Journal of the American Association for Laboratory Animal Science Ahead of Print

Purpose

The Association of Primate Veterinarians (APV) recognizes that primates housed in a research setting may be susceptible to weight fluctuations that can affect their welfare and research outcomes. Obesity and poor body condition can occur spontaneously, from mismatches between food provided and caloric requirements, and/or secondary to research aims. These guidelines provide recommendations for managing research NHPs that have a non-ideal body condition to maximize their health and welfare.

Background

NHPs in research settings require an appropriate diet to support healthy development, consistent maintenance, and optimal welfare. Veterinary and research staff involved in weight management of NHPs can use

In laboratory mice, the 21-day weaning standard is the most commonly applied strategy across institutions. However, this strategy has numerous drawbacks, including potential for litter overlap, pup mortality, and weaning extensions. In pursuit of a more objective marker for weaning, we compared the short-term growth of C57BL/6J mice weaned at 3 different body lengths. To recapitulate various weaning scenarios, mice (n = 90) were weaned at a litter average of 5.5, 6, or 6.5 cm. Body lengths and weights of mice were measured twice weekly from weaning to 10 weeks of age. Resulting growth curves revealed no significant differences in body length or body weight found across treatment groups. Although all groups achieved similar adult body length and body weight, unexpected mortality was experienced in the 5.5-cm group (n = 11). Multiple blinded observer comparisons did not result in significant inconsistencies in body length measurements. Our findings indicate that C57BL/6J mice can be safely weaned at an average minimum litter body length of 6 cm. This body length allows for normal physical development into adulthood without the requirement for additional nutritional support. Furthermore, the use of body length is a practical and reliable tool for personnel charged with determining weaning readiness in mice.

Use of soiled bedding sentinels (SBS) for rodent colony health monitoring is limited by inconsistent pathogen detection, reliance on live animals, high costs, and labor intensity. Sentinel-free soiled bedding (SFSB) offers a viable alternative for all rodent housing systems, overcoming limitations by using PCR testing of matrices exposed to soiled bedding. As an alternative, a matrix may be exposed to all cages via direct colony dredging (DCD). This study compared pathogen detection and costs between SFSB, DCD, and SBS for mice housed in individually-ventilated cage rack system cages. For each study rack, SFSB was performed with one matrix shaken in composite soiled bedding, while DCD was performed with a second matrix exposed to all soiled cages on the rack using a dredging method. We hypothesized that the SFSB and DCD matrices would detect Rodentibacter heylii, Rodentibacter pneumotropicus, Helicobacter typhlonius, Helicobacter mastomyrinus, Helicobacter hepaticus, Helicobacter bilis, Helicobacter rodentium, Helicobacter ganmani, and murine norovirus (MNV) with equal or superior efficacy to SBS, at a comparable or reduced program cost. All SBS failed to detect R. heylii, R. pneumotropicus, H. typhlonius, H. mastomyrinus, H. hepaticus, H. bilis, H. rodentium, and H. ganmani when tested by fecal PCR, and 25% failed to detect MNV when tested via serology. In contrast, SFSB and DCD matrices detected MNV, R. heylii, R. pneumotropicus, H. typhlonius, H. mastomyrinus, H. hepaticus, H. bilis, H. rodentium, and H. ganmani even with low pathogen prevalence, although neither method achieved 100% detection. DCD had negative ergonomic, workflow, and labor challenges compared with SFSB. Overall, SFSB and DCD had reduced costs and superior pathogen detection compared with SBS, while SFSB provided the most efficient and user-friendly approach for health monitoring by this institution.

The purpose of this study was to track seroconversion in a cohort of 12, pair-housed, macaques that were previously screened negative for adeno-associated virus-9 neutralizing antibody (AAV9-NAb). Over a 6-month period, specific biosecurity strategies were implemented with the intention of understanding if following defined protocols could play a role in preservation of AAV9-NAb negative status. AAV9-NAb-negative animals were selected for shipment to the facility approximately 2 months after the initial screening. After arrival, animals were paired and housed in a single room with a dedicated housing corridor, cage wash, and equipment. They were then screened for AAV9-NAb status monthly by 2 different labs to confirm results and ascertain potential for variation of results. Upon initial screening at the facility (within one week of arrival), 2 of the 12 NHPs that were seronegative before shipment had seroconverted to AAV9-NAb positive status. The positive animals and their negative partners were moved to a different room but remained within the same isolated corridor with the same biosecurity practices. Serum that was taken on a monthly basis was also used to screen other AAVs. At the end of the 6-month period, AAV9 NAb status did not change from the time the animals were initially screened on site until the end of the study. Paired animals that were cohoused in the same cage with a positive partner did not seroconvert. Although a control group was not used to validate that biosecurity practices played a role in mitigating seroconversion, unpublished data from a facility employing less restricted biosecurity strategies suggest that the seroconversion process involves a more intricate process.

Body Length as an Objective Marker of Time to Wean in Laboratory Mice

Rachel L WilsonDVM,

William D DupontPhD,

Courtney L HunterDVM, PhD, DACLAM, and

Michael M McKinneyDVM, DACLAM

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