Author of the article “Social-housing and use of Double-Decker cages in rat telemetry studies”, recently published on the prestigious Journal of Pharmacological and Toxicological Methods.
I have read your interesting article titled “Social housing and use of double-decker cages in rat telemetry studies”, recently published on the prestigious Journal of Pharmacological and Toxicological Methods. Firstly, on behalf of the whole Tecniplast Group, let me make our compliments to you for the interesting discussion and clear conclusions. Can you summarize for your readers the objective of the study and conclusions vs expected results?
My interest in double decker caging arose when I started working at a new establishment (laboratories of the University of Nottingham) where double decker IVCs were in use. I had used only single storey cages previously. I was immediately impressed with the DD cages and the enhanced space that they offered the animals and I thought the rats looked very content when group housed within them. We wanted to investigate if these cages would be compatible with telemetry recording which is a procedure we conduct routinely within Vivonics for preclinical safety assessment. Firstly, we wanted to determine if telemetry recordings could be reliably made from these cages without too much telemetry signal drop-out. Secondly, we had to investigate whether the use of DD cages had any effect on the power of detection of drug-induced changes in blood pressure or heart rate. Since we were in the business of detecting potential adverse effects of new medicines, we didn’t want to make any change that was going to reduce our assay sensitivity. We compared the effects of a reference cardivascular drug in the same animals housed in single storey and also DD cages.
How important was the Double Decker cage for collecting the information to reach the study objective?
By using multiple telemetry receivers around each DD cage, we were able to make good recordings, actually with less signal drop-out than our single storey cage arrangement. Given that the animals may be more active in the DD cages we thought that this may introduce more variability in the telemetry data and affect the power of detection. However, detection of drug-induced effects appeared to be very similar to standard single storey caging. Put simply, use of DD cages is compatible with telemetry and doesn’t appear to compromise the detection of drug-induced cardiovascular effects.
Can we summarize that the one of the most important benefits in using the Double Decker cage is the improvement of animals’ welfare level?
We didn’t include any measures in our study to directly assess the animals’ welfare; however, the use of double decker caging has been shown by others to improve wellbeing and to induce a positive affective state.
How important is the full upright posture known to be an integral and important part of a rat's welfare? Is it an easy posture in Double Decker cage?
A paper published recently (Makowska & Weary) suggests that full upright posture is an integral and important part of a rat's welfare. Although we could measure activity levels via telemetry, we could not quantify time spent in an upright position. However, working with the animals in these DD cages it is clear that upright posture is very easy and they do spend significant amounts of time, when active, in a fully upright position which cannot be achieved in the standard single storey cage.
Do you think that socially house telemetered rats on recording days will become the standard within the industry and academia worldwide because of this added value in terms of refinement? Do you think that it will help to standardize and reproduce data in the research?
Rats are gregarious animals and social housing is a recognised best practice. All the experiments in our paper were made with animals socially housed (in either single storey or DD cages) . The results of our survey showed that whilst most researchers socially house during non-recording days, only half of respondents socially house rats during the telemetry recordings.
There are several reasons why researchers may choose to singly house telemetry animals which may include cross talk of telemetry signals or cross contamination (of test item) between animals. Recent advances in telemetry technology may address this first issue and may indeed make social housing on recording days become standard practice. Preliminary data from our study shows that social housing has no adverse impact on data variability and the detection on drug induced effects.
Would you suggest the Double Decker cage? Can you give our readers 3 main reasons to adopt Double Decker cages after your experience with this nice study?
Yes I would recommend the DD IVC cages to other researchers. They enable social housing of rats in a generous amount of space, offer an enhanced multilevel environment and also the ability to adopt fully upright posture.
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Leopoldo Zauner – Marketing Director