FELASA Module 5: Laboratory Animal Health
Disease in laboratory animals usually refers to infectious diseases
Microorganisms in laboratory animals may be zoonotic (cause disease
in humans)
They may cause disease in the animals
They may interfere with the research
Some bacteria may be important for the models you want to induce
in animals
Fulminant disease- the infection causes clinical symptoms that we can
observe
Latent infection- an infection without a clinical expression
Infections can cause disease but don’t always cause disease
Impact of latent infection on animal research
Direct effects on research
Immune modulation (can change the immune system)
Physiological modulation (change the physiology)
Oncological modulation (change the sensitivity to cancer)
Fertility modulation (may impact the fertility of an animal)
Microbiological competition (may compete with experimental
infections you want to induce)
Indirect effects on research
Contamination of biological products
When animals are stressed due to experiments the direct effects
may be activated
Zoonoses are not a huge problem in laboratory rodents
They can be easily purchased though
Rodent diseases
Nude mouse no thymus (and thus no T-cells which means it is
immune deficient)
It can be infected with mouse hepatitis virus that is a coronavirus
Symptoms include wasting, cachexia (thin + muscle loss),
diarrhea and jaundice
Infection with mouse hepatitis impacts liver function
This infection is serious in an animal like the nude mouse that
has no immune system
Infection will cause the mouse to die
B6 mice are sensitive to clinical disease rom mouse hepatitis
B6 mice from hepatitis infected colonies are paretic (partial
paralysis) and have problems walking
The coronavirus will also effect the central nervous system
Rats can also have similar coronaviruses
The clinical symptoms include sneezing, corneal ulcerations and
porphyrin rings around the eyes
Tyzzer’s disease in mice
Bacterial disease caused by Clostidium pilliforme
, Causes high fatality in mice
Can see white spots on the liver where it is infected
Slightly different presentation in rats
Often latent and no clinical expression
Sprague-Dawley rats may have whirls on abdominal surface
Small intestine (ileum) is usually enlarged (megaloileitis)
In mice with fulminant Tyzzer’s disease the half life of the antibiotic
Trimethoprim is increased
However when mice recover from Tyzzer’s disease the half life of
the antibiotic returns to normal
In mice with fulminant Tyzzer’s disease the half life of the anti-
coagulant warfarin is also increased
However upon recovery, mice still have long half-lives for this
drug
This shows there is permanent damage to the liver function
Disease in non-rodent species
Different species experience different infections but they have
similar outcomes
Glasser’s disease in pigs (Haemophilus parasuis)
At death you can see that connective tissue adheres all surfaces
of the organs to each other
Mouse norovirus (MNV)
Non-enveloped RNA virus
Most prevalent viral infection in mouse
Four described strains (MNV-1, MNV-2, MNV-3, MNV-4)
Causes enteric infections and can also exit the gut to effect
macrophages and dendritic cells in lymph nodes and liver
Transmission through fecal oral route- virus is shed in feces
Symptoms include weight loss, hunched posture, ruffled fur and
death
No clinical symptoms have been reported in immunocompetent
mice or immunocompromised mice with intact innate immunity
Pathology: no pathology with natural infection
Following experimental inoculation mice have mortality with
lesions including encephalitis, cerebral vasculitis, pneumonia,
meningitis and hepatitis
Diagnosis: Serological assays to detect all strains, PCR of feces
useful for screening
Heliobacter infections
Caused by gram negative bacteria (heliobacters)
Common in mice
Species include: Helicobacter hepaticus, H. bilis, H. rodentiumH.
trogontum, H. ganmani and H. typhlonius
Transmission through fecal-oral route
Normally colonize the lower intestine tract
Disease in laboratory animals usually refers to infectious diseases
Microorganisms in laboratory animals may be zoonotic (cause disease
in humans)
They may cause disease in the animals
They may interfere with the research
Some bacteria may be important for the models you want to induce
in animals
Fulminant disease- the infection causes clinical symptoms that we can
observe
Latent infection- an infection without a clinical expression
Infections can cause disease but don’t always cause disease
Impact of latent infection on animal research
Direct effects on research
Immune modulation (can change the immune system)
Physiological modulation (change the physiology)
Oncological modulation (change the sensitivity to cancer)
Fertility modulation (may impact the fertility of an animal)
Microbiological competition (may compete with experimental
infections you want to induce)
Indirect effects on research
Contamination of biological products
When animals are stressed due to experiments the direct effects
may be activated
Zoonoses are not a huge problem in laboratory rodents
They can be easily purchased though
Rodent diseases
Nude mouse no thymus (and thus no T-cells which means it is
immune deficient)
It can be infected with mouse hepatitis virus that is a coronavirus
Symptoms include wasting, cachexia (thin + muscle loss),
diarrhea and jaundice
Infection with mouse hepatitis impacts liver function
This infection is serious in an animal like the nude mouse that
has no immune system
Infection will cause the mouse to die
B6 mice are sensitive to clinical disease rom mouse hepatitis
B6 mice from hepatitis infected colonies are paretic (partial
paralysis) and have problems walking
The coronavirus will also effect the central nervous system
Rats can also have similar coronaviruses
The clinical symptoms include sneezing, corneal ulcerations and
porphyrin rings around the eyes
Tyzzer’s disease in mice
Bacterial disease caused by Clostidium pilliforme
, Causes high fatality in mice
Can see white spots on the liver where it is infected
Slightly different presentation in rats
Often latent and no clinical expression
Sprague-Dawley rats may have whirls on abdominal surface
Small intestine (ileum) is usually enlarged (megaloileitis)
In mice with fulminant Tyzzer’s disease the half life of the antibiotic
Trimethoprim is increased
However when mice recover from Tyzzer’s disease the half life of
the antibiotic returns to normal
In mice with fulminant Tyzzer’s disease the half life of the anti-
coagulant warfarin is also increased
However upon recovery, mice still have long half-lives for this
drug
This shows there is permanent damage to the liver function
Disease in non-rodent species
Different species experience different infections but they have
similar outcomes
Glasser’s disease in pigs (Haemophilus parasuis)
At death you can see that connective tissue adheres all surfaces
of the organs to each other
Mouse norovirus (MNV)
Non-enveloped RNA virus
Most prevalent viral infection in mouse
Four described strains (MNV-1, MNV-2, MNV-3, MNV-4)
Causes enteric infections and can also exit the gut to effect
macrophages and dendritic cells in lymph nodes and liver
Transmission through fecal oral route- virus is shed in feces
Symptoms include weight loss, hunched posture, ruffled fur and
death
No clinical symptoms have been reported in immunocompetent
mice or immunocompromised mice with intact innate immunity
Pathology: no pathology with natural infection
Following experimental inoculation mice have mortality with
lesions including encephalitis, cerebral vasculitis, pneumonia,
meningitis and hepatitis
Diagnosis: Serological assays to detect all strains, PCR of feces
useful for screening
Heliobacter infections
Caused by gram negative bacteria (heliobacters)
Common in mice
Species include: Helicobacter hepaticus, H. bilis, H. rodentiumH.
trogontum, H. ganmani and H. typhlonius
Transmission through fecal-oral route
Normally colonize the lower intestine tract
