Between mice and rats, which typically has a larger maximum safe blood draw?

Between mice and rats, which typically has a larger maximum safe blood draw?

• A. Mice
• B. Rats
• C. Gerbils
• D. Hamsters

Answer: (B)

Drawing blood safely from a rodent depends on its total blood volume, which scales with body size. The amount you can collect is usually a percentage of that blood volume, so a larger animal can yield a larger absolute volume without harming it. Rats are bigger than mice and thus have a greater blood volume; the same proportional draw translates to a larger safe amount in rats. Gerbils and hamsters are smaller than rats, so their safe draw volumes are smaller. So, between the two, rats have the larger maximum safe blood draw.

Drawing blood safely from a rodent depends on its total blood volume, which scales with body size. The amount you can collect is usually a percentage of that blood volume, so a larger animal can yield a larger absolute volume without harming it. Rats are bigger than mice and thus have a greater blood volume; the same proportional draw translates to a larger safe amount in rats. Gerbils and hamsters are smaller than rats, so their safe draw volumes are smaller. So, between the two, rats have the larger maximum safe blood draw.