A healthy rodent colony is vital to the scientific integrity of research results, emphasizing the importance of monitoring colonies for pathogens. However, reliably detecting pathogens can be difficult in laboratory animal facilities.
To understand the challenges of colony health surveillance, Andy Dickinson, BSc, MRSB, Health Monitoring and Biospecimen Manager, and Paula Roesch, PhD, Senior Director, Biosecurity, Genetic and Health Monitoring, shared details on how rodent health monitoring has evolved and discussed how Inotiv’s sentinel free filter testing (SiFT) provides researchers with a highly sensitive diagnostic tool.
Understanding the basics of contamination and detection
Pathogens, such as viruses, bacteria and parasites, may be inadvertently introduced to a colony from a variety of sources. These can include feed, water, air, caging materials, or even human contact.
“Traditionally, in facilities with individually ventilated cages (IVCs), it is common to transfer soiled bedding to a cage containing sentinel animals and get a representative sample of a colony’s health status,” explained Andy. “After a set period, the sentinels are sacrificed, and serology, microbiology, and PCR testing are performed.”
Unlike soiled-bedding sentinels, Direct Colony Sampling (DCS) collects data from live animals with an oral swab, a fur swab, a fecal sample, or a dried blood spot. This is considered a non-invasive or minimally invasive collection method and can be useful in detecting emerging pathogens.
“Both soiled-bedding sentinels and DCS face several limitations,” said Paula. “Not all organisms are going to be shed in the bedding or in feces, or they may only shed for a very short window of time, or shed inconsistently. Therefore, the sentinel or representative animal may not pick up the organism, and it can remain undetected.”
The role of sentinel free filter testing
To better capture an accurate snapshot of pathogens and reduce the use of live sentinel animals, filter materials represent an effective and ethical method. Our system at Inotiv places a filter into a sentinel free cage in lieu of a live sentinel animal.
Following protocols that closely mirror those of traditional soiled-bedding sentinels, the filters pick up any contaminants found in fecal or bedding material that the animals may have shed.
“As a nonintrusive methodology, sentinel free filter testing (SiFT) aligns with the 3Rs (Replacement, Reduction, Refinement) by reducing or replacing the use of sentinel animals and also reducing or replacing the procedures required with Direct Colony Sampling,” shared Andy.
The team at Inotiv also found that SiFT improves pathogen detection rates in laboratory mouse colonies compared to conventional sentinel methods. In a case study, they compared methods for detecting 13 pathogens that were known to be present in the facility. Between SiFT, dirty bedding sentinels, and fecal samples, they found that not every pathogen was detected at every time point, but the overall performance of Inotiv’s SiFT demonstrated a ~30% increase in recovery of infectious agents
SiFT as a complementary diagnostic solution
“One of our goals is to help researchers understand why they need to approach environmental health monitoring with multiple test methods to understand the health of their colony,” said Paula. “We found that no single method will capture 100% of the present pathogens 100% of the time. SiFT uses a highly sensitive qPCR technology to detect the presence of pathogens and adds an extra layer of sensitivity to provide more robust and comprehensive colony surveillance.”
Our experienced team is here to help you design a welfare-focused approach to colony health surveillance. Contact us for more details on how to best support your health monitoring program.