Chapter Eighteen

Hamsters

ALAT Presentations Study Tips

 If viewing this in PowerPoint, use the icon to run the show (bottom left of screen).

 Mac users go to “Slide Show > View Show” in menu bar  Click on the Audio icon: when it appears on the left of the slide to hear the narration.

 From “File > Print” in the menu bar, choose “notes pages”, “slides 3 per page” or “outline view” for taking notes as you listen and watch the presentation.

 Start your own notebook with a 3 ring binder, for later study!

Hamsters

 Syrian (Golden) – most popular for research 

Mesocricetus auratus

 Chinese – diabetes mellitus research 

Cricetulus geiseus

 Djungarian 

Phodopus sungorus

 Armenian 

Cricetulus migratorius

Hamsters II

 Cheek pouch is a sac of thin epithelial tissue on each side of the pharynx that extends cheek.

 used for storing food, bedding or nesting material, to hide newborn babies  blood vessels readily visible & vascular studies performed in vivo  lack lymphatic vessels; this + unusual immunologic system = ideal for studies w/ tumor & tissue transplants  Stomach has 2 compartments.  non-glandular forestomach & glandular stomach  forestomach similar to ruminant

Cheek Pouch

Hamsters II

 Flank organ (scent gland) on right & left dorsolateral flanks  Mature males - areas darkly pigmented, black & bristly.

 Function of sebaceous glands probably related to sexual attraction.

 Secrete musk-like fluid.

 Much time spent grooming around glands.

 Used in cancer studies, cytogenic (genetic) studies & research on cavities.

Handling & Restraint

 Grasp skin across shoulders or scoop w/ hands.

 Place on cage top or flat surface & gently press palm of hand down against hamster’s back, keeping fingers straight.

 Curl fingers & thumb around opposite sides, gathering in as much loose skin as possible.

 With loose skin bunched tightly in hand, skin will be taut against the abdomen and thorax.  Do not hold too tightly or too loosely.

Restraint

Physiological Data

 Body temp: 37 °- 38°C (98.6°-100.4°F)  Heart rate: 250 - 600 / min  Respiration rate: 35 - 120 / min  Weight: adult 80-120 g; newborn 8-12 g  Water: 10 ml/100 g body weight per day  Food: 10 g/100 g body weight / day  Feces: firm, rice-sized, & dark brown  Urine: thick, milky fluid  Life span: 1.5 - 2 years

Sexing & Breeding

 Adult male has large testes.

 Four different mating systems used:  hand, monogamus, intermittent, harem  Hand mating: Female during estrus introduced into cage, mating usually occurs within 5 minutes & separated following mating.

 Harem mating: A male & 2=3 females housed together, females removed at least 2 days prior to parturition.  Intermittent mating: females placed sequentially w/ 1-2 males & females then removed to give birth.

Sexing & Breeding II

 Monogamous pairing: place together immediately after weaning, litters will appear at 35 - 40 day intervals.

 Provide w/ nesting material.

 Female may hide pups in cheek pouches.

 Sexual maturity: 42-70 days  Estrous cycle: 4 days; no postpartum estrus  Gestation: 15-16 days  Litter size: 5-10  Cannibalism: Do not disturb female until pups 7 days old  Females may eat their first litter.

 Weaning: 21 days, begin eating solid food at 7-10 days

Behavior

 Nocturnal, aggressive  Sleeping hamster may bite when startled.

 Gently & carefully awaken before picking it up.

 Frequent, careful handling makes them gentle.

 Female usually dominates male.

 Usually large animals dominate smaller ones.

 Once a dominant/subordinate relationship is formed, it tends to stabilize.

 Aggressive animals require solitary housing.

 May hibernate if room temp drops to around 5 °C.

Asleep / Alert

Husbandry

 Housed in 6 inch high shoebox cages.

 Like to burrow; include contact bedding in cage.  Adept at escaping, secure cage top firmly.

 Will gnaw their way out if given the opportunity.

 Sanitation requirements are similar to rats & mice.

Diet

 Thrive on commercially prepared rodent diets.

 Feed & water available ad libitum.

 Water provided in bottles or automatic watering.

 Fastidious - 1 corner for wastes & another for food storage.

 Their food can be placed on cage floor.

 Young begin to eat solid food at 7 - 10 days of age & may have trouble reaching cage-top feed hoppers.

Additional Reading

Anderson, R.S. and A.T.B. Edney.

Practical Animal Handling

. Pergamon Press, Oxford, UK. 1991.

Field, Karl, and Amber Sibold.

The Laboratory Hamster and Gerbil

. CRC Press, Boca Raton, FL. 1998.

Harkness, J.E. and J.E. Wagner.

The Biology and Medicine of Rabbits and Rodents

. Williams and Wilkins. 1995.

Hrapkiewicz, Karen, Leticia Medina, and Donald D. Holmes.

Clinical Laboratory Animal Medicine: An Introduction

, 2nd Ed. Iowa State University Press, Ames, IA. 1997.

Laber-Laird, K., M.M. Swindle, P. Flecknell,

Handbook of Rodent and Rabbit Medicine

. Pergamon Press, Oxford, UK. 1996.

Van Hoosier, G.L. and C.W. McPherson, (eds.)

Laboratory Hamsters

. Academic Press, Orlando, FL. 1987.