rodents Flashcards
T or F: rodents are the most numerous of all mammalian species
true
are rodents herbivorous, omnivorous or carnivorous?
can be either herbivorous or omnivorous
why do rodents have nocturnal habits and most have rapid flight?
because they are subject to predators
what do rodents gain due to their nocturnal habits
good sense of smell and hearing ( due to their lack of vision)
what does it mean when someone says rodents are on the fast track?
they develop rapidly, reproduce quickly and have a short lifespan
what is the sexual maturity, gestation and lifespan of small rodents ( gerbils, rats and mice)?
sexual maturity - 6-10 weeks
Gestation - 3 wks
lifespan- 1-3 yrs (mouse: 1.5-2.5 yrs , rat: 2.5 - 3.5 yrs)
what is the gestation and lifespan of guinea pigs?
gestation - 2-2.5 months
lifespan - 8 yrs
what is the gestation and lifespan of chinchillas?
gestation - 3.5 months
lifespan - 18 yrs
what is the largest known rodent species?
Capybara (66 kg) most rodents weight less than 100g
why are rodents prone to heat stress?
have no sweat glands and cannot pant
T or F mice are coprophagic but mice are not.
false they are both corporphagic
they need to do this because their feces contain nutrients produced by colonic bacteria
common name for Mus musculus is
house mouse
common name for Rattus norvegicus is
Norway rat
T or F rats and mice are not social but can be very intelligent
false they are social and active intelligent
why do most labs like to keep mice and rats around for research instead of other species?
they are adaptive, small reproduce rapidly extensive genetic characterization over 1000 inbred and outbred strains thousands of genetic mutants
you have a new client bring there mouse into your clinic due to it not acting right. what are somethings you need to tell them when they bring it in?
bring animal in its home cage
need to make an evening appointment
do not clean their cage before coming
why is it better to feed rodents a pelleted diet vrs a mixed diet?
because they are selective eaters and may only eat one ingredient
what is the best way to perform a physical exam on rodent?
observe in cage it’s: posture, grooming activity, respiration and if it is acting depressed.
if it is dyspneic need to handle carefully and caution the owner.
what to most rodents do when you handle them?
they urinate and defecate, so be prepared to collect samples
in small rodents what diagnostics do you usually do with the blood you collect?
PCV and smear - because you can only collect a small amount of blood
in large rodents what diagnostics do you usually do with the blood you collect?
CBC and chem - because you can usually get a higher quantity of blood in large rodents compared to small rodents.
where do you collect blood from a rodent?
lateral tail vein
lateral saphenous vein
you prick the vein and use a hematocrit tube(small or large) to collect it or a small green top tube (large)
what is the normal temperature for a rat? A mouse?
rat - 99.5-100.6
mouse - 98 - 101
what are some signs of illness in rodents?
weight loss Hunched posture Lethargy rough hair coat rapid or labored breathing closed or squinted eyes perineal staining or stain around the eyes
If a rodent bites you what should you not do?!!!
don’t drop it or throw it across the room!! Clients will not like you!!
how do you hold/restrain a mouse?
scruff whole body and stabilize tail with ring or little finger (one handed)
or you can scruff the neck with one hand and stabilize the base of the tail with the other
how do you hold/restrain a rat?
place two fingers behind jaws/ears
one finger in front of leg and one finger behind leg
with other hand stabilize base of the tail
IF YOU PICK THEM UP BY THE TAIL THEY WILL TURN AND BITE YOU!!!!
what will happen in you pick a mouse or rat up by the end of the tail?
there skin might slough off - called tail degloving injury
why you handle them by the base of the tail
they may also bite you
what would happen if you put two adult, unrelated male rodents in together?
they will fight to the death, can be very aggressive. except with hamsters : females tend to be more aggressive.
what can you do to decrease aggression in rodents
raise littermates together or introduce them at weaning
introduce animals in clean cage ( no pheromones and neutral territory)
provide hiding places
observe closely for first few days
what are some ways you can give medications to rodents
orally with ball ending dosing needles (gavage needles) 20 gauge in rats and 22 gauge in mice
intraperitoneal or subQ ( IV injections are difficult)
how much oral medication can you give to rats? mice?
1 ml rats
0.1 ml in mice
where do you give subQ injections in rodents and how much can you give
flank or intrascapular
5 ml in rats
1 ml in mice
where do you give intraperitoneal (IP) injections in rodents and how much can you give?
lateral aspect of the lower left abdominal quadrant with the rodents head slanted downward
5 ml rats
2 ml mice
if you have to give an IV injection in a rodent what can you do to the lateral tail veins to make it easier
dilate vessels with warm water or a heat lamp ( any heat source)
T or F rodents incisors grow continuously, but the upper incisors are longer than the lower incisors. Do not clip them.
false. they do grow continuously, but the lower incisors are longer than the upper incisors
what structure is useful in the rodent for giving oral meds
diastema
what is the Harderain Gland and where is it located
it produces porphyrin rich secretions during stress or disease - these secretions look red
located behind the eye
you see red discharge from the eye and nose of a rat, how can you tell this is really blood?
shine UV light/ woods lamp on the area. if it is blood it will not fluoresce. if it is porphyrin it will.
where is mammary tissue found in rodents
wide distribution including back
you feel a SQ mass on a male mouse what is your top differential?
mammary tumor until proven otherwise
mammary tumors can be found anywhere on body in males and females.
how do you tell the difference between a male and female rodent?
look at the anogenital distance. males are further apart than females
testicles can be manipulated into scrotum (open inguinal rings)
males do not have nipples
when do testicles descend in male rodents
3-4 wks
when do nipples become visible in rodents
10 days and only on females
what is the main common health problem in mice and rats and what signs go along with it
respiratory disease ( can be upper or lower, viral or bacterial) signs include: sniffling, sneezing, chattering, labored breathing
for husbandry with rats and mice what do you want to avoid and what is the main reason to change bedding often
avoid direct sunlight, drafts, temperature or humidity changes
change bedding often to prevent ammonia build-up
what vaccines do we have for rats and mice
none, our role is more educational, to help prevent the disease and to trim teeth when needed
when choosing beading for rats and mice cages what do you want to avoid and why
cedar shavings because it can affect microsomal liver enzymes and they are hypersensitive to the aroma
why must the temperatures in their cages be 64-70 degrees and humidity be 40-70%
due to their limited ability to thermoregulate, esp around the tail vein
why do we not fast before anesthesia in rodents?
because they don’t vomit due to ridge present between esophagus and stomach.
with anesthesia in rodents is it better to do intubation or using a mask or injectable anesthetics
use of a face mask following chander induction
intubation is impractical and difficult
injectable anesthetics can be used but they tend to take longer to recover and get chilled easily.
T or F you can’t perform an ovariohysterectomy on a mouse or rat but can do castration.
false can do both but, castration is easier than spaying
T or F it is ok to put skin sutures in rodents as long as you house them alone
false close skin with subcuticular, tissue glue or staples. never put in skin sutures because they will gnaw on them
when do inguinal rings in male mice and rats close
they are always open
T or F when castrating mice and rats you can choose any technique as long as you tie the testicle off instead of using suture.
false only use closed technique to prevent herniation
what are some non-infectious diseases in rats and mice? (6)
Barbering fight wounds skin swellings chronic progressive nephropathy overgrown incisors ulcerative pododermatitis
what are some infectious diseases in rats and mice?
Fur mites
dermatophytosis
pinworms
pneumonia
what is the cause for barbering in mice and rats
in cage mice only, dominant mouse nibbles whiskers and fur of subordinate cage mice
what are the clinical signs of barbering in mice and rats
skin appears normal, only dominant mouse has normal fur
what is the treatment for barbering
usually don’t worry about it
environmental enrichment
can remove dominant mouse, but another mouse will become dominant and could start doing it again
what causes fight wounds in mice and rats and how can we prevent them
due to incompatible males, usually introduced after weaning
to prevent raise together from birth, introduce a weaning or keep male and female pairs
how do you treat fight wounds in mice and rats
separate offenders
put enrofloxacin on infected wounds
A mice comes in with a subQ mass what are your top differentials and how would you rule these things out
adenocarcinoma or abscess
do FNA to rule out abscess
what is the most common tumor in mice and what is the Tx and prognosis
adenocarcinoma - can occur anywhere on males and female
Tx: surgical excision, but there is a high recurrence rate making the prognosis poor
A rat comes in with a SubQ mass what are your top differentials
fibroadenoma, adenocarcinoma, abscess
what is the most common tumor in rats
fibroadenoma - can occur anywhere on males and females
Tx: surgical excision, recurrence is common, but has a good prognosis because benign
what causes chronic progressive nephropathy and do you usually see it in mice or rats
in older rats
causes: advanced age > 1yr and more severe in males
what are the clinical signs of chronic progressive nephropathy
PU/PD, proteinuria,
hydrothorax and ascites in advanced stages
what is the Tx for chronic progressive nephropathy
supportive, fatal disease
what helps prevent chronic progressive nephropathy
calorie and protein restriction, this also helps limit the severity
T or F yellow color of incisors in rats and mice is normal
true
what are the causes of overgrown incisors
opposing tooth missing, improper alignment and diet
what are the clinical signs of overgrown incisors
hypersalivation, anorexia, weight loss
how do you Tx overgrown incisors
trim every 2-3 months
cut with bone/wire cutter or nail clippers (but may fracture) bust to sedate and drill them to prevent splitting teeth
what are some causes of ulcerative pododermatitis in rodents
obesity, limb neuropathies, rough cage floor, genetic disposition, pine or cedar shavings
what are the clinical signs of ulcerative pododermatitis in rodents
raised, red, keratinized lesions on soles of hind feet
bleeding
abscesses
Tx for ulcerative pododermatitis in rodents
clean with chlorhexidine
topical antibiotics: blur cote, granulex, TAO, zymox
oral antibiotics - clavamox
Mobia musculi, myocoptes musculinus and radfordia affinis are what and what clinical signs do they cause
fur mites
CS: thin greasy hair coat, pruritus, self-inflicted trauma
can be subclinical for weeks to months
T or F to diagnosis fur mites on a rodent do a deep skin scrape
false they are non-burrowing so a skin scrape not needed. diagnosis by seeing them with a magnifying glass or a tape test. can also do a PCR
what is the Tx for fur mites in rodents
ivermectin (PO, SQ or topical)
trim hind toenails
Trichophyton mentagrophytes and microsporum canis are what and what clinical signs do they cause
Are fungal organisms that cause dermatophytosis in rodents
CS: crusty skin lesions
how to you Tx dermatophytosis in rodents
miconazole topically
griseofulvin orally
Syphacia obvelata(mice), Aspiculuris tetraptera and S. muris (rat) are common in mice and rats, what are they and what do they cause
pinworms
can be asymptomatic
CS: mild enteritis, rectal prolapse in imunocompromised
how do we Tx pinworm infections in rats and mice
piperazine in water
ivermectin (PO, SC)
fenbendazole (feed)
disinfect environment and equipment ( eggs may aerosolize)
A rat comes in with a head tilt, while observing it you notice it hase rapid/labored breathing, piloerection and a hunched posture. what is one of your differentials at this point
pneumonia - all of these are CS of pneumonia
what is the most common cause of pneumonia in rats and mice
Mycoplasma pulmonis
how can you diagnosis pneumonia in rats and mice
radiographs
serology (viral causes)
CBC - low WBC may indicate mycoplasma or virus
how can we Tx pneumonia
broad spectrum antibiotics ( unless have C&S)
Streptococcus pnumonia - Amoxicillin
Klebsiella - Cephalosporin
Mycoplasma - doxycycline, enrofloxacin
Tx is difficult due to multiple pathogens usually
T or F once you treat pneumonia in rodents it is not likely to recur due to antibiotics sticking around for long time in their system
false mycoplasma pulmonis is resistant in the environment, so reinfection is common
stress can also cause recurrence - need to control ammonia levels
T or F rats and mice are polyestrous and females cycle every 7 days
false they are spontaneous ovulators
what influences puberty and estrous cycle in rats and mice
pheromones
how long is gestation for rats and mice
mouse: 19-21 days
rats: 21-23 days
