issue during anesthesia, only when a cow is alert and awake
False
When sedated or restrained and recumbent, ruminants can’t eructate and eliminate gas so bloat can affect respiratory and cardiovascular: decrease venous return, stroke volume and cardiac output. Again, fasting will decrease this process.
Ruminants get really high CO2, most rumiannts if under anesthesia for a long period of time (over an hour) will need mechanical ventilation. Because of their big rumen, cattle take smaller breaths but more often. Similar minute ventialion but tidal volume is smaller. Position is important, have padding, limbs on the bottom should be moved forward to protect nerves, top limbs should be supported and not hanging.
T or F: Ruminants are more sensitive than horses when it comes to xylazine
What are some properties of xylazine?
True, 10x more sensitive
Also be aware that xylazine should be avoided in pregancy as it has oxytocin like properties. We can antagonize this drug to reverse in case we get in trouble (tolazine, yohimbine). Avoid xylazine (or at least be cautious) in sheep, can cause pulmonary edema and hemorrahge.any alpha 2 in sheep most commonly can cause this.
Why is it important to monitor temperature during anesthesia in swine?
Malignant hyperthermia can be triggered by anesthesia (high calcium, animal gets hot, muscles contracting and creating heat, eventually animal will become rigid and can often become fatal) triggered by halothane but all inhalant drugs can do it, a paralytic like succinycholine does it but not normally used, stress can also do it.
What is Ket-Stun?
Ket-Stun is a combination used to keep ruminants standing: butorphanol, xylazine, ketamine. Good for things that take up to 45 minutes. Small ruminants will use the same combination but at a lower dose. xylazine , keep eye out for hypoxemia and edema.
Will atropine work as an induction agent in all species?
No, rabbits have atropinases.
True or False: Intraosseous catehters are an efficient nd safe option across all species.
False, you can drown a bird by putting in an intraosseous catheter in the wrong bone. they have pneumatic bones.
What is a go-to drug cocktail for induction in most wildlife species?
BAM: butorphanol, azaperone, and medetomidine
