Rats and Mice Flashcards
explain rodent incisor, common complications and how to fix them
Rodent incisors grow continuously throughout their lives and wear down by grinding across each other. However if the animal has a malocclusion then they wont get worn down and then get overgrown. This can be fixed by trimming them (toenail trimmers work) about every month to where the teeth are equal lengths.
rats/mice have __ to generate heat “non shivering thermogenesis
brown fat deposits
T/F: the rodent brain lacks gyri and sulci
T, they’re smooth brained boys not a thought behind those eyes
what do red tears indicate on a rat or mouse?
STRESS, red tears are porphyrin (iron containing reddish pigment) hypersecreted in times of stress from the harderian gland
Rats lack a __
Rats lack a gallbladder
Rats cannot __ and have a limiting ridge formed by __ and __ portions of the stomach
Rats cannot vomit and have a limiting ridge formed by glandular and non-glandular portions of the stomach
T/F: the rat/mouse cecum is small
F, Its LARGE
describe the location of the urethra in male and female rats/mice
In males the urethra opens in the penis which is within the genital papilla and in the female the urethra opens within the genital papilla near the base of the clitoris
what do the glands of the male reproductive tract yield?
a sperm plug that prevents other males semen from getting in
T/F: rat testicles can be withdrawn into the abdomen
T, rats have an open inguinal ring
T/F: the rat has two cervices
T
how do you sex a rat/mouse, especially if they are a neonate?
measure the anogenital distance which is the distance from the anus to the genital papilla
females = shorter
males = longer
Rats have __ pairs of nipples while mice have __ pairs of nipples
Rats have 6 pairs of nipples while mice have 5 pairs of nipples
T/F: mammary tumors are easy to remove and and unlikely to recur
F, they are easy to remove but its likely they will recur
describe barbering or trichotillomania/OCD
once individual nibbles hair off another as a means of social dominance
how often should mice/rats be fed?
ad libitum
briefly explain the two basic rodent feeds
pelleted feed is the standard rodent chow
powdered mash is used to dosed studies but may lead to incisor tooth overgrowth and it may be more difficult to measure how much they’re eating
explain the rat estrous cycle
the rat estrous cycle is 5 days long with estrus occuring at night on day 3
explain the mouse estrous cycle
the mouse estrous cycle is 4-6 days and estrus occurs at night on day 3
vaginal impedence
electrical determination of the cycle stage
seeing a sperm plug =
gestation day 1
can use and otoscope to see it
what is the more economical method of breeding rats/mice?
harem breeding (one male and 2-4 females)
females in heat/estrus will exhibit __
lordosis
rat gestation length
21 days
mouse gestation length
19 days
what is unique about parturition for rats/mice?
the fetuses can be delivered breech with no issues
what would increase intervals between the births of mice pups?
handling, moving, stress
pups are weaned by about __ days
21 days
pheromones can cause __, __ and __
false pregnancy, estrus synchronization, spontaneous termination
what happens if you grab the tip of a rats tail?
degloving injury, make sure you only grab at the base
what restraint method is best for mice
scruff because in a tail restraint they can climb the tail and bite the handler
what is the ideal method of restraint for rats?
thoracic encirclement
what should you NOT do for intraperitoneal injections?
- use an overly long needle
- insert a needle to its hub
- insert perpendicular to the body wall
- reuse the needle
T/F: ketamine should be given IM to rats/mice
F, it can cause irritation and necrosis of the muscles so give it intraperitoneal instead
where should you draw blood from a rat/mouse and how much is ok to take?
the facial, saphenous, lateral tail veins or superficial temporal veins
safe collection for a mouse is < 0.2ml
safe collection for a rat is 1.9 (f) -3.3 (m) ml
how should you check anesthetic depth?
corneal reflex and toe pinch reflex
briefly explain how an ovariectomy is performed in rodents?
a dorsal midline incision is made and then two cuts in the muscle are made to access each ovary that is snipped off. You don’t have to close the muscle incision but close the skin incision. The ventral midline may drag on the cage floor so a dorsal midline approach is preferred.
if you smell ammonia in a rodent cage, should you be concerned?
yes the ammonia smell is from the breakdown of urine and feces and if you can smell it then damage is already happening to the respiratory system
what issues might arise with cedar bedding?
it is fragrant and may cover up the smell of ammonia which would mask potential problems
if a client brings in a rat with allergy signs, what should they consider changing?
get them off cedar chip bedding and make sure they keep the cage clean
T/F: female rodents don’t like having companions
F, they like to have other females around
a head tilt indicates an __ in rodents and is likely __
a head tilt indicates an inner ear infection in rodents and is likely ipsilateral
if a young rodent comes in with cataracts, what should you ask about?
lighting conditions
what is the most common mammary tumor?
fibroadenoma
viral diseases of the digestive system
mouse parvovirus 1
mouse rotavirus
reovirus type 3
not likely to test for these but should provide supportive care
viral disease of the respiratory system
- pneumonia virus of mice
- sendai virus: highly infectious and one of the most important mouse viruses (test by serology)
what should you do if you see white spots on the liver of a rodent?
glove and maske up because they have the zoonotic potential of being clostridium piliforme (tyzzers) or salmonella
you hold a mouse by its tail and it starts spinning like a propeller, what do you suspect?
pseudomonas aeruginosa, treat their water with acid/HCL
what 2 bacterial diseases may cause weight loss, hunched back and dyspnea?
klebsiella pneumoniae
streptococcus pneumoniae
what bacteria is the culprit for retrobulbar abscesses?
pasteurella pneumotropica
pinworms in rodents
- clinical signs may include poor weight gain, perianal irritation, rectal prolapse
- to dx take a piece of tape across the anus and then look at it under the microscope
fur mites in rodents
intense itching with secondary pathogenic bacteria and anemia that can be id’d by a skin scrape.
SDAV (sialodacryoadenitis virus)
A highly contagious virus that causes dry eyes with red tears, no saliva and the animal stops eating. It typically resolves in ~10 days and cannot be reinfected. However, post-disease the animal may have corneal ulceration and glaucoma
Murine Respiratory Mycoplasmosis (MRM)
This is a significant rat disease that causes red tears, a head tilt, circling, dyspnea and chattering. It can be treated with tetracycline and if caught early enough the head tilt will go away.
corynebacterium kutscheri
rat disease where the lungs have a cobblestone appearance similar to tuberculosis
what does ringtail indicate about a rats environment?
Humidity problems, low relative humidity
old rat nephropathy
causes chronic progressive renal condition in abino rats where the kidneys are pale and, enlarged with numerous cysts
