Age/Weight Correlation
Age/weight correlation charts are presented for each sex of most stocks and strains. The information is specific to the conditions maintained in Charles River barrier production rooms. The shaded areas on each chart are the mean weight, plus or minus two standard deviations, at a given age, averaged across all production facilities. This represents the majority of the population. Overlaps in the full range of weights occur between age groups and will be more pronounced in outbred animals.
Surcharges
Our research models are sold within specific weight ranges or at a certain age. For specific orders outside the standard weight range or age, additional charges may apply.
| 1 gram weight range for inbred mice | Add 5% |
| 5 gram weight range for non-obese rats and hamsters | Add 25% |
| 10 gram weight range for non-obese rats | Add 15% |
| Retired breeders with specified weight or approximate age | Add 50% |
Pregnant Animal Guarantee Details
Charles River produces pregnant animals to your specifications. Most barrier-reared rats and mice can be safely and accurately palpated for pregnancy after 13 days of gestation. Prior to that, pregnancy is determined by observation of a vaginal plug. Following timed exposure to the male, the date the copulatory plug is found (plug date) is considered to be day one of gestation, unless noted otherwise.
Percent Guaranteed Pregnant at Time of Shipment
| Stock or Strain | Timed Pregnant Up to 12 Days Gestation | Timed Pregnant 13 Days Gestation and Over | Untimed Pregnant 13 – 17 Days Gestation Only |
| Outbred Rats | Plug guarantee only | 100% | 95% |
| Outbred Mice | Plug guarantee only | 100% | 100% |
| Inbred Rats and Mice | Plug guarantee only | 75% | 75% |
| NZW Rabbits* | Plug guarantee only | 100% | N/A |
Note: We do not guarantee the number of offspring per litter. Due to natural variations in the length of gestation, the exact day of parturition is not guaranteed. To avoid charges, cancellations for pregnant animals must be received prior to the scheduled mating day.
* For the NZW rabbit, the breed date is day 0 for all timed pregnant orders.
Health Reports
We understand the health status of your research models is critical to your studies. Review health reports before placing your order to ensure the area your animal model is shipping from meets your health status needs.
Shipping and Transportation
Our responsibility for an animal's health and wellbeing does not end when they leave our facilities. The transportation of animals must be conducted under strictly controlled conditions to ensure they are delivered in a safe and timely manner and without compromising their microbiological integrity. View details.
Surgical Models and Services
We perform surgical procedures at our AAALAC-accredited production facilities throughout the United States. Our experienced surgeons are available to perform simple procedures and highly complex catheterizations and cannulations, including jugular vein, carotid artery, and femoral vein. Dedicate more time to your research by outsourcing surgical needs for your animal models.
Pre-ID™ Services
Accurately identifying and keeping track of your study animals can help prevent potential mistakes in your research. Our Pre-ID™ services, including Labstamp®, microchip, and tattooing are performed by experienced technicians adhering to the highest standards of animal welfare.
National Cancer Institute (NCI) Grantee Orders
We also offer special pricing for NCI grantees. Many animal models are the original ones that NCI had contracted Charles River to produce for more than 25 years. Visit our NCI Grantee Program site for more information.