Nomenclature: NTac:SD

• Used in virtually all disciplines of biomedical research including toxicology and pharmacology
• Excellent reproductive performance makes the SD rat a good model for generating timed pregnant females

SD rats are useful as health sentinels, clean fosters or where co-housed with immunodeficient/genetically modified models.

 

Origin: The Sprague Dawley® outbred model was developed by Sprague Dawley, Inc. NIH received stock from Sprague Dawley, Inc in 1945. The rats are maintained as an outbred closed colony. Taconic received stock from the NIH Animal Genetic Resource in 1970. The rats were refreshed with NIH Genetic Resource stock in 1998.

Average litter size: 10

Phenotyping Procedures:

Animal Receipt and Maintenance

A quantity of twenty rats (ten males and ten females) was submitted for testing, strain identified as Line Sprague Dawley® (NTac:SD), age 7 weeks. Rats were received at RBU 3, Taconic Biotechnology, Albany NY and acclimated for three days on irradiated NIH #31M Rodent Diet and sterilized water ad lib, sterile contact bedding (paper chip) and a 12:12 light:dark cycle. All animals appeared normal during this period and routine health surveillance of this colony detected no microbial pathogens. Rats were assigned study unique identification numbers (males 1-10, females 11-20).

 

Urinalysis

All rats were placed in metabolic cages and an overnight urine sample was collected. Urine analysis was performed using Multistix 10 SG (Bayer). Strips were read and recorded as per the manufacturer’s instructions, and the results are presented in Table 2.

 

Clinical Chemistry and Hematology

A terminal blood sample was taken from Carbon Dioxide – anesthetized rats via cardiac puncture. The collected blood was divided into two samples. One sample was treated with EDTA and stored at 4°C for hematological evaluation. Another sample was allowed to clot at 4°C for 30 minutes, and then centrifuged at 7000rpm for 10 minutes, and the serum was decanted and frozen at -80°C for clinical chemistry analysis. A slide smear was made from a single drop of whole blood. Frozen serum, chilled whole blood and slides were delivered to LabCorp (RTP, NC) for analysis; the results are presented in Table 3. Unless otherwise indicated, serum chemistry data is generated from a Hitachi 717 automated analyzer and hematological data is generated from a Celldyne 3500. WBC differential counts are performed manually.

 

Necropsy and Organ Weights

All rats were euthanized and bodyweights were recorded. Representative tissues were collected, weighed, and immersion fixed in 10% Neutral Buffered Formalin. Tissues were delivered to the Taconic Anmed lab (Rockville, MD) for histological preparation and evaluation. Tabulation of organ weights is presented in Table 4. The pathologist’s summary and detailed histological descriptions follow.

 

Discussion

All animals were thrifty on arrival and appeared clinically normal. Locomotor behavior was normal and there were no visible lesions or discharges at the mucous membranes. All tissues appeared normal on gross necropsy evaluation and weights were within normal limits. There were no unusual findings upon collection of these tissues nor otherwise observed in the body cavities.

The overall profile of these rats is consistent with expectations of a general-purpose rat. None of the parameters are indicative of impaired system function.

One Year Growth Chart