Common Problems in Laboratory Animals Nirah H Shomer, DVM PhD Dip. ACLAM

Barbering Normal grooming behavior Usually, but not always, one unmarked barber Barber is usually dominant Usually harmless, but can precipitate conjunctivitis, ulcerative dermatitis Barber

Periocular irritation (secondary to barbering)

Fight Wounds Characteristic wound locations on fleeing mice: Tails, rear feet, genitals

There is typically a dominant aggressive mouse Even if you remove the aggressor, another mouse may take his place. Fights are almost exclusively between males In some strains, even littermates raised together will fight (BALB/c, SJL)

Fight wounds (fatal) Mice may die, rapidly, of septicemia Treat with broad spectrum antibiotics

Ulcerative Dermatitis

Ulcerative Dermatitis

Skin lesions Etiology Pattern Treatment Barbering Normal grooming any (same all mice) remove barber Fight Wounds Fighting tail, back, genitals remove aggressor Ulcerative Dermatitis Unknown nape of neck, none under arms ointments pain drugs Linked to C57BL 2° infection common antibiotics

Emaciation Look for underlying cause Report objectively using Body Condition Score

These are littermates. What is the mouse on the right? Runt What should you check for?

Malocclusion Rodent incisors grow continuously Can be maintained by weekly clipping

Malocclusion is heritable

Diarrhea Mouse diarrhea is usually very subtle All you see is bedding stuck to pellets and anus

Rabbit feces Normal pellets Diarrhea True or False: diarrhea is normal in rabbits False: they do have “night feces”, cecotrophs, which are usually eaten directly from the anus

Hamster with “wet tail” Bacterial infection (Lawsonia intracellularis)- proliferative ileitis Clostridial overgrowth (spontaneous, age- or stress-related) Antibiotic toxicity (causes clostridial overgrowth)

Rectal Prolapse Rectum protrudes through anus Associated with diarrhea, Helicobacter infection

Seizures

Dystocia (difficult birth) Dam neonate pup from last litter

What’s wrong with this mouse?

Note that this mass is reducible. Inguinal Hernia Protrusion of an organ (e.g. gut) through a natural opening (e.g. inguinal canal) or unnatural rent (e.g. diaphragmatic rupture) in a body wall. Note that this mass is reducible.

Why is this rabbit matted? Obesity

“Hunched” “Scruffy” Non-specific sign indicating mouse is too ill to groom itself.

Tumor Size/dimensions 1.5x2.5x2.5cm Shape irregular/lobulated Location scapular/right flank Color mottled Texture firm/fluctuant Ulceration ulcerated

Zymbals Gland Tumor

Circling Head Tilt

Porphyrin staining Pigment comes from Harderian glands Increased in stress, respiratory disease, sialodacryoadenitis virus (SDA) infection Prominent in rats and gerbils, not in mice Found around eyes, nares, paws (from grooming face)

Conjunctivitis Inflammation of the conjunctival tissues; aka pink-eye. Usually bacterial, may not respond well to antibiotics.

Proptosis Bulging or protruding eye Causes include tumor, abscess, retroorbital bleed/hematoma, glaucoma Secondary effects include keratitis, loss of eye

Paralysis Theiler’s mouse encephalomyelitis virus (TMEV strain GD VII) Spontaneous or iatrogenic trauma Experimental Allergic Encephalitis (EAE) (multiple sclerosis model)

Find the barber X

Pop Quiz

1. What’s wrong with these mice?

2. List all rule-outs for this condition

3. Describe this mouse

4. Which mouse should you remove from the cage, and why? 1 2 3 4

5. What’s wrong with this rabbit?

6. What is wrong with this mouse?

7. Name the condition.

8. What is wrong with this rat?

1. What’s wrong with these mice? Barbering

2. List rule-outs for this condition Fight wounds Ectromelia (pox virus) Footpad injection (swollen feet) Tail bleeding/overheating (tail lesions)

3. Describe this mouse Emaciated Also nude (but this is not a problem)

4. Which mouse should you remove from the cage, and why? 1 2 3 4 These are fight wounds. Remove the aggressor. Hint: he is the one without lesions

5. What’s wrong with this rabbit? Malocclusion

6. What is wrong with this mouse? Tumor. Most common tumor in this area=? Mammary tumor

7. Name the condition. Head tilt

8. What is wrong with this rat? Reddish discharge around eyes What is this substance? Porphyrin

The End

What’s wrong with this frog? normal Xenopus Severe emaciation Skin lesions

What’s wrong with this frog? Emaciation chronic kidney disease Mycobacteria spp. chronic bacterial infection, zoonotic

Skin lesions No pattern Pseudocapillaroides xenopi (nematode parasite) Fungal infection Discoloration

Mastitis

E. coli Mastitis in a ferret