Hamsters in Research.

 The Syrian golden hamster, Mesocricetus auratus, is a unique animal in many respects. All the animals used in research, as well as those bred as pets, are descended from 3 animals, one male and two females discovered in Syria in 1930. These animals were captive bred, and imported into the country several years later. Over time, "fanciers" have bred multiple varieties of colors and coats. In the wild, hamsters live independently in deep burrows[i] They are omnivores, eating seeds, vegetables, grain and meat; feed is stored in the burrows.

 Hamsters are small, relatively healthy and easy to maintain. They have short life cycles with a gestation period of only 16 days. As with most rodents, the young are altricial, meaning hairless, blind and helpless. Unlike most rodents, the female is larger, territorial, and more aggressive than the male. Because of this behavior trait, males and females should be housed separately.

 In the eyes of some, hamsters have a bad reputation. This may be due to the fact that they are extremely nocturnal, and don't like to be disturbed. When disturbed, they bare teeth and rear on their hind legs in an aggressive posture. They do respond well to routine gentle handling. Providing exercise and hiding places also reduces aggression. As burrowing is a natural behavior, a thick layer of bedding allows the animal to engage in this species specific behavior.

 Hamsters are covered by the Animal Welfare Act, specifying cage floor area based on weight. A 6 inch cage height is required. According to the AWA, nursing females with a litter should be housed alone, with at least 121 sq. inches of floor space. Low room temperatures will trigger hibernation with some strain variation. Other factors, such as shortened light cycle, isolation and food availability also affect hibernation. Animals normally store food before hibernation, as they do not "fatten up” but instead periodically waken to feed.[ii] While in hibernation, metabolism slows, but animals are still sensitive to temperature change and touch. They will awaken if disturbed or placed in a warmer area.

 Hamsters have several anatomic differences from other rodents. Incisors are present at birth. They have a cheek pouch, used for storing food. In times of danger, it is also a convenient place to store pups. The pouch has another significance, as it is an immunologically privileged site, due to the lack of lymph glands or lymph drainage. This allows tumors to grow without rejection. This feature makes hamsters a good model for tumor transplantation and cancer research. Both males and females have a flank gland which is most pronounced in intact males. It is used to mark territory and during mating.

 Hamsters are also used for dental research due to the special anatomical features that cause quick formation of cavities.

 Syrian golden hamsters comprise roughly 90% [iii]of all hamsters used in research. The other 10% used are the Chinese (cricetulus griseus) and the Siberian (Phodopsus sungorus). Unlike the Syrian hamster, these animals can be housed in family groups[iv]. These models are used for carcinogenic, and mutagenic research. The Chinese hamster is also a natural model for diabetes.

 They have only one major health problem, enteritis. There is the potential for zoonotic disease, though not likely in animals bred for research. All three species are sensitive to antibiotics, so care must be used in their administration.

For information on laboratory Hamster feed please visit: http://www.animalspecialties.biz/RodentDiet.html

[i] Harkness, J., et al., Harkness and Wagner’s The Biology and Medicine of Rabbits and Rodents, Fifth Ed., Hoboken:Wiley-Blackwell, 2010, p. 66.