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NC3Rs | 20 Years: Pioneering Better Science
Office-led project

Replacing sentinel animals with environmental health monitoring

A mouse looks out of a nest

At a glance

In progress
Current contacts
  • Dr Khia Dobbinson


  • Replacement


Monitoring rodent research colonies for pathogens and parasites is important for animal welfare and conducting high quality science. Traditionally, sentinel animals are maintained within the colony and culled for health surveillance purposes.

Technological advances mean molecular analysis of environmental samples (e.g. dust debris and soiled bedding) can replace the use of sentinel animals. We feature some of the individuals driving this change at the Universities of Chicago and University of Southern California.

Do you work in a UK institution that has switched to using environmental sampling for colony health surveillance, or are you interested in trialling these methods? We want to hear from you:

An animal technician’s perspective

We featured Chago Bowers (University of Chicago) in Tech3Rs, our newsletter for animal technicians, where he spoke to us about replacing 1,676 sentinel mice annually by switching to exhaust air duct sampling.

Read the interview and publication from Chago and colleagues at the University of Chicago in Issue 14 of Tech3Rs (PDF, 3.2MB).

Chago Bowers in a mask, scrubs and gloves checks an air duct. The picture is to the right of a quote from Chago stating "Collecting exhaust air dust samples has been such a refreshing change and the switch has improved the quality of my work life.


A veterinarian’s perspective - audio interview

We spoke to Dr Lynlee Stevey-Rindenow DVM (University of Southern California) about making the switch to environmental monitoring for colony health surveillance. Lynlee shared that approximately 5,600 mice and rats per year have been replaced, in addition to estimated savings of $30k in resources and 1,290 hours of staff time. She also highlighted the emotional cost to staff who have to cull healthy sentinel animals cannot be fully quantified.

Listen to what Lynlee had to say about replacing live sentinels with environmental sampling methods. Key questions that make up the interview have been highlighted below.

Interview question breakdown


What have you done to reduce animal use with environmental health monitoring?

What were the cost and time implications of switching to using environmental health monitoring in place of live animal sentinels?

What does this change mean to you as a veterinarian?

Have you faced any push back on this approach? What advice do you have for people who might face push back?

How did you approach the practical aspects of making this change with your team?

3RsC rodent health monitoring resource

The 3Rs Collaborative (3RsC) have produced a rodent health monitoring resource covering the evidence base, practical considerations, including cost analysis, and guidance on how to make the switch: Health Monitoring Resources - 3RsC (

Dr Kerith Luchins, DVM, DACLAM (The University of Chicago) and Dr Megan LaFollette, PhD (3RsC) presented the practicalities of implementing environmental monitoring for both rack-level filtration systems and cage-level options at a joint webinar hosted by NC3Rs and 3RsC.