Environmental Enrichment for Laboratory Animals

Environmental conditions such as housing and husbandry have a major impact on the laboratory animal throughout its life and will thereby influence the outcome of animal experiments. However, housing systems for laboratory animals have often been designed on the basis oeconomic (minimal use of space and resources), and ergonomic (reduction of variation) aspects. 

One possible way to improve the living conditions of laboratory animals is to provide opportunities for the animals to perform a species-specific behavioral repertoire.  

Rats and mice perform an increased range of behaviors, such as hiding, climbing, and foraging1. Semi-aquatic turtles, such as painted turtles or red-eared sliders, require both water and land areas in their enclosures. Turtles, being reptiles, are ectothermic; therefore, proper heat and UVB light are extremely important for their general health. Basking strengthens a turtle’s shell and reduces algae growth on its shell5 

 Environmental enrichment should be regarded both as an essential component of the overall animal care program and equally important as nutrition and veterinary care (Vera Baumans). 

According to the Guide for the Care and Use of Laboratory Animals, there are key features that contribute to environmental enrichment 3,4: 

  • Group housing of compatible animals 
  • Providing animals with sensory and motor stimulation 
  • Promoting species-specific behaviors 
  • Providing animals with a means for control over their environment (e.g., nest-building materials, hiding places) 
  • Novel items (e.g., toys, special food treats) 
  • Opportunity for exercise (e.g., running wheels, climbing structures) 

FIGURE 1. In an enriched environment, mice will divide their cage space into zones, including a latrine area, a nest, and clean activity areas1. 

FIGURE 2. ‘Nestlets’ are pre-sterilized pieces of compressed cotton fibers. Rodents will tease them apart and use them to form a nest1. (Image courtesy of Plexx BV, Netherlands)  

FIGURE 3. The ‘Mouse House’ or ‘Mouse Igloo’  is a cage insert molded of autoclave safe, transparent red plastic. Since mice see red as black, the Mouse House is a dark place for them to rest and hide1. (Image courtesy of Tecniplast, Buguggiate, Italy.) 


 FIGURE 4. The ‘Shepherd Shack’ is cage insert composed of autoclavable paper. Mice can shred it and use the paper for nest building1.  

FIGURE 5. Running wheels promote voluntary activity in mice. It increases physical and cognitive activity, reducing anxiety in mice. (Image courtesy of Tecniplast, Buguggiate, Italy.)  

FIGURE 6: Turtles can be housed in a variety of environments depending on research requirements; however, housing should meet following criteria5 

  • Whenever possible, turtles should be group-housed.
  • Tanks should be large enough to allow ample swimming space. 
  • Tanks should have enough water so that the largest turtle can fully submerge. 
  • Tanks should include an area where turtles can haul out of the water and bask. 
  • Basking lights should be provided.


  1. Environmental Enrichment Options for Laboratory Rats and Mice, David Key, FIAT.
  2. Mouse & Rat Husbandry Procedures, SOP 5.11.0 
  3. IACUC Policy on Animal Housing and Enrichment. Accessed: May 1, 2019.
  4. Committee for the Update of the Guide for the Care and Use of Laboratory Animals; National Research Council. Guide for the Care and Use of Laboratory Animals: Eighth Edition; 2010.
  5. Turtle Care and Husbandry (BSF), SOP 5.31.5 


  • Adding live plants to guppy fish tanks can help eliminate toxic waste and provide hiding places for baby guppies.  
  • Duckweed thrives in nearly any aquarium, and in most cases experiences explosive growth. It has a well-deserved reputation for reducing algae growth and helps clean and purify the tank water. 



  • Plants help to emulate the natural habitat of the fish. 
  • Plants provide a shelter. 
  • Plastic aquarium plants are very easy to obtain and maintain while providing adequate hiding space.