"For some inbred mouse strains, housing in IVCs reduced activity and increased anxiety-related behaviour. To improve visibility, the food hopper can be moved to the rear of the cage... Care must be taken that the noise and vibration of air handling units is not transferred to the cages. This should include any frequencies beyond the normal human range. Noise level considerations should also extend to the cabinet where cage changes or procedures may be conducted...
Reduced frequency of cleaning may mean that welfare problems may go unnoticed unless a strict discipline of observation by animal care staff is enforced. This practice may also require the use of large food hoppers and drinking bottles that may intrude upon and reduce the amount of three-dimensional cage space available to the occupants."
UFAW (2010, p. 152).

IVC_Back_1

"Before animal research facilities began using individually ventilated cage (IVC) systems for mice, cages were often changed one or more times per week. When using IVC systems, however, it is standard practice to change cages only once every 2–3 weeks. When deciding how often to change cages, personnel may consider the cost of labor needed to change the cage, as well as the cage type and bedding type, rather than animal preference or concern for animal well-being.
The authors carried out a simple preference test in groups of mice. Mice were allowed to choose between an unsoiled cage and cages that had not been changed for 1 day, 7 days or 14 days. When evaluating where mice positioned their nests and the amount of time mice spent in the various cages, the authors found that the mice preferred the unsoiled cage."
Godbey et al. (2011, p. 225).

IVC_Back_2

But that aside, yeah, so IVC cages, big change. And the other thing about the IVC cages, it wasn't just a change for the animals, it was a change for the technicians. So instead of going in a room in the morning, because as you're probably aware, mice sort of doze most of the day and they do all their action at night, so you used to come in, in the morning, and there'd be diet all on the floor perhaps or sawdust kicked out, et cetera, et cetera. And the place was fairly…you know, you had to sweep it all up or tidy it all up, or whatever. With IVC cages, the next morning it will be exactly the same within the outer environment in the room than it was when you left it. So that's a different way of working.    And obviously, everything becomes, you know, worried about cross-contamination, the way you clean your animals, you wear gloves all the time. All the things that have come in recently, you need a different mindset. And a lot of animal technicians, especially the older ones, they struggled at first to actually change from what was basically, when I used to look after them, you know, working in a giant pet shop, picking up the rats, doing this, doing that. But then you're working in a change station, you know, a clean hood and doing all sorts of stuff. So the youngsters that come in today or the younger people, they adapt to it a lot easier in many ways than perhaps the older staff. But the older staff have got other techniques and they upskill themselves. And, of course, if they know the importance of keeping the animals clean, they'll work to the new SOPs. 

IVC_Bottom_1

So, you know, it is different. And as I mentioned earlier, the other big change, of course, is with the cage wash and autoclaves, et cetera, the labour saving, not so much saving of time but actually making the job a lot lighter, we are very attractive now. And indeed, most animal facilities have probably more female staff than male staff, you know, because they…well, we just attract female staff. So that's quite an interesting change. That's a change in the industry. Obviously, in large animals, there's not many people do farm animal research, but even there now, I would expect there's lots of women that work in those areas.

IVC_Bottom_2

Individually ventilated cages (IVCs) – each cage with its own filtered air supply – mean that research animals can be virtually germ free, and they stop diseases spreading through facilities. They also keep out dust, dander, and smells, creating a cleaner working environment for animal technologists and reducing exposure to allergens. Fewer changes of bedding and cleaning allow mice to remain settled, but the noise and intense air circulation may cause anxiety behaviours in some strains.

IVC_Front_1

"By the mid-1970s, filtered roof techniques began to be combined with newly emerging plastic cages to produce an effective and affordable microbially secure microenvironment. One of the first widely adopted commercial examples was that of Robert Sedlacek [...] marketed as Lab Products Inc.’s “Micro-Isolator™ System.” Within the “Micro-Isolator™ System” mice existed in a secure microbial environment separated from that of the wider animal facility. The adoption of isolation cages provided a simple material solution to previously complex ecological and practical relations.
In contemporary mouse facilities, this problem has been reduced by the development of Individually Ventilated Cage (IVC) systems where each isolation cage has its own regularly circulated air supply. Multiple IVC cages had emerged in the 1960s in response to various local needs. One early IVC was designed to allow work on dangerous pathogens to be pursued relatively safely by safeguarding researchers, technicians and animal carers from accidental exposure to infected animals (Cook 1968). Others, such as an IVC designed by Edwin P. Les of the Jackson Laboratory, Bar Harbor (Maine, USA) and Bill Thomas of Thoren Industries, was intended as a means to promote animal health and welfare... As such, the IVC again illustrates the complexity of concerns and values that were enacted in the material form of the animal cage."
Kirk (2016).

IVC_Left_1

One big advantage of them [IVC cages] is, apart from keeping the animals super clean inside, so once you do certain protective measures for yourself and you run them properly, not like an open cage but they're an IVC, you've got to run them properly, is that you can get so many more cages on a footprint**.** So whereas you might have had 36 cages of preventional cages, you can get 60 of IVC, so you can double your holding capacity in the same space.

"One big advantage of them [IVC cages] is, apart from keeping the animals super clean inside, so once you do certain protective measures for yourself and you run them properly, not like an open cage but they're an IVC, you've got to run them properly, is that you can get so many more cages on a footprint. So whereas you might have had 36 cages of preventional cages, you can get 60 of IVC, so you can double your holding capacity in the same space."
Retired animal facility manager

IVC_Right_1

Now we've gone onto IVCs and the new guidance says the environment should be appropriate to the animal species, all of a sudden we're now working probably 12 air changes max. Because individually ventilated cages, what's the point of putting in all that air, you know, 12 times. The air is only there to get rid of the heat from the room, it's not there to ventilate the cages because the cages are being ventilated themselves. So I think there's been a bit of common sense come in now and hopefully the extra money can be spent on, you know, providing the environmental enrichment, making the animal welfare standards high, checking them, not overstocking them. And yeah, as I say, I think it's a good move.

IVC_Right_2

Q:  So individually ventilated cages came in for other reasons as well?  A: Well, a) they came in because they were invented, I mean, that's part of it. But the driver behind it…up until then, we used to have things like filter top cages and various barriers to keep the animals clean, especially for immunological studies. And then someone hit on the idea of these so-called individually ventilated cages. And when they first came out, they were a bit clunky, to be honest, but over time they've been quite sophisticated.

IVC_Top_2

This isolator set up to keep germ-free mice is an extreme example of maintaining a sterile environment. With these levels of precaution, mice can be reared completely free of bacteria, including in their gut, to study influences of various microorganisms on them.

IVC Housing

What does a sterile environment mean for care?