Note: The below data was taken from several sources and is indicative of average measurements, therefore, variation will exist.

Rats / Mice

Rats (Rattus norvegicus):

• Adult body weight: Male 3000-520 g; Female 250-300 g
• Adult body length: 12-18 in (32-46 cm)
• Adult tail length: 4 3/4-8.5 in (122-215 mm)
• Body surface area (cm²): 10.5 (wt. in grams)^2/3
• Diploid number: 42
• Age of puberty: 50-60 days
• Age when most fertile: 3-10 months
• Average weight when breeding begins: 9-10.5 oz (250-300 g)
• Estrous cycles: every 4-5 days
• Length of estrous periods: 12-24 hours
• Postpartum estrous: within 48 hours of parturition
• Ejaculation: usually after 6-10 couplings
• Average number of litters per year: 3-7 (up to 12, 16 theoretically)
• Number of pups in litter: 6-12 (max 22, min 2)
• Theoretical number of descendants from one pair: 1 year-- 15,000, 3 years--359 milllion
• Surviving young in wild: only 20 per year
• Sex ratio: 52% male, 48% female
• Length of gestation: 21-23 days
• Time for delivery of litter: 1.5 hours
• Average weight at birth: 2/10 oz (6 g)
• Age at weaning: 21 days
• Average weight at weaning: 1.5 oz (45 g)
• Age when vagina opens: 35-90 days
• Age when testes descend: 20-50 days
• Age when body hair erupts: 10 days
• Age when eyes open: 14-17 days
• Age when ears open: 12 days
• Mammary development: 14 days
• Pseudopregnancy: uncommon, if occurs-lasts 13 days
• Average age at menopause: 15 months
• Average life span: 24-60 months; in wild--6 months; Females live longer than males
• Ear size: Less than 3/4 in (2 cm)
• Sound emittance: 22 Hz
• Sight: Color blind--see in shades of gray, insensitive to red light, can recogniz motion up to 30 ft away
• Tail: Shorter than length of body and head combined
• Feet: Front= 4 toes, Hind= 5 toes
• Length of hindprint: 2 in.
• Dental Formula: 1/1 incisors, 3/3 molars x 2=16 teeth
• Incisor erupts at: 8 days
• Tooth growth: Upper incisors--5 3/4 in./year, lower incisors--4 1/2 in./year
• Teeth pressure: exert 24,000 lbs/in²
• Food consumption: 5-6 g/100g/day, 50 lbs/year
• Begin dry food consumption: 12 days
• Water consumption: 10-12 ml/100g/day or more (0.5-1 oz/day)
• Milk composition: 13 % fat, 9.7% protein, 3.2% lactose
• GI transit time: 12-24 hours
• Body temperature: 38.2 C; infants can survive as low as 34 F for short periods, adults die when drop to 59 F, infants self regulate at ~73 days
• Scat: about 3/4 in. long (Norway), 1/2 in. (Roof)
• Swimming ability: can swim as far as 1/2 mile in open sea, tread water for 3 days, dive and swim underwater for 30 sec at a time, diving 100 ft down
• Rectal temperature: 35.9-37.5 C
• Respiratory rate: 70-115/min
• Tidal volume: 0.6-2.0 ml
• Oxygen use: 0.68-1.10 ml/g/hour
• Heart rate adult: 250-600/min
• Heart rate newborn: 81-241/min
• Blood volume: 50-70 ml/kg
• Blood pressure: 84-134/60 mm Hg
• Blood pH: 7.35
• Blood clotting time: 20 sec
• Hematocrit: 36-48%; 46ml/100ml
• Hemoglobin: 11-18 g/dl (gm/100ml)
• Erythrocytes (RBC): 7-10 x 10⁶/mm³
• RBC life span: 45-68 days
• RBC diameter: 6.8 microns
• RBC rate of sedimentation: 0.7-1.8 mm/hour
• Leukocytes: 6-17 x 10³/mm³
• Neutrophils: 9-34%; 3.1 x 10⁶/mm³
• Lymphocytes: 65-85%; 10.2 x 10⁶/mm³
• Eosinophils: 0-6%; 0.3 x 10⁶/mm³
• Monocytes: 0-5%; 0.3 x 10⁶/mm³
• Basophils: 0-1.5%; 0.10 x 10⁶/mm³
• Platelets: 500-1300 x 10³/mm³
• Serum water: 92-94 g/100ml
• Serum protein: 5.6-7.6 g/dl
• Albumin: 3.8-4.8 g/dl
• Globulin: 1.8-3.0 g/dl
• Serum glucose: 50-135 mg/dl
• Blood urea nitrogen (BUN): 15-21 mg/dl
• Creatine: 0.2-0.8 mg/dl
• Total bilirubin: 0.20-0.55 mg/dl
• Serum lipids: 70-415 mg/dl
• Phospholipids: 36-130 mg/dl
• Triglycerides: 26-145 mg/dl
• Cholesterol: 26-82 mg/dl
• Serum sodium: 144 mEq/L
• Serum chloride: 110 mEq/L
• Serum calcium: 5.3-13.0 mg/dl
• Serum phosphate: 5.3-8.3 mg/dl
• Serum magnesium: 1.6 mg/100ml
• Serum potassium: 5.9 mEq/L
• Specific gravity of urine: 1.02-1.05
• Urine volume: 3.3-4.2 ml/100 g/day
• Urine pH: slightly acidic
• Urine protein levels: up to 30 mg/dl
• Developmental events:
  • Blastocyst formation: 3-4 days
  • Blastocyst implantation: 6 days
  • Organogenesis: 6-17 days
  • Primitive streak: 9 days
  • Neural plate: 9 days
  • First somite: 9-10 days
  • First pharyngeal arch: 10 days
  • 10 Somites: 10-11 days
  • Upper limb buds: 11 days
  • Lower linb buds: 12 days
  • Forepaw rays: 14 days
  • Testes differentiation: 14-15 days
  • Heart septation: 16 days
  • Palate closure: 16-17 days

Mice (Mus musculus):

• Adult body weight: 5/8-1 oz (18-28 g) wild, max 2.14 oz (60 g) white/colored
• Adult body length: 5 1/8-7 3/4 in (130-198 mm)
• Adult tail length: 2.5-4 in (63-102 mm)
• Body surface area (cm²): 10.5 (wt in grams)^2/3
• Diploid number: 40
• Sexual maturity occurs at: 5-7 weeks
• First estrous occurs at: 28-40 days
• Length of fertility: 7-18 months
• Estrous cyle: every 4-6 days
• Length of estrous periods: 12 hours
• Postpartum estrous: 24-48 hours after parturition
• Time of vaginal plug: 16-14 hours
• Average number of litters per year: 5-10 (max 14)
• Number of pups in litter: 5-7 (max 16 min 3)
• Length of gestation: 17-21 days
• Time for delivery of litter: 0.5 hours
• Average weight at birth: 1/28-1/14 oz (1-2 g)
• Average length at birth: 0.5 inch
• Age at weaning: 21-28 days
• Average weight at weaning: 2/7-3/7 oz (10-12 g)
• "Leap age", "flea age" occurs at: 16 days
• Age when eyes open: 10-16 days
• Age when ears open: 3 days
• Age when hair erupts: 2-5 days, fully covered at 10 days
• Age when vagina opens: 28-49 days
• Mammary development: 14 days
• Age when incisors become visible: 11-13 days
• Average life span: 1.5-3 years
• Body temp.: 100.4-102.2 F (38-39 C), 107.6 F (42 C) is fatal
• Optimal housing temp.: 70-80 F, 21-27 C
• Optimal housing humdidity: 45-55% relative humidity
• Max running speed: 7.5 mph (12 kph) over short distances
• Threshold of hearing: 100,000 Hz
• Dental Formula: 1/1 incisors, 3/3 molars x2=16 teeth
• Feet: Front= 4 toes, Hind= 5 toes
• Milk composition: 12.1% fat. 9.0% protein. 3.2% lactose
• Length of small intestine: ~18 inches
• Vertebral formula: C 7, T 12-14, L 5-6, S 4, Caudal 27-30
• Mammary glands: ~5 pairs; 3 thoracic, 2 abdominal
• Food consumption: 12-18 g/100 g/day
• Begin dry good consumption: 10 days
• Water consumption: 15 ml/100 g/day
• GI transit time: 8-14 hours
• Scat: 0.25 inch (6 mm)
• Rectal temperature: 36.5-38.0 C
• Heart Rate: 500-600/min
• Respiratory rate: 60-220/min
• Tidal volume: 0.09-0.23 ml
• Oxygen use: 1.63-2.17 ml/g/hour
• Heart rate: 325-780/min
• Blood Pressure: 147/106
• Weight of heart: 1.15 g
• Blood volume: 70-80 ml/kg
• Blood clotting time: 14 sec
• Hematocrit: 39-49%; 41.5 ml/100ml
• Hemoglobin: 10.2-16.6 g/dl
• Erythrocytes (RBC): 7-12.5 x 10⁶/mm³
• RBC life span: 45-68 days
• RBC diameter: 6.6 microns
• Leukocytes: 6-15 x 10³/mm³
• Neutrophils: 10-40%; 2.0 x 10³/mm³
• Lymphocytes: 55-95%; 5.5 x 10³/mm³
• Eosinophils: 0-4%; 0.15 x 10³/mm³
• Monocytes: 0.1-3.5%; 0.3 x 10³/mm³
• Basophils: 0-0.3% ; 0.05 x 10³/mm³
• Platelets: 800-1100 x 10³/mm³
• Serum water: 92-94 g/100ml
• Serum protein: 3.5-7.2 g/dl
• Albumin: 2.5-4.8 g/dl
• Globulin: 0.6 g/dl
• Serum glucose: 62-175 mg/dl
• Blood urea nitrogen (BUN): 12-28 mg/dl
• Creatine: 0.3-1.0 mg/dl
• Total bilirubin: 0.1-0.9 mg/dl
• Cholesterol: 132-244 mg/100ml
• Serum calcium: 3.2-8.5 mg/dl
• Serum phosphate: 2.3-9.2 mg/dl
• Serum mangesium: 1.3 mg/100ml
• Urine volume: 0.5-2.5 ml/day; males are proteinuric

Known References:

Himsel, Carol A. Rats: A Complete Pet Owner's Manual. Hauppauge, NY: Barrons's Educational Series, Inc. 1991
Bielfeld, Horst. Mice: A Complete Pet Owner's Manual. Hauppauge, NY: Barron's educational Series, Inc. 1984.
Witaker, John O., Jr. National Audubon Society Field Guide to North American Mammals. New York: Chanticleer Press. 1994.
Harkness, John E. and Joseph E. Wagner. The Biology and Medicine of Rabbits and Rodents. Media, PA: Williams and Wilkins. 1995.
Hendrickson, Robert. More Cunning Than Man. Briarcliff Manor, NY: Stein and Day Publishers. Inc. 1983.
PMI Feeds, Inc. Animal Diet Reference Guide. Richmond, IN.