General context
Any medical drug to be marketed will need to prove efficacy but also safety. Therefore, even compounds intended for use in very different areas
Day 0 1 2 3 4
Appearance
Body weight (g) (score) 340 (1) 305 (3) 320 (2) 323 (2) 335 (1)
Coat unkempt/piloerection 1 1 1 1 1
Behaviours
Gait 3 3 3 3 3
Response to handling 0 0 2 0 0
Total clinical score 4 7 8 5 5
Total neurological score 15 14 14 10 10
Lesion volume (MRI assessment)* 7%
Other observations Recovered
uneventfully from surgery
Moving around incubator (with severe controlateral deficit)
Attempt to reach food with ipsilateral hand
*‘Lesion volume’ (assessed using MRI) is included for the investigator to fill in at the end of the study. This data can then be correlated with clinical and behavioural observations to enable further refinement of monitoring, animal care and procedures.
(e.g. neuropharmacology) will have to be evaluated for their potential cardiovascular effects.
Cardiovascular effects of compounds can be tested in a variety of ways: in invasive terminal procedures on anesthetised animals, in animals which are momentarily restrained and externally equipped with monitoring devices or in freely moving animals previously implanted with monitoring devices (telemetry systems).
Over the past decades, telemetry systems have been increasingly applied in drug research and development for measurement of physiological and bioelectrical vari-ables (e.g. blood pressure, heart rate, ECG).1 The absence of tethering, handling and restraint during measurement provides a unique opportunity to study laboratory animals without additional stress or physio-logical disturbance (anaesthesia) during a longer period of time. In between measurements, animals can more-over be group-housed.
Telemetry can also enable reduction in animal num-bers. Firstly, because telemetry systems are stable for months (and possibly even years), animals can be used as their own controls, reducing data variability and consequently the number of animals needed per treat-ment group. Secondly, telemetry provides an ability to continuously record a number of variables so that there is a significant increase in the amount of data that can be obtained from a given number of animals, compared to the use of conventional methods. Thirdly, in the absence of potential stressors, such as restraint or exter-nalised catheters, the quality of data obtained is improved. Telemetry systems can also provide indica-tors of animal wellbeing to help implement earlier, more humane end-points.2 Telemetry thus is widely regarded as benefiting science while minimising impact on animal welfare. However, the requirement for appropriate surgical training should not be under-estimated, as this has a direct impact upon animal wel-fare. A sound basic and advance training in experimental surgery and good working knowledge of the devices are absolutely essential before progressing into implant insertion
Illustrative procedure
Study design. In this example, three pre-selected male beagle dogs (suitable temperament) will be used.
Animals will act as their own control.
After overnight fasting, animals will be anesthetised.
Telemetry devices allowing for continuous measurement of body temperature and cardiovascular parameters (ECG, blood pressure) will be surgically implanted. The implantation of these telemetric devices is a surgical pro-cedure not invading body cavities, as the emitter is not implanted intraperitoneally, but in an inter-muscular pouch. The catheter is inserted in the femoral artery and further advanced into the aorta. ECG electrodes are tunnelled subcutaneously. The discomfort provoked is linked to the implantation and the surgical wounds created, and the animals’ need to be anaesthetised.
During the 3 week recovery period, animals will be trained to be socially isolated for 2 h (e.g. telemetric recording).
After recovery, the procedure calls for continued use: animals will be used weekly (one day with vehicle, and another with compound) to evaluate cardiovascu-lar effects of the novel therapeutic agent at two different dose levels. The first treatment will consist of vehicle administration, followed by administration of the novel pharmaceutical agent. In-between recordings, animals will be socially housed. A minimal wash-out period will be allowed between test sessions (as determined by PK studies).
The study is intended to assess the potential cardio-vascular effects of novel agents at proposed thera-peutics doses.
At the end of the experiment, animals will be socially housed, while awaiting possible re-use.
Consideration of specific refinements and humane end-points.
Initial prospective assessment. The procedure is clas-sified as MODERATE as it requires anaesthesia and surgical intervention.
What does this study involve doing to the animals?
What will the animals experience? How much suffering might it cause?
What might make it worse Adverse effects
How will suffering be reduced to a minimum
Methodology and
interven-tions to minimise severity End-points Pre-surgical
prepar-ation of the animal
Single housing prior to surgery
Food withdrawal overnight prior to surgery
NA
Surgical implantation of telemetry devices
Possible pain and discom-fort
Appropriate perioperative care: appropriate
Decision to humanely kill the animal during surgery if
(continued)
The administration of the compound is expected to have no clinical effect on the animal. However, admin-istration of the compound is MILD, as it involves injec-tion according to Good Veterinary Practice.
Could the severity classification be MILD?
No: the procedure involves anaesthesia and surgery;
thus classification is MODERATE.
In the case of re-use of previously implanted animals that have been used in another project, the simple administration and evaluation through the use of tel-emetry of test compounds at therapeutic dose levels, and as no restraint is involved (freely moving) the pro-spective severity is to be classified as MILD
Could the severity classification be SEVERE?
Yes, if the compound tested at doses administered would have toxic effects (cardiovascular or other). This would def-initely mean that the flow chart of testing is not accurate, as a model of telemetry is definitely not intended to evaluate
toxic doses, but rather clinical/therapeutic doses of com-pounds. The study design would need to be reviewed.
Clinical observation/scoring system. Animals are carefully monitored at every step of the procedure. A specific anaesthesia sheet, as well as a clinical observa-tion sheet, are developed, and included at the end of this example. During techniques, any clinical observa-tion is recorded daily. During the wash-out periods, animals are observed and weighed at least weekly.
Results and assessment of actual severity. Three dogs underwent the procedure. All recovered from sur-gery without any complication, no cardiovascular side-effects were observed in any of the animals at any of the doses tested.
The three animals were considered to have experi-enced MODERATE severity.
Continued
What does this study involve doing to the animals?
What will the animals experience? How much suffering might it cause?
What might make it worse Adverse effects
How will suffering be reduced to a minimum
Methodology and
interven-tions to minimise severity End-points Potential adverse effects
of anaesthesia and sur-gery (hypothermia, dehydration, distress on recovery
anaesthesia and anal-gesia, etc.
Non-pharmacological con-trol of pain and distress:
aseptic technique, heat-ing,
well-trained personnel, optimised surgical
procedure
unacceptable complications arise and persist
Period of recovery (3 weeks), including training
Possible pain, infection, discomfort
Post-operative complica-tions
Single housing during post-operative period (24 h) and training (2 h a day)
Adequate post-operative care (analgesics, anti-biotics) as needed Daily observation and
wound care
Any animal with clinical signs of infection will be examined, treated and temporarily excluded from the study
Administration of test compound (i.v., s.c., i.p., p.o.) before rec-ording parameters
Possibly transient discom-fort following adminis-tration of compound Potential
compound-related unexpected side effects
Animals are individually housed for short-term periods (determined by the pharmacokinetics of the drug).
Blood pressure, ECG and body temperature are continuously monitored in freely moving animal, housed in pen equipped with telemetry receiver.
Between studies animals are group housed and observed daily, Body weight is recorded
weekly.
In case of prolonged side effects after test compound treat-ment: possibly treat and allow animal longer wash-out period and clinical check-up before new dosing and deci-sion on possible euthanasia.
End of battery life: animal is either proposed for re-use as blood donor, or if competent authorities authorise, explanted and depending on vet examination proposed for rehoming or proposed for re-use as blood donor.
At the end of the procedure the animals were again socially housed. The level of severity was MODERATE, due to the surgical implantation ani-mals underwent, but the general state of health has been fully restored. No cumulative severity was observed due to administration of the novel therapeutic agent under evaluation. Therefore it is considered that
animals may be re-used in future MILD, MODERATE or Non-recovery procedures pending an appropriate wash-out period and after positive veterinary advice.
Example clinical observation/scoring sheets
Food
aspect Other Analgesic Antibiotics Wound care Other drug D-1
*: Administer analgEsics and antibiotics according to procedure In case of abnormalities detected, contact the veterinarian
Date
Observations and other actions Visa Batch n° of telemetry device
Post-op follow-up sheet Micro-chip: Dog n°:
Date Time Fasting Isolation Admin. of compound (dose, route)
Observe Salivation, Myosis, Mydriasis, Defaecation, Miction, Posture of animal, Sedation, Locomotor activity, Rigidity, Vocalisation, etc.
Describe any unexpected abnormalities and contact the Veterinarian Also note time quantity and containers of blood samples obtained
g
Start/end of
telemetric recordings Behavioural observations Other acons Batch n° of telemetry device
Study follow-up sheet Micro-chip: Dog n°:
Dog Name:
Researcher:
Batch: Date surgery:
References
1. Morton DB, Hawkins P, Bevan R, et al. Refinements in telemetry procedures: seventh report of the BVA(AWF)/
FRAME/RSPCA/UFAW Joint Working Party on Refinement, Part A.Lab Anim2003; 37: 261–299.
2. Hawkins P, Morton DB, Bevan R, et al. Husbandry refinements for rats, mice, dogs and non-human pri-mates used in telemetry procedures: seventh report of the BVA(AWF)/FRAME/RSPCA/UFAW Joint Working Party on Refinement, Part B. Lab Anim2004;
38: 1–10.