There is a concern that moving from a soiled bedding sentinel program to environmental health monitoring (EHM) is going to be more costly. There are especially concerns of increased costs from PCR testing versus serology and when new equipment needs to be purchased to support EHM. However, the cost savings related to no longer using sentinel animals (purchase of animals, husbandry and maintenance and sampling), may balance the increased costs associated with EHM methods. In fact, several institutions have found that switching to EHM does not result in an overall increase in costs and may even save money as shown in formal cost analysis and reported in EHM papers (Luchins, 2020; Mailhot 2020; O’Conell 2021; Pettan-Brewer 2020).
University of Chicago conducted and published a detailed cost analysis when making the switch to exhaust dust testing (Luchins 2020). This institution found that EHM was 26% less expensive than SBS. Cost savings came from:
Below is their comparison of the total annual costs of EHM versus SBS.
Additionally, they found that moving to EHM reduced the amount of time the veterinary technician spent on the health monitoring program. For every veterinary technician, this amounted to ~1.5 hours each week per 10,000 rodent cages. This extra time would be greatly appreciated in any animal care and use program.
Cost savings or break-even points have also been found at University of Colorado Anschutz Medical Campus and University of Washington
Since that paper, University of Chicago has also switched their static cages over to sentinel-free soiled bedding (SFSB) sampling. Although this was a much smaller program, a cost analysis found that EHM was still 7% less expensive than SBS.
There are a number of factors to consider in your own cost analysis. We’ve created a downloadable spreadsheet to make calculations easier for you. Click here to access.
In any cost analysis we recommend the below factors as a starting place:
For diagnostic testing for EDT, if you have double-sided racks, you can conduct half as many diagnostic tests than with SBS. This is due to the fact that you typically have one sentinel mouse per rack side, but only one media for EDT.
Additional costs that may be difficult to calculate can also be related to veterinary care for sentinel mice.