bioterios

1. Mongolian GerbilMongolian Gerbil
Meriones unguiculatusMeriones unguiculatus

2.  The Mongolian gerbilThe Mongolian gerbil isis
also known as the jird,also known as the jird,
clawed jird, sand rat, orclawed jird, sand rat, or
desert rat. It is native todesert rat. It is native to
China and MongoliaChina and Mongolia andand
was introduced into thewas introduced into the
United States in 1954.United States in 1954.
 The most common color isThe most common color is
the agoutithe agouti, shown here:, shown here:
light buff to white ventrum,light buff to white ventrum,
with mixed white, yellowwith mixed white, yellow
and black hairs dorsally,and black hairs dorsally,
giving an overall brown furgiving an overall brown fur
color.color.

3. AppearanceAppearance
 Gerbils may also beGerbils may also be black,black,
gray, white, or piebald. Theygray, white, or piebald. They
are characterized by a long,are characterized by a long,
fully furred tail, strong clawsfully furred tail, strong claws
for burrowing, and elongatedfor burrowing, and elongated
hindlimbs, uhindlimbs, used for jumpingsed for jumping
and for maintaining a semi-and for maintaining a semi-
erect posture.erect posture.
 TheThe body and the tail arebody and the tail are
each about 11-15 centimeterseach about 11-15 centimeters
in lengtin length, with the bodyh, with the body
slightly longer than the tail.slightly longer than the tail.
Adults weigh 70-150 gramsAdults weigh 70-150 grams,,
with males slightly larger thanwith males slightly larger than
females.females.

4. TaxonomyTaxonomy
 The Mongolian gerbil,The Mongolian gerbil, MerionesMeriones
unguiculatus,unguiculatus, is in the order Rodentia,is in the order Rodentia,
suborder Myomorpha and the familysuborder Myomorpha and the family
Cricetidae - the same family as theCricetidae - the same family as the
hamster.hamster.

5. Dental and vertebralDental and vertebral
formulasformulas
Their dental formula is typical of rodents.Their dental formula is typical of rodents.
Gerbils have a single maxillary andGerbils have a single maxillary and
mandibular incisor on each side. There aremandibular incisor on each side. There are
no canines or premolars. The gerbil has 3no canines or premolars. The gerbil has 3
maxillary and 3 mandibular molars on eachmaxillary 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 thoracic,They have 7 cervical vertebrae, 13 thoracic,
6 lumbar, 4 sacral and 7 or more coccygeal6 lumbar, 4 sacral and 7 or more coccygeal
vertebrae.vertebrae. ( C7 T13 L6 S4 Cy7+)( C7 T13 L6 S4 Cy7+)

6. FactsFacts
 Life SpanLife Span:: 3-4 years3-4 years on average (up to 8on average (up to 8
reported, though this is exceptional!)reported, though this is exceptional!)
 Mongolian gerbilsMongolian gerbils are not nocturnalare not nocturnal althoughalthough
they are sometimes active at night; they gothey are sometimes active at night; they go
through severalthrough several sleep/active cycles in thesleep/active cycles in the
course of 24 hourscourse of 24 hours

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

8. Sexual dimorphismSexual dimorphism
 Gerbils have a prominent,Gerbils have a prominent,
elliptical ventral markingelliptical ventral marking
gland, composed ofgland, composed of
sebaceous glands andsebaceous glands and
overlying coarse hair.overlying coarse hair.
 TheThe marking gland is moremarking gland is more
prominent in males than inprominent in males than in
females and is helpful infemales and is helpful in
sexing mature animalssexing mature animals..
 TheThe males also have amales also have a
prominent, darklyprominent, darkly
pigmented scrotumpigmented scrotum..

9. Adrenal glandsAdrenal glands
 TheThe adrenal glands (arrow) are largeadrenal glands (arrow) are large forfor
their body weight.their body weight.

10. Breeding andBreeding and
reproductionreproduction
 Female gerbils areFemale gerbils are polyestrous,polyestrous,
spontaneous ovulators with an estrous cyclespontaneous ovulators with an estrous cycle
of 4-6 daysof 4-6 days..
 They may display a slight winter breedingThey may display a slight winter breeding
depression.depression. Males and females that areMales and females that are
paired before seven weeks of age bond inpaired 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 ofHousing of
two females with a single male is anothertwo females with a single male is another
acceptable mating system.acceptable mating system.

11. ReproductionReproduction
 Gestation lasts 24-26 daysGestation lasts 24-26 days; but if the; but if the
female is bred during the postpartumfemale is bred during the postpartum
estrus, implantation may be delayed,estrus, implantation may be delayed,
increasing gestation to a total length ofincreasing gestation to a total length of
42 days42 days..
 The male gerbil should not beThe male gerbil should not be
removed from the cage when theremoved from the cage when the
young are born, because fighting mayyoung are born, because fighting may
occur when he is reintroduced.occur when he is reintroduced.

12. Reproduction cont..Reproduction cont..
 The average litterThe average litter
consists ofconsists of 3-7 blind,3-7 blind,
hairless pupshairless pups
weighing 3-4 gramsweighing 3-4 grams
each.each.
 The ears of theThe ears of the
newborn will open atnewborn will open at
3-7 days postpartum3-7 days postpartum..
 The young will beThe young will be
covered with furcovered with fur by 7-by 7-
1 0 days and their1 0 days and their
eyes will open at 2-3eyes will open at 2-3
weeks.weeks.

13. Maturation/ life cycleMaturation/ life cycle
 Gerbils are ready to be weaned atGerbils are ready to be weaned at 20-20-
30 days of age.30 days of age.
 They reach puberty atThey reach puberty at 65-85 days65-85 days..
 The reproductive lifespan of theThe reproductive lifespan of the
female lasts until aboutfemale lasts until about 12-17 months12-17 months
of ageof age and the male until two years ofand the male until two years of
age.age.

14. HUSBANDRYHUSBANDRY
 Satisfactory housing in aSatisfactory housing in a
research setting includesresearch setting includes
polycarbonate "shoebox"polycarbonate "shoebox"
cages, as shown here.cages, as shown here.
They should be at least 15They should be at least 15
centimeters (6 inches)centimeters (6 inches)
high.high.
 Each gerbil should have aEach gerbil should have a
minimum ofminimum of 116 sq.116 sq.
centimeters (1 8 sq. in.) ofcentimeters (1 8 sq. in.) of
floor space.floor space.
 A breeding pair with theirA breeding pair with their
litter should have alitter should have a
minimum of 900 sq.minimum of 900 sq.
centimeterscentimeters (140 sq. in.)(140 sq. in.)
of floor space.of floor space.

15. ManagementManagement
Cages should beCages should be
constructed with roundedconstructed with rounded
corners to discouragecorners to discourage
chewing.chewing.
Optimal temperature rangeOptimal temperature range
for gerbils is betweenfor gerbils is between 6565
and 80° F, with babiesand 80° F, with babies
doing best at 70 to 75° Fdoing best at 70 to 75° F..
The relativeThe relative humidityhumidity shouldshould
be betweenbe between 30 and 50%.30 and 50%.

16. Bedding and nestingBedding and nesting
materialsmaterials
 Absorbent bedding forAbsorbent bedding for
burrowing should beburrowing should be
provided in the cage.provided in the cage.
Opaque tubes orOpaque tubes or
boxes for hidingboxes for hiding
provide environmentalprovide environmental
enrichment and softenrichment and soft
shreddable materialsshreddable materials
for nesting mayfor nesting may
improve reproductiveimprove reproductive
performance.performance.

17. FoodFood
 Gerbils should be fedGerbils should be fed adad
libitumlibitum from feed hoppersfrom feed hoppers
that have wide openingsthat have wide openings
for easy accessibility. Thefor easy accessibility. The
feed hopper should befeed hopper should be
mounted low as newbornsmounted low as newborns
will begin to consume solidwill begin to consume solid
food at about 2 weeks offood at about 2 weeks of
age. Each adult gerbil willage. Each adult gerbil will
consume approximatelyconsume approximately 5-5-
8 grams of pelleted rodent8 grams of pelleted rodent
ration per day.ration per day.

18. WaterWater
 Captive gerbilsCaptive gerbils
need a waterneed a water
supply - either asupply - either a
water bottle or anwater bottle or an
automatic wateringautomatic watering
devicedevice

19. USES IN RESEARCHUSES IN RESEARCH
 One of the first uses of gerbils in research was inOne of the first uses of gerbils in research was in
radiation studies, because theyradiation studies, because they can tolerate muchcan tolerate much
greater whole-body radiation exposuregreater whole-body radiation exposure than otherthan other
animal species.animal species.
 They have also been used in studies ofThey have also been used in studies of endocrineendocrine
gland metabolismgland metabolism, as they have one of the largest, as they have one of the largest
ratios of adrenal weight to body weight of all animals.ratios of adrenal weight to body weight of all animals.
 Gerbils have a high incidence of spontaneousGerbils have a high incidence of spontaneous
epileptiform seizuresepileptiform seizures, usually precipitated by being, usually precipitated by being
startled or by a novel environment. This makes themstartled or by a novel environment. This makes them
an important animal model for study of epilepsy.an important animal model for study of epilepsy.

20. USES IN RESEARCHUSES IN RESEARCH
 They have been used in reproduction studies toThey have been used in reproduction studies to
evaluate antifertility drugs and in auditory research,evaluate antifertility drugs and in auditory research,
because their hearing curve is closer to man's thanbecause their hearing curve is closer to man's than
most common laboratory animals.most common laboratory animals.
 In toxicology research, gerbils have been used inIn toxicology research, gerbils have been used in
studies of food additives, pesticides, industrialstudies of food additives, pesticides, industrial
solvents and heavy metals.solvents and heavy metals.
 Gerbils are also useful in infectious diseaseGerbils are also useful in infectious disease
research. Although they are relatively free ofresearch. Although they are relatively free of
spontaneous diseases, they are susceptible tospontaneous diseases, they are susceptible to
agents from other species.agents from other species.
 And finally, they are used in parasitology research,And finally, they are used in parasitology research,
as they have been successfully infected withas they have been successfully infected with
parasites common to other species.parasites common to other species.

21. HANDLINGHANDLING
 To physicallyTo physically
restrain a gerbil,restrain a gerbil,
grasp it at thegrasp it at the basebase
of the tail - not theof the tail - not the
tip. If the tip istip. If the tip is
grasped, the skingrasped, the skin
may come offmay come off
(degloving).(degloving).

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

23. Injection siteInjection site
 The loose skin ofThe loose skin of the neck is a site forthe neck is a site for
subcutaneous injectionsubcutaneous injection

24. IM, IV injectionsIM, IV injections
 The muscles of theThe muscles of the thigh arethigh are
a site for intramusculara site for intramuscular
injections. Care must beinjections. Care must be
taken totaken to avoid the sciaticavoid the sciatic
nerve,nerve, which lies parallel towhich lies parallel to
the femur, it may be helpfulthe femur, it may be helpful
for one person to restrain thefor one person to restrain the
gerbil while a second persongerbil while a second person
pulls the leg out for injection.pulls the leg out for injection.
 After the gerbil is adequatelyAfter the gerbil is adequately
sedated or anesthetized,sedated or anesthetized,
intravenous injections can beintravenous injections can be
made into the femoral,made into the femoral,
saphenous or tail veinssaphenous or tail veins..

25. IP InjectionsIP Injections
 IntraperitonealIntraperitoneal
injections areinjections are
accomplished offaccomplished off
midline in the caudalmidline in the caudal
abdomenabdomen, after tilting, after tilting
the head of the gerbilthe head of the gerbil
down to displacedown to displace
internal organsinternal organs
forward.forward.

26. ReviewReview
 http://www.bva-awf.org.uk/resources/tutorials/BVA03-Gerhttp://www.bva-awf.org.uk/resources/tutorials/BVA03-Ger

27. Chemical restraintChemical restraint
 Chemical restraint can be accomplishedChemical restraint can be accomplished
with sodiumwith sodium pentobarbital, administeredpentobarbital, administered
intraperitoneally at 60 mg/kg body weightintraperitoneally at 60 mg/kg body weight..
 A cocktail containingA cocktail containing ketamine, xylazine andketamine, xylazine and
acepromazine can also be used at theacepromazine can also be used at the
following dosage: 0.6 ml/kg body weight,following dosage: 0.6 ml/kg body weight,
administered intramuscularly, oradministered intramuscularly, or
subcutaneously, of a mixture of 1.5 ml (150subcutaneously, of a mixture of 1.5 ml (150
mg) 100 mg/ml ketamine HCI, 1.5 ml (30mg) 100 mg/ml ketamine HCI, 1.5 ml (30
mg) of 20 mg/ml xylazine HCI and 0.5 ml (5mg) of 20 mg/ml xylazine HCI and 0.5 ml (5
mg) of 10 mg/ml acepromazinemg) of 10 mg/ml acepromazine
 P#120P#120

28. Chemical restraintChemical restraint
 Inhalation anesthesia can beInhalation anesthesia can be
accomplished withaccomplished with IsofluraneIsoflurane

29. INFECTIOUS DISEASESINFECTIOUS DISEASES
 Tyzzer's diseaseTyzzer's disease
The most commonly reported infectiousThe most commonly reported infectious
disease in gerbils is Tyzzer's disease, andisease in gerbils is Tyzzer's disease, an
acute, often fatal, hepatoenteric disease. Itacute, often fatal, hepatoenteric disease. It
is caused byis caused by Clostridium piliformiClostridium piliformi,, anan
obligate intracellular, spore-forming,obligate intracellular, spore-forming,
filamentous, argyrophilic rod.filamentous, argyrophilic rod.
 The organism is transmitted by the fecal-The organism is transmitted by the fecal-
oral route; spores survive in theoral route; spores survive in the
environment for months or years.environment for months or years.
 Clinical signs includeClinical signs include sudden death,sudden death,
perianal fecal staining, watery diarrhea,perianal fecal staining, watery diarrhea,
anorexia, lethargy and rough hair coatanorexia, lethargy and rough hair coat

30. Gross lesionsGross lesions
 Gross lesions ofGross lesions of
Tyzzer's diseaseTyzzer's disease
includeinclude hepatomegalyhepatomegaly
with yellow-whitewith yellow-white
hepatic foci ofhepatic foci of
necrosisnecrosis, as seen here,, as seen here,
typhlitis andtyphlitis and enteritisenteritis
with watery entericwith watery enteric
contents.contents.

31. TreatmentTreatment
 Treatment of Tyzzer's disease is oftenTreatment of Tyzzer's disease is often
unsuccessful in gerbils, butunsuccessful in gerbils, but
oxytetracyclineoxytetracycline has been reported tohas been reported to
reduce mortality in mice.reduce mortality in mice.

32. Nonspecific enteritisNonspecific enteritis
 Nonspecific enteritis inNonspecific enteritis in
gerbils may result fromgerbils may result from
bacterial infections, suchbacterial infections, such
as withas with SalmonellaSalmonella spp.spp.
Other possible causalOther possible causal
agents include heavyagents include heavy
protozoal infections andprotozoal infections and
food deprivationfood deprivation
 Signs of enteritis includeSigns of enteritis include
perianal fecal stainingperianal fecal staining
(seen in photo), anorexia,(seen in photo), anorexia,
depression and rough hairdepression and rough hair
coatcoat

33. Facial DermatitisFacial Dermatitis
 In juvenile and adult gerbils, environmentalIn juvenile and adult gerbils, environmental
stressors such as incompatible cagemates, highstressors such as incompatible cagemates, high
humidity, and overcrowding cause release ofhumidity, and overcrowding cause release of
Harderian gland porphyrinHarderian gland porphyrin secretions around thesecretions around the
external nares and eyes.external nares and eyes.

34. Sore noseNasal dermatitisNasal dermatitis
 Accumulation of theAccumulation of the
reddish-brownreddish-brown
porphyrin pigmentporphyrin pigment
causes skin irritationcauses skin irritation
and eventually leadsand eventually leads
to self-trauma,to self-trauma,
localized alopecia,localized alopecia,
and moist dermatitisand moist dermatitis
with erythema, scabs,with erythema, scabs,
and ulcerationand ulceration

35. 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

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

37. Viral DiseasesViral Diseases
 No naturally-occurring viral diseasesNo naturally-occurring viral diseases
have been reported in gerbils.have been reported in gerbils.

38. ParasitesParasites

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

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

41. MISCELLANEOUSMISCELLANEOUS
DISEASESDISEASES

42. Management-relatedManagement-related
conditionsconditions
 Management-relatedManagement-related
problems includeproblems include
inadvertentinadvertent starvation andstarvation and
water deprivationwater deprivation. The food. The food
may simply be too high tomay simply be too high to
reach or inaccessible. Thereach or inaccessible. The
hopper may have openingshopper may have openings
that are too narrow, or thethat are too narrow, or the
food may be too hard forfood may be too hard for
weanlings to chew.weanlings to chew.
Similarly, the water sourceSimilarly, the water source
may be too high to reachmay be too high to reach

43. EpilepsyEpilepsy
 The gerbil displays spontaneousThe gerbil displays spontaneous
epileptiform seizures. These seizures mayepileptiform 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 aboutIncidence of this syndrome is about 50% in50% in
natural populations. The condition appearsnatural populations. The condition appears
to be inherited, and both seizure-resistantto be inherited, and both seizure-resistant
and seizure-sensitiveand seizure-sensitive strains have beenstrains 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

44. Epileptiform seizureEpileptiform seizure
 Seizure onset occursSeizure onset occurs
at 2 to 3 months of ageat 2 to 3 months of age
with seizure incidencewith seizure incidence
and severity increasingand severity increasing
with age until thewith age until the
animal reaches sixanimal reaches six
months of age.months of age.
 After a seizure, it mayAfter a seizure, it may
be several hoursbe several hours
before seizurebefore seizure
threshold is reachedthreshold is reached
againagain

45. Treatment/ preventionTreatment/ prevention
 The seizures have noThe seizures have no
obvious adverse effectsobvious adverse effects
and do not requireand do not require
treatmenttreatment. They should. They should
notnot be treated withbe treated with
diphenylhydantoindiphenylhydantoin, as it, as it
can be fatal to gerbils.can be fatal to gerbils.
 Handling weanlingsHandling weanlings
frequently is recommendedfrequently is recommended
to reduce the incidence ofto reduce the incidence of
seizures later on.seizures later on.

46. NeoplasiaNeoplasia
 Older gerbils commonly develop aOlder gerbils commonly develop a
number of spontaneousnumber of spontaneous neoplasms mostneoplasms most
commonly affecting the skin, adrenalcommonly affecting the skin, adrenal
gland, kidney, spleen, intestine and thegland, kidney, spleen, intestine and the
female reproductive tracfemale reproductive tract. The mostt. The most
frequently seen neoplasms includefrequently seen neoplasms include
leiomyomas, subcutaneousleiomyomas, subcutaneous
fibrosarcomas, sebaceous glandfibrosarcomas, sebaceous gland
adenomas and adenocarcinomasadenomas and adenocarcinomas

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

48. Tail barberingTail barbering
 GerbilsGerbils may barbermay barber
each other, particularlyeach other, particularly
if they areif they are
overcrowded.overcrowded. ThisThis
results in subordinateresults in subordinate
animals having hairanimals having hair
chewed off in a closely-chewed off in a closely-
shaven pattern,shaven pattern,
especiallyespecially around thearound the
base of the tail.base of the tail.

49. Degloving tail woundDegloving tail wound
 The tail of the gerbil is especially sensitive toThe tail of the gerbil is especially sensitive to
degloving wounds.degloving wounds. GerbilsGerbils must notmust not be picked upbe picked up
by the tip of the tail.by the tip of the tail. If the tail is degloved, itIf the tail is degloved, it
should be amputated at the level of the breakageshould be amputated at the level of the breakage

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

51. A slipped tail- ouch!

52. Questions??Questions??