Critical care monitoring for small rodent patients is notoriously challenging, complicated further by physiologic idiosyncrasies and limitations on applicable treatments and interventions (Hawkins and Graham, 2007, Lichtenberger, 2007, Lichtenberger and Ko, 2007). This chapter offers important supplementary information for critical care for the laboratory rodent patient, with specifics on types of models with inherent potential for pain and distress. The comprehensive subject matter herein was consolidated from a variety of institutional guidance documents, publications, and abstracts to highlight particular regulatory, clinical, and experimental facets of working with these species. Due to the diversity of material covered here, the topics are in alphabetical order, akin to the listings of considerations in previous chapters, for ease of location.