Hamster biology, husbandry and management

Family of hamsters

Family of hamsters

cricetidae

Species of syrian (golden) hamster

Mesocricetus auratus

Genus and species of Armenian hamster?

Cricetulus migratorius

Is the genus and species of the Chinese hamster?

Cricetulus griseus

What are the species within the Djungarian hamsters?

Phodopus campbelli, Phodopus sungorus, Cricetus cricetus

What is the genus and species of the european hamster?

Cricetus cricetus

What is the genus and species of the Russian Dwarf hamster?

Phodopus campbelli

What is the genus and species of the siberian hamster?

Phodopus sungorus

Syrian hamster life history

Syria/SE Europe/Asia Minor, Deep tunnels, ↓ temp, ↑ humidity

Nocturnal in lab (♀ diurnal wild)

Why are syrian hamsters good models?

Available, reproductive ease, rapid development, short life cycle

Unique anatomy/physiology

Susceptible to a variety carcinogens → TUMORS

Relatively pathogen-free,

Susceptible to experimentally-induced infectious disease

Dietary manipulation → Metabolic disease

Develop inherited diseases similar to human syndromes

What are the male and female size differences in syrian hamsters

females larger than males,

Life span: female<male 18-24 mo (2y average)

Digits for hamsters:

4 front, 5 back

Dental anatomy for hamster

Hypsodont incisors, cuspidate molars, Incisors at birth

Do hamsters get caries?

Yes they are susceptible to dental caries

Amount/form carbohydrate

Presence/absence of vitamins

Infectious bacteria via oral transmission

Historically a model for caries-induced lesions

Now other rodents are more common

Cheek pouch unique anatomy

No glands, rich in mast cells

Highly vascular – external carotid artery

Stratified squamous epithelium

Easily everted

Artery for cheek pouch

external carotid

Is the cheek pouch immunologically privileged?

yes, there is no lymphatic drainage

Because the cheek pouch is immunologically privileged, what is used for to model for research?

Supports long-term survival of transplanted tissue w/out rejection

Model of carcinogenesis in cheek pouches is one of the best animal systems for the evaluation of human oral cancer development

Hamster stomach

Glandular Stomach + Nonglandular Forestomach (rumen)

Are hamsters coprophagic and can they vomit?

Coprophagic, unable to vomit

Unique pancreatic ducts of hamsters and what are they models for?

Pancreatic ducts + common bile duct → prior to emptying duodenum.

Good models for pancreatic carcinogenesis

Do hamsters have a gall bladder?

yes

Hamster respiratory systems and models for resp disease in people

Limited glandular structures (esp. proximal trachea)

Model chronic bronchitis

Pulmonary vascular bed similar to humans

Develop lesions resembling human emphysema => intratracheal porcine pancreatic elastase

Spontaneous bronchogenic and pulmonary cancers are rare

Good model for chemical carcinogenesis

What type of cervix do syrian hamsters have?

double

Kidney and estrogen in hamsters

Kidneys are highly susceptible to estrogen in hamsters.

Males given estrogen much more likely to get renal tumors.

Adrenal glands and sex in hamsters

adrenals are sexually dimorphic in hamsters.

Males have ↑ # reticular cells in the adrenal cortex

Produce cortisol (not corticosterone like other rodents)

1^st model Addisonian adrenal necrosis

What immunoglobulin do hamsters not have?

IgD

Hamsters MHC diversity and grafts

Not very diverse thus do not reject skin allografts

Syrian hamster harderian gland and sex

Glandular Sexual Dimorphism– female secrete 10³X ↑ porphyrin than males

Do other hamster species have harderian gland sexual dimorphism

No.

What is the harderian gland?

Pigmented lacrimal glands posterior to globe (lubricate)

Site of immune response, thermoregulatory lipids/pheromones, photoprotective organ, part of retinal-pineal axis

Flank gland

Sebaceous glands

Secretions in response to androgens

Male = Coarse hair/darkly pigmented skin in the costovertebral area

Wet/pruritic when excited marking

Female = less prominent

Secretions associated w/ estrus cycle

Pharmacology of hamsters regarding histamine, morphine, radiation and steroids/ serotonin (HAMSTERS)

Resistant to Histamine And Morphine + Radiation

Sensitive to STEroids + Serotonin

Are hamsters prone to drug associated C. dificile enteritis ?

Yes

How may chromosomes do hamsters have?

44 diploid chromosomes

female on left, male on right

Age at which reproduction decreases significantly?

Ability to reproduce decreases by 14 mons

How long is the estrus cycle of hamsters?

4 days

What is this photo showing?

Vaginal Discharge

Copious creamy white post-ovulatory discharge can extrude through vagina

End of ovulation (~DAY 2)

When does mating occur? What test can you use to determine this?

Evening after post-ovulatory discharge observed (~DAY 3)

Female receptive 16hrs from early evening to mid-afternoon next day = BLANDAU TEST

Ways to test mating in hamsters

Test Mating

Cage individually 1 wk (male dominance, female cycle normal)

On DAY 3 following discharge female introduced to male cage 1-2 hrs prior to start dark cycle

NO MATING in 5 min/female aggressive = remove and replace

MATING OCCURS = leave pair together until following light cycle

What is trio breeding?

1male (older better), 2 females for 1-2 weeks, female aggression

Ways to assess for successful pregnancy?

Pregnant = weight gain, abdominal distention DAY 10 post-breeding

Gestation of hamster

15-18 days (most common 16th day)

Pseudopregnancy in hamsters

Infertile mating

Post-ovulatory discharge DAY 5 or 9 post-breeding – normal estrus

What day of pregnancy is it optimal to conduct teratogenic studies?

8^th day gestation = optimal time teratogenic studies

Signs of parturition

Restlessness/grooming/nest building/eating

ways to minimize fetal cannibalism in hamsters?

Put food on the floor – only species which this is allowed

No cage change until 7-10days after parturition

when does estrus commence after parturition?

Estrus cycle resumes 1-8 days post-partum

DAY 0 pup characteristics?

Hairless, Eyes/Ears CLOSED, Incisor teeth VISIBLE

DAY 4-5 pup characteristics?

Ears OPEN

DAY 9 pup characteristics?

Hair growth, vagina open

DAY 7-10 pup characteristics?

Eat solid food

DAY 14-16 pup characteristics?

Eyes OPEN

DAY 21 - 28 pup characteristics?

WEAN

Are hamsters artificial?

yes

What are important minerals for hamster?

Zn, CU, K. Soy bean meal better than fish meal

What does vitamin E help prevent?

Vit E prevents myocytolysis in cardiomyopathic hamsters

What happens when you do Diet changes from rodent chow to semi-purified

colocolic intussusception within 7-10 days

Are hamsters typically single house or group?

single, they are aggressive

You find food on the floor in a hamster cage, is the normal or a management concern?

normal

AWA regulations for cage sizing: < 60 g

Weight (g)	Floor area/animal (in²)	Height (in)
< 60	10	6
60 to 80	13	6
80 to 100	16	6
>100	19	6

AWA regulations for cage sizing: 60 - 80

Weight (g)	Floor area/animal (in²)	Height (in)
< 60	10	6
60 to 80	13	6
80 to 100	16	6
>100	19	6

AWA regulations for cage sizing: 80-100

Weight (g)	Floor area/animal (in²)	Height (in)
< 60	10	6
60 to 80	13	6
80 to 100	16	6
>100	19	6

AWA regulations for cage sizing: >100

Weight (g)	Floor area/animal (in²)	Height (in)
< 60	10	6
60 to 80	13	6
80 to 100	16	6
>100	19	6

Nursing female housing requirements for hamsters, and for dwarf hamsters

Nursing female w/ litter shall be housed in primary enclosure that contains NO other hamsters and provides 121 in² floor space (dwarf 25 in²)

What is the limit for number of hamsters being shipped in the primary enclosure?

No more than 50 live hamsters shall be transported in the same primary enclosure

Temperature requirements for hamsters

Cages maintained in environment of 68 – 79^oF

Adaptable to cooler temps

humidity for hamsters

30 - 70%

photoperiod for hamsters

12 - 14 hrs

lighting requirements for hamsters

323 lux, 1 m above the floor

which hamsters are permissive hibernators?

syrians

Decreased temp, light, food

5ºC (+/-2ºC)

which hamsters are true hibernators?

Cricetus cricetus (European hamster)

Which hamsters do not hibernate?

Djungurians (Hungarian)

Why are hamsters good models for fat saturation control studies?

Desaturate white adipose tissue – useful for studies of fat saturation control

blood collection locations in hamsters?

lateral saphenous v., jugular v., cranial vena cava, retroorbital sinus, cardiac puncture (terminal)

acceptable conditions for hamster euthanasia?

A: Inj. barbiturates/dissociative combos

acceptable with conditions for hamster euthanasia?

A/C: Inhaled anesthetics, CO₂, CO, Avertin, ethanol, cervical dislocation, decapitation, focused beam microwave irradiation