1. Chapter Eighteen Hamsters

2.  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! ALAT Presentations Study Tips

3. Hamsters  Syrian (Golden) – most popular for research  Mesocricetus auratus  Chinese – diabetes mellitus research  Cricetulus geiseus  Djungarian  Phodopus sungorus  Armenian  Cricetulus migratorius

4. 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

5. Cheek Pouch

6. 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.

7. 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.

8. Restraint

9. 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

10. 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.

11. 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

12. 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.

13. Asleep / Alert

14. 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.

15. 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.

16. 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.