Health monitoring

The text on this page is taken from an informal compilation of opinions of contributors to the online VOLE List. As such, they are not peer reviewed and may contain differences of opinion. Those wishing to contact the list may contact Adrian Smith.

I am a part time NVS for a toxicology CRO. I have been asked to  oversee the introduction of health monitoring schemes for rats mice and rabbits. They are housed in separate units with several rooms per unit all with open top cages. Before my time they had sentinel animals which were used for monitoring but these were stopped because I believe it was felt nothing was ever found on them.

I have read the paper from FELASA giving guidelines on the tests that can be done. However, a lot of the studies performed are short term studies and I am struggling to work out how best to apply these guidelines in a way that gives meaningful and helpful data.

I was a full-time NVS for a large part of my career at a UK toxicology CRO that was part of an international corporate with multiple labs around the world.

(1) The fact that nothing was found is exactly what sentinels are for. It provides assurance to your sponsors that your studies have not impacted by sub-clinical infections. Without the sentinel data how would you ever know (particularly relevant if studies produce "odd" results). It’s when the sentinels show something that the proverbial hits the fan.

(2) Depending on your circumstances, any sponsors' QA and veterinary audits might expect it, as might external accreditation schemes such as AAALAC, unless you can justify why it would not be meaningful in your situation.

(3) You are quite right to ponder over meaningful and helpful implementation in your specific situation, particularly with short term studies. FELASA guidelines are primary aimed at breeders, though many users use them as guidance, not necessarily with much thought.

The bottom line is - which agents are potential risks to your work, and this depends on their prevalence (general data is published) and their potential impact on your scientific endpoints in your timeframes (again this information is generally available). You should check, but commercial breeders will exclude nearly all agents with any potential worries, including the FELASA list, and will provide you with reports for each batch of animals ordered.

So the principal points to consider may be (1) what do you mean by short term (2) how does this relate to possible exposure and subsequent possible scientific impact.

One option if you have a lot of short term animals would be to perform periodic new arrival screens (serology and/or faecal PCR) as a confirmatory check on the breeders' reports.  A second option is to have open cage sentinels (with soiled bedding and used water bottles transferred from the short term animals) in the unit for 3-6 months to identify any agents that may be circulating within the facility (a good way of identifying wild rodent ingress).

It is also possible to use PCR on IVC/room filters but the sensitivity may be a bit lower than the animal-specific tests.

One other thing is that sometimes a critical model will change/stop working and you never get to the bottom of it with traditional health monitoring.  With advances in bioinformatics likely over the coming years routine screening of the microbiota is likely to have an increasing prominence in this scenario.

In the CRO situation there is no "right" answer - just options for a discussion with your facility as to what level of quality assurance they and their clients are comfortable with.

This resource from the NA3RsC may be of interest.