African dormice (Graphiurus spp.) are small nocturnal rodents that currently are uncommon in laboratory settings. Their use may increase as they have recently been shown to develop an infection with monkeypox virus and may prove to be a valuable animal model for infectious disease research.
The few publications about African dormice are primarily the result of field studies. Studies involving captive Graphiurus provide minimal detail on feeding or housing. Food preference testing of captive G. murinus has shown these rodents to be omnivorous, with a marked preference for arthropods in addition to consumption of shelled eggs, nuts, and soft fruits. This pattern is similar to that seen in the field in which stomach contents of Graphiurus species comprise primarily insects but also other animals and fruits.
This diet correlates well with the lack a cecum capable of supporting the digestion of fibrous plant matter. Graphiurus spp. imported from Ghana were associated with the human monkeypox outbreak in 2003.
Here we describe the housing and breeding of G. kelleni at our institution and discuss health and welfare concerns of this unique species. Although our emphasis was on adapting our experience with Mus spp. to this novel species rather than preference testing for optimization, we have produced a viable colony that is capable of reproduction.
This report is the first description of optimization of housing and production of Graphiurus kelleni.
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Thanks to many years of research, the ban on dormice is now lifted and we can once again have dormice as pets. The Graphiurus murinus species is the species most commonly kept as pets. Nocturnal in nature, dormice are most commonly active at dusk and dawn and can be heard making chirping, almost bird like sounds. The life expectancy for dormice in captivity is four to six years.
Graphiurus murinus
General Information About African Pygmy Mice
As the name suggests, the African pygmy mouse is one of the smallest rodents (some are as small as 3cm!) and is found throughout Subsaharan Africa. For a tiny mammal, they can live for quite a while; ages up to 4 years have been documented, but they generally average around 2 years. In African pygmy mice, the X chromosome determines their gender and not the Y. They're a nocturnal and omnivorous rodent with a fast metabolism. Interestingly, they also have cheek pouched similar to hamsters.
Housing and Enrichment
Despite their small size, African pygmy mice do need a large enclosure. A 10-20 gallon tall tank (or a 45x45x60 cm terrarium) is often sufficient for a pair. However, bigger is better. Use several hides in the enclosure for large colonies. The larger the colony the more hides are necessary. It is critical to have several hides in the enclosure for large colonies. The larger the colony the more hides are necessary. Plenty of climbing surfaces should be provided.
Dormice were housed in individually ventilated, sterile, microisolation caging (Allentown Caging, Allentown, NJ) with paper bedding (Diamond Soft, Harlan Teklad, Madison, WI), 2 nesting structures (Mouse Igloo or Tunnel, Bioserve, Frenchtown, NJ), and nesting material (Nestlet, Ancare, Bellmore, NY). Cages were changed weekly by using aseptic technique within a class II biosafety cabinet.
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Animal holding room temperatures were maintained between 20 °C and 23 °C, and relative humidity was maintained between 30% to 70%. Dormice were housed on a 14:10-h light:dark cycle with the light intensity at cage level less than 325 lx.
Never use cedar shavings because the oils and dust from cedar can be harmful to small mammals.
Bonding products designed for sugar gliders work well for dormice.
To optimize consumption of a high-protein diet, we tested the palatability of several high-protein foods in a series of preference trials.
Африканские сони
Diet and Palatability
Due to their quick metabolism, African pygmy mice often consume more food and water than you'd initially expect. They're omnivores, so they require both plant and animal material to be healthy. Mixing a variety of bird foods, adding millet, and dried insects should be suitable for your pygmy mice.
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Breeder cages were provided with a high-fat, high-protein autoclaved pelleted rodent diet (2019S, Harlan Teklad). Adult offspring were provided with an autoclaved pelleted rodent diet (2018SX, Harlan Teklad) and sterilized water. Dormice received protein enrichment consisting of 3 to 5 live mealworms 3 times weekly or 1 tablespoon of diced hard-boiled egg weekly.
Many types of bird food and sunflower seeds are acceptable. Just about any type of fresh fruits are acceptable with the exception of citrus fruits. Treats can include meal worms or other insects, hard-boiled egg, scrambled egg, tuna, plain cooked chicken and canned cat food.
Food was aliquoted at 2 g protein per dormouse per cage, placed on culture dishes, distributed to experimental animals in the late afternoon, and weighed after the completion of a single light:dark cycle. Food remained in the cage for less than 16 h. This process was repeated 4 times with a maximum of 3 trials per week. Cages contained 2 to 5 dormice with an even gender distribution. Rodent diet pellets and water were available ad libitum.
To evaluate the suitability of each food option as means of protein enrichment, we adapted a published preference score system. Suitability was measured on a 5-point scale (0 to 4, least to most preferable) determined by the percentage of an item that was consumed during the 16-h feeding period.
Initially, hard-boiled eggs were provided to the dormice as standard protein enrichment. Because the eggs required additional preparation time and rarely were consumed in entirety during the first 16 h, we sought a more palatable, easily prepared, high-protein, lowfat supplement.
The most palatable foods identified in the diet trial were wax worm larvae, cottage cheese, soy nuts, and chicken. All food options with a score of 3 or 4 were consumed in entirety within 48 h, unlike hard-boiled eggs, tofu, parmesan cheese, sunflower seeds, pistachio nuts, peanut butter, and black walnuts.
Low-fat cottage cheese proved significantly (P < 0.005) more palatable than canned chicken, soy beans, and tofu. Both fat and fiber were significant (P < 0.0001) predictors of consumption. Lowfat foods (less than 0.2 g fat/g) were highly preferable. As fat content increased, there was a significant (P < 0.0001) decline in preference.
Although comparison trials judged waxworm larvae significantly (P < 0.02) more preferable than soy nuts, consideration of cost, ease of preparation, and nutritional analysis deemed soy nuts a more suitable alternative. Soy nuts are cost-efficient and contain a relatively low amount of fat. They can be distributed easily, are nonperishable, and necessitate minimal preparation.
| Food Option | Palatability Score (0-4) |
|---|---|
| Wax Worm Larvae | 4 |
| Cottage Cheese | 3-4 |
| Soy Nuts | 3-4 |
| Chicken (Canned) | 3-4 |
| Hard-boiled Eggs | 0-2 |
| Tofu | 0-2 |
| Parmesan Cheese | 0-2 |
| Sunflower Seeds | 0-2 |
| Pistachio Nuts | 0-2 |
| Peanut Butter | 0-2 |
| Black Walnuts | 0-2 |
Table 1: Palatability of Different Food Options for African Dormice
Socializing
African pygmy mice are not safe to handle as you can easily inflict damage on them, but you can often see pygmy mice out and about in their enclosure. They startle fairly easily.
Pygmy mice are a communal rodent and will live happily together. Take care when housing males together, as they're reported to be more aggressive towards each other than females.
Breeding
African Pygmy Dormice can breed year-round if kept warm and well fed. Gestation is ~24 days, and litters typically range from 3 to 4 pups. Breeders sell them unsexed.
Dormice used for breeding were initially established as permanent pairs or trios of 2 female and 1 male animals. Dormice were mated by using animals that were at least 4 mo old without a history of aggression or obesity. Offspring were weaned at least 28 d after birth. Weaned offspring were housed as littermates until they were sexed at 4 to 8 wk of age, at which point they were housed in unisex groups of 5 or fewer dormice per cage.
Of the 70 mating pairs that were established, 44 pairs (63%) weaned at least one litter. The average litter size was 3 pups born and 2 pups weaned. Sexing was performed by palpation of the os penis: if a penis was not palpable by 8 wk after birth, the dormouse was considered female. The female breeder was 16 to 19 mo old when her first litter was weaned and the male breeder was 8 to 11 mo of age.
Breeding will naturally occur in a colony setting so one must be intentional in having a breeding plan that includes introducing new bloodlines and for selling excess offspring.
Fighting occurred in all the breeder trios (2 female mice with 1 male), with the subsequent removal of 1 female mouse and establishment of a permanent pair.
Health and Veterinary Care
Watch closely for changes in weight, coat condition, or activity level. These warrant immediate veterinary attention.
Self-groom thoroughly. African Pygmy Dormice can become chilled or stressed.
Isoflurane anesthesia was administered at 3% in an induction chamber. Although visual observation was a good indicator of anesthetic depth in dormice, a toe pinch was used to determine whether an animal had reached an adequate plane of anesthesia. This reflex was usually lost after 3 min at 3% isoflurane.
All blood collections were performed in isoflurane-anesthetized dormice. Mandibular blood collection was performed by using a 23-gauge needle to pierce the skin approximately 0.5 to 1 cm ventral from the ear base. Blood (maximum, 300 µL) could be collected from the mandibular region on a monthly basis without obvious resultant clinical abnormalities. More than 1 mL was collected from the cranial vena cava of dormice or by cardiocentesis as a terminal phlebotomy. Collection of blood from the retroorbital sinus or tail vein was unsuccessful. Shaving the tail fur did not enhance visualization of the tail vein nor improve the ability to collect blood from this vein. Depending on the depth and width of the puncture, dormice often hemorrhaged from the ear or cheek. During anesthesia recovery, many dormice developed tremors of large muscle groups.
We selected isoflurane over intraperitoneal injection of ketamine and xylazine (125 mg/kg and 20 mg/kg, respectively) based on speed of recovery in domestic Mus species, and the same proved true for dormice. In comparison with recovery times seen in mice housed in the facility, dormice appear to have prolonged recovery from isoflurane; the application of a heat source and physical stimulation shortened the recovery time.
The weight of mature dormice ranged from 15 to 42 g, with an average weight of 24.4 g.
Veterinary care for dormice was adapted from that provided to Mus spp., with most of the care directed at recovery from traumatic injuries and dehydration in young animals. Because dormice had a pronounced tendency to develop myositis from wounds, aggressive treatment with local and systemic antibiotics was required to minimize this condition.
Of a total colony of 700 dormice, 122 (fewer than 20% of the colony) dormice presented with clinical problems over a period of nearly 2 y, 77 (63%) of the cases were traumatic injuries in group-housed animals. The remaining 46 dormice displayed either lethargy or dehydration. Dehydrated dormice tended to be younger than 3 mo (43%), and no sex predilection was noted. Treatment for dehydration consisted of twice-daily administration of subcutaneous warm lactated Ringers solution (1 mL/10 g) and feed supplementation on the cage floor; 37 of the 46 dormice responded to the treatment.
Injuries incurred from fighting occurred predominantly in breeder cages within 72 h before parturition. The most common injury was traumatic amputation of the tail and resulting myositis and cellulitis in male breeders. Wounds were treated with a variety of topical antibiotics, including twice-daily application of topical antibiotic ointment (Bacitracin, Perrigo, Allegan, MI) and continuously supplied oral amoxicillin (0.5 mg/mL in drinking water; Axoxil, GlaxoSmithKline, Research Park, NC) and required an average of 40 d for resolution.
Traumatic injury was most prevalent in harem breeder cages.
