Volume 39 | Issue 2 Article 8

1977 The onM golian Gerbil Lorene Stockberger Iowa State University

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Recommended Citation Stockberger, Lorene (1977) "The onM golian Gerbil," Iowa State University : Vol. 39 : Iss. 2 , Article 8. Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol39/iss2/8

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by Lorene Stockberger*

The Mongolian dark-clawed jird, required to be kept under maximum security. unguiculatus has become an increasingly Of course, with the increasing popularity of popular and laboratory animal during the gerbils as , controls are unenforcable. past ten years. The gerbil has several characteristics which Referred to in popular literature as the make it a satisfactory pet. They are almost Mongolian gerbil, M. unguiculatus is a small without fear, and seldom (if ever) bite unless of the Family Cricetidae, somewhat severely provoked. They have an appealing larger than a and much smaller than a appearance, and are alert and active most of rat. It belongs to the Subfamily Gerbillinae, the time. which includes twelve genera. To be The most characteristic quality of the taxonomically correct, the name "gerbil" gerbil is it's curiosity. They are intelligent and should be reserved for those members of the have been shown to acquire avoidance genus , also in the Subfamily responses ten times more rapidly than rats. Gerbillinae. But because of the widespread But as one frustrated researcher found, they (mis)usage of the common term "gerbil," M. will not run mazes. Even when starved to the Unguiculatus will be referred to as the gerbil point of losing weight, they curiously examine in the remainder of this article. the walls of the maze rather than try for Gerbils are also called desert rats or sand record times. If a gerbil should accidently get rats. They are native to the desert areas of out of its cage, its curiosity helps to locate it. northeastern China and Eastern . It may first run to someplace inaccessible, but All of the gerbils in the were within a short time will become bored with derived from stock bred in the laboratory that and reappear. since 1935, when Dr. C. Kasuga captured 20 Besides its personality, the gerbil has a pairs along the Amur River basin in Eastern remarkable physiology that makes it ideal for Mongolia. In 1954, Dr. Victor Schwentker a pet. Gerbils thrive on what would constitute obtained 11 pairs from the colony started with neglect for any other species. And since many Dr. Kasuga's captives and started the gerbil pets that are taken care of by children live in a colony at Tumblebrook Farm. state of constant semi-neglect, the gerbil may As late as 1963, the gerbil was a prohibited be a good species to suggest. species in California. It was feared by some The easy care and wide range of bacterial that t~ey might escape and due to their and viral susceptabilities have made the burrowing habits wreak havoc on irrigation gerbil popular as a laboratory animal, also. systems and crops. This fear was not entirely But one author noted that there was a unfounded, because a related species of problem with the lab personnel becoming Gerbillinae in the western prqvinces of South more attached to the friendly gerbils than to Africa had done just that. mice or rats. But through litigation, the laws have been In the laboratory, the gerbil has been used relaxed and the gerbil is now a legal to bio-assay steroid hormones via weight laboratory animal, although officially changes in its ventral sebaceous gland. It has also become somewhat of a paradox in serum cholesterol research because of the fact that it *Ms. Stockberger is a third year student in the College of Veterinary Medicine. exhibits a natural lipemia without developing

62 Iowa State Unz"versity Veterznarian atherosclerosis. It may serve as a model for dry, they need to be cleaned only about once epilepsy. It shows a very high radiation every two weeks. tolerance. It is susceptible to many viral and Like most other , gerbils depend on bacterial diseases and is an especially good coprophagy for their B-vitamins. About 50% model for Leptospirosis. There is ongoing of the feces are normally eaten to satisfy this research using gerbils in tumor induction and requirement. So gerbils may develop a graft-rejection studies. As more data is vitamin deficiency if the cage is cleaned too compiled, gerbils will no doubt become often or if they are kept on wire floors unless almost as common for laboratory use as rats their diet is supplemented with a B-complex and mice. From the gerbil's standpoint, this preparation. mayor may not come as good news. In the wild, gerbils require only metabolic Gerbils are found in many pet stores, water. Their adrenals are four times as large usually for under $2 each. The average as the rat's, perhaps indicating increased weight for adult males is 80-90 grams and 70­ aldosterone activity. And the fat deposits 80 grams for adult females. In adults, the tail resulting from their unique fat metabolism is 90 % as long as the body, while at birth it is have been hypothesized to relate to a water only 25 % of the body length. storage mechanism. In the laboratory, they The color is typically ag-outi, although may consume about 4 m!. ofwater per day. black mutations have appeareli in laboratory The nutritional requirements of gerbils are colonies. The under-side is creamy to grey; not known. They reproduce and seem to the sides light brown, and the dorsum a thrive on commercial rat or mouse chow. The darker brown. The tail is furred and may high fat varieties should be avoided because have a black tuft at the tip. There is a large the gerbil's increased deposition of fat while sebaceous gland on the abdomen which is on such a ration may cause him to become used for scent-marking territories. It is obese. Also, fat deposition around the ovaries present in both sexes. of the female may lead to reproductive The gerbil is very adaptable and adjusts to failure. a wide range of housing without stress. Cages Because of their curiosity, gerbils will try to at least 6 inches high are required because eat anything that is offered to them, from gerbils like to sit up to eat. They are very anchovies to zucchini. They are especially active, both day and night, and enjoy exercise fond of sunflower seeds. Probably the best wheels and crawling through tubes. diet would be a commercial mouse or rat In the home, their curiosity lets them enjoy chow supplemented with mixed grains such as watching day to day family activity. A corn, oats, wheat, and barley; and also some transparent plastic cage or a glass aquarium sunflower seeds. Succulent foods such as provides them with security and at the same lettuce or cabbage may be offered oc­ time allows maximum interaction. casionally. Since they are, desert , humidity Gerbils are monogamous and mate for life. below 50% is bes·t. Above this level, their fur A mature gerbil that has lost its mate will not may appear matted and damp, although no usually take another. However, one other physiological effects have been noted. researcher claims that when he kept several They are tolerant of wide ranges of tem­ pairs in one cage, occasional "cheating" was perature. Temperatures from 20-25 degrees observed. Perhaps their association with man F. to 80-85 degrees F. have no effect, except and successive generations of laboratory that there is no reproduction at the lower rearing are gradually influencing their temperatures. behavioral patterns. Gerbils require some form of bedding, as Gerbils are also somewhat selective in they like to . Ground corn cobs, wood accepting a mate. In the wild, this is no shavings, sand, hay, and paper-have all been problem, because there are a lot to choose used. The paper need not be shredded, as the from. But in the laboratory, gerbils may think gerbils will enjoy doing this themselves. matings based on selection and planning are Because gerbils produce only 2-3 drops of merely arbitrary and refuse to participate. highly concentrated urine per day, ab­ The most severe reaction of this kind is when sorbancy of the litter material is not a prime the female kills the male. But she may allow consideration. And because the cages remain him to live with her and just reject

Issue No.2, 1977 63 copulation. found and no lesions are associated with this. Gerbils become sexually mature at 10-12 The frequency of seizures lessens with age weeks and mating them at 9-10 weeks so they because of evidence of a variable genetic mature together helps to eliminate rejection threshhold, individuals that exhibit frequent ofeach other. seizures should be culled from breeding The estrous cycle is probably about 4 days, programs. The seizures may be controlled with the heat period lasting less than 24 with diphenylhydantoin, but this is probably hours. Gestation is 24-25 days with a litter size not necessary. of 1-12. Litters of 1 or 2 are usually ignored Older gerbils may develop neoplasms, but by the mother and die of starvation or the data is not sufficient to make any neglect. The reason for this is unknown. generalized conclusions about type or Cannabalism is rare and any young that die distribution. The female gerbil is quite prone before weaning are often buried under the to development ofovarian cysts. bedding by the parents. The male also helps Overgrown incisors are rare, but a single to care for the young. case has been reported. There is a post-partum estrus, but im­ Blood samples may be obtained by orbital plantation may be delayed if the female is bleeding or lancing a vein. A large number of nursing a large litter. The young should be "abnormal" erythrocytes that resemble ,.veaned at 21 days to avoid competition reticulocytes prompted one investigator to between litters, since the mother may have report that 94% of gerbils had Hemabar­ another litter at day 24 if she was bred at the tonellosis. But more plausible explanations post-partum estrus. are continuous erythropoiesis caused by lipid­ The breeding life of the female may extend induced hemolysis or perhaps genetically to 20 months. Gerbils may live up to 4 years, controlled continuous hyperactive although most do not. erythropoiesis. Disease problems of the gerbil are No normal values for uninalysis have been negligible. There have been a few reports of published, probably because of the scant naturally occurring Tyzzer's Disease (Bacillus quantities produced. piliformis) in laboratory colonies. Parasites In conclusion, the gerbil's friendly, curious are not a problem because the secondary hosts nature, minimal care requirements and few remain in Mongolia. Sporadic pneumonia natural disease problems make it a good pet may occur, usually following stress, such as and laboratory animal. surgery. Diarrhea may occur in response to toxins from unwashed lettuce or spoiled food. The gerbil may be infected with Salmonella, BIBLIOGRAPHY but the disease is self-limiting and a carrier state does not result. Dermatitis of the nose and jaw may be David, Tony D. Aeromedical Review: Selected TOPics in caused by gna\ving on ,"vireo It is aggravated Laboratory Animal Medicine. Volume XXIII. 7-74. by poor sanitation. Very old animals may "The Mongolian Gerbil.. develop a protrusion of the nictitating Marston, J. H. Chapter 21, "The Mongolian Gerbil" in: membrane and conjunctiva with The UFA W Handbook on the Care and Management ofLaboratory A nimals, 4th Ed. London, 1972. exophthalmia. The cause of this is unknown. Rich, Sigmund T. "The Mongolian Gerbil (M. Newborn gerbils may show abnormalities inguiculatus) in Research." of pigment and hair growth that resolves with Schushman, Stephen M. "Individual Care and Treat­ age. However, most of the affected animals ment of Mice, Rats, Guinea Pigs, , and do not survive to weaning. Some gerbils, Gerbils" in: Current Veterinary Therapy V. W. B. Saunders Co. 1974. especially young ones, will exhibit spon­ Schwentker, Victor. "Care and Maintenance of the taneous hypnotic or cataleptic seizures when Mongolian Gerbil- a basic manual for laboratory handled or otherwise stressed. The legs are animal technicians." Tumblebrook Farm, Inc. Brant stiffly extended and the body trembles. The Lake, New York. White, D. J. and Waldron, M. M. "Naturally-occurring seizures last for up to a minute, after which Tyzzer's Disease in the Gerbil." Veterinary Record, normal activity resumes. No cause has been August 2, 1969. pp. 111-114.

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