What does this mean in practice?
Balanced anaesthesia must be used and appropriately monitored to ensure the animal remains at a sufficient depth of anaesthesia and is not aware of pain during invasive procedures.
A key part of this is understanding that anaesthetic responses vary between species, so you must know how to assess anaesthetic depth in the species you are working with. For example, this may include checking pedal reflexes in mice or pupil responses to light in larger animals.
Anaesthesia should be applied with guidance from Veterinary staff and in line with good veterinary practice, provided this does not interfere with the scientific outcomes of the study.
You should also regularly consider opportunities for refinement during the induction, maintenance, and monitoring stages of anaesthesia. This applies to both recovery and non-recovery procedures.
How do I comply with PIL Standard Condition 10?
You should develop a robust anaesthetic plan in consultation with the Veterinary team. This plan should consider both the needs of the species and the requirements of the experimental procedure being performed.
Clear monitoring procedures must be in place to ensure an appropriate depth of anaesthesia is maintained throughout the procedure. Monitoring should be carried out by a competent individual who understands animal anaesthesia, can recognise signs of recovery, and is able to make appropriate adjustments where required.
This applies not only to recovery procedures, but also to longer non-recovery procedures.
At Newcastle University, Veterinary guidance would generally expect formal anaesthetic monitoring for procedures lasting longer than 15 minutes. For shorter procedures, such as intramuscular (IM) injections in mice or cardiac puncture in rats, a more basic assessment of anaesthetic depth may be appropriate. This could include checking pedal reflexes before starting the procedure and reassessing the animal if any signs of recovery are observed during the procedure.
Even during short procedures, you should maintain concise anaesthetic records. These records demonstrate that anaesthetic depth was assessed appropriately and provide important evidence if concerns or incidents need to be reported to ASRU.
Records may include:
- Time of induction
- Start time of the procedure
- Monitoring observations during the procedure
- Any adjustments made to anaesthesia
- Recovery time or confirmation of death in non-recovery procedures
Maintaining clear records demonstrates good practice and supports both animal welfare and regulatory compliance.
What resources are available to support me?
There are a range of people and resources within the establishment available to support you in meeting this Standard Condition, and you are expected to use them where appropriate.
- The Named Veterinary Surgeon (NVS) is a key source of guidance when developing and applying anaesthetic protocols. They can advise on appropriate induction, maintenance, recovery, and the use of balanced anaesthesia tailored to both the species and the procedure being performed. The Veterinary team at Newcastle University for example has developed standard anaesthetic monitoring sheets for a variety of species.
- The Named Animal Care and Welfare Officer (NACWO) can support you with the practical aspects of monitoring animals under anaesthesia, recognising signs of appropriate anaesthetic depth or recovery, and identifying welfare concerns.
- The Named Training and Competency Officer (NTCO) is responsible for ensuring that you are appropriately trained and competent in anaesthetic techniques. They can also arrange additional support or refresher training where required.
- The Project Licence Holder (PPLh) is another important source of guidance, particularly regarding protocol-specific requirements or scientific constraints associated with anaesthesia.
In addition to named persons, local Standard Operating Procedures (SOPs) and Experimental Plans provide essential guidance on approved anaesthetic regimens, monitoring expectations, and intervention points. These documents help ensure consistency, animal welfare, and regulatory compliance.
If at any stage you are unsure about anaesthetic depth, monitoring, or the suitability of an anaesthetic approach, you should pause and seek advice before continuing rather than proceeding with uncertainty.
What happens if I don’t comply with PIL Standard Condition 10?
In practice, common failures include:
- Inadequate monitoring of anaesthetic depth
- Failure to recognise signs of light anaesthesia or recovery
- Failure to adjust anaesthetic levels during longer procedures
- Relying on a fixed dose of anaesthetic without ongoing assessment
Even brief periods of inadequate anaesthesia are treated seriously by both ASRU and the establishment, as animals are expected to be fully protected from pain throughout the procedure.
If an animal begins to recover during a procedure that requires a maintained surgical plane of anaesthesia, it may experience pain, distress, or trauma. This would likely be reportable to ASRU as a breach of Project Licence Standard Condition 18, relating to failure to comply with the controls and limitations of the licence.
Most procedures carried out under anaesthesia are expected to result in minimal adverse effects when appropriately managed in line with good veterinary practice. Failure to maintain appropriate anaesthetic depth suggests that these controls were not adequately applied.
Consequences may include:
- Retraining in anaesthesia and monitoring
- Reassessment of competency
- Increased supervision during future procedures
- Reflective review or formal documentation relating to the incident
These actions are intended to ensure future procedures are carried out safely, competently, and with appropriate protection of animal welfare.
How does ASRU assess compliance with PIL Standard Condition 10?
ASRU assesses compliance with PIL Standard Condition 10 by reviewing whether anaesthesia is applied and monitored appropriately to ensure animals are protected from pain throughout regulated procedures.
During an inspection, ASRU may review Standard Operating Procedures (SOPs), anaesthetic records, monitoring sheets, training materials, and competency assessments relating to the use of anaesthesia and anaesthetic monitoring.
Inspectors may also speak directly with the PEL holder, PPL holder, Named Veterinary Surgeon (NVS), NACWO, animal care staff, and PIL holders to confirm understanding of anaesthetic depth, monitoring requirements, and appropriate responses to signs of recovery or light anaesthesia.
Compliance may also be assessed through direct observation of procedures involving anaesthesia to ensure animals are monitored appropriately, anaesthetic depth is maintained throughout the procedure, and any adjustments are made promptly where required.
How do I know if I am complying with PIL Standard Condition 10?
You can be confident that you are fulfilling this Standard Condition if you are actively managing and assessing anaesthesia throughout the procedure.
This means that an appropriate anaesthetic plan has been developed with input from the Veterinary team, taking into account the species, the nature and duration of the procedure, and whether the animal is expected to recover.
You, or another competent individual, should consistently monitor the animal using appropriate indicators of anaesthetic depth, such as reflex responses, breathing patterns, muscle tone, and species-specific signs. You should understand what is considered normal for the species you are working with and be able to recognise changes that suggest the animal is becoming too lightly or too deeply anaesthetised.
Importantly, you must be able to respond appropriately to these changes, either by adjusting the anaesthetic or seeking support where necessary. Your decisions should be based on an ongoing assessment of the animal rather than assumption, habit, or routine practice.
You should remain engaged with monitoring for the full duration of anaesthesia, including during long-term or non-recovery procedures.
You should also be able to clearly explain:
- How you determine that the animal is at an appropriate depth of anaesthesia
- What monitoring methods you are using
- What actions you would take if the anaesthetic depth changed