Module 8: Pain, anesthesia, surgery and euthanasia

Question 1

Give examples of behavioural changes and other signs of discomfort, pain, suffering, or distress in a rat or a mouse, as well as signs of positive well-being and principles of how pain, suffering and distress can be managed.

Answer 1

Discomfort, pain, suffering & distress:
- decreased activity
- no natural behavior (grooming, nesting)
- weight changes
- isolation
- aggression
- stereotypic behaviors
- hunched posture
- piloerection (raised fur)

Management:
- analgesia
- regular monitoring
- environmental enrichment
- humane endpoints
- gentle handling
- comfortable housing
- good nutrition, …

Signs of positive well-being
- nesting
- bedding
- explorative
- social
- stable weight
- no urination problems

Question 2

Describe what a humane endpoint is. Identify criteria to be used to set humane endpoints. Define action to be taken when a humane endpoint is reached and consider possible options for refining methods to finish at an earlier endpoint. Discuss also factors to be considered and methods available for assessing and recording the welfare of animals e.g. score sheets.

Answer 2

• human endpoint = predefined criterion that signals to end an animal’s participation in
  a study to minimize unnecessary pain, suffering, or distress.
  Criteria for Setting Humane Endpoints
  o Changes in behavior: decreased activity, withdrawal, or stereotactic behavior
  o observable changes such as weight loss, hunched posture, porphyrin staining,
  o body temperature, heart rate, and respiratory rate.
  o lack of response to analgesics, antibiotics, or other treatments
• Actions to be Taken at a humane endpoint = euthanasia or recovery period
• refining methods to reach an earlier endpoint
  o Increase frequency observations to detect early signs of distress
  o use non-invasive techniques
  o Use standardized body condition scoring systems to monitor physical health
  and identify when an animal’s condition is declining
  o Employ validated pain scoring systems to evaluate and quantify pain levels,
  enabling earlier decisions to alleviate suffering.
  o Provide environmental enrichment to reduce stress & improve well-being
  o minimize stressors
  o use well trained staff
  o Conduct pilot studies to identify potential issues & humane endpoints
• Methods for assessing and recording welfare = Score Sheets
  systematically record observations
  o include: Behavioral indicators (e.g., activity levels, grooming), Physical signs
  (e.g., body condition, coat appearance), Clinical symptoms (e.g., signs of pain
  or distress) & Physiological measures (e.g., weight, temperature)

Question 3

Describe the severity classifications included in the Directive and give examples of each category; explain cumulative severity and the effect this may have on the severity classification.

Answer 3

Non-recovery
- procedures which are performed entierly under general anaesthesia from which the animal shall not recover consciousness

Mild
- procedures on animals as a result of which the animals are likely to experience short-term mild pain, suffering or distress, as well as procedures with no significant impairment of the well-being or general condition of the animals

Moderate
- procedures on animals as a result of which the animals are likely to experience short-term moderate pain, suffering or distress, or long-lasting mild pain, suffering or distress as well as procedures that are likely to cause moderate impairment of the well-being or general condition of the animals

Severe
- procedures on animals as a result of which the animals are likely to experience severe pain, suffering or distress, or long lasting moderate pain, suffering or distress as well as procedures, that are likely to cause severe impairment of the well-being or general condition of the animal

Question 4

Describe the principles of humane killing (euthanasia) and give examples of different methods by which animals are allowed to be killed. In addition, explain why someone competent to kill animals should be available at all times.

Answer 4

Euthanasia
- overdose of anaesthetic compund is allowed in all species (shall, where appropriate, be used with prior sedation)

Rodents:
- CO2: gradual fill (to avoid stress), cheap, quick and easy
- cervical dislocation: only rodents under 1 kg, and rodents above 150 g needs to be sedated, dies from rupture to the brain stem and the carotid arteries
- concussion: under 1 kg
- decapitation: only if other methods are not possible
- inert gases, e.g., N2

Always confirm death by one of the following:
1) confirmation of permanent cessation of the circulation
2) destruction of the brain
3) dislocation of the leck
4) exsanguination
5) confirmation of the onset of rigor mortis

It is crucial to always have someone competent in euthanasia available:
o In emergencies immediate euthanasia is necessary to prevent suffering
o Ensuring that euthanasia is performed correctly
o provide training & supervision

Question 5

Define sedation, local and general anaesthesia. Explain the triad of anaesthesia and the term balanced anaesthesia, and give examples of how to achieve this.

Answer 5

local: block certain nerves in a small area

general: the animal is unconsious
- purpose: to bring the animal in a state where you can perform a surgical or other procedures without the animal suffering
- it has to be reversible and controlable

The anaesthetic triad:
- loss of consciousness
- no feeling of pain (analgesia)
- muscle relaxation

Balanced anasthesia:
- using a mix of anaesthetics instead of one
- reduces the side effects of each drug, as a smaller amount is issued
- disadvantage: the different side effects of each can interfere with the research protocol
- the strategy most often used

Sedation: state of calm or sleepiness induced by drugs, where the animal remains conscious but with reduced anxiety and responsiveness

Question 6

Discuss the preanaesthetic considerations necessary for a successful anaesthetic procedure, including evaluation of the animal, as well as selection of agents.

Answer 6

Evaluation of the animal:
- animals should be clinically healthy
- animals should not carry hidden infections
- animals should be acclimated to the experimental facility
–> reuces mortality
–> faster recovery of the animals
–> less variation in experimental results
–> all in all, better research quality

Clinical examination:
- discharge from eyes or nose
- matting fur
- hygeine: soiling of perianal ragion with feaces
- monitoring food and water intake as well as body weight change pre- and post-operatively

Practical considerations:
- assistance needed
- fasting - purpose: specific experimental purposes, prevent risk of suffocating, body function not busy with digestion, prevent vomiting - drawbacks: stressful, weakening, harmful for digestive function for some species) - rodents: no fasting as they cannot vomit

Pre-anaesthetic medication
- reduces fear and stress
- provides smoother induction and recovery of anaesthesia
- reduces the amount of other anaesthetic agents required, the volume of salivary and bronchial secretions and blocks the vaso-vagal reflex
- often used in larger animals

Choise of anaesthesia:
- objective of the experiment
- the surgical procedure
- the estimated time of surgery
- loss of animals can be accepted, if a specific anaesthesia is needed for the specific study
One or more?:
- advantage of using multiple: reduces the side effects of each one (balanced)

Monitoring and plan of action

Analgesia: pre-emptive, intra- or postoperative

Postoperative supervision and treatment

Question 7

Discuss relevant maintenance of anaesthesia, and how to monitor the anaesthetic level. Describe what problems that might arise during anaesthesia and discuss what actions to be taken to prevent or counteract these.

Answer 7

Monitor:
- absence of reflexes:
Righting reflex:
- Animal turns back on feet if it is on its back
Withdrawal reflex:
- are there any nociceptive response?
- pinch between toes (in rodents)

• circulatory functions
• respiratory functions
• body temp
• in short and low-risk procedures, monitoring can be non-electronic

What can go wrong:
Insufficient anaesthesia:
- animal responds to noxious stim
- animal is moving
–> provide more anaesthesia

Too much/long lasting anaesthesia:
- poor respiration
- poor circulation/oxygenation
–> reduce anaesthetic
–> provide O2
–> provide heat
–> provide fluid

Question 8

Describe and discuss methods of optimising post anaesthetic recovery to ensure a smooth and rapid recovery from anaesthesia

Answer 8

Problems:fixing
- pain: provide analgesia
- dehydration: fluid therapy
- hypothermia: heating blankets, infraret heating (very important, as the animal cannot regulate body heat properly until fully recovered)
- infections: asepsis, observe wound healing, provide antibiotics if necessary
- restlessness and self injury (can be caused by pain or severe distress): consult vet, use sedatives/analgesic

Special needs (rodents):
- seperate recovery area
- incubator/warmed cage (higher temp than normally)
- bedding should be soft and comfy
- avoid unnecessary human contact

Question 9

Describe and discuss good working practices with regard to use, storage and disposal of anaesthetic and analgesic agents.

Answer 9

Anaesthetic gases:
- ensure adequate ventilation to scavenge waste gases
- handle equipment correctly

Gas cylinders:
- risk of explotion in case of fire
- heavy, keep properly attached

Needles:
- careful handling
- disposal designated waste containers

Drugs:
- store in locked cupboards
- keep record of purchases and usage
- destroy non-used drugs according to legislation