Exam 4: Lecture 25 - Ruminant Anesthesia Flashcards
What are the 4 factors can determine the anesthetic approach to a case
- production animal vs pet
- cost
- field anesthesia vs in-hospital anesthesia
- standing surgery vs general anesthesia
T/F: For simple diagnostic procedures and some surgical procedures we can just restrain ruminants and use local anesthesia
true! Do not always need to use full anesthesia
T/F: Complex procedures for ruminants does not always require general anesthesia
false! complex procedures usually require us to use general anesthesia
what procedures are standing procedures for ruminants
- castration
- displaced abomasum
- c-section (routine)
- wound repair
- teat surgery
- enucleation
- dehorning
what procedures need general anesthesia for ruminants
- ortho sx
- umbilical hernia repair
- MRI/CT
- difficult c-section
- mass removal in an area that cant be blocked
- extensive wound repair
what are the 8 general considerations for anesthesia for ruminants
- PE
- bloodwork
- fasting requirements
- IV catheter
- gather any special equipment/personnel
- drugs
- intubation can be a challenge
- padding
why can a PE be limited for ruminants
if the patient is uncooperative then the PE can be limited
what bloodwork is a minimum for ruminants
PCV/TS at minimum and a glucose if patient is a neonate
what do we need to keep in mind for IV catheter placement in ruminants
they may need to be sedated first
what website can we consult to determine drug withdrawal times for food animals
FARAD (Food Animal Residue Avoidance Databank)
why do we need padding for ruminant anesthesia
they can get myopathy or neuropathy
what are some anticipated complications for ruminant anesthesia
- hyper salivation
- bloat
- hypoventilation
- regurgitation can lead to potential aspiration pneumonia (active or passive regurg)
why is bloat a concern for ruminant anesthesia
leads to decreased venous return and hypoventilation
what makes hypoventilation more prominent in ruminant anesthesia
dorsal recumbency will worsen the ability to ventilate
what steps can be taken to prevent regurgitation for ruminant anesthesia
- intubate swiftly and inflate cuff after induction
- position head to promote drainage
- keep head elevated during sedation and recovery
- during anesthesia, the head and neck should be positioned to encourage drainage
what can happen from aspiration of acidic stomach/rumen contents
- immediate reflex airway closure
- destruction of type II alveolar cells and pulmonary capillary lining
what happens when there is destruction of type II alveolar cells and pulmonary capillary lining
can lead to pulmonary edema, hypoxemia, cyanosis, and death in extreme cases
what does the severity of aspiration of acidic stomach/rumen contents depend on
rumen pH and amount of material aspirated
what is the most important thing we can do to avoid aspiration of acidic contents for ruminants
withholding food and correct ET tube placement with a properly inflated cuff
what is the most important consideration of ruminant anesthesia
always take into account the safety of the animal and the personnel working nearby
what is recommended fasting time for adult large ruminants
no food for 24-48 hours and no water for 24 hours
what is recommended fasting time for sheet and goats
no food 12-18 hours and no water for at least 6 hours prior
what is recommended fasting time for calves, lambs, and kids
NPO generally not required if <1 month but can withhold food for 2-4 hours if >1 month
how does the GI tract function in ruminants less than 3 weeks of age
functions as a simple stomach
how does the GI tract function in ruminants greater than 3 months of age
functions as a full ruminant
What does fasting help with for ruminants
reserves functional residual capacity since ruminants have a decreased tidal volume compared to horses (gives more room for lungs to expand)
T/F: Fasting can cause mild alkalosis and bradycardia in cattle
true!!!
even if precautions are taken, as many as ________ % of adult cattle regurgitate under anesthesia
25%
which vein has the easiest acces for ruminants in surgery
jugular vein
what gauge catheter do you use for IV in adult cattle
12-14g
what gauge catheter do you use for IV in calves, goats, and sheep
16-18g
T/F: you always give premeds to ruminants
false! It is not always given…it depends on the clinician
T/F: Acepromazine is approved for use in food animals by FDA
false, it is NOT
describe the use of acepromazine in ruminants
it may increase the risk of regurgitation and is contraindicated in hypovolemic/debilitated patients
where should we NOT inject acepromazine and why
DO NOT inject in coccygeal vein because you can potentially hit the artery and slough off the tail
T/F: Xylazine is approved for use in food animals by FDA
false! It is NOT approved for food animals
xylazine is ___ potent in ruminants
more potent…its why we can use 1/10th of the equine dose IV
what ruminant is the MOST sensitive to xylazine
goats
rate the following breeds in order of sensitivity to xylazine:
herefords, brahmans, and holsteins
brahmans>herefords>holsteins
T/F: stressful environments can cause a prolonged response in cattle
true!!
what are some of the negative side effects of xylazine
bradycardia, rumen atony and bloat, hyperglycemia, hypoinsulinemia, hypoxemia, hypercarbia, and increased urine production
why are alpha-2 agonists not recommended for sheep
because they are at risk for developing pulmonary hemorrhage and edema leading to hypoxemia!
what can happen to a pregnant ewe or cow if they are given xylazine
it has an oxytocin-like effect on the uterus which can lead to premature delivery during the last trimester of pregnancy
T/F: Xylazine and detomidine both have the same effects on pregnant sheep/cattle
false, detomidine does NOT seem to have this effect
what are the alpha-2 antagonists used
atipamezole, yohimbine, tolazoline
what can happen with giving tolazoline in camelids
toxicosis has been reported
do we need to use a lower dose of tolazoline for ruminants
yes! They are more sensitive to it compared to other species
are anticholinergics used in ruminants? Why?
not typically
it decreases GI motility leading to bloat and the salivary secretions become more viscous and can obstruct airway
what is the problem with using benzodiazepines for ruminants
no analgesia and minimal sedation
what do we usually combine benzodiazepines with in ruminants for induction
ketamine
how do we reverse benzodiazepines
flumazenil
We can use opioids in ruminants but what do we need to remember
they can be given BUT may cause excitement or vocalization
T/F: morphine and hydromorphone are typically used in cattle
false, it is not typically used
why do we not use buprenorphine in cattle
because it is EXPENSIVE
what drugs can we use for induction for ruimnants
ketamine, telazol, or propofol
what should we combine ketamine with for induction of ruminants
combine with a benzodiazepine or GG to make a double drip
why is propofol good for ruminants
it is a smooth induction and recovery
what is the downfall of using proprofol in ruminants
apnea may occur with rapid administration and we need to consider cost of using it
why should we always intubate a ruminant during anesthesia
to prevent aspiration of salivary secretions or rumen contents if regurg occurs
what can happen if we try to intubate a patient when they are too light
regurg may occur so have suction ready
___1_____ likely to regurg if placed in dorsal recumbency and ___2____ likely to regurg if placed in right lateral or sternal
- more
- less
what size ET tube do we use for adult cattle
20-30 mm ID
what size ET tube do we use for calves
8-12mm ID
what size ET tube do we use for adult sheep and goats
7-12mm ID
what do we need to do when we intubate ruminants
hyperextend the head and neck to make an orotracheal axis of 180 degrees
in adult cattle or small ruminants do we usually do a blind intubation/intubate with hand
adult cattle
explain the steps of intubation of adult cattle
- insert a dental speculum
- manually find the larynx with hand
- insert ET tube between arytenoids
- must do these steps quick to avoid airway obstruction with the hand
when can we use a small animal anesthesia machine
if the patient is <60kg or if we are using an ET tube less than 18mm
what is our o2 flow rate for ruminants
10-22 ml/kg/min
is isoflurane or sevoflurane more cost effective for ruminant anesthesia
iso!
what is the proper positioning for ruminant general anesthesia
- padding to prevent myopathy/neuropathy
- minimize pressure on radial nerve
- support up leg and align parallel to table
- head down for saliva/regurg to drain out
what are the 8 things we do to monitor anesthesia
- HR and pulse quality
- muscle relaxation
- respiratory rate
- CRT/MM
- BP
- ocular rotation, palpebral reflexes, pupil size
- temp
- arterial blood gases
what is normal temp, HR, and respiratory for cattle
temp: 101-103
HR: 70-90bpm
respiratory: 20-30 rpm
what is normal temp, HR, and respiratory for camelids
temp: 100-102
HR: 60-80 bpm
resp: 10-30 rpm
what is normal temp, HR, and respiratory for goats
temp: 102-104
HR: 70-95 bpm
resp: 15-30 rpm
what is normal temp, HR, and respiratory for sheep
temp: 102-104
HR: 70-80 bpm
resp: 20-30 rpm
what type of BP monitoring is typically done for in-hospital cases for ruminants
direct via auricular artery
what should we always maintain MAP above
60-70 mmHg
why do we do this (16g needle) with our leads for ruminents (esp in cattle)
because the placement of ECGs is hard with the tough hide
what is the goal end-tidal CO2 for ruminants
35-45mmHg
ruminants tend to _______ under anesthesia
hypoventilate
when using IPPV, what can we set out tidal volume and resp rate at
tidal volume: 10-20 ml/kg
resp rate: 6-12 bpm
do cows have more or less fibrous connective tissue in their lungs compared to horses
less fibrous connective tissue
what can excessive airway pressure cause in cows
pneumothorax and emphysema
what does the palpebral reflex do with light anesthesia for ruminants
disappears
how does the eyeball rotate at induction of anesthesia for ruminants
rotates ventrally and cornea obscured partially by lower lid
what happens to the eye with deepening anesthesia for ruminants
pupil completely hidden by lower lid
when does the eyeball rotate dorsal in ruminants
with further increase of anesthetic depth
what do we do for recovery of anesthesia in ruminants
- leave ET tube in place until strong laryngeal reflex returns and patient can remain sternal
- immediately check for airway patency after extubation
- check for regurg and bloat
T/F: we should expect sheep and goats to hypoventilate under general anesthesia
true! we should anticipate giving IPPV
T/F: in sheep and goats, there is not rotation of the globe under anesthesia BUT we can see nystagmus
true!!
how do we check that for regurg and bloat in ruminants
if the ruminant eructates then it was successful anesthesia
