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Vet Med (Auckl). 2018 Oct 10;9:69-72. doi: 10.2147/VMRR.S181531. eCollection 2018.

Environmental enrichment alleviates chronic pain in rats following a spared nerve injury to induce neuropathic pain. A preliminary study.

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Department of Veterinary Biomedicine, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC J2S 2M2, Canada,



In mice, chronic pain can be alleviated with enriched environments (EEs). The purpose of this preliminary study is to investigate whether pain behaviors in rats with peripheral neuropathy would be altered when keeping these animals in either 1) standard laboratory cages or in 2) a significantly EE.


Two groups of rats (n=8/group) underwent a spare nerve injury surgery of the right hind leg; one group (n=8) was returned to standard ventilated cages (2 rats/cage), the other (n=8) placed in an EE (8 rats/ferret cage with toys). A third group (n=8) underwent a sham surgery and was used as control. These animals were returned to standard ventilated cages (2 rats per cage). Spare nerve injury surgery consisted of ligation/transection of the tibial and common peroneal branches of the sciatic nerve of the right leg only. Von Frey Filaments were applied to test mechanical sensitivity of both hind paws.


The right paw of nerve-injured animals was hypersensitive to mechanical stimuli at 2, 4, and 8 weeks following the surgery; however, animals in the EE conditions showed significantly (P<0.05) less mechanical sensitivity than rats left in the standard caging environment (2, 4, and 8 weeks postsurgery: standard environment 2.8±0.5, 2.8±0.7, and 2.6±0.4 and EE 4.7±0.6, 5.8±0.5, and 5.5±0.7). Sham animals were unaffected by the surgery.


Environmental enrichment alleviated mechanically induced chronic pain in a spared nerve injury rat model of neuropathic pain. Findings also suggest that environmental enrichment, as a method to alleviate pain, may be species-specific, motor behaviors being a very important parameter when considering pain modulation.


chronic pain; environmental enrichment; neuropathy; rats; spare nerve injury

Conflict of interest statement

Disclosure Madeleine Parent-Vachon, daughter of Pascal Vachon, is admitted in a Master’s program of Veterinary Biomedicine at the University of Montreal. The Department of Veterinary Medicine, the Vice-Dean of student affairs of the Faculty of Veterinary Medicine, and the Faculty of Graduate Affairs have all accepted the master’s project and the admission of Madeleine Parent-Vachon. The authors report no other conflicts of interest in this work.

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