Bacterial Diseases: Bordetella Pneumonia, Streptococcal Pneumonia, Cervical Lymphadenitis (Lumps), Pododermatitis (Bumblefoot), Mastitis, Tyzzer’s Disease, Salmonellosis. Parasitic Diseases: Coccidia, Fur Mites, Helminths, Lice, Mange, Mites, Cryptosporidiosis. Fungal disease: Dermatophytosis, VIRAL AND CHLAMYDIAL DISEASES, MISCELLANEOUS DISEASES

1. Diseases of Guinea Pigs
Presented by: Rakshith K
MVHK1742
Presented to:
Prof. Suguna Rao
Department of Veterinary Pathology
Veterinary college, Banaglore

2. Bacterial Diseases
• Bordetella Pneumonia
• Streptococcal Pneumonia
• Cervical Lymphadenitis (Lumps)
• Pododermatitis (Bumblefoot)
• Mastitis
• Tyzzer’s Disease
• Salmonellosis

3. Bordetella pneumonia
• Etiology: Bordetella bronchiseptica, small, motile Gram-
negative rod
• Lesser extent- Streptococcus pneumoniae and Streptococcus
zooepidemicus
• Transmission : Direct contact, aerosol, or contaminated fomite
• The organism can be carried by rats, rabbits, dogs, cats, swine,
and primates
• Incidence: uncommon in laboratory guinea pigs.

4. Clinical signs
• Dull and depressed appearance
• Loss of appetite
• Loss in body weight
• Respiratory distress(dyspnea)
• Discharge from nose and eyes
• Sneezing
• Coughing
• Inflammed eye lining( conjunctivitis) or reddening

5. Purulent bronchopneumonia
• Bronchopneumonia and
fibrinosuppurative
pleuritis

6. Pathology
• Lesions include mucopurulent
rhinitis, tracheitis and
pulmonary consolidation.
• Typical histopathologic lesions
of purulent bronchitis and
bronchopneumonia with large
accumulations of neutrophils
and intraluminal debris (arrow)

7. • Severe otitis media may be
accompanied by head tilt
(torticollis).
• Exudate can be present in the
tympanic bullae.

8. • Diagnosis:
• Culture of exudates and bacterial identification
• Impression smears
• PCR
• Treatment:
• Antibiotics of choice include chloramphenicol, sulfamethazine
and trimethoprim-sulfa.
• Effective prevention includes good husbandry and maintenance
of a closed Bordetella free colony

9. Streptococcus pneumoniae
• Etiology: Streptococcus pneumoniae , aerobic Gram-positive
coccus
• Incidence: Incidence of infection is uncommon in laboratory
guinea pigs. Predisposing factors include pregnancy,
environmental temperature changes, shipping, and
stressful experimental procedures.
• Transmission: occurs primarily by direct contact and
aerosol. Rats and humans can serve as carriers.

10. • Clinical Signs: Nasal discharge, rhinitis,
conjunctivitis, dyspnea, and acute
death. Guinea pigs may be lethargic,
anorexic, and have a ruffled hair
coat. Pregnant dams may abort.
• Fibrinopurulent pericarditis
PATHOLOGY

11. • Fibrinopurulent bronchopneumonia
• Diagnosis: A tentative diagnosis can
be made during the necropsy exam
because the fibrinopurulent exudate
is characteristic of infection with S.
pneumoniae.
• Diagnosis is based upon
demonstration of paired, Gram-
positive cocci (diplococci) on
impression smears

12. Cervical lymphadenitis
(Lumps)
• Etiology: Streptococcus zooepidemicus , Gram-positive coccus
Streptobacillus moniliformis is rarely implicated.
• Incidence: Infection is rare in laboratory guinea pigs.
• Transmission: Bite wounds or direct contact with oral
secretions are the major modes of transmission.

13. Bacteria gains access
Mucosal surfaces through abrasions
Localized infection of the cervical
lymph nodes
Enlarged and develop abscesses.

14. • Pathology: Enlarged lymph nodes
progressing to development of
well encapsulated abscesses
filled with a thick, yellow to white
purulent exudate is characteristic
of this infection.
• Diagnosis: Diagnosis is based on
clinical presentation and culture
of the organism from lesions.

15. • Lymph nodes progress to
encapsulated abscesses filled
with yellow-white purulent
exudate
• Treatment may include
drainage and lavage of lesions
and antibiotic therapy with
chloramphenicol or
trimethoprim-sulfa.

16. Pododermatitis (Bumblefoot)
• Etiology: Staphylococcus aureus , Gram-positive coci.
• Incidence: Guinea pigs have a moderate incidence of
pododermatitis but colonization with bacteria is an uncommon
complication.
• Transmission: Transmission occurs primarily by direct
contact. Interspecies transmission of S. aureus has been
documented

17. • Clinical Signs:
• There are two disease presentations associated with S.
aureus overgrowth.
• Pododermatitis is commonly seen on the palmar surface of
the feet of animals housed on rough wire cage floors. Feet
are swollen with crust-covered ulcers.
• Exfoliative dermatitis is commonly seen in multiparous
dams and their offspring. Ventral abdominal alopecia and
erythema, epidermal cracks and flaking (exfoliation) are
visible.

18. Tyzzer’s Disease
• Etiology: Clostridium piliforme ,Gram-negative, spore-
forming, obligate intracellular bacterium.
• Incidence: The incidence of disease is rare and occurs
in young or recently weaned guinea pigs as a result of
an abrupt change in diet, antibiotic therapy,
immunosuppressive therapy or environmental
stressors.
• Transmission: The disease is spread by spore ingestion
(fecal-oral route).

19. • Clinical Signs: In acute clinical
disease, profuse watery brown
diarrhea, dehydration and death
within 12 to 48 hours after onset of
diarrhea are typical.
• The mortality rate is high.
• Pathology : Pinpoint white foci on
and within the liver may or may not
be present and correspond
histologically to coagulative necrosis
with peripheral neutrophilic
infiltrates.

20. • Diagnosis: PCR of feces, intestinal tissue or liver can be used
to document the presence of the bacterium.
• Serologic tests can be used for diagnosis but are best used for
health monitoring purposes.

21. Salmonellosis
• Salmonella typhimurium and other
Salmonella spp will infect guinea pigs.
• Guinea pigs becoming most
susceptible around parturition,
weaning, or other times of physiologic
stress.
• Clinical signs of salmonellosis include
anorexia, rough haircoat, lethargy,
weight loss, soft feces, reproductive
inefficiency and abortion.

22. Transmission
• Many animal species harbor Salmonella organisms which are
shed intermittently in the feces. Transmission is fecal-oral;
organisms often are introduced in contaminated foods such as
fresh fruits and vegetables, or through the water supply.

23. • Necropsy findings may
include gas and fluid
contents in the
gastrointestinal tract as
seen here.
• Enlargement of the liver,
spleen and lymphoid
tissues may also be found.

24. • Management Culture-positive animals should be removed
from the colony.
• The room and equipment should be disinfected and restocked
with clean animals.

25. Mastitis
• Mastitis is common in lactating sows. Milk provides an excellent media for the
growth of bacteria that may invade when young traumatize the teats.
• Multiple agents have been implicated, including Pasteurella spp, Klebsiella
spp, Staphylococcus spp, Streptococcus spp and others. Mammary glands
become warm, enlarged and hyperemic.
• The milk may appear bloody; depression and even death may follow.
Diagnosis is based on clinical signs.
• Treatment includes hot packs and antibiotic therapy

26. • Mastitis
• Etiology: Mastitis may be caused by a variety of organisms,
including Pasteurella sp., Klebsiella sp., coliforms, streptococci, and
staphylococci.
• Incidence: Mastitis is fairly common in lactating Guinea pigs.
• Transmission: Inoculation of bacteria occurs secondary to trauma
to the mammary tissue caused by nursing pups.
• Clinical Signs: The affected gland becomes diffusely or focally
enlarged, hyperemic and warm, and later becomes cyanotic and
cool. Depression ensues and the animal may die of septicemia [1].
• Diagnosis: Diagnosis is made based on clinical signs and culture.

27. PARASITES
• Many parasites are known to infect guinea pigs, but as a rule,
parasites are more a problem in hobby and breeding colonies than in
the research setting.

28. Parasitic Diseases
Coccidia
Fur Mites
Helminths
Lice
Mange Mites
Cryptosporidiosis

29. Parasitic Diseases
• Coccidiosis
• Etiology: Eimeria caviae , a colonic coccidian.
• Incidence: Incidence of infection with Eimeria caviae
is common.
• Transmission: Transmission occurs by ingestion of a
sporulated oocyst.

30. • Clinical Signs: Development of disease is
often associated with exposure to an
environmental stressor. Diarrhoea may
develop 11 to 13 days post-exposure.
• Pathology: In severe infections, edema of
the colonic wall and serosal hemorrhages
may be seen.
• Diagnosis: identification of the oocyst by
performing a mucosal scrape or a direct
smear or flotation of feces. Histology can
also be used to demonstrate the presence
of Eimeria (gametocytes, highlighted by
arrowheads )

31. Ectoparasites of guinea pigs
• Common ectoparasites includes
• Mites
• Lice

32. Acariasis
• Acariasis in guinea pigs is
primarily associated with
two species of mite
1. Trixacaris caviae
2. Chirodiscoides caviae.
• Mild to severe alopecia may
be seen

33. Trixacaris caviae
A sarcoptic mange mite, burrows through the
keratin layer of the epidermis
Alopecia, crusting, and an intense pruritus
Self mutilation, debility and death.
• Diagnosis: Deep skin scraping at the edges
of suspected lesions.

34. Chirodiscoides caviae , fur mite of guinea pigs
• Incidence: Uncommon in guinea pigs.
• Transmission: Transmission occurs by direct contact with
the host, animal bedding, or hair and debris..
• Distribution: Mites are most numerous over the rump and
flanks
• Clinical Signs: Clinical signs are not usually observed. In
heavy infestations, pruritus and alopecia may be evident.

35. • Trixacaris caviae, a burrowing mite,
poses a significant threat to the health
of a guinea pig colony.
• Trixicaris caviae tend to distribute on
the neck, shoulders, lower abdomen,
and inner thighs, whereas
Chirodiscoides caviae distribute
more randomly

36. Lice of Guinea Pigs
• Gliracola porcelli
• Gyropus ovalis
• Chewing lices that cause occasional
alopecia and mild pruritus with heavy
infestations
• Gliricola porcelli is seen more
commonly.
• Lice are spread by direct contact with
the host or contaminated bedding.
Gliricola porcelli Gyropus ovalis

37. Cryptosporidiosis
• Etiology: Cryptosporidium wrairi , a
protozoan parasite
• Incidence: Cryptosporidiosis is fairly
uncommon in guinea pigs.
• Transmission: Transmission occurs by
the fecal-oral route.
• Clinical signs: Intestinal colonization by
this organism may cause diarrhoea, weight
loss, pot belly, poor growth rates as well
as perineal fecal staining in weanlings and
juveniles

38. • Pathology: In the
ileum parasites can be
visualized in parasitophorous
vacuoles (arrowheads) at the
apical portion of infected
enterocytes.
• Diagnosis: Histopathologic
exam of intestinal biopsies or
PCR of mucosal scrapings are
other methods for diagnosis of
this condition

39. Helminths
• Etiology: Paraspidodura uncinata , cecal helminth
(roundworm).
• Incidence: uncommon
• Transmission: Transmission occurs by consumption of
embryonated eggs.
• Distribution: Worms reside in the cecum and colon.

40. Fungal disease
• Dermatophytosis (Ringworm)
• Etiology: Trichophyton mentagrophytes
• Incidence: While clinical infections are uncommon,
asymptomatic carriers are abundant. Spores may be found in
hair, bedding and soil.
• Transmission: Direct contact with the spores. Young, aged,
pregnant, and stressed animals are most susceptible to the
disease.

41. • Clinical signs
• Animals become susceptible when stressed and
may develop irregular alopecia with occasional
crusting over the dorsal body surface
Barbered guinea
pig

42. • Microscopic examination
of a skin scraping or
histologic skin sections
may reveal fungal spores
(as seen here) and hyphae.

43. Diagnosis and Treatment
• Culture of hair shafts from a lesion
onto dermatophyte test media ( DTM)
may also be used to confirm a
diagnosis.
• Treated orally or topically with
antifungal medications
• Prevention of outbreaks - strict
sanitation, screening suspect animals
and culling affected animals.
• Public health significance:
Trichophyton mentagrophytes is
infective to humans and other animal
species.

44. VIRAL AND CHLAMYDIAL DISEASES
• Some viral and chlamydial disease agents are
documented, but they are of limited
importance

45. Conjunctivitis
• Etiology: Chlamidia psittaci
• Inclusion body conjunctivitis are found
primarily in one to three week old
guinea pigs.
• Transmission: feces, saliva and nasal
secretions; infections may be spread by
direct contact or aerosol
• Zoonotic
• Erythematous conjunctiva, serous
ocular discharge and photophobia are
found in affected animals.

46. • Definitive diagnosis is made
from microscopic examination
of scrapings of the
conjunctival mucosa as shown
here
• Identification of cytoplasmic
inclusion bodies (arrow) in
epithelial cells
Cytoplasmic inclusion bodies

47. Lymphosarcoma
• Etiological agent: Type C Oncornavirus
• responsible for the leukemia found in
aged guinea pigs
• The highest incidence is observed in
strain 2 guinea pigs.
• Transmission: leukemia virus is
widespread and usually transmitted
transplacentally, remaining dormant in the
animal until aging or stress trigger disease
expression.
• Lymphadenopathy is frequently found on
postmortem examination, seen here as
enlarged lymph nodes in the axillary and
inguinal regions.
Enlarged lymph nodes

48. • Hepatomegaly, splenomegaly and
diffuse lymphadenopathy are found
frequently in guinea pigs with viral-
induced leukemia/lymphosarcoma.
• Enlarged organs appear mottled and
light in color. Anemia and leukocytosis
are often present.
• Microscopic examination of these
lesioned organs reveals the presence of
lymphoblastic cellular infiltrates
obliterating the architecture of tissues.

49. • Viral Diseases
• Lymphocytic Choriomeningitis Virus (LCMV)
Guinea Pig Cytomegalovirus (GPCMV)
Adenovirus
Parainfluenza Viruses
Corona-Like Virus

50. • Etiology: Lymphocytic Choriomeningitis Virus (LCMV) is an enveloped
RNA virus (arenavirus).
• No naturally occurring cases have been reported in guinea pigs.
• Transmission: Wild mice are the natural reservoir; they shed virus in saliva
and urine that may infect other rodent species via direct contact, aerosol
spread, fomites, or mechanical vectors.
• Pathology: Lesions in subclinically infected guinea pigs are not
described. Splenic necrosis is present in the acute phase of experimental
infection. Lymphocytic infiltrates in meninges, choroid and around vessels in
the liver and kidney have been observed.
Lymphocytic Choriomeningitis

51. • Usually there are no clinical
signs, but rear limb paralysis
and CNS disturbances from
meningitis have been reported
in guinea pigs with LCM.
Rear limb paralysis

52. Guinea pig Cytomegalovirus (GpCMV)
• Etiology: Guinea pig Cytomegalovirus (GPCMV) , an
enveloped DNA virus and a member of herpesvirus subfamily.
• Incidence: Incidence of GPCMV is common.
• Transmission: The virus is transmitted by horizontal (direct
contact with saliva or urine) and vertical routes. This virus can
remain latent for the life of animal.
• Clinical Signs: Acute disease is usually subclinical. In
pregnant sows, clinical signs include abortion storms and
variable mortality. This virus is associated with
immunosuppression.

53. • Pathology: Lesions of systemic
disease may not be noticed unless an
animal is immunosuppressed
• In subacute and chronic infections,
viral replication can be seen in the
ductal epithelium of the submandibular
salivary gland with inclusions in the
ductal epithelium (arrowheads).
• Diagnosis: Diagnosis can be made by
histologic documentation of viral-
infected tissues

54. Adenovirus
• Etiology: Adenovirus is an enveloped DNA virus that causes
respiratory disease in guinea pigs.
• Transmission: Adenovirus is spread by direct contact.
• Incidence: Prevalence is unknown but subclinical infections
likely occur. There is low morbidity with high mortality,
especially in young animals
• Clinical Signs: Tracheobronchitis is the most common disease
manifestation. Animals can develop pneumonia with minimal to
moderate cranioventral consolidation of the lungs.

55. • Pathology: Infection causes
necrotizing bronchiolitis with
desquamation of the
epithelium. Basophilic
intranuclear inclusions are
present in desquamated or intact
cells.
• Diagnosis: Diagnosis is made by
histopathologic identification of
inclusions and serology (MFI,
IFA) using guinea pig adenoviral
antigens.

56. Parainfluenza Virus
• Etiology: Parainfluenza viruses (PI-1, -2 and -3) are
enveloped RNA viruses.
• Transmission: Transmission occurs by direct contact and
aerosol.
• Incidence: The incidence of infection with Parainfluenza
viruses is rare.
• Clinical signs: PI-1 (Sendai virus) produces transient
infection and generally subclinical disease, but rhinitis has
been noted in experimental infection

57. MISCELLANEOUS
DISEASES

58. Overgrown incisors
• In guinea pig, the anterior most cheek teeth
tend to become overgrown and maloccluded
first.
This may be followed by an overgrowth of the
incisors
• Etiology: There is a genetic predisposition to
this problem, but it may be modulated by
environmental factors, such as diet.

59. • Malocclusion is common in
guinea pigs and is easily
overlooked at the time of
clinical examination because the
cheek teeth are difficult to see
• Clinical signs: Excessive
salivation, halitosis, chronic
weight loss, and trauma to the
tongue are frequently observed.

60. Scurvy or Vitamin C deficiency
• Hypovitaminosis C is a common and frequently
unrecognized or subclinical problem in guinea pigs.
• Guinea pigs lack the enzyme L-gulonolactone oxidase
required for conversion of glucose to ascorbic acid (vitamin
C), and, therefore, must have a dietary source of this
vitamin.
Swollen limbs

61. • Signs of scurvy include
enlarged costochondral
junctions

62. Joint hemorrhages
• Cartilaginous, muscular (seen
here), periosteal, and
subcutaneous hemorrhages
are observed frequently on
postmortem examination

63. • Clinically ill guinea pigs should receive vitamin C daily until
improvement is seen.
• A daily source of ascorbic acid should be provided to every
guinea pig.
Treatment and Prevention

64. Urinary calculi
• Urinary calculi may occur in guinea pigs, but are a rather
uncommon incidental finding.
• Clinical signs are observed if obstruction (evidenced here as
an enlarged urinary bladder) or inflammation occurs.

65. Urinary calculi
• Clinical signs can include uremia,
anuria or oliguria, pyuria,
depression, and anorexia.
Hematuria may be observed even
without obstruction.
• Treatment/prevention : Treatment
involves retrograde flushing of the
urinary tract and maintenance of
proper hydration status. If this is
unsuccessful, surgery will be
necessary.

66. Diarrhoea
• Antibiotic-induced enterotoxemia,
also called hemorrhagic typhlitis
• This disease is produced by
overgrowth of enterotoxin producing
enteric bacteria, or increased
enterotoxin production, most
commonly associated with the
administration of certain antibiotics.
• Clinical signs may include anorexia,
rapid weight loss, dehydration,
depression, diarrhea, and death

67. Antibiotics to avoid
• Antibiotics implicated include penicillin, erythromycin,
lincomycin, chlortetracycline, oxytetracycline,
bacitracin, and dihydrostreptomycin

68. Ptyalism
• Guinea pigs are highly susceptible to heat
stress
• Heat stress may occur even at moderate
environmental temperatures, particularly if
the animal is housed in a confined, humid
and poorly ventilated space.
• Diagnosis is based on a good history and
clinical signs, such as wet hair under the
chin.
• Malocclusion and vitamin C deficiency
can also produce excessive salivation in
guinea pigs.

69. Pregnant guinea pig
• Pregnancy toxemia or ketosis, similar to
that seen in sheep, is a
metabolic/nutritional disease of obese
female guinea pigs.
• It is most commonly associated with a
sudden dietary change and environmental
stress
• Clinical signs of pregnancy toxemia
appear in the last one to two weeks of
gestation or the first week postpartum.
• Signs include anorexia, depression,
dyspnea, convulsions, stillbirths, and
abortions The urine will be clear with a pH
of 5-6, with protein and ketones present.

70. • Pathologic lesions include fatty
liver (seen here), fatty
kidneys,ample fat stores, and an
empty stomach.
• A pre-eclampsia syndrome also
may be seen in these females due
to uteroplacental ischemia,
secondary to aortic compression
by large foetuses
• In this photomicrograph,
numerous fatty droplets are seen
in hepatocytes.

71. Pregnancy Toxemia
Fatty
liver
Uterine hemorrhages
Renal disease

72. Thank you…