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Questions and Answers
What is unique about the rat's stomach?
What is unique about the rat's stomach?
What is the average weight of an adult female rat?
What is the average weight of an adult female rat?
What is the lifespan of a rat?
What is the lifespan of a rat?
What is the respiratory rate of a rat?
What is the respiratory rate of a rat?
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What is the breeding onset for male rats?
What is the breeding onset for male rats?
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How long does it take for a rat to wean?
How long does it take for a rat to wean?
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What is the scientific name of the species from which laboratory rat strains are believed to be domesticated?
What is the scientific name of the species from which laboratory rat strains are believed to be domesticated?
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What is the average weight range of an adult rat?
What is the average weight range of an adult rat?
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What is a characteristic of the Long-Evans rat?
What is a characteristic of the Long-Evans rat?
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What is a common use of rats despite the fear they invoke in people?
What is a common use of rats despite the fear they invoke in people?
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Why do humans frequently develop allergies to rats?
Why do humans frequently develop allergies to rats?
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How do rats typically respond to being roughly handled?
How do rats typically respond to being roughly handled?
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What is a characteristic of the Fischer 344 rat strain?
What is a characteristic of the Fischer 344 rat strain?
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What is a recommended housing arrangement for rats?
What is a recommended housing arrangement for rats?
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Study Notes
Laboratory Rats
- Commonly used strains in research are domesticated albino strains of the Norway rat (Rattus norvegicus).
- Rats belong to the order Rodentia and the family Muridae.
Physical Characteristics
- Adult rats generally weigh between 200 and 400 g, with males significantly larger than females by 9 weeks of age.
- Most laboratory rats are albino with white coat and pink eyes.
- Other color varieties include brown, black, and hooded rats.
Genetics
- Rats can be classified as outbred stocks, inbred strains, or F1 hybrids.
- Examples of outbred stocks include Sprague-Dawley, Wistar, and Long-Evans.
- Examples of inbred rat strains include Fischer 344, spontaneously hypertensive rat, and buffalo rat.
- Mutant strains of rats include the Zucker Diabetic rat and the nude rat.
Uses
- Rats make quiet, gentle pets that are intelligent and easily trained.
- They are extremely proficient breeders.
- Humans frequently develop allergies to rat dander and urine proteins.
Behavior
- Rats are social animals and do well housed as pairs or in small groups.
- They are docile and curious, and easily adapt to various environments.
- Rats will bite out of fear when roughly handled.
- They are nocturnal, sleeping much of the day.
Anatomic and Physiologic Features
- Rats are much larger than mice, with conical heads and longer, cylindrical bodies.
- They have a unique gastrointestinal system, with no gallbladder and a highly developed cecum.
- Rats cannot vomit due to a fold in the limiting ridge between the two parts of the stomach.
- They have a large pigmented, horseshoe-shaped lacrimal gland called the Harderia gland.
Biologic and Reproductive Data
- Adult body weight: Male (300-520 g), Female (250-300 g)
- Life span: 2.5-3.5 years
- Body temperature: 35.9-37.5°C
- Heart rate: 250-450 bpm
- Respiratory rate: 70-115
- Food consumption: 5-6g/100g/d
- Water consumption: 10-12ml/100g/d
- Breeding onset: Male (65-110d), Female (65-110d)
- Estrous cycle length: 4-5d
- Gestation period: 21-23d
- Postpartum oestrus: Fertile
- Litter size: 6-12
- Weaning age: 21d
- Breeding duration: 350-440d
- Chromosome number: 42
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Description
Discover the characteristics and uses of laboratory rats in research, including their origins, physical features, and varieties.
