Dwarf care & considerations. A dwarf rat is not just a small rat, it is a specific recessive gene that causes dwarfism and reduced growth hormones. They are quite small around 80-120g fully grown, or 1/3 a standard adult size. They also have cosmetic features that let you know they are a dwarf: smaller feet, thinner shorter tails, larger-looking eyes or sometimes a stout, squished body shape. Because of their reduced growth hormone, they’re less prone to tumors and tend to have a longer lifespan as a result. Their average life expectancy is 3 – 3.5 years. Though they can also be prone to obesity, so should be fed in moderation.

Comparisons to their standard siblings.