Pain, anesthesia, surgery and euthanasia Flashcards
Examples of behavioral changes and other signs of discomfort, pain, suffering, or distress in a rat or a mouse
- Face: Grimace expression (whiskers back, eyes closed, ears flattened back, bulcky nose and flattened cheeks)
- Body posture: Hunched and scruffy
- Lack of activity: No nest building
- Urinating and defecates more (diarrhea)
- Under grooming
- Not active
- Weight loss
- Stereotype behavior including over grooming (cannot cope with the environment)
Examples of signs of positive well-being in a rat or a mouse
How to avoid:
Nest-building
Social activity
Explorative
Grooms itself (good looking fur)
Avoiding pain and distress is essential – gentle handling of the animals, optimal environment, cage mates (single housed mice are stressed), avoid fighting, pain relief if necessary according to the experiment.
Examples on principles of how pain, suffering and distress can be managed
Assessment protocol: Favorable to have as it guides you and the caretakes in what to look for. There should be a specific protocol for that specific experiment and species/strain of animal.
Subjective pain assessment score: pain yes or no: 1-10 points.
Objective pain assessment: echtogram, grimace scale, activity: yes/no, nest-building: yes/no
Optimize the welfare of the animal by optimize the surroundings and gentle handling of the animal included train the animal for the procedures.
What is a humane endpoint?
A humane endpoint is stated within the application for the license. At what point (clinical signs including weight loss) does the animal have to be euthanized - excluded from the experiment? Even though the experiment is not finished yet and you haven’t collected all your needed data (experimental endpoint).
Examples of humane endpoints (mice)
Criteria’s must be relatively objective – so everyone handling the animals assess them evenly, it could be:
- Weight loss (procentage of weight/BCS)
- Heart rate/respiration rate – hard to observe
- Hunched posture and scruffy fur = bad welfare
- No nest building/non-active animals
- Grimace scale (mouse/rat)
- Diarrhea
- Coughing
- Behavior: echtograms
Model specific humane endpoints (tumor/artheritis)
Model specific: tumor size, wounds yes/no, altered gait due to tumor: yes/no
Humane endpoint scoring sheets
You must know the normal behavior, anatomy and physiology of the species as well as signs of pain in the specific species.
If the animals have been genetically modified you must take into consideration that there is a risk that it won’t act like a normal animal.
- General condition (mice): explorative? Nest building? Eating? Drinking? Fur (nice or scruffy)?
- Posture: hunched / abnormal / normal
- Movement: abnormal (paralyzed/hypermetric) / normal
- Weight loss? 5 % might be too much in normal mice, and 20% might be the humane-endpoint for tumor-model mice
Humane endpoints - options for refinement - is it possible to finish at an earlier endpoint?
Refinement: (reduction of stress, fear and distress) if you already know that the drug you are testing will affect the animal in a specific way and that the animal only will get worse over time, then the animal must be euthanized when seeing the first small clinical signs
EU Directive Severity classification: cumulative severity/non-recovery/mild/moderate/severe
The license for the experiment has to describe the severity classification, does the animal suffer, feel pain, distress or lasting harm? Intensity, duration, frequency and multiplicity.
Cumulative severity: a procedure is done over and over – how is the animal affected – it must be assessed worse than if the pocedure was done once; “moderate” to be exposed to pain over and over again despite the fact the pain is considered “mild”.
Non-recovery: procedures under general anesthesia, the animal will not recover consciousness
Mild:
- Short-term mild pain, suffering or distress
- No significant impairment of the well-being or general condition of the animal
- E.g. administration of anesthesia or short term restriction
Moderate:
- Short-term moderate pain, suffering or distress
- Long-lasting mild pain, suffering or distress, or
- Moderate impairment of the wellbeing or general condition
o E.g. Surgery under general anesthesia
Severe:
- Severe pain, suffering or distress or long-lasting moderate pain, suffering or distress
- Servere impairment of the wellbeing or general condition of the animal
o E.g. servere restriction of movement over a prolonged period (the period has to be defined by the competent authority)
Euthanasia - principles
Euthanasia: a good death. No stress or fear and as quick as possible. It must be safe for the person performing it.
The death must be confirmed:
- No circulation of blood/respiration stops
- Destruction of brain
- Dislocation of the neck
- Complete bleed of (exsanguination)
- Rigor mortis/drop of temperature
Euthanasia - legislation EU directive: examples on methods
Cervical dislocation: rodents (rats awake must be <150g)
Carbon dioxide (gradual fill): rodents (adult)
Medical euthanasia (overdose of anaesthesia: Pentobarbital)
Different methods for the different species!
Euthanasia - why must someone competent in killing animals be available at all times?
A person competent in killing animals should always be available as anything can happen and the need for a quick death is needed. No animal should suffer unnecessary according to both EU- and Danish legislation. If the animal gets hurt you need to euthanize it immediately.
Define sedation, local anaesthesia and general anaesthesia
Sedation: depression of CNS - only the consciousness is altered, no pain relief
local anaesthesia: a small area with analgesia - fx nerve block
general anaesthesia: loss of consiousness and feeling no pain, preferred with muscle relaxation
Explain the triad of anaesthesia
- Loss of consciousness
- Analgesia
- Muscle relaxation
Only possible with a combination of drugs = balanced anaesthesia.
Explain balanced anaesthesia
The mixture of drugs providing you with an unconscious animal, that feels no pain and with relaxed muscles throughout the entire procedure. Goes down well and recovers fast is optimal.
Advantage: You need less of each drug used and thereby avoids some of the adverse effects.
The use of multiple drugs:
o pre-operative: sedativa and opiods often used in large animals to reduce stress and fear (not used for rodents – they go down well with only the anasthesia)
o Anaesthesia: inhalation or injection (hard to handle the dept)
o intra-operative analgesia or supplementing anaesthesia
o post-operative: analgesia
Discuss the pre-anaesthetic considerations necessary for a successful anaesthetic procedure:
acclimatization and evaluation of the animal
Acclimatization for 1-2 weeks –> the animal return to normal physiological parameters
Evaluation of the animal: reduce mortality, faster recovery, less variation in results.
Healthy (sick animals have increased risk of dying under anaesthesia).
Known health status (not subclinical ill)
Not stressed?
Fasting? Not in rodents (cannot vomit) – only large animals.
Discuss the pre-anaesthetic considerations necessary for a successful anaesthetic procedure:
Selection of agents (mind the experiment)
The drugs chosen for anesthesia should be something you have experience with, or you colleagues can advise you in. it should be suitable for the species of the animal and the duration of effect must match the procedure – use literature and your experienced colleagues! Remember to use proper analgesia before, under, during and after the procedure being done!
The drugs influence on the parameters you wish to measure should be limited to minimum even if it gives you a less efficient anaesthesia.
The advantage of using pre-anaesthetica? (large animals, not rodents)
Pre-anesthesia is not relevant in rodents but used for large animals – often sedatives to reduce fear and stress. Gives you a smother induction of the anasthesia and reduced the amount of drugs needed.
Monitor anaestetic level: short-term
- Righting reflex
- Withdrawal reflex
- Body temperature
- Respiration
- Heart rate (circulation)
Large animals: palpebral reflex, corneal reflex
The swallowing reflex might be present in well anesthetized animals (50% of rodents.).
Simple monitoring as a pulseoximeter and rectal temperature
Monitor anaesthetic leve: long-term
- Righting reflex
- Withdrawal reflex
- Body temperature
- Respiration
- Heart rate (circulation)
More complicated monitoring – ECG, direct arterial blood pressure (large animals) tidal volume/gas concentration (intubated on a respirator)
Maintenance of anaesthesia: two options incl. advantages and disadvantages
Injection (hard to control the dept of anaesthesia, not as fast as inhalation). Very easy to use, minimum demands for equipment. Cheap!
Inhalation: fast induction and can easily be controlled, recover fast. Need of special equipment and a specific ventilated room (gasses) might need a hand for monitoring the anasthesia
Describe what problems that might arise during anaesthesia and discuss what actions to be taken to prevent or counteract these.
Animal is moving: more anaesthesia/analgesia
Low body temperature: provide heat – heating plate/wrap in bubble plast, heated saline (SC, IV or IP for rodents)
Cyanosis: provide oxygen
Cardiac arrest: stop operating, adrenaline and CPR
Describe and discuss methods of optimising post anaesthetic recovery to ensure a smooth and rapid recovery from anaesthesia.
- Secure maintenance of body temperature - heating pad/SC/IV or IP heated saline fluid.
- Provide sufficient analgesia pre, intra and post anaesthesia.
- Rodents must be touched as little as possible
- Be silent
- Provide rodents with recovery gel or ensure that the water nipples are long enough.
- Provide oxygen as long as possible
Large animals (pigs and dogs) react well with being petted and cared for while recovering – rodents not at all!
Describe and discuss good working practices with regard to use, storage and disposal of anaesthetic and analgesic agents
The drugs must be held in a locked cabinet, you must record the uses of the drug and at any times know how much of the drug is used and how much you have left.
The drug and the syringe/needles used must be disposed according to national legislation if not needed anymore or the date is exceed.
Avoid spilling drugs when handling them – do not injure yourself with needles!
Discuss strategies for successful perioperative pain management, and difficulties that may arise in connection to this
You must ensure that the animal is not suffering – it is only allowed for the animal to feel pain (suffer) when it is approved in the license for the experiment.
Analgesia is most effective if given before the nerves are activated = before the animal feels pain.
You must understand how the analgesia might conflict with the experimental data needed - chose the drug with the best analgesic effect with minimal impairment of your experimental data (literature!).
- Most opioids suppress the immune system - buprenorphine to a lesser extent
- NSAIDs can have an unwanted effect on bone healing – studies are not conclusive
It can be difficult to observe the heart rate and the respiration rate in rodents – but it might be the only indicators of pain. – use clear covers while operating.
The relevance of pre-operative assessment
Assessment: is the animal healthy? No sub-clinical infections (rely on health reports) and proper acclimatized (1-2 weeks for rodents)
Healthy animals = better research quality!
1. reduces mortality during anaesthesia
2. faster recovery
3. less variation in results
Halsteads principles - minimizing trauma and increases healing (good surgical practice)
Halsteds principles:
- Aseptic procedures
- Gentle handling of tissue
- Hemostasis
- Avoid dead space
- Approximation of tissue without tension = correct suture pattern
- Avoid foreign materials
An unexperienced surgeon will cause more damage to the tissue than an experienced surgeon = higher risk of complications. The surgeon must always be prepared and know the procedure!
Instruments must be cleaned and sterilized, keep your dirty instruments separated from the clean instruments.
Good surgical practice including the competences of personnel
Plan the procedure in depth, prepare and train including the assistants.
Work aseptic
Proper assessment of the animal; pre- inter and post surgery.
Know your limits and seek guidance and help from experienced colleagues.
The animal must be induced in a silent, darkened room with a minimum of stress.
The recovery site should be separated from the operation site being darkened, silent and heated (rodent) with appropriate bedding.
The animal must be treated with analgesia, pre-peri- and post surgery. The only time your are not to relive the pain is if the pain is measured for the experimental data collection.
Give examples of commonly used surgical instruments, suture materials and needles and how they are applied
Hemostat – pean – used for hemostasis
Material scissor – used for cutting suture and other materials
Needle holder
Tissue scissor – used for cutting tissue
Scalpel – cutting tissue
Suture material:
- synthetic such as vicryl - non-ansorbable monofilament outside and absorbable polyfilament inside.
Suture pattern: suitable for the tissue and tension
Correct needle: cutting/blunt - curved/straight ect.
Discuss the principles of post-surgical care and monitoring, and describe common post-surgical complications and their causes
The animal recovering from surgery must be relieved from pain (analgesia provided pre-inter and post surgery).
The rodents prefer a silent, warm and darkened place to recover with no human contact (stressful)
The companion animals prefer tender loving care while recovering. In a warm, silent place.
The animal must be closely observed for any signs of pain (grimace scale, body posture, activity, attention to operation wound, water and food intake, urination (dehydration) and defecating). The animal must be supplied with sufficient fluid.
Complications:
- Infections and thereby prolonged recovery are common if not aseptic or an unexperienced surgeon.
- Dehydration – not sufficient supplied with fluid under surgery and not supplied post surgery
- Respiratory depression – anesthesia affects the respiration and the animal is not fully breathing by itself – supply with oxygen or even intubation
- Hypothermia – the temperature must be measured frequently. Adult: 25-30 and neonatal: 35-37 (incubator)
- Eye damage due to wrong bedding (sawdust is bad for the rats eyes and nose) and no eye protection under surgery
