Farm animal and camelid anaesthesia Flashcards Preview

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Flashcards in Farm animal and camelid anaesthesia Deck (58)
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What are some examples of surgeries do you need a GA for?

- umbilical hernia repair
- urethrostomy
- orthopaedic (not all)
- enucleation (depends on species)


Give some examples of surgeries you can use a sedation and local anaesthetic technique

- flank laparotomy
- csection
- RDA or LDA
- rumenotomy
- declaw
- dehorning
- teat surgery
- castration


List pre-anaesthetic considerations for ruminants - 8

- handling, restrain, accurate weight
- regurgitation/aspiration
- salivation
- bloat (tympany)/rumen atony
- hypotension/hypertension
- hypoventilation and hypoxaemia
- myopathy/neuropathy
- fluid and electrolyte problems


Outline regurgitation as a consequence of anaesthesia in ruminants

Can lead to aspiration pneumonia which can be fatal
- ACTIVE - light plane of anaesthesia (commonly at intubation)
- PASSIVE - deep anaesthesia (cardia relaxation)


How can you reduce the risk of regurgitation in ruminants? 6

- Reduce rumen fill (starve 18-24 hours, not if < 3 months old)
- good depth of anaesthesia when intubating
- good fitting ETT and properly blown up cuff
- position of head (fluid to drain into mouth)
- stomach tube


How does ketamine affect salivation?

- Ketamine (licensed induction agent) stimulates further production. Can lead to problems at intubation and electrolyte imbalances.
- Tx = atropine (L but never in UK food chain)


Why do you get bloat (tympany)/ rumen atony with with anaesthesia?

no eructation when anaesthetised --> reduces FRC and venous return --> continued fermentation can lead to pH shift and atony


How can you prevent bloat (tympany)/ rumen atony with anaesthesia? 2

- adequate starvation and water withholding time
- placement of a rumen tube or trochar to evacuate gas


Describe hypotension in ruminants under GA

- much less likely compared to horses
- deep planes of anaesthesia
- high xylazine doses or use of ACP (NL) implicated
- support required


What might cause hypertension in adult bulls and cattle under GA? (2 theories)

- High CO2 (due to hyperventilation, causes increased CO, when ventilated to reduce CO2, the ABP remains high)
- changeover from PS to S dominance as a result of anaesthesia


Why are ruminants more prone to airway damage during IPPV?

less fibrous connective dtissue


Why does hypoventilation and hypoxaemia occur in GA ruminants? 3

- drug induced respiratory depression
- chemoreceptor depression
- large rumen (and any bloat) --> small TV and only slightly increased RR, reduction in FRC (causes airway closure and VQ mismatch), decreased venous return (reduced CO).


Outline the likelihood of myopathy and neuropathy in ruminants under GA versus horses?

Ruminants are less prone to myopathy but neuropathy is more common.
AVOID BY: positioning, padding, ABP, oxygenation and perfusion


What sedative is used in ruminants?

ALPHA 2 AGONISTS --> sedation, anxiolysis, recumbency, analgesia, mm relaxation. Ruminants are very sensitive to these (esp. sheep and goats). Xylazine and detomidine (L-cow)


What are the side effects of alpha 2 agonists in ruminants? 7

* Pulmonary oedema - sheep and goat (xylazine)*
- reduced eructation (tympany)
- reduces swallowing (saliva in oropharynx)
- copious urine production
- osmotic diuresis
- urethral outflow issues
- oxytoxin like effect --> uterine contractions


What can be used for induction in ruminants? 2

Ketamine or thiopentone


Properties - induction with ketamine in ruminants - 4

- dissociative anaesthetis (use IV or IM)
- excellent analgesic
- mm rigidity
- laryngeal reflexes remain


Properties - induction with thipentane in ruminants - 5

- very fast acting
- no veterinary licence available
- very irritant so must go IV (extravasation --> necrosis)
- accumulation can lead to prolonged recoveries
- not in thin/debilitated animals


Are there any injectable agents for induction in ruminants?

No (but they include propofol, benzodiazepines, GCE, alphaxalone, chloral hydrate)


What is propofol good for?

Injectable induction of small ruminants as smooth induction and recovery. NOT LICENSED.


What are benzodiazepines good for?

Injectable induction. small ruminants, sedate neonates and debilitated animals well. NOT LICENSED


What is GCE good for?

Injectable induction. good centrally acting mm relaxant. NOT LICENSED


What is alfaxalone good for?

Injectable induction. used for goat disbudding. NOT LICENSED


What is chloral hydrate good for?

Injectable induction. old drug for sedation/anaesthesia. sedation acceptable, poor for GA. NOT LICENSED.


What are the 2 main ways or providing analgesia in ruminants?

*** NSAIDs (licensed - meloxicam, flunixin, ketoprofen, carprofen, tolfenamic acid)***
- OPIODIS (NL in UK, include butorphanol, buprenorphine, morphine/methadone, pethidine)


Name 4 inhalation agents used in ruminants

* Isoflurane (licensed)
- Sevoflurane (NL)
- Desflurane (NL)
- Halothane (NL) - hepatotoxicity


How can you anaesthetise smaller ruminants?

you ca mask them down


What are your venous access options in ruminants?

- JUGULAR - deeper than horse
- TAIL VEIN - often artery is used
- CEPHALIC - small ruminants
- MILK VEIN - don't use unless nothing left


What do you need to consider when intubating ruminants?

Laryngoscope as blind is difficult (long blade). Method is by internal palpation in adult cattle. In young cattle and small ruminants use a laryngoscope as in small animals - need a stylette to stiffen the ETT.


What can be used for local anaesthesia in ruminants?

LICENSED: procaine, benzocaine, tetracaine
NOT LICENSED: lidocaine
DOSES vary depending on toxicity. Sheep and goats are quite susceptible.

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