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Aneasthesia > Farm Animal Anaesthesia > Flashcards

Flashcards in Farm Animal Anaesthesia Deck (54)
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1
Q

Which sedatives are allowed in food producing animals?

A
  • xylazine
  • detomidine (bovine/equine)
  • azaperone (pig)
2
Q

Which induction agents are allowed in food producing animals?

A
  • ketamine
  • thiopentone
    > EU legislation not UK
3
Q

Which inhalational agent is allowed in food producing animals?

A
  • isoflurane (equine) so FA under cascade
4
Q

which local anaesthetics are allowed in food producing animals? Which analgesics?

A
  • procaine
  • lidcaine
    + various analgesics (NSAIDs, butorphanol etc.)
5
Q

How are majority of GA drugs used in food producing animals?

A

VIa cascade usually from horses (Must be another food producing animal)
*NB: some drugs never allowed in food chain

6
Q

Which procedures in farm animals commonly require GA?

A
  • umbilical hernia repair
  • urthrostomy
  • orthopaedic
  • enucleation
7
Q

Which procedures in farm animals can be performed standing?

A
  • flank laparotomy
  • c-sec
  • RDA/LDA
  • rumenotomy
  • declaw
  • dehorning
  • teat surgery
  • castration
8
Q

Preanaesthetics considerations in ruminants

A
  • manual handling and restraint, accurate weight
  • regurgitation/aspiration
  • salivation
  • bloat (tympany)/ruman atony
  • hypo/hypertension
  • hypoventilation and hypozaemia
  • myopathy/neuropathy
  • fluid and electrolyte problems
9
Q

2 forms of regurgitation?

A

active (light plane of anaesthesia)

passive (deep plane of anesthesia due to cardia relaxation)

10
Q

How can regurgitation and subsequent pneumonia be minimised? Risks of this?

A
  • starve 18-24hrs (not ,3mo)
  • no water 12 hrs (not 3mo)
    > starvation and dehydration -> ketoacidosis?
  • good depth of anaesthesia when intubating
  • good fitting ET tube and properly blown up cuff
  • position head so fluids can drain out
  • stomach tube
  • extubate with cuff still inflated
  • put in sternal asap
11
Q

Which induction agent may stimulate salivation? Why is this a problem?

A

ketamine (licensed in FPAs)

- can lead to intubation problems and electrolyte imbalance

12
Q

Treatment of excessive salivation?

A
  • atropine (Licensed by EU for equine) BUT never into food chain in UK
13
Q

Why may bloat (tympany) or rumen atony occour under anaesthesia? Prevention?

A
  • fermentation continues but cannot eructate
  • reduces functional residual capacity and venous return
  • pH shift can result in atony
    > prevent by adequate starvation and water
    > placement of rumen trochar to evacuate gas
14
Q

Is hypotension a common problem in ruminants? Tx?

A

Less than horses

  • only at deep planes of anaesthesia
  • due to high xyalzine doses or ACP (NL)
  • Tx as for hroses
15
Q

Define hypertension. Is hypertension common in ruminants? Cause?

A

MAP >200mmHg

  • seen in adult bulls and cattle but RARE
  • due ^ CO2?
  • due to switch sympathetic dominance under GA?
16
Q

How does IPPV differ in ruminants to horses? Why may it be necessary?

A

^ risk airway damage due to lack of fibrous connective tissue
- often required to manage CO2 levels (drug induced resp depression, chemoreceptor depression, large rumen/bloat -> small TV with minimally ^ rate, v FRC, airway closure and VQ mismatch, v VR and CO

17
Q

How does risk of myopathy/neuropathy differ to horses?

A
  • less prone to myopathy

- neuropathy more common

18
Q

What should be expected with a slow recovery in ruminants?

A
  • hypomagnesaemia (esp. as many animals being operated on are pregnant)
19
Q

Which sedatives may be used in ruminants, what other effects do these drugs have?

A

> a2 ags: sedation, anxiolytic, recumbence, analgesia, muscle relaxation

  • ruminants v sensitive esp. sheep and goats
  • xylazine 2% (L), detomidine (L cow)
  • side effects:
  • pulmonary oedema sheep and goat (xylazine) -> bronchoconstriction (allergy?)
  • v eructation
  • v swallowing
  • ^ urine production
  • osmotic diuresis (cf. AVP horses)
  • urethral outflow issues
  • OT like effect -> uterine contraction
20
Q

What type of drug is ketamine and what effects does it have?

A
  • dissociative anaesthetic induction agent
  • IV/IM
  • excellent analgesic
  • muscle rigidity
  • laryngeal refelxes remain
  • licensed by EU for all food producing species
21
Q

What type of drug is thiopentone and what effects does it have?

A
  • very fast acting induction agent
  • no vet licence but licensed by EU for all food producing animals
  • very irritant, will cause necrosis, must go IV
  • accumulation -> prolonged recoveries
  • not for use in thin/debilitated animals
22
Q

Which agents are used in ruminants with NO LICENSE?

A
  • propofol (v good small ruminants, smooth induction and recovery)
  • benzodiazepines (small ruminnats, will sedate neonates and debilitated animals and muscle relax)
  • GGE (good centrally acting mm. relaxant)
  • Alfaxalone (goat disbudding)
  • Chloral hydrate (old drug for sedation/anaesthsia, sedation good, poor for GA)
23
Q

Which NSAIDs are licensed for use in ruminants?

A
  • meloxicam
  • flunixin
  • ketoprofen
  • carprofen
  • tolfenamic acid
    > see lecture for doses
24
Q

Which opioids are licensed for use in ruminants?

A
NONE
- Butorphanol licensed for equine EU so legally allowed under cascade
- buprenorphine
- morphine/methadone
- pethidine 
.. used but not lic
25
Q

Which inhalation agents are licensed for use in ruminants?

A
  • isoflurane licensed for equine EU so legally allowed under cascade
  • sevoflurane( NL)
  • desflurane (NL)
  • halothane -> hepatotoxicity (NL)
  • mask induction for smaller ruminants
26
Q

Venous access points in the ruminant?

A
  • jugular (deeper than horse, skin loose in cattle)
  • tail vein (beware artery lies next to it!)
  • cephalic in small ruminants
  • milk vein last resort (risk of thrombophlebitis)
27
Q

How large an endotracheal tube should be used for ruminants? Anything else required?

A
  • Smaller than for horses

- stylette and laryngoscope needed for small ruminants

28
Q

WHich local anaesthetics are licensed in ruminants? Which are used?

A
> Lic
- procaine 
> EU FPA lic
- benzocaine
- tetracaine 
> non-lic cascade
- lidocaine
29
Q

What head local blocks can be performed in ruminants?

A
  • infraorbital
  • mental
  • cornual
  • retrobulbar
  • peterson’s/auriculopalpebral
30
Q

Which limb blocks can be performed on ruminants?

A
  • perineural infiltration
  • ring infiltration
  • IVRA (Bier’s block) using a touniquet
    > do not leave on >2 hours
    > lidocaine only IV drug usable
    > release tournequet slowly
31
Q

Which body blocks can be performed on ruminants?

A
  • paravertebral (prox/dist)
  • inverted L
  • segmental lumbar epidural
  • line
  • teat
32
Q

Which caudal body/genital blocks can be performed on ruminants?

A
  • epidural
  • pudendal
  • intra-testicular
33
Q

Which animals are camelids (alpacas and llamas) like?

A
> ruminants
- 3 compartment stomach, ruminate
- prone to bloat/regurge/salivation
- lingual torus (tongue)
> horses
- temperamental
- obligate nose breathers
- prone to resp obstruction 
- can develop stomach ulcers with stress
34
Q

Why is catheter placement often problematic in camelids?

A
  • must be placed high (4cm below angle of jaw)
  • or low (rostral to ventral process of C5) * care carotid a. v close*
  • tucked under vertebral processes
    > blood v. red as evolved to live at altitude so will know if hit artery
35
Q

What issues are associated with intubating camelids?

A
  • torus linguae and soft palate
  • long narrow face
  • larynx far back
  • sternal and positioning so head down to prevent saliva inhalaiton
  • protect eyes from saliva -> ulceration
36
Q

What drugs can be used in camelids?

A
> similar to ruminants but mostly NON FPA
> sedation 
- xylazine [no pulmonary oedema seen in camelids cf. ruminants]
- benzodiazepines
> analgesia 
- NSAIDs - flunixin 
- buprenorphine/methodone
- nn. blocks/epidural 
> induction 
- ketamine
- propofol
> maintainance 
- isoflurane
- sevoflurane
37
Q

What special precautions should be taken when ruminants/camelids are recovering?

A
  • sternal
  • allow to eructate
  • DO NOT REMOVE ET TUBE until fully awake and keep cuff inflated on extubation
  • suction prior to extubation
  • usually recover quickly*
38
Q

Where are majority of injections performed in pig?

A
  • IM (IV too deep due to thick fat)
39
Q

Pre-anaesthetic considerations for pigs?

A
  • vomit so starve at least 6 hours
  • handling difficult and prone to stress
  • difficult to intubate (may obstruct even with sedation)
  • prone to temperature fluctuation and sunburn
  • suscpetable to malignant hyperthermia
40
Q

Which drugs can be used for sedation in pigs?

A
> azaperone (butyrophenone) LIC
- cheap and effective
- beware penile prolapse 
- wait min 20 mins for sedation to take effect 
> a2s (NL)
- may cause vomiting
- combo with ket and butorphanol for field anaesthesia
> acepromazine (NL)
- unpredictable
- can ^ heat loss due to vasodilation
> benzodiazepines (NL) 
-  midazolam better bioavailability, can be used intranasally for smaller pigs)
- not for food animals
41
Q

Which analgesics are licensed in the pig?

A

NSAIDS

  • flunixin (finadyne only)
  • ketoprofen
  • meloxicam
42
Q

Which induction agents are licensed in the pig? Which are used?

A
> ketamine (lic EU FPA)
- after sedation 
- may need top up 
> thiopentone (lic EU FPA) 
- IV only 
- after sedation 
> editomidine (NL)
> alfaxolone (NL) 
> propofol (NL) 
> Mask
43
Q

Which maintainance inhalation agents are licensed and used in pigs?

A
  • iso (lic EU FPA)
  • sevo (NL)
  • des (NL)
44
Q

How is induction practically carried out in the pig?

A

Extension set - IM needle, stab into neck (poor meat cut)

  • inject drug and flush with saline
  • pig can run around and not escape you
45
Q

IV access points in the pig?

A
  • Ear v. (peripheral, aa. central)
  • limbs when asleep
  • jugular blind or cut down
  • tail
  • epigastrics
46
Q

how do pigs larynxes differ to other spp?

A
  • Small
  • marked laryngeal reflex (Local spray?)
  • need small tube with stylette
  • shape of laryngotracheal junction odd, rotate tube 180* once half way in
47
Q

What environmental factor are pigs particularly susceptable to?

A

Temperature

  • hypothermia esp if small
  • malignant hyperthermia (genetic disease also seen in horses, cats, people. Can be tested for)
48
Q

What may trigger malginant hyperthermia episodes in pigs?

A
  • inhalation agents
  • caffeine
  • suxamethonium
    > often fatal
49
Q

Clinical signs of malignant hyperthermia?

A
  • muscle rigidity
  • pyrexia sudden onset (>42*)
  • sudden ^ CO2 and moisture
50
Q

Tx malignant hyperthermia

A
  • active cooling
  • maitain IV fluids to minimise myoglobinurea
  • remove trigger (inhalation agent) clean circuit, start TIVA
  • ventilate to remove CO2
  • bicarbonate to v acidosis
  • monitor K+ (hyperkalaemia associated with muscle damage)
  • Tx: Dantrolene $$$ prophylactic use best
51
Q

How does dantrolene work? Side effects?

A
  • reduces Ca release
  • only affects striated muscle (minimal smooth and caridac muscle effect)
    > side effects
  • muscle weakness
  • sedation
  • hepatitis occasionally
  • arrythmogenic
52
Q

Differences in monitoring ruminants under GA?

A
  • eyes toll down with deepening anaesthesia towards surgical plane
  • roll back to a central position when surgically deep
53
Q

Differences in monitoring alpacas under GA?

A
  • retain blink reflex

- chew or swallow

54
Q

Differences in monitoring pigs under GA?

A
  • retain laryngeal reflex to deeper plane of anaesthesia