How much should a three‑month‑old rat weigh? - briefly
A typical three‑month‑old laboratory rat weighs roughly 150–250 g, with exact weight depending on strain and diet. Male rats tend toward the upper end of this range, while females are usually lighter.
How much should a three‑month‑old rat weigh? - in detail
A rat that is approximately three months old typically weighs between 250 g and 350 g. The exact figure depends on several variables:
- Strain: Laboratory strains (e.g., Sprague‑Dawley, Wistar) generally fall near the lower end of the range, while larger pet strains (e.g., Fancy, Dutch) can approach 350 g.
- Sex: Males tend to be 10‑15 % heavier than females of the same age and strain.
- Nutrition: Diets rich in protein and balanced calories promote growth toward the upper limit; under‑feeding results in weights nearer the lower limit.
- Health status: Illness, parasitic infection, or chronic stress suppress weight gain; a healthy animal will stay within the expected interval.
Weight measurement should be performed with a calibrated digital scale, recording the value to the nearest gram. Repeated measurements over several days provide a reliable average and help detect abnormal trends.
Comparative data:
- At 1 month: 100‑150 g
- At 2 months: 180‑250 g
- At 4 months: 300‑400 g
For pet owners, maintaining the weight within the 250‑350 g window indicates proper development. Sudden deviations of more than 20 g in either direction warrant veterinary evaluation.