A 2-Year Comparison Study of Crl:CD BR and Hsd:Sprague–Dawley SD Rats

Abstract

In this 2-year study, the suitability of the Hsd:Sprague-Dawley SD (SD) as a replacement for the Crl:CD BR (CD) rat was assessed by comparing survival rates, palpable mass incidence, body weights, food consumption, clinical laboratory parameters, and necropsy and histopathology observations. At week 104, survival rates in the CD and SD males were 29 and 49%, respectively. Corresponding survival rates in females were 44 and 63%. The total numbers of animals with palpable masses and animals with neoplasms were similar in the CD and SD rats; however, the total numbers of palpable masses and neoplasms were higher in the CD rats. The incidence of corneal lesions was higher in the SD rats, whereas the incidence of lenticular opacities was higher in the CD rats. Body weights, food and water consumption, and organ weights were significantly lower in the SD rats. In contrast, food intake per kilogram of body weight was slightly higher in the SD rats. Numerous differences in clinical laboratory parameters between the CD and SD rats were observed. Some of these were consistent with the increased prevalence of kidney disease and secondary sequelae in the SD rats. Taken together, the better survival, smaller size, and lower food consumption of the SD rat may make it a better model for chronic bioassays. However, the increased propensity for spontaneous renal disease may limit the utility of the SD rat for studying nephrotoxic compounds.

Spontaneous Neoplasm Incidences in Fischer 344 Rats and B6C3F1 Mice in Two-Year Carcinogenicity Studies: A National Toxicology Program Update

“…The major reason for this gradual increase in body weight may be related to the selection of breeding stock for faster growth and earlier reproduction to satisfy user preference for larger rodents at low cost (30). Increasing body weights and decreasing control survival have also been reported for Sprague-Dawley rats (23) and seem to be present in many other commercially available rat strains (23,24,28).…”

Endocardial Myxomatous Change in Harlan Sprague-Dawley Rats (Hsd:S-D) and CD-1 Mice: Its Microscopic Resemblance to Drug-Induced Valvulopathy in Humans

“…However, further studies are required to determine the progression of EMC and to characterize further complications, including MPC, bacterial endocarditis, and/or congestive cardiac failure. It is also possible that MPC and EMC may occur independently as has been reported anecdotally (10,23,29,40). Atrial thrombosis has been described in the aged rats and mice, and is often associated with myocardial lesions, such as degeneration, focal inflammation, mineralization, amyloid deposition, or degenerative myxoid lesions in the heart valves (15).…”

“…EMC is likely to produce volume overload to the cardiac chamber proximal to the affected valve with development of myocardial hypertrophy, and subsequent degeneration and inflammation, which may resemble typical changes of MPC and/or exacerbation of existing MPC. MPC is common in Han Wistar rats and other strains, and occurs at higher prevalence in older males (29). Females have less extensive changes than males of the same age (29).…”

“…MPC is common in Han Wistar rats and other strains, and occurs at higher prevalence in older males (29). Females have less extensive changes than males of the same age (29). Similarly, MPC occurs in mice of various strains (10,40).…”

Development and characterization of a novel rat model of type 2 diabetes mellitus: the UC Davis type 2 diabetes mellitus UCD-T2DM rat

“…51). The OSD rats exhibit adult-onset obesity and are hyperphagic and more metabolically efficient than normal weight animals (35,39,51). This obese phenotype appears polygenic in origin (31), with the OSD littermates exhibiting a wide continuum of body weights, rather than distinct "obese" and "lean" phenotypes as observed in monogenic models of obesity.…”