Anaesthesia for imaging cases workshop

Question 1

An uncooperative male tom cat of an unknown age, approximately 5kg, covered in bite wounds, with numerous obvious abscesses is presented to you in wire cat carrier. The cat is distressed, hissing, growling, and thrashing in the carrier. The cat’s tail is damaged and bleeding badly.

List your concerns and the cat.
Which drugs would you choose?
What tests do you want to do?

Answer 1

Concerns:
- stress, further injury
- pain
- haemorrhage
- restraint
- FIV/FeLV status
- hospitalisation/treatment without impacting welfare

Chemical restraint:
- Dexmedetomidine + ketamine squirted into mouth followed by IM opioid
- OR IM combinations (e.g., ketamine + BZD, or alpha-2 + ketamine) followed by opioid when sedated

+/- Physical Restraint

Tests:
- Tail radiograph
- Snap tests for FIV/FeLV

Question 2

Beginners Luck is a 500Kg thoroughbred stallion with a penetrating wound (nail) in the sole of the foot. You want to do a series of foot radiographs. The horse is a fidget and not very cooperative.
The quality of the radiographs is good, but you are unsure about the draining sinus track and penetration of structures in the foot, so decide to do a standing MRI later that day when the scanner is free.

What considerations are there for the procedure?
How would you sedate the horse?

Answer 2

Considerations:
- more anaesthesia required due to duration of surgery and need for foot to remain still in MRI machine
- Remove shoes
- Need supervision during MRI
- neck/nose twitch to allow administration of sedation
- dark, quiet room

Sedation:
- alpha-2-agonist + opioid
- possible alpha-2 agonists = xylazine, detomidine and romifidine
- Acepromazine beforehand due to fidgeting

Question 3

Describe the sedation and monitoring of an ASA 4/5 patient

Answer 3

Run bloods prior to anaesthesia if possible

No alpha-2s
Opioid may be sufficient alone e.g., methadone or butorphanol
Can use alfaxalone and opioid, potentially BZD if necessary

Use PIVA to reduce induction agent

IVFT, no NSAIDs, low dose induction agent, care with not giving too much volatile agent (exacerbates the compromise)

Question 4

Its 9.15 and Gerald a 3 YO Cockerpoo has just come in and covered the waiting room in blood. His owner slammed Gerald’s tail in the door by accident 30 min ago. Nobody can get near Gerald’s tail but as he’s waving it around and wagging it’s getting blood on EVERYTHING. Reception are getting twitchy already. Gerald only wants to lick you enthusiastically while wagging++++. One of reception are managing to hold a towel on with some pressure while you sort out sedation, he weighs 14.5kg and ate breakfast at 8am.

How would you sedate him?

Gerald is barely responding after sedation and lies v still for his Xray. His gums are pale.

Why are his gums pale?

Answer 4

Alpha 2 agonists would probably be needed + opioid for pain
Acepromazine may not give adequate sedation (too hyper)
Gerald needs an opioid (suggest methadone – good analgesia, and will help with sedation)
Vomiting is a risk so soon after a meal
Vomiting after sedation is preferable to at induction, or regurgitation, so tolerate it and try and keep the mouth clean so it isnt inhaled

Pale gums:
- alpha-2-agonists causing vasodilation and AV block
- can use atipamezole to reverse if worried