Adobe PDF - Charles Louis Davis DVM Foundation

7/15/2013
Photograph Credits
Pathology of Guinea Pigs, Hamsters and Gerbils
Dr. Paul Stromberg
Dr. Dean Percy
Bruce H. Williams, DVM,
DACVP
Email:
williamsb@afip.osd.mil
Dr. Charles Clifford
Dr. John King
Dr. Marti Hanes
Dr. Michael Eckhaus
Dr. Francisco Carvalho
Coloring
Guinea Pigs
Albino guinea
pigs are
actually not
albino at all,
but
“acromelanic.”
Mammary glands
Two inguinal
conical nipples.
2-4 pups per
litter. (Not
“piglets”!)
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Vesicular glands
Boars have
prominent
vesicular glands
which have
been
misinterpreted
as uterine
horns!
Vaginal closure membrane
The membrane
is open at
estrus,
parturition, and
day 26-27 of
gestation.
Pulmonary arterial media
Walls of
pulmonary
arterioles are
naturally thick.
Pulmonary lymphoid nodules
Cause??
Pregnancy
Imminent
delivery
signalled by
separation of
symphysis.
Pups are
precocious.
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Kurloff bodies
Kurloff bodies
Normal
inclusions in
leukocytes –
elevated in
pregnancy and
with estrogen
supplementation.
Most common in spleen in non-pregnant animals.
Bordetella bronchiseptica
•In pet guinea pigs, is
important.
•Mortality most
common in young
guinea pigs in winter.
•Interspecies
transmission can
occur.
• Transmission is
primarily airborne.
Streptococcus pneumoniae
•Fibrinous
pleuopneumoniae
•Not common today,
but infected colonies
can have up to 50%
carriers.
Adenovirus infection
• Necrotizing
bronchopneumonia
• Focuses on airways
•Low morbidity and
mortality, so current
estimates of incidence
may be low.
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Rhabdomyomatosis
Incidental finding – foci of glycogen
laden cardiomyocytes.
Metastatic calcification
May affect soft
tissues or
viscera.
Cause unknown
by dietary factors
are suspected.
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Malocclusion
Moist dermatitis
Continuous
growth like
other rodents.
Overgrown
cheek teeth a
worse
management
problem than
incisors.
Cytomegalovirus
• Rarely clinical
• Inclusions also in
liver, spleen, lung,
kidney
•Systemic disease in
weanlings, rarely in
pregnant animals.
Gastric torsion/bloat
intusussusception
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Eimeria caviae
• Common in
breeding colonies
•Weanlings
•Clinical disease is
seen only with
heavy infections
Fecal impaction
Seen in older
guinea pigs
due to muscle
atrophy or
impaired
cecotrophy.
Van Robaesys M et al. Typhlitis caused by intestinal Serpulina-like bacteria in domestic
guinea pigsJ Clin Microbiol. 1998 Mar;36(3):690-4.
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Yes, I know this picture sucks!!!
Liver – lipidosis – preg toxemia
Spleen salmonella
Idiopathic hepatic necrosis
Subcapsular
areas of
coagulative
necrosis. May
be due to
terminal
hypoxia. Have
to rule out
infectious
causes.
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Malignant lymphoma
• Cavian leukemia
• C-type
retrovirus???
• Usually lung
adults
• Usually associated
with leukemia
Liver – leukemia - percy
Malignant lymphoma
• Leukemia may
reach >150,000 mm3
•Cells are
lymphoblastic
Vitamin C deficiency
• Guinea pigs
require Vit C.
supplementation
•Vitamin C is
cofactor of lysyl
oxidas and proline
hydroxlase, which
are integral in
tropocollagen
formation
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Ribs - scurvy
Bumblefoot
• Predisposed by
poor sanitation,
rough flooring,
unclipped nails.
•May develop
osteomyelitis
Parasitic dermatitis - trixascarus
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Alopecia
• Pregnancy
• Weaning (loss
of baby fur)
• Protein
deficiency
• Rough cages
• Parasites
• Infections
Guinea Pig Inclusion Conjunctivitis
• “Weepy eye”
• Chlamydophila
psittaci
•Widespread selflimiting disease
•Young guineas
•Can see
genitourinary and
respiratory lesions.
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Williams, D. Ocular disease in the guinea pig. Vet Opthalmol 2010 Sep; 13 Suppl 4:54-62.
Williams, D. Ocular disease in the guinea pig. Vet Opthalmol 2010 Sep; 13 Suppl 4:54-62.
Torres-Velez F J et al. Vet Pathol 2008;45:576-585
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Bordetella – endometritis - percy
Cystic ovary - percy
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Glomerulosclerosis
Kidney - polycystic
Multifactorial
disease of gp’s
>1yr. Cause
unknown, but
glomeruli are
largely spared.
Urinary calculi
Dystocia-anasarca
• Proximity of
urethra to anus in
older sows
predisposes to E.
coli cystitis
Hamsters
Syrian Hamsters
•“Golden Hamster”
• 22 chromosome pairs
• Popular pet – comes
in a variety of colors
and angora (teddy
bear)
• Will bite you as soon
as look at you
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Chinese Hamster
•“Grey Hamster”
• 11 chromosome pairs
Hip glands
• Pigmented
sebaceous
glands
• Mark territory
•Secrete during
sexual arousal
Lawsonia intracellularis
• “Wet-tail”
• Diffuse proliferative
ileitis
•High morbidity and
mortality in Syrian
hamsters
•Hamsters resistant to
experimental disease
by 10-12 weeks
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Bloat enterocolitis– hp infection
Fox et al. J Clin Microbiol. 2009 Nov;47(11):3673-81. Epub 2009 Sep 16. Chronic hepatitis, hepatic dysplasia, fibrosis, and
biliary hyperplasia in hamsters naturally infected with a novel Helicobacter classified in the H. bilis cluster.
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Tyzzers
Hymenolepis
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Rectal prolapse
Hepatocyte inclusions
Look hard
enough
you can
see them
in any
species.
Polycystic disease
Common
problem in
hamsters –
liver most
common site.
Also seen in
repro organs,
pancreas,
adrenals.
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Atrial thrombosis
Amyloidosis
• Syndrome
ranges from
asymptomatic to
CHF.
• May show
evidence of
organization and
hypertrophy of
heart muscle.
Atrial thrombosis
Arteriolar Nephrosclerosis
Very
similar to
disease
seen in rat.
Cause
unknown.
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Paraovarian cysts
Nothing
new here –
let’s keep
moving…
Fig. 1. Brain; hamster.
Edwards J F et al. Vet Pathol 2006;43:523-529
Spontaneous hemorrhagic necrosis
• Fetal hamsters
deficient in Vitamin
E during
development.
•Recognized in last
third of pregnancy.
•Dam may
cannibalize (yum
yum!).
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Hamster
papovavirus
• Polyomavirus vey
similar to PVM.
•Transmissible
lymphoma
•Keratinizing hair
follicle tumors
•Virus can cause
lytic infection or
transformation of
cells.
•Passed in urine
Demodicosis
Demodicosis
• D. aurati or D.
criceti
•Very common in
old hamsters ot
those being
experimentally
manipulated
D criceti – live in epidermal
pits
D aurati – live in hair follicles
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Martorell,J. Bacterial pseudomycetoma in dwarf hamster. Vet Dermatol 2006 Dec; 17(6):449-452.
Cutaneous lymphoma
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26
PATHOLOGY OF
GUINEA PIGS, HAMSTERS and GERBILS
Instructor:
Bruce H. Williams, DVM, DACVP
Senior Pathologist, Joint Pathology Center
(301) 295-6193
Email: bruce.williams2@amedd.army.mil
PURPOSE
The purpose of this 1.5-hour block of instruction is to gain knowledge and experience in
the gross diagnosis of diseases of these three rodent species which are actually very
rarely used in research today. In most cases, among pathologists, interest in these
species generally stems from board preparation.
There is extensive overlap in diseases affecting these species (especially infectious
disease) and other rodents such as rats and mice, although each species does have
one or two unique spontaneous diseases to call their own. When confronted with
disease presentation in this species, the observer is well-cautioned to consider the
presentation in light of their experience with other rodents and lagomorphs.
I have included a brief morphologic diagnosis for each entity. The formulation of
concise, accurate morphologic diagnoses is a major pursuit of every good pathologist,
especially those who seek certification in this specialty. The formulation of a good
morphologic diagnosis is a learned skill; for those seeking additional experience in this
endeavor, I would suggest attendance at the annual CL Davis Descriptive Pathology
Course at a vet school near you (check www.cldavis.org for the location of the 2013
course.
1
Slide Organ
No.
1
Condition
Morphologic
Diagnosis
TITLE SLIDE
2
PHOTOGRAPH CREDITS
3
GUINEA PIGS
4
Skin, pinna
5
Plantar aspect of
feet
6
Notes
Acromelanism
Acromelanism
Teats
Normal
GPs have two paired conical
inguinal nipples
7
Vesicular glands
Normal
Male GPs have extremely large
vesicular glands.
8
Penis
Normal
The end of the penis has to horny
“styles” on either side of the
urethra.
9
Vulva
Vaginal closure
membrane
Like other hystricomorphs,
females have a vaginal closure
membrane which is perforated
only at estrus and parturition.
10
Lung
Pulmonary arterial
hyperplasia
11
Lung:
Perivascular
lymphoid nodules
These are common findings in
guinea pigs and do not necessarily
12
Presentation
Pregnancy
Sows can more than double their
weight during pregnancy – infants
are large and precocious.
13
Peripheral blood
Kurloff body
14
Spleen
Kurloff cells
Kurloff cells contain a single PASpositive secretory granule, are
more prevalent in females, and
may serve anti-cancer or immunemodulating functions. They are
seen in increased numbers in the
Smooth muscle
hyperplasia of
pulmonary arteries
2
This is a normal finding in guinea
pigs and should not be construed
as evidence of pulmonary
hypertension.
placenta and spleen, and estrogen
administration causes a rise in
numbers.
15
16
Lung
Bordetella
bronchiseptica
Multifocal to coalescing
suppurative
bronchopneumonia
B. bronchoseptica is one of the
most important GP pathogens.
Due to its predilection for ciliated
epithelium, it causes classic
bronchopneumonia and may be
also recovered from the tympanic
bulla and uterus. Rabbits may
serve as a source of infection.
17
Lung, heart
Streptococcus
pneumonia
Diffuse severe
fibrinosuppurative
pleuropneumonia and
fibrinous pericarditis
Not as commonly seen today,
pneumococcal infections often are
triggered by environmental
changes. Suppurative lesions in
multiple organs and
fibrinosuppurative exudates in
body cavities are characteristic.
High mortality may be seen in
outbreaks.
18
19
Lungs
Adenoviral
pneumonia
Bilaterally symmetrical
necrotizing bronchitis
and bronchiolitis
Adenoviral pneumonia,
characterized by necrosis of airway
epithelium and prominent
intranuclear inclusions, may have
up to 100% in outbreaks.
Outbreaks usually occur following
experimental manipulation.
20
21
Heart
Rhabdomyoma
Focally extensive
Cardiac muscle
glycogenosis
This is a common incidental finding
seen in increased prevalence with
age. The condition is currently
thought to be a glycogen
metabolism disorder
22
Aorta
Aortic
mineralization
Focally extensive aortic
mineralization
23
Heart
Metastatic
calcification
Multifocal to coalescing
epicardial and
myocardial
mineralization
Metastatic calcification is a
common finding in older guinea
pigs, and maybe worsened by diets
with low magnesium, high calcium,
and high phosphorus diets.
3
24
Intestine, stomach,
kidneys
Multifocal to coalescing
gastric and intestinal
serosal mineralization,
multifocal to coalescing
renal mineralization.
25
Cheek teeth
Malocclusion
Malocclusion of cheek
teeth with lingual
entrapment
Normal growth of cheek teeth in
guinea pigs results in lingual spur
formation in the mandible, and
buccal spurs in the maxilla.
26
Facial skin
“Slobbers”
Moist facial dermatitis
“Slobbers” is a result of
malocclusion in rodents and
lagomorphs.
27
Salivary gland
Cytomegalovirus
28
Lung
Multiple intranuclear
inclusions in salivary
ductular epithelium
Cytomegalovirus is a latent
infection in many gp colonies
which infects salivary gland,
kidney, and liver. Rare cases of
systemic CMV have been reported
in weanlings, and occasional cases
of lymphoproliferative disease
may be seen.
Stomach
Bloat
Diffuse gastric
dilatation
Gastric dilatation and volvulus are
occasionally seen as a sporadic
finding; predisposing factors have
not been identified.
30
Intestine
Intussusception
Focal jejunal
intussusception
31
Cecum
Coccidiosis
Diffuse chronic
necrotizing typhlitis.
E. caviae may cause increased
severity of a number of other
enteric diseases, or weight loss
and debilitation in weanlings.
32
Kidney
Multifocal tubular
epithelial coccidial
schizonts
Klossiella equi is a relatively nonpathogenic coccidian which
parasitizes renal tubular
epithelium and oocysts are shed in
the urine.
33
Presentation
Diffuse catarrhal and
Young guinea pigs less than 6
29
Cryptosporidium
4
34
Intestine
wrairi
hyperplastic enteritis
months manifest disease with ill
thrift, weight loss, and diarrheic
feces.
35
Colon
Colonic
spirochetosis
Diffuse marked colonic
spirochetosis
A 1998 article in J. Clin Micorbiol
described a lethal outbreak of
colonicspirochetosis similar to that
seen in pigs and primates. Bacteria
were seen in thick mats covering
cecal mucosa. Animals would
break with watery diarrhea and die
within 24 hr.
36
Anus
Anal impaction
Anal impaction
Seen as a result of perineal muscle
wasting in older guinea pigs.
37
38
Liver
Salmonellosis
Multifocal to coalescing
necrotizing and
granulomatous
hepatitis
39
Spleen
Now uncommon in lab animal
colonies, the “paratyphoid
nodules” of Salmonella
typhimurium are a rare finding.
Outbreaks claim 50% mortality,
with weanlings and pregnant sows
hardest hit. Zoonotic potential
(and potential for human sources)
must be considered.
40
Liver
Idiopathic hepatic
necrosis
Multifocal to coalescing
hepatic coagulative
necrosis
An occasional finding in guinea
pigs, terminal blood flow changes
in the liver are postulated to be
the cause.
41
Liver
Pregnancy toxemia
Diffuse hepatic lipidosis
Two forms, the metabolic and
circulatory forms are identified in
gps. The metabolic form is seen in
obese sows during last 2-3 weeks
of pregnancy is the result of caloric
deprivation due to changes in diet
or environment. The circulatory
form results in uteroplacental
ischemia due to compression of
the aorta caudal to the renal
vessels by the gravid uterus, and is
also associated with uterine and
Multifocal to coalescing
necrotizing and
granulomatous
splenitis
5
placental hemorrhage and
necrosis.
42
43
Cervical lymph
node
Cervical
lymphadenitis
Focally extensive
suppurative cervical
lymphadenitis
Cervical lymph nodes are a
characteristic location for
abscesses due to S. zooepidemicus
(Lancefield Group C). Inoculation
is usually the result of oral
abrasions with contamination.
Most guinea pigs harbor the
organism in the nasopharynx.
44
Cervical lymph
nodes
Cavian leukemia
Cervical node
lymphoma
45
Liver
46
Liver
Cavian leukemia is a leukemic form
of lymphoma (as the name
suggests) with massive numbers of
lymphoblasts within circulating
blood and infiltrating numerous
organs. Both type C retrovirus
particles have been seen in the
disease, and it has been
transmitted by transplanted cells
and cell-free extracts.
47
Stifles
Hepatic lymphoma
Hypovitaminosis C
(scurvy)
Bilateral periarticular
hemorrhage
Focally extensive
physeal elongation with
failure of remodeling
48
49
Costochondral
junction
50
Hind feet
Diffuse costochondral
osteodystrophy
Ulcerative
pododermatitis
Bilateral chronic
suppurative
pododermatitis
6
Vitamin C is a cofactor for lysyl and
proline hydroxylases, a
requirement of the proper crosslinking of Type I and IV collagen.
Deficiency results in mineralized
abnormal cartilage that cannot be
remodeled and converted to bone.
Deficient type IV collagen results in
increased capillary fragility. Other
lesions include odontoblastic
defects, decreased cholesterol
metabolism, decreased resistance
to bacterial infections, and
aberrations in amino acids.
Ulcerative pododermatitis (also
known as “bumblefoot”, is a
common problem in guinea pigs
associated with wire cages, poor
sanitation, and obesity. The
infection is often due to coagulasepositive S. aureus and severe cases
may be associated with systemic
amyloidosis.
51
Face
Sarcoptic mange
Focally extensive
ulcerative and
eosinophilic dermatitis
Trixacarus caviae, the sarcoptid
mite of the guinea pig causes
intense pruritus and crusting
excoriations over the body.
Hematologic signs may be seen,
and severe pruritus may result in
seizures. Affected animals may
lose boy condition and die.
52
Hair
Pediculosis
Diffuse pelagic
peiculosis
Gliricola porcelli and G. ovalis are
large common lice that are often
seen in guinea pigs.
53
Face
Dermatophytosis
Focally extensive
proliferative and
hyperkeratotic
dermatitis
Usually due to T. mentagrophytes,
dermatophytosis is common in
guinea pig colonies (although most
animals are asymptomatic.
Environmental condition may
predispose to outbreaks.
56
Abdomen
Telogen effluvium
Diffuse alopecia
Telogen effluvium can occur in a
number of conditions, especially
pregnancy, weaning, or other
stressful conditions.
57
58
Haired skin
Trichofolliculoma
Cutaneous
trichofolliculoma
Trichofolliculoma is the most
common skin neoplasm of gps, is
invariable benign, and
differentiates toward all three
segments of the hair follicle.
59
Perineum
Urine scald
Focally extensive
perineal exfoliative
dermatitis
Urine scald in any pet rodents or
lagomorphs suggests poor
husbandry/sanitation.
54
55
7
60
Eye
Guinea pig
inclusion
conjunctivitis
Focally extensive
suppurative
conjunctivitis
Usually seen in gps from 4-8
weeks, GPIC (due to C. psittaci )is
usually a self-limiting disease.
Other syndromes, such as
pneumonia or abortions have been
reported.
61
Eye
“Pea eye”
Unilateral prolapse of
the third eyelid
The third eyelid is prolapsed as a
result of swelling of the lachrymal
gland and/or local fatty tissue.
62
Eye
Cataracts
Lenticular cataract
In a 2010 publication in Vet
Opthalmology, a study of 1000
guinea pigs revealed lenticular
abnormalities to be the most
common, wth 17% of animals
having cataract, and 21% to
haveother lens abnormalities, such
as lenticular sclerosis.
63
Eye
Heterotopic bone
Multifocal to coalescind
iridal osseous
metaplasia
Choristomas of bone within the
periphery of the iris has been
reported in the guinea pig, and
seen in almost 3% of individuals. It
is an incidental finding.
64
Presentation
Lethal white
Multiple defects
25% of the offspring of roan or
Dalmatian guinea pigs are
homozygous for the roan allele,
resulting in a constellation of birth
defects including white coloration,
microopthalmia, deafness,
malocclusion, malabsorption, and
a poor immune system.
65
Spleen,cerebrum
Nipah virus
Multifocal splenic
vasculitis; neuronal
inclusion
Guinea pigs are animal models for
Nipah virus, a virus causing
widespread vasculitis in the
spleen, lung, and brain of humans,
which results in 92% mortality.
66
Presentation
Otitis
media/interna
Torticollis
67
Radiograph
Normal middle ear
The most common cause of otitis
media/interna in the guinea pig is
Bordetella bronchiseptica – a
bacterium that is found amost
8
68
Otitis
media/interna
Bilateral suppurative
otitis media
exclusively in areas containing cilia
(respiratory tract, inner ear,
genital tract.
69
Uterus
Bordetella
bronchiseptica
Diffuse chronic and
suppurative
endometritis
B. bronchiseptica is occasionally
isolated from the uterine tract,
and during outbreak, pregnant
sows may abort or deliver
stillborn.
70
Ovaries
Cystic rete ovarii
Bilateral ovarian cysts
Cystic rete ovarii are associated
with decreased reproductive
performance in sows aged 1.5
years or older.
71
Uterus
Mucometra
Mucometra
Mucometra, hydrometra, and
cystic endometrial hyperplasia
have all been reported in
association with cystic rete ovarii.
72
Kidney, adrenal
gland
Segmental
nephrosclerosis
Multifocal to coalescing
fibrosing interstitial
nephritis
GPs have a characteristic pattern
of segmental fibrosis which
parallels chronic progressive renal
disease in other species. Note the
very large size of the adrenal gland
in the GP.
73
Kidney
Segmental
nephrosclerosis
74
Kidney
Polycystic kidney
Multiple renal cortical
cysts
It happens in guinea pigs just like
in other species.
75
Urinary bladder
Urolithiasis
Multiple cystic calculi
Cystic calculi are seen in older
sows, and chronic bacterial UTIs
are considered a major
predisposing cause.
76
Fetus, presentation
Anasarca
Dystocia is a common problem in
gps due to the large size at births.
HANSTERS
77
78
In segmental nephrosclerosis, the
glomeruli are largely spared.
Presentation
Syrian or Golden
Hamster
Most Golden Hamsters today
originated from the same litter
captured in Syria in 1930, resulting
9
in a low number of MHC genes due
to extensive inbreeding.
79
Presentation
Chinese or gray
hamster
80
81
Cheek pouches
Normal
82
Hip glands
Normal
83
Presentation
Diarrhea
84
85
Ileum
Lawsonia
intracellulare
Diffuse proliferative
ileitis
The classic cause of “wet-tail” in
this species, L. intracellulare
results is epizootics in younger
animals, primarily weanlings, with
resistance occurring about 10-12
weeks. Environmental changes
can result in disease in older
animals. In outbreaks, morbidity of
60% and mortality of 90% is
expected.
86
87
88
Small intestine
Helicobacter
pylori
Diffuse proliferative
ileitis
A range of Helicobacter species
have been identified in hamsters,
and they can also be infected with
H. pylori. Gastritis and intestinal
metaplasia have been identified in
hamsters infected with H. aurati.
89
Liver
Helicobacter
aurati
Diffuse fibrosisng
hepatitis with
nodular regeneration
Lesions similar to that seen with H.
bilis in mice.
90
91
Cecum
Giardia muris
Chronic
lymphoplasmacytic
typhlocolitis
Giardiasis in hamsters are usually
asymptomatic, but some animals
develop marked distention, both
acute and gaseous and chronic
with marked mural thickening.
Infections may be associated with
wasting and hepatic amyloidosis in
this species.
Cheek pouches are highly
distensible and an anatomically
privileged site.
Sebaceous glands used for scent
marking.
“Wet tail” is a commonly abused
term for a variety of bacterial
causes of enteritis in this species.
10
92
93
Intestine
Clostridium difficile
Focally extensive
transmural necrotizing
enteritis
Clostridial infections in this species
are associated with antibiotic
administration. The most common
bacteria in the hamster enteron
are Lactobacillus and Bacteroides.
Administration of –mycins and –
cillins will precipitate overgrowth
with C. difficile, toxin production,
and death. Even non-treated
animals in the same room may
result in fatal typhlocolitis.
94
Liver
Clostridium
piliforme
Multifocal to coalescing
necrotizing hepatitis
Epizootics of Tyzzer’s disease,
primarily in weanlings, may occur
following environmental changes.
Clostridial spores persist for up to
2 years in the environment.
96
97
Small intestine
Rodentolepis nana
Segmental catarrhal
enteritis
R. nana infections are common but
asymptomatic, and the life cycle is
a direct one. There is zoonotic
potential for a related tapeworm,
Hymenolepis diminuta, in man.
98
Rectum
Rectal prolapse
Focally extensive rectal
prolapsed and
exenteration
This sequel to the multiple forms
of “wet-tail” in this species is not
uncommon. Pick one.
99
Liver
Hepatocellular
inclusions
100
Liver, accessory sex
glands
Polycystic disease
Multiple hepatic,
intestinal, and
peritesticular cysts
Considered to be on congenital
origin, liver cysts (generally of
biliary origin) are often
accompanied by cysts in the
gonads, accessory sex glands, and
pancreas. They are considered
incidental findings at necropsy..
101
102
Liver
Amyloidosis
Diffuse hepatic
Amyloidosis is a common cause of
95
Non-specific inclusions are comon
n the liver of the hamster. IC may
be lysosomes and represent liver
injury, IN may represent nuclear
membrane invaginations.
11
amyloidosis
103
Kidney
Diffuse renal
amyloidosis
104
105
Left atrium
Focally extensive atrial
thrombosis
renal insufficiency and mortality in
older hamsters, but may be seen
as early as 5 mos. Affected livers
have a prominent lobular pattern,
and in the kidney, deposition being
in the glomerulus.
Atrial thrombosis is often
associated with amyloidosis,
although cardiac insufficiency may
also play a role. Changes also
occur in coag and fibrinolytic
parameters in affected animals.
May be seen in up to 33% in some
colonies.
Hypoalbuminemia due to loss of
albumin through the deranged
glomerulus may be seen with
amyloidosis.
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Pancreas
Diabetes mellitus
Focally extensive
pancreatic islet
degeneration and
necrosis
Diabetes mellitus is autosomal
recessive in some lines of Chinese
hamsters. Unlike traditional
diabetes, islet cells involute and
become necrotic, rather than
accumulate glycogen.
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Kidneys
Nephrosclerosis
Diffuse bilateral chronic
progressive
nephropathy.
Very similar to that seen in rats, it
is a common cause of disease in
mortality in older hamsters, and
may confound chronic renal
research protocols in this species.
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Ovary
Paraovarian cysts
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Meninges, choroid
Lymphocytic
choriomeningitis
This finding is occasionally seen in
hamsters.
Diffuse
lymphoplasmacytic
meningitis and
choroiditis
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This arenavirus has zoonotic
potential, especially for
immunosuppressed owners. Most
hamsters are asymptomatic, and
the virus is spread through saliva
or urine. Serology is the
recognized method for diagnosis.
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Brain
Congenital
hydrocephalus
Internal hydrocephalus
In a 2006 article in Vet Path, a
syndrome of hydrocephalus was
reported in a colony of hamsters.
Unlike previously reported forms
of hydrocephalus in the hamster,
affected individuals manifested no
clinical signs. No cause was
identified.
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Brain
Spontaneous
hemorrhagic
necrosis of the CNS
Focally extensive
liquefactive cerebral
necrosis
This condition has been seen in
third trimester fetuses and
newborn hamsters and is
reproduced by feeding dams a
vitamin E-deficient diet. Most
affected pups are cannibalized.
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116
Liver, mesenteric
lymph nodes
Hamster
papovavirusassociated
lymphoma
Hepatic lymphoma
Hamster papovavirus is the agent
of transmissible lymphoma, which
primarily causes epizootics within
naïve colonies. Tumors do not
have detectible virus. It is spread
in the urine. Enzootic infections of
colonies require slaughter to rid
the colony of the virus.
That’s a LOT of lymphocytes in the
sinusoids! Numbers may exceed
300,00/cm3
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118
Haired skin
Hamster
papovavirusassociated
trichoepithelioma
Cutaneous
trichoepitheliomas
Caused by the same virus as
transmissible lymphoma, this form
is more commonly seen in infected
adults, and tumors do contain
infectious virus (although it is likely
not necessary for transmission.)
These tumors are only seen in
association with virus.
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Haired skin
Demodicosis
Diffuse hyperkeratotic
and proliferative
D. auratus and D. criceti occur
naturally in the Syrian hamsters.
Infection is common, and lesions
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dermatitis
120
121
are rarely seen except in older
animals.
D aurati is a long, slender parasite
that lives in hair follicles, while D.
criceti are stubbier mites which
live in epidermal “pits”.
Presentation
D aurati is a long, slender parasite
that lives in hair follicles, while D.
criceti are stubbier mites which
live in epidermal “pits”.
122
Presentation
123
Haired skin
124
125
Foot
126
Haired skin
An alternate location for D. aurati
is within the ostia of sebaceous
glands.
Diffuse hyperkeratotic
and proliferative
dermatitis
D. auratus and D. criceti occur
naturally in the Syrian hamsters.
Infection is common, and lesions
are rarely seen except in older
animals.
Botryomycosis
Focally extensive
suppuriative
pododermatitis with
Splendore-Hoepple
material
Botryomycosis or psedomycetoma
has been reporte din the skin of
hamsters.
Histologically it
resembles botryomycosis in the
mouse, with Staph aureus colonies
surrounded by aggregated protein.
T-cell
epitheliotrophic
lymphoma
T-cell epitheliotrophic
lymphoma
Spontaneous neoplasm with no
relationship to viral infection.
GERBILS
126
Presentation
Mongolian gerbil
Mongolian gerbils are the most
common type of gerbil used in
research today. Additional types
include jirds, sand rats, and
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antelope rats. Gerbils are diurnal
and won’t bite you like hamsters.
127
Presentation
Gerbils
All sorts of pretty colors. The
agouti pattern is the standard
color.
128
Presentation
Fat sand rat
Psamommys obesus, the fat sand
rat is gaining in popularity due to a
predilection to develop diabetes
mellitus on normal rodent chows,
and its extremely efficient kidney
function.
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130
Ventral abdomen
Ventral making
gland
The ventral marking gland of male
gerbils is a modified sebaceous
gland, and a site for cutaneous
neoplasia.
131
Adrenal glands
132
Presentation
Gerbil pups
133
Nasal planum
“Sorenose”
134
135
Tail
Presentation
Gerbils have extremely large
adrenal glands (up to 4x that of
other species.)
Pups are not precocious, and eyes
do not open until around 3 weeks
– at which time they may be
weaned. Distressed mothers will
cannibalize young..
Focally extensive
ulcerative nasal
dermatitis
Sorenose is a common problem in
gerbils. When not groomed,
porphyrin pigments from the
nasolacrimal duct accumulate and
irritate the nasal skin. This area is
commonly infected by S. aureus as
a sequel.
“Tail slip”
Gerbils should not be picked up by
the tail. Tail slip is a degloving
injury which is used to escape
predators.
Epilepsy
Epileptiform seizures are common
among Mongolian gerbils under
stress. Up to 40% are afflicted
with the condition, and lines with
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high incidence are sought after for
research purposes. No histologic
lesions have been reported.
136
Cerebrum
Incomplete circle
of Willis
Gerbils have an incomplete circle
of Willis. Ligation of the common
carotid artery results in cerebral
ischemia, which makes them a
good model for stroke research.
137
Presentation
Aural
cholesteatoma
138
139
Ear canal
140
141
142
Liver
Clostridium
piliforme
Multifocal to coalescing
necrotizing hepatitis
Mongolian gerbils are very
susceptible to the disease, and are
often used as a sentinel to detect
the presence of C. piliforme in the
research facility.
143
144
Liver
Salmonella
enteritidis
Multifocal to coalescing
pyogranulomatous
hepatitis
Fatal salmonellosis may be seen as
epizootic in weanlings with
evidence of paratyphoid nodules,
enteritis, and septicemia.
145
Intestine
Rodentolepis nana
Very similar situation to that seen
in hamsters. R. nana may be cause
debilitation in severely affected
gerbils.
146
147
Colon
Dentostomella
translucida
The flattened eggs are unusual,
but pinworms don’t really cause
any problems in this species.
Syphacia obvelata has been
reported in gerbils.
Aural cholesterol
granuloma
Head tilt is a common presenting
sign of aural cholesteatoma.Up to.
50% of gerbils over 2 years of age
have aural cholesteatomas. These
are masses of keratinizing
epithelium which arise from the
external surface of the eardrum
and external auditory canal.
Compression can result in
destruction of the temporal bone
and inner ear structures
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148
Kidney
Chronic
progressive
nephropathy
149
Mite
Demodex meriones
150
51Haired skin
Diffuse chronic
interstitial nephritis
This common lesion of aging
gerbils results in thickening of
glomerular and tubular basements
membranes and abundant protein
tubular casts.
It is unknown whether this actually
may be one of the hamster mites.
These are usually not a problem in
healthy gerbils
Ventral marking
gland carcinoma
Ventral marking gland
carcinoma
These neoplasms are consistent
with squamous cell carcinomas.
151
152
Ovary
Granulosa cell
tumor
Ovarian granulose cell
tumor
This is one of the most common
neoplasms in gerbils
153
Adrenal gland
Adrenocortical
adenoma
Adrenocortical
adenoma
Another commonly recognized
neoplasm in gerbils.
154
Eye
Cataracts
Yeah, they get them.
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