Exotics- Small Mammal- Rats and Mice

kelseyfmeyer's version from 2015-11-03 14:30

Rodents in general

Question Answer
what kinda diets do rodents usually have?maybe herbivorous or insectivorous
what time are rodents usually awake, and what are their senses like?mainly nocturnal, poor vision but great smell and hearing (three blind mice)
what does she mean by rodents are on the "fast track"?they develop fast, reproduce early, and have a short lifespan
largest rodent?capybara
why are rodents prone to heat stress?no sweat glands AND cant pant
is it normal for rodents to eat their feces?yes, they are coprophagic (feces contain nutrients produced by colonic bacteria)

Rats and Mice

Question Answer
when an owner is bringing their pet in with the cage, what should you tell them?DONT clean the cage! you want to see what the normal environment is for the animal
what time of day is best for appointments for rats?evening- rats are nocturnal.
how difficult is it to collect a sample of urine/feces from a mouse or rat?Rodents urinate and defecate when handled – be prepared to collect samples on your hands
how might bloodwork differ between a small rodent and a larger rodent?Small: only PCV and smear. you can get a CBC and chem on a larger rodent, though
explain which gender is more agressive (and the exception is?)agression is more common between males than females. The exception is female hamsters, of course
if you want to have mice or rats that all get along, what are the best two options?either raise littermates together, or introduce at weaning
for any introduction, what do you wanna do with the environment?Introduce animals in clean cage (neutral territory) (or do “soft introduction”), also make sure there are hiding places and observe closely for the first few days
when medicating mice/rats what must you be very mindful of?get an ACCURATE WEIGHT and be CAREFUL with calculations. Use a compounding pharmacy or dilute medication appropriately. Can be mixed with food or water if palatable.
what kinda instrument can you use to medicate rats/mice?TB or insulin syringes. If oral admin, can use a ball ended dosing needle
which injection routes are most preferred for mice/rats?IV injections may be difficult, use intraperitoneal or subcutaneous routes instead
what should you think if you see a rat or mouse with orange teeth?nothing-- it's normal
what is the growth of rat/mouse incisors like? molars? the incisors are open rooted and grow continuously. the molars are fixed rooted
which incisors are longer in the rat/mouse, and what should you know about this?Lower incisors are longer than upper – DO NOT CLIP
what is a diastema, and why do we like it?the gap between the incisors and molars-- and it's great for getting medications in their mouth
what's a Harderian Gland? Where is it/what does it do?this is a gland which is located behind the eye, and it Produces porphyrin and lipid rich secretions (lubrication, pheromones).
If you see "red tears" or red nasal discharge, what is happening?This is the porphyrin and lipid rich secretions from the harderian gland, NOT BLOOD. The secretions can become excessive during stress or dz which is when you'd see them. You can make sure it's not blood because porphyrin will fluoresce under UV (Wood's lamp)
where are mammary tumors usually found?can be found anywhere on the body in females OR males (the glands have wide distribution including the back)
If there is a SQ mass on a rat/mouse, it's probably?mammary tumor until proven otherwise
how long should you fast a rat/mouse before anesthesia?TRICK QUESTION! YOU DO NOT FAST before anesthesia
why do you not fast a mouse/rat before anesthesia?two reasons: (1) they have a ridge between stomach and esophagus, so they do not vomit (2) they have a high metabolic rate
how do you sex rats/mice? sex by the anogenital distance-- Male>Female. ((also male testicles can be manipulated into scrotum (open inguinal rings)- good for sexing also ).
what's interesting about rat/mice nipples?males DONT HAVE NIPPLES
what's a mouse/rats repro/cycle like?polyestrous and spontaneous ovulators
what is the Whitten effect?Female mice housed in large groups may not cycle
what is the bruce effect?females may not implant if exposed to a strange male
four signs of respiratory dz in rats or mice?sniffling, sneezing, chattering, labored breathing
what are some normal geriatric signs in pet rats?Yellowing, dry scaly tail, brown secretions at base of hair
what kind of bedding should you never use?aromatic bedding! Such as pine or cedar (VOCs aka volatile organic compounds).. Cedar shavings--> affect microsomal liver enzymes (research), aromatic (hypersensitivity)
PE stuff--> are there vx for rats/mice? what should you always check? what parameter should you always have?no vx. Always check dentition (incisors grow continuously), and always get an accurate weight (always do full PE and make complete medical record)
how often should you change the water of rats/mice?DAILY. they pee/poop in it
what kinda bedding is recommended?coconut husk shavings, corncob, recycled paper, aspen bedding
anesthesia--> what's up with intubation in rats/mice?impractical because they are so small. (There is a Technique using IV catheter silicone sleeve for trach tube in rats)...most of the time there is chamber induction followed by maintenance via face mask. (injectable anesthetics can be used)
(not sure how important) explain doing an ovariohysterectomy in rats/miceposition with tape--> vental midline incision--> Double ligate ovarian pedicles and uterine body with (4/0-5/0) absorbable--> Close SQ with 5/0-7/0 absorbable--> Close skin with subcuticular, tissue glue, staples (Remember, rodents chew!--> so they might chew staples out)--> Post-op analgesics
*what is important to keep in mind when doing a castration?inguinal rings are OPEN
(not sure how important) explain doing a castration in a rat/mouseIncise scrotal skin over testicle (like a cat)--> elevate testicle--> Use closed technique (close tunic)--> Close scrotum with tissue glue (Apply to apposed wound edges, Do not drop into wound then appose edges – foreign body reaction)
who does barbering- rats or mice?MICE
*what is barbering? who does this and why does it happen? How can you tell that it's barbering? how do you tx it?this happens with groups of housed mice. Dominant mouse nibbles whiskers and fur of subordinate cage mates. You can tell it's barbering because the skin of the affected mice appears normal, and only dominant mouse has all its fur. TX: enrichment or removal of dominant mouse
MICE--> two main causes of fight wounds?incompatible males, introduction after weaning
what is the most common tumor in mice? what is tx/prognosis?adenocarcinoma. You can sx excise, but there is a high recurrence rate and poor prognosis
*explain the size/relative location of the maxillary and mandibular incisors(*remember incisors grow continuously) the mandibular incisors are longer than the maxillary, and the mandibular incisors are CAUDAL to the maxillary
(causes?) clinical signs of overgrown incisors? treatment?(if opposing tooth is missing, or there is improper alignment or improper diet, this can happen.) you will usually see hypersalivation, anorexia and weight loss. TX: TRIM TEETH every 2-3mo.
what are some ways you can trim teeth in rats/mice?(should be done every 2-3mo) Cut with bone/wire cutter, dremel or nail clippers (may fracture). Sedation and drill preferred to prevent splitting teeth.
what are the clinical signs of fur mites?thin, greasy haircoat, pruritus, SELF-INFLICTED TRAUMA (most of it isnt from the mites themslves). May be subclinical for weeks or months
are fur mites burrowing or non burrowing? how do you tx them?they are non-burrowing so you can see the mites/nymphs/eggs with a magnifying glass. Tx with ivermectin (PO, SQ, topical) and trim hind toenails to prevent self mutilation
MICE---> Mouse Hepatitis Virus. What kinda virus is this? Age affected? what are the clinical signs? what's the tx?this is a corona virus which affects neonates. you will see WASTING because of severe enteritis--> diarrhea, dehydration, jaundice. There will be no milk in the GI tract and the pups will be small. (also the liver looks all messed up) The only tx is supportive until the dz runs its course
MICE---> rotavirus. age this affects? clinical signs? treatment/prognosis?Usually affects neonates. It's rota, so of course enteritis (milder than mouse hepatitis though), and you'll see diarrhea with soiling of hair coat. Tx is supportive, most of the time pups continue to nurse and usually survive
Sendai Virus--> affects who? what kinda body system does this virus manifest in? what's the DDX?Rats AND mice, it's a resp. virus. DDX-mycoplasma
Sendai Virus--> what are the clinical signs? prognosis? tx?CS: mild resp distress. Adults will recover in 2mo, FATAL in neonates and weanlings. TX is supportive, and to control ammonia levels (keep clean cage), and give abx (in case it is mycoplasma and not sendai)
Mycoplasma affects who? what kinda body system does it affect? How common is this dz?Rats and mice, it is a resp. dz (Mycoplasma pulmonis). MOST PET MICE ARE CARRIERS and they will develop clinical dz when stressed or ill.
Mycoplasma--> clinical signs? tx?dyspnea, pneumonia(may become chronic and abscesses may develop), rhinitis, otitis media. TX: Antibiotics (Tetracycline, Doxycycline + enrofloxacin) <--alleviate the CSs but doesnt elim infxn, and then control ammonia levels
mice AND rats--> Dermatophytosis. which specific agents? CSs? Dx? tx?Trichophyton mentagrophytes, Microsporum canis. CS: crusty skin lesions. DX: culture of hair sample TX:Miconazole topically/ Griseofulvin orally (in corn oil)
RATS: SKIN SWELLINGS. what are your R/Os if you have a rat with skin swellings?fibroadeonoma, adenocarcinoma, abscess
what's the most common tumor of RATS? (where does it occur and is there a gender preference)fibroadenoma, anywhere on the body and happens in males and females
what's tx like for fibroadenoma in RATS? prognosis?surgical excision, good prognosis (benign), recurrence common
RATS--> Chronic Progressive Nephropathy. Age and gender specifics? clinical signs and tx?Advanced age >1yr. More severe in males. CS: PU/PD, proteinuria, Hydrothorax and ascites in advanced stages. TX is only supportive because this is a fatal dz, but calorie and protein restriction limits severity
Sialodacryoadenitis Virus--> who does this affect, what kinda virus is it, and what parts of the body are affected?this is a viral dz of RATS, which is caused by a corona virus. *HIGHLY CONTAGEOUS*. Sialo= salivary gland. dacryo= tears. aden= gland. Itis=inflammation. Therefore, it's an inflammation of the salivary glands, cervical LNs, and Harderian gland
Sialodacryoadenitis Virus--> CSs and TX/prog?CS: Red ocular and nasal discharge (hence the dacryo in the name). TX: no tx, it is a self-limiting infection of ~30 days, with high morbidity and low mortality.
RATS--> resp. dz. what are the 4 most likely agents?Mycoplasma pulmonis, Streptococcus pneumoniae, Corynebacterium kutscheri, Cilia-associated Respiratory Bacillus (CAR).
RATS--> clinical signs of resp dz? (resp and general)Respiratory - snuffling, mucopurulent nasal discharge, conjunctivitis, tachypnea. General - weight loss, hunched posture, ruffled haircoat, head tilt, red ocular and nasal discharge