Gerbil neoplasia: high spontaneous tumor incidence (25–40%) in gerbils over 2–3 years old
Source: Merck Veterinary Manual (merckvetmanual.com), a copyrighted professional veterinary reference. Per COPYRIGHT_POLICY §3, the points below are paraphrased derived fact summaries: numerical values and proper nouns are preserved from the source, but sentences are rewritten and not quoted verbatim.
Claims
*[Paraphrased derived summary — non-Open-Access source.]* In laboratory colonies of Mongolian gerbils, spontaneous tumours are common: 25–40% of animals older than 2–3 years develop neoplasia (Merck cites references 15 and 16).