High-Density Mouse Housing for Microbiome Studies

High-Density Mouse Housing for Microbiome Studies

It is widely recognized that the intestinal microbiota plays an essential role in health and disease and the standardization of the gut microbiome (GM) in research animals is important to study that role. It has been suggested that co-housing more than one litter and dams in a primary enclosure may offer some degree of gut microbiome standardization among offspring, and provide a larger number of animals from which to establish experimental and control groups with similar GM.

Requirements for High-Density Housing

The following instructions refer to housing mice in a standard mouse primary enclosure (75 sq. in.) at densities departing from Guide recommendations (pp. 56-58). Two female mice and two litters may be housed in a standard mouse primary enclosure if all of these requirements are followed.

1. To include this standard procedure in an IACUC protocol, an investigation of the effects of the mouse microbiome must be described in at least one set of experiments.
2. IACUC protocol must include a brief description of this housing paradigm as a Special Instruction in the Non-Standard Care section of the protocol form.
3. After IACUC approval, a harem breeding cage is set up with one male and multiple female mice.
4. Once 2 female mice have been confirmed to be pregnant, all additional mice (male and any other females) will be removed immediately. The 1^st litter and dam will be removed if the 2^nd litter is born more than 3 days apart.
5. High-density enclosures will be regularly monitored for waste accumulation, high humidity, and unexpected clinical conditions. Enclosure may need to be changed more frequently than usual, which may result in more stress to the animals.

Any concerns regarding the welfare of mice will be addressed by VCS.  A veterinarian or veterinary technologist will evaluate these cages and determine if separation is necessary. If a humane concern is present or imminent, YARC technicians may separate the animals immediately