Biology, Husbandry and Diseases of the Hamster VCM 656 - PowerPoint PPT Presentation

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Biology, Husbandry and Diseases of the Hamster VCM 656

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Regional enteritis. Terminal ileitis. Transmissible ... E. coli. Campylobacter-like. Desulfovibrio-like. Transmission. Fecal-oral. Fomites. Direct contact ... – PowerPoint PPT presentation

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Title: Biology, Husbandry and Diseases of the Hamster VCM 656


1
Biology, Husbandry and Diseases of the
HamsterVCM 656
2
Taxonomy
  • Order Rodentia
  • Family Cricetidae
  • Genera Cricetus, Mesocricetus, Cricetulus,
    Phodopus
  • Animals of these genera are characterized by
    large cheek pouches and short tails
  • Native to SE Europe and Asia Minor
  • Live in deep tunnels and hoard grain
  • Nocturnal, mostly solitary

3
Syrian hamster Golden hamsterMesocricetus
auratus
  • Advantages as a research model
  • Availability and ease of reproduction.
  • Relatively free of spontaneous diseases, but
    susceptible to many induced pathogens.
  • Special anatomical and physiological features
  • Cheek pouches
  • Hibernation
  • Radioresistance
  • Others
  • Short life cycle and rapid development.

4
  • Syrian hamster Mesocricetus auratus
  • 22 chromosome pairs
  • 18 centimeters long, 85-130 gm adult weight
  • Chinese hamster Cricetulus griseus
  • 11 chromosome pairs
  • 9 centimeters long, 42 gm adult weight

5
Biological Data
  • Average life span 18-36 months
  • Sexual maturity 2 months
  • Average adult weight 85-130 gm
  • Heart rate 300-470 bpm
  • Respiratory rate 38-110 bpm
  • Rectal temperature 37.6 oC (100oF)

6
Sexual Dimorphism
7
Sexual Dimorphism
  • Male
  • Greater anogenital distance
  • Scrotal bulges at tail base
  • Female
  • 3 distinct openings rectum, vulva, urethra

8
Mouth
  • Dentition
  • I 1/1, C 0/0, P 0/0, M 3/3
  • Continuously growing teeth
  • Cheek pouch
  • Storage food, bedding, young
  • Immunological privileged site

9
Flank glands
  • Sebaceous glands on each flank
  • Sexual odors and olfactory territorial marking
  • More noticeable in sexually active males.

10
Two-Chambered Stomach
  • Distinct separation
  • Squamous forestomach
  • Glandular stomach

11
Reproductive Anatomy
  • Female
  • Bicornuate uterus
  • Each uterine horn opens separately into vagina
  • 12-14 nipples
  • Male
  • Os penis
  • Large seminal vesicles

12
Husbandry
  • Solid bottom caging
  • Wide feeder slots
  • Nocturnal
  • Coprophagic
  • Tend to eliminate in 1 corner
  • Like hiding places, are escape artists
  • Females are dominant and may attack males
  • Mature animals are usually housed separately
  • Untamed or startled hamsters may bite

13
Reproduction
  • Estrus cycle 4 days
  • Gestation 16 days
  • Litter size 6-8
  • Weaning 21-28 days
  • Neonates hairless, toothless, eyes and ears
    closed
  • Cannibalism
  • Do not disturb mother for 7-10 days postpartum
  • Provide fresh greens, treat food just prior to
    parturition
  • Young require access to water, in addition to
    mothers milk
  • Estrus end marked by postovulatory vaginal
    discharge
  • Copious, white, thick, tenacious, distinctive
    odor

14
Hibernation
  • Cold stimulates food gathering
  • Do not fatten prior to hibernation
  • May hibernate at 5oC (41oF)
  • Intermittent sleep 1-7 days, arousable
  • Will starve if dont eat periodically
  • Normally eat several times a day
  • Food intake does not vary from day-to-day
  • Hamsters do not respond to fasting by increased
    food consumption.

15
Restraint
16
Restraint - Scruffing
17
Bacterial Disease
  • Predisposing Factors
  • Shipping
  • Overcrowding
  • Poor nutrition
  • Sanitation
  • Parasitic or viral disease
  • Experimental manipulation

18
Proliferative Ileitis
  • Common synonyms
  • Wet tail
  • Regional enteritis
  • Terminal ileitis
  • Transmissible ileal hyperplasia
  • Enzootic intestinal adenocarcinoma

19
Proliferative Ileitis
  • Clinical signs
  • Watery diarrhea
  • Dehydration
  • Lethargy
  • Irritable
  • Anorexia
  • Weight loss

20
Proliferative Ileitis
  • Intracellular bacteria
  • Undetermined etiologic agent
  • E. coli
  • Campylobacter-like
  • Desulfovibrio-like
  • Transmission
  • Fecal-oral
  • Fomites
  • Direct contact
  • Rapid spread
  • Most susceptible
  • 3-8 weeks of age

21
Proliferative Ileitis
  • Gross pathology
  • Thick, congested ileum
  • Enlarged mesenteric lymph nodes
  • Peritonitis
  • Adhesions

22
Proliferative Ileitis
  • Microscopic pathology
  • Epithelial hyperplasia
  • Crypt, villous and glandular
  • Markedly increased mucosal thickness
  • Villar necrosis
  • Microabscesses
  • Crypt and wall
  • Mucosal edema
  • Lymphoid hyperplasia

23
Proliferative Ileitis
  • Treatment
  • Antibiotics and fluid support
  • Variable results
  • Control
  • Remove infected hamsters
  • Sanitation
  • Research complications
  • May have high prevalence
  • Variable morbidity 20-60
  • High mortality 90

24
Clostridial Enterotoxemia
  • Clostridium difficile
  • Anaerobic, cytotoxin production
  • Normal gut inhabitant low numbers in cecum
  • Environment
  • Bacterial overgrowth
  • Secondary to antibiotic administration
  • High fat diets, stress
  • Clinical Signs
  • Anorexia, rough hair coat
  • Diarrhea, marked dehydration
  • Death within 4-10 days

25
Clostridial Enterotoxemia
  • Gross pathology
  • Characteristic gross lesions
  • Markedly hemorrhagic distal ileum
  • Distended cecum
  • Acute case
  • Hyperemia of SI
  • Vascular congestion of cecal vessels
  • Mucosal hemorrhages
  • Fluid-filled cecum

26
Clostridial Enterotoxemia
  • Microscopic pathology
  • Marked mucosal hemorrhage
  • Loss of mucosal architecture
  • Submucosal edema

27
Clostridial Enterotoxemia
  • Diagnosis
  • History and clinical signs
  • Characteristic gross and microscopic lesions
  • Isolation of large numbers of C. difficile on
    anaerobic culture
  • Cell culture assay for clostridial cytotoxin B
  • Treatment
  • Vancomycin, 20 mg/kg, daily, PO
  • Effective in controlling preventing clostridial
    disease
  • Major adverse effect severe gaseous cecal
    distention death

28
Tyzzers Disease
  • Clostridium piliforme
  • Obligate, intracellular, spore-forming bacteria
  • Fecal-oral transmission
  • Lesions may occur in
  • Heart
  • Intestine
  • Liver

29
Tyzzers Disease
  • Clinical signs
  • Subclinical until stressed
  • Death without signs
  • Hunched posture, rough hair coat
  • Diarrhea
  • Pale yellow and watery
  • Staining tail and ventral abdomen

30
Tyzzers Disease
  • Gross pathology
  • Liver - most common
  • Hepatomegaly
  • Multifocal hepatic necrosis
  • Intestine
  • Ileum through colon
  • Serosal edema
  • Gaseous distention
  • Occasional hyperemia or hemorrhage

31
Tyzzers Disease - Microscopic pathology
32
Tyzzers Disease
  • Diagnosis
  • Gross and histologic lesions
  • Typical bacteria clusters on silver stain
  • ELISA tests
  • Treatment
  • Antibiotics may control outbreak, but not
    eliminate infection
  • Control
  • Remove symptomatic and/or serological positive
    animals
  • Improve sanitation

33
Salmonellosis
  • Uncommon
  • S. typhimurium or S. enteriditis
  • Fecal-oral transmission
  • Clinical signs
  • Lethargy, rough hair coat, anorexia, weight loss,
    increased respiratory rate
  • Gross pathology
  • Pulmonary hemorrhages, multiple liver white
    spots, hyperemic lymph nodes
  • Microscopic pathology
  • Thrombosis hepatic and pulmonary veins
  • Multifocal interstitial pneumonia
  • Multifocal hepatic necrosis
  • Control Depopulation - Zoonotic

34
Respiratory Disease
  • Usually associated with streptococcal or
    pasteurella infections
  • Clinical signs include
  • Nasal and ocular discharge, anorexia, depression,
    dehydration, labored breathing, weight loss
  • Gross lesions
  • Lung consolidation
  • Conjunctivitis
  • Otitis interna
  • Diagnosis
  • Clinical signs
  • Gross lesions
  • Culture

35
Lymphocytic Choriomeningitis
  • Arenavirus, RNA
  • Transmission
  • Urine (feral mice possible reservoir), direct
    contact, fomites, aerosols, tumor transplantation
  • Clinical signs
  • Vary with age, animal strain, viral strain, route
    dose of infection, immunocompetence
  • Naturally occurring disease persistent,
    subclinical
  • Experimental neonatal infection chronic wasting
    disease

36
Lymphocytic Choriomeningitis
  • Zoonotic
  • Spread by aerosol and direct contact
  • Pet research hamsters
  • Virus-infected tissues, transplantable tumors,
    cell lines
  • Human clinical symptoms
  • Initially
  • Fever, headache, myalgia, nausea, vomiting, sore
    throat, photophobia
  • Recurrence
  • Sudden appearance of meningeal signs, focal
    hemorrhagic meningoencephalitis
  • Differential diagnosis
  • Influenza, mononucleosis, herpes encephalitis,
    tuberculous meningitis

37
Demodecosis
  • Two demodectic mites in hamsters
  • Clinical signs
  • Alopecia without pruritis and without
    inflammation
  • Increased incidence with age
  • More common in males

38
Demodecosis
  • Demodex criceti
  • Small, rounded
  • Epidermal pits
  • Demodex aurati
  • Long, thin
  • Hair follicles

39
Pinworms
  • Hamster pinworm
  • Syphacia mesocriceti
  • Mouse pinworms
  • Syphacia obvelata
  • Aspicularis tetraptera

40
Tapeworms
  • Hymenolepis nana dwarf tapeworm
  • Usually resides in lower small intestine
  • Very small 7-100 mm long
  • Indirect life cycle pass through a vector
  • Direct life cycle
  • Can reinfect via coprophagy
  • Zoonotic

41
Tapeworms
  • Hymenolepis diminuta
  • Rat tapeworm
  • Upper small intestine
  • Much larger 60 cm
  • Indirect life cycle
  • Severe infections
  • Retarded growth, emaciation
  • Intestinal impaction/occlusion
  • Death

42
Atrial Thrombosis
  • Spontaneous cardiac thrombi in aged hamsters
  • Common 13 to 27 months of age
  • Usually left atrium
  • Both sexes affected
  • Occurs earlier in females
  • Clinical signs
  • None prior to death
  • Tachypnea cyanosis
  • Postmortem findings
  • Ventricular hypertrophy
  • Nonseptic inflammation
  • Myocardial degeneration
  • Pulmonary edema and plural effusion

43
Amyloidosis
  • Most common disease of aging in hamsters
  • 80 over 18 months
  • Clinical signs
  • Edema, ascites, wasting, hypoproteinemia,
    proteinuria
  • Multiple tissues may be affected
  • Kidneys first and most common
  • Normal glomerular architecture obscured by pink
    amyloid

44
Amyloidosis
  • Liver
  • Deposits in vascular walls and portal areas
  • Diagnosis
  • Confirmed by Congo red stain of tissues
  • Apple green birefringence with polarized light

45
Polycystic Liver Disease
  • Common, incidental finding in hamsters over 1
    year of age (76)
  • Development of large cysts
  • Surface parenchyma
  • Congenital in origin
  • No clinical signs

46
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