Mongolian GerbilMongolian Gerbil Meriones unguiculatusMeriones unguiculatus

The Mongolian gerbil The Mongolian gerbil is is also known as the jird, also known as the jird, clawed jird, sand rat, or clawed jird, sand rat, or desert rat. It is native desert rat. It is native to China and Mongolia to China and Mongolia and was introduced into and was introduced into the United States in the United States in 1954. 1954.

The most common color The most common color is is the agoutithe agouti, shown , shown here: light buff to white here: light buff to white ventrum, with mixed ventrum, with mixed white, yellow and black white, yellow and black hairs dorsally, giving an hairs dorsally, giving an overall brown fur color.overall brown fur color.

AppearanceAppearance

Gerbils may also be Gerbils may also be black, black, gray, white, or piebald. gray, white, or piebald. They are characterized by They are characterized by a long, fully furred tail, a long, fully furred tail, strong claws for burrowing, strong claws for burrowing, and elongated hindlimbs, and elongated hindlimbs, uused for jumping and for sed for jumping and for maintaining a semi-erect maintaining a semi-erect posture. posture.

The The body and the tail are body and the tail are each about 11-15 each about 11-15 centimeters in lengtcentimeters in length, with h, with the body slightly longer the body slightly longer than the tail. than the tail. Adults weigh Adults weigh 70-150 grams70-150 grams, , with males with males slightly larger than slightly larger than females.females.

TaxonomyTaxonomy

The Mongolian gerbil, The Mongolian gerbil, Meriones Meriones unguiculatus,unguiculatus, is in the order is in the order Rodentia, suborder Myomorpha Rodentia, suborder Myomorpha and the family and the family Cricetidae - the Cricetidae - the same family as the hamster.same family as the hamster.

Dental and vertebral Dental and vertebral formulasformulasTheir dental formula is typical of rodents. Their dental formula is typical of rodents.

Gerbils have a single maxillary and Gerbils have a single maxillary and mandibular incisor on each side. There are mandibular incisor on each side. There are no canines or premolars. The gerbil has 3 no canines or premolars. The gerbil has 3 maxillary and 3 mandibular molars on each maxillary and 3 mandibular molars on each side.side.

2 ( I 1/1 C 0/0 PO/O M3/3 ) = 162 ( I 1/1 C 0/0 PO/O M3/3 ) = 16 They have 7 cervical vertebrae, 13 They have 7 cervical vertebrae, 13

thoracic, 6 lumbar, 4 sacral and 7 or more thoracic, 6 lumbar, 4 sacral and 7 or more coccygeal vertebrae. coccygeal vertebrae. ( C7 T13 L6 S4 Cy7+)( C7 T13 L6 S4 Cy7+)

Facts Facts

Life SpanLife Span: : 3-4 years 3-4 years on average (up to on average (up to 8 reported, though this is exceptional!) 8 reported, though this is exceptional!)

Mongolian gerbils Mongolian gerbils are not nocturnal are not nocturnal although they are sometimes active at although they are sometimes active at night; they go through several night; they go through several sleep/active cycles in the course of 24 sleep/active cycles in the course of 24 hours hours

They are very curious and will explore anything, and can be quite entertaining.

Sexual dimorphism Sexual dimorphism

Gerbils have a Gerbils have a prominent, elliptical prominent, elliptical ventral marking gland, ventral marking gland, composed of sebaceous composed of sebaceous glands and overlying glands and overlying coarse hair. coarse hair.

The The marking gland is marking gland is more prominent in males more prominent in males than in females and is than in females and is helpful in sexing mature helpful in sexing mature animalsanimals. .

The The males also have a males also have a prominent, darkly prominent, darkly pigmented scrotumpigmented scrotum. .

Adrenal glandsAdrenal glands

The The adrenal glands (arrow) are large adrenal glands (arrow) are large for their body weight.for their body weight.

Breeding and Breeding and reproductionreproduction Female gerbils are Female gerbils are polyestrous, polyestrous,

spontaneous ovulators with an estrous spontaneous ovulators with an estrous cycle of 4-6 dayscycle of 4-6 days. .

They may display a slight winter breeding They may display a slight winter breeding depression. depression. Males and females that are Males and females that are paired before seven weeks of age bond in paired before seven weeks of age bond in lifelong monogamous pairslifelong monogamous pairs. Remating is . Remating is difficult if one dies or is removed. difficult if one dies or is removed. Housing Housing of two females with a single male is of two females with a single male is another acceptable mating system.another acceptable mating system.

Reproduction Reproduction

Gestation lasts 24-26 daysGestation lasts 24-26 days; but if the ; but if the female is bred during the female is bred during the postpartum estrus, implantation postpartum estrus, implantation may be delayed, increasing may be delayed, increasing gestation to a total length of gestation to a total length of 42 42 daysdays..

The male gerbil should not be The male gerbil should not be removed from the cage when the removed from the cage when the young are born, because fighting young are born, because fighting may occur when he is reintroduced.may occur when he is reintroduced.

Reproduction cont..Reproduction cont..

The average litter The average litter consists of consists of 3-7 blind, 3-7 blind, hairless pups hairless pups weighing 3-4 grams weighing 3-4 grams each. each.

The ears of the The ears of the newborn will open at newborn will open at 3-7 days postpartum3-7 days postpartum. .

The young will be The young will be covered with fur covered with fur by by 7-1 0 days and their 7-1 0 days and their eyes will open at 2-3 eyes will open at 2-3 weeks.weeks.

Maturation/ life cycleMaturation/ life cycle

Gerbils are ready to be weaned at Gerbils are ready to be weaned at 20-30 days of age. 20-30 days of age.

They reach puberty at They reach puberty at 65-85 65-85 daysdays. .

The reproductive lifespan of the The reproductive lifespan of the female lasts until about female lasts until about 12-17 12-17 months of agemonths of age and the male until and the male until two years of age. two years of age.

HUSBANDRYHUSBANDRY

Satisfactory housing in a Satisfactory housing in a research setting includes research setting includes polycarbonate "shoebox" polycarbonate "shoebox" cages, as shown here. cages, as shown here. They should be at least 15 They should be at least 15 centimeters (6 inches) centimeters (6 inches) high. high.

Each gerbil should have a Each gerbil should have a minimum of minimum of 116 sq. 116 sq. centimeters (1 8 sq. in.) of centimeters (1 8 sq. in.) of floor space. floor space.

A breeding pair with their A breeding pair with their litter should have a litter should have a minimum of 900 sq. minimum of 900 sq. centimeters centimeters (140 sq. in.) of (140 sq. in.) of floor space.floor space.

ManagementManagement

Cages should be Cages should be constructed with rounded constructed with rounded corners to discourage corners to discourage chewing. chewing.

Optimal temperature range Optimal temperature range for gerbils is between for gerbils is between 65 65 and 80° F, with babies and 80° F, with babies doing best at 70 to 75° Fdoing best at 70 to 75° F. .

The relative The relative humidityhumidity should be between should be between 30 30 and 50%. and 50%.

Bedding and nesting Bedding and nesting materialsmaterials

Absorbent bedding Absorbent bedding for burrowing should for burrowing should be provided in the be provided in the cage. Opaque tubes cage. Opaque tubes or boxes for hiding or boxes for hiding provide provide environmental environmental enrichment and soft enrichment and soft shreddable materials shreddable materials for nesting may for nesting may improve reproductive improve reproductive performance.performance.

FoodFood

Gerbils should be fed Gerbils should be fed ad ad libitum libitum from feed from feed hoppers hoppers that have wide that have wide openings for easy openings for easy accessibility. The feed accessibility. The feed hopper should be hopper should be mounted low as mounted low as newborns will begin to newborns will begin to consume solid food at consume solid food at about 2 weeks of age. about 2 weeks of age. Each adult gerbil will Each adult gerbil will consume approximately consume approximately 5-8 grams of pelleted 5-8 grams of pelleted rodent ration per day. rodent ration per day.

WaterWater

Captive gerbils Captive gerbils need a water need a water supply - either a supply - either a water bottle or water bottle or an automatic an automatic watering device watering device

USES IN RESEARCHUSES IN RESEARCH

One of the first uses of gerbils in research was One of the first uses of gerbils in research was in radiation studies, because they in radiation studies, because they can tolerate can tolerate much greater whole-body radiation exposuremuch greater whole-body radiation exposure than other animal species. than other animal species.

They have also been used in studies of They have also been used in studies of endocrine gland metabolismendocrine gland metabolism, as they have , as they have one of the largest ratios of adrenal weight to one of the largest ratios of adrenal weight to body weight of all animals.body weight of all animals.

Gerbils have a high incidence of spontaneous Gerbils have a high incidence of spontaneous epileptiform seizuresepileptiform seizures, usually precipitated by , usually precipitated by being startled or by a novel environment. being startled or by a novel environment. This makes them an important animal model This makes them an important animal model for study of epilepsy.for study of epilepsy.

USES IN RESEARCHUSES IN RESEARCH

They have been used in reproduction studies They have been used in reproduction studies to evaluate antifertility drugs and in auditory to evaluate antifertility drugs and in auditory research, because their hearing curve is closer research, because their hearing curve is closer to man's than most common laboratory to man's than most common laboratory animals.animals.

In toxicology research, gerbils have been used In toxicology research, gerbils have been used in studies of food additives, pesticides, in studies of food additives, pesticides, industrial solvents and heavy metals.industrial solvents and heavy metals.

Gerbils are also useful in infectious disease Gerbils are also useful in infectious disease research. Although they are relatively free of research. Although they are relatively free of spontaneous diseases, they are susceptible to spontaneous diseases, they are susceptible to agents from other species.agents from other species.

And finally, they are used in parasitology And finally, they are used in parasitology research, as they have been successfully research, as they have been successfully infected with parasites common to other infected with parasites common to other species.species.

HANDLINGHANDLING

To physically To physically restrain a gerbil, restrain a gerbil, grasp it at the grasp it at the base base of the tail - of the tail - not the tip. If the not the tip. If the tip is grasped, tip is grasped, the skin may the skin may come off come off (degloving).(degloving).

Fractures of the Fractures of the tail vertebrae, and slipping of the tail skin can all occur tail vertebrae, and slipping of the tail skin can all occur with improper handlingwith improper handling (A.).  This usually involves picking up animals by (A.).  This usually involves picking up animals by the distal portion of the tail.  Surgical amputation with cautery (silver the distal portion of the tail.  Surgical amputation with cautery (silver nitrate cautery shown in B.) supportive post-surgical care may be nitrate cautery shown in B.) supportive post-surgical care may be necessary when large amounts of tissue are compromised.  Such necessary when large amounts of tissue are compromised.  Such injuries may be prevented by handling animals by the base of the tailinjuries may be prevented by handling animals by the base of the tail

Injection siteInjection site

The loose skin of The loose skin of the neck is a site the neck is a site for subcutaneous injection for subcutaneous injection

IM, IV injectionsIM, IV injections

The muscles of the The muscles of the thigh thigh are a site for intramuscular are a site for intramuscular injections. Care must be injections. Care must be taken to taken to avoid the sciatic avoid the sciatic nerve,nerve, which lies parallel to which lies parallel to the femur, it may be helpful the femur, it may be helpful for one person to restrain for one person to restrain the gerbil while a second the gerbil while a second person pulls the leg out for person pulls the leg out for injection.injection.

After the gerbil is After the gerbil is adequately sedated or adequately sedated or anesthetized, anesthetized, intravenous intravenous injections can be made into injections can be made into the femoral, saphenous or the femoral, saphenous or tail veinstail veins..

IP InjectionsIP Injections

Intraperitoneal Intraperitoneal injections are injections are accomplished off accomplished off midline in the midline in the caudal abdomencaudal abdomen, , after tilting the head after tilting the head of the gerbil down of the gerbil down to displace internal to displace internal organs forward. organs forward.

Review Review

http://www.bva-awf.org.uk/resources/tutorials/BVA03-Gerbil/Gerbil.html

Chemical restraintChemical restraint

Chemical restraint can be accomplished Chemical restraint can be accomplished with sodium with sodium pentobarbital, administered pentobarbital, administered intraperitoneally at 60 mg/kg body weightintraperitoneally at 60 mg/kg body weight..

A cocktail containing A cocktail containing ketamine, xylazine ketamine, xylazine and acepromazine can also be used at the and acepromazine can also be used at the following dosage: 0.6 ml/kg body weight, following dosage: 0.6 ml/kg body weight, administered intramuscularly, or administered intramuscularly, or subcutaneously, of a mixture of 1.5 ml subcutaneously, of a mixture of 1.5 ml (150 mg) 100 mg/ml ketamine HCI, 1.5 ml (150 mg) 100 mg/ml ketamine HCI, 1.5 ml (30 mg) of 20 mg/ml xylazine HCI and 0.5 (30 mg) of 20 mg/ml xylazine HCI and 0.5 ml (5 mg) of 10 mg/ml acepromazine ml (5 mg) of 10 mg/ml acepromazine

P#120P#120

Chemical restraintChemical restraint

Inhalation anesthesia can be Inhalation anesthesia can be accomplished with accomplished with Isoflurane Isoflurane

INFECTIOUS DISEASESINFECTIOUS DISEASES

Tyzzer's diseaseTyzzer's diseaseThe most commonly reported infectious The most commonly reported infectious disease in gerbils is Tyzzer's disease, disease in gerbils is Tyzzer's disease, an acute, often fatal, hepatoenteric an acute, often fatal, hepatoenteric disease. It is caused by disease. It is caused by Clostridium Clostridium piliformipiliformi, , an obligate intracellular, an obligate intracellular, spore-forming, filamentous, argyrophilic spore-forming, filamentous, argyrophilic rod. rod.

The organism is transmitted by the The organism is transmitted by the fecal-oral route; spores survive in the fecal-oral route; spores survive in the environment for months or years.environment for months or years.

Clinical signs include Clinical signs include sudden death, sudden death, perianal fecal staining, watery diarrhea, perianal fecal staining, watery diarrhea, anorexia, lethargy and rough hair coat anorexia, lethargy and rough hair coat

Gross lesions Gross lesions

Gross lesions of Gross lesions of Tyzzer's disease Tyzzer's disease include include hepatomegaly with hepatomegaly with yellow-white hepatic yellow-white hepatic foci of necrosisfoci of necrosis, as , as seen here, typhlitis seen here, typhlitis and and enteritis with enteritis with watery enteric watery enteric contents.contents.

TreatmentTreatment

Treatment of Tyzzer's disease is Treatment of Tyzzer's disease is often unsuccessful in gerbils, but often unsuccessful in gerbils, but oxytetracyclineoxytetracycline has been has been reported to reduce mortality in reported to reduce mortality in mice. mice.

Nonspecific enteritisNonspecific enteritis

Nonspecific enteritis in Nonspecific enteritis in gerbils may result from gerbils may result from bacterial infections, bacterial infections, such as with such as with Salmonella Salmonella spp. spp. Other possible Other possible causal agents include causal agents include heavy protozoal heavy protozoal infections and food infections and food deprivation deprivation

Signs of enteritis Signs of enteritis include perianal fecal include perianal fecal staining (seen in photo), staining (seen in photo), anorexia, depression anorexia, depression and rough hair coat and rough hair coat

Facial DermatitisFacial Dermatitis

In juvenile and adult gerbils, environmental In juvenile and adult gerbils, environmental stressors such as incompatible cagemates, stressors such as incompatible cagemates, high humidity, and overcrowding cause high humidity, and overcrowding cause release of release of Harderian gland porphyrin Harderian gland porphyrin secretions around the external nares and secretions around the external nares and eyes. eyes.

Sore noseNasal dermatitisNasal dermatitis

Accumulation of the Accumulation of the reddish-brown reddish-brown porphyrin pigment porphyrin pigment causes skin irritation causes skin irritation and eventually leads and eventually leads to self-trauma, to self-trauma, localized alopecia, localized alopecia, and moist dermatitis and moist dermatitis with erythema, with erythema, scabs, and scabs, and ulcerationulceration

Sore nose

Staphylococcus saprophyticus , S xylosis , and S aureus may secondarily invade and exacerbate the dermatitis, spreading to the forepaws and ventral thorax and abdomen. Skin lesions are pruritic and frequent scratching may result in bleeding. The condition may be self-limiting with spontaneous recovery or, more often, progressive with bacterial infection

Treatment includes carefully cleaning the skin Treatment includes carefully cleaning the skin lesions and applying lesions and applying topical antibiotics topical antibiotics (chloramphenicol 1% ophthalmic ointment, tid). (chloramphenicol 1% ophthalmic ointment, tid). Prevention requires careful control of Prevention requires careful control of environmental temperature and humidity or other environmental temperature and humidity or other sources of stress and providing sand baths or clay sources of stress and providing sand baths or clay

bedding.bedding.

Viral DiseasesViral Diseases

No naturally-occurring viral No naturally-occurring viral diseases have been reported in diseases have been reported in gerbils.gerbils.

Parasites Parasites

Parasitism of the gerbil rarely causes clinical Parasitism of the gerbil rarely causes clinical disease problems. Alopecia in aged or debilitated disease problems. Alopecia in aged or debilitated gerbils may be due to demodicosis (A.). gerbils may be due to demodicosis (A.). Scrapes Scrapes of affected areas may reveal hamster demodectic of affected areas may reveal hamster demodectic mange mites, mange mites, Demodex aurati or Demodex criceti Demodex aurati or Demodex criceti

(B.) (B.) ..

Endoparasites of the gerbil may include Endoparasites of the gerbil may include mouse mouse pinworms (pinworms (Syphacia obvelataSyphacia obvelata) which ) which can be found in the cecum and a small can be found in the cecum and a small intestinal gerbil pinworm intestinal gerbil pinworm Dentostomella Dentostomella translucidatranslucida (A.). (A.). SyphaciaSyphacia ova can be ova can be recovered on a cellophane tape test (see recovered on a cellophane tape test (see mouse parasitic diseases), while mouse parasitic diseases), while DentostomellaDentostomella ova (B.) are identified by the ova (B.) are identified by the fecal floatation test fecal floatation test

MISCELLANEOUS MISCELLANEOUS DISEASES DISEASES

Management-related Management-related conditionsconditions

Management-related Management-related problems include problems include inadvertent inadvertent starvation starvation and water deprivationand water deprivation. . The food may simply be The food may simply be too high to reach or too high to reach or inaccessible. The hopper inaccessible. The hopper may have openings that may have openings that are too narrow, or the are too narrow, or the food may be too hard for food may be too hard for weanlings to chew. weanlings to chew. Similarly, the water Similarly, the water source may be too high source may be too high to reach to reach

EpilepsyEpilepsy

The gerbil displays spontaneous The gerbil displays spontaneous epileptiform seizures. These seizures may epileptiform seizures. These seizures may be precipitated by sudden stress, handling, be precipitated by sudden stress, handling, or introduction to a novel environment.or introduction to a novel environment.   

Incidence of this syndrome is about Incidence of this syndrome is about 50% in 50% in natural populations.  The condition appears natural populations.  The condition appears to be inherited, and both seizure-resistant to be inherited, and both seizure-resistant and seizure-sensitiveand seizure-sensitive strains have been strains have been developed by selective breeding.  developed by selective breeding. 

Inbred animals can have up to 100% Inbred animals can have up to 100% incidenceincidence

Epileptiform seizure Epileptiform seizure

Seizure onset occurs Seizure onset occurs at 2 to 3 months of at 2 to 3 months of age age with seizure with seizure incidence and incidence and severity increasing severity increasing with age until the with age until the animal reaches six animal reaches six months of age. months of age.

After a seizure, it After a seizure, it may be several hours may be several hours before seizure before seizure threshold is reached threshold is reached again again

Treatment/ preventionTreatment/ prevention

The seizures have no The seizures have no obvious adverse effects obvious adverse effects and do not require and do not require treatmenttreatment. They should . They should not not be treated with be treated with diphenylhydantoindiphenylhydantoin, as it , as it can be fatal to gerbils. can be fatal to gerbils.

Handling weanlings Handling weanlings frequently is frequently is recommended to recommended to reduce the incidence of reduce the incidence of seizures later on.seizures later on.

Neoplasia Neoplasia

Older gerbils commonly develop a Older gerbils commonly develop a number of spontaneous number of spontaneous neoplasms neoplasms most commonly affecting the skin, most commonly affecting the skin, adrenal gland, kidney, spleen, adrenal gland, kidney, spleen, intestine and the female intestine and the female reproductive tracreproductive tract.  The most t.  The most frequently seen neoplasms include frequently seen neoplasms include leiomyomas, subcutaneous leiomyomas, subcutaneous fibrosarcomas, sebaceous gland fibrosarcomas, sebaceous gland adenomas and adenocarcinomasadenomas and adenocarcinomas

MelanomaMelanoma

Cutaneous tumors include Cutaneous tumors include squamous cell squamous cell carcinomas carcinomas and melanomas affecting the ear and and melanomas affecting the ear and feet. Masses may be surgically removed. The feet. Masses may be surgically removed. The prognosis varies with the size, stage, and timing prognosis varies with the size, stage, and timing of surgical excision.of surgical excision.

Tail barberingTail barbering

Gerbils Gerbils may barber may barber each other, each other, particularly if they particularly if they are overcrowded. are overcrowded. This results in This results in subordinate animals subordinate animals having hair chewed having hair chewed off in a closely-off in a closely-shaven pattern, shaven pattern, especially especially around around the base of the tail.the base of the tail.

Degloving tail woundDegloving tail wound

The tail of the gerbil is especially sensitive The tail of the gerbil is especially sensitive to degloving wounds. to degloving wounds. Gerbils Gerbils must not must not be be picked up by the tip of the tail. picked up by the tip of the tail. If the tail is If the tail is degloved, it should be amputated at the degloved, it should be amputated at the level of the breakage level of the breakage

Hey buddy, don’t look now but your tail slipped !

A slipped tail- ouch!

Questions?? Questions??