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Pocket Pets > Rats/Mice > Flashcards

Rats/Mice Flashcards

1
Q

What is the order, suborder, family and genus that rats belong to?

A

Order: rodentia
Suborder: myomorphia
Family: muridae
Genus: rattus

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2
Q

What is the species of rat seen in private practice? What is the other species of rat?

A

Rattus norvegicus (norway rat)

Rattus rattus is the other species (black or roof rat)

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3
Q

What is the order, suborder, family and genus that mice belong to?

A

Order: rodentia
Suborder: myomorphia
Family: muridae
Genus: mus
Species: musculus

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4
Q

Describe some of the obvious external characteristics of rats and mice

A

Short hair, long naked tails, erect round ears, protruding eyes, pointed snouts, five toes on hind feet (4 on front), variety of coat colors

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5
Q

T/F: rodent incisors grow continuously throughout life

A

True
- very important that lower and upper incisors match up to prevent overgrowth, and that they have enough solid food/chew teeth to wear teeth down

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6
Q

What are some causes of incisor overgrowth in rodents?

A

-lack of solid food/chew toys
- broken teeth
-calcium deficiency- leads to wobbly teeth

Leads to malocclusion and overgrowth

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7
Q

What is the treatment for malocclusion of rodent teeth?

A

Clipping of teeth (nail trimmer, human nail clippers)
- nerves are deep within root

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8
Q

What are brown fat deposits?

A

-also known as hibernating gland
- used to generate heat during exposure to cold environments
- allows for non-shivering thermogenesis (rodents dont shiver)

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9
Q

T/F: the brain of rodents lacks gyri and sulci

A

True

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10
Q

What is the issue with prolonged light exposure in rodents (24 hrs a day for several days)?

A

Can lead to retinal degeneration
- can be avoided by cage rotation in a lab animal setting

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11
Q

What is the function of the harderian gland?

A

It secretes porphyrin, an iron containing reddish pigment
- stress leads to hypersecretion (red tears) aka chromodacryorrhea
- can see redness in other areas due to grooming

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12
Q

T/F: There is 3 left lung lobes and 1 right lung lobe in rats

A

F- other way around (1 left, 3 right)

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13
Q

Which animal contains a gall bladder: rats or mice?

A

Mice have a gall bladder, rats do not

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14
Q

Why can rats not vomit?

A

The limiting ridge between the glandular and non-glandular stomach blocks the esophagus during contraction of the stomach
-rodenticides contain emetic agents as protective mechanism for animals that vomits

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15
Q

Describe the cecum of rodents

A

Large- where microbes aid in digestion of cellulose and other plant materials
-in germ free animals, the cecum became enlarged and distended with ingesta leading to the death of these animals early in life

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16
Q

Where does the urethra open in males and females?

A

Males- in the penis (within genital papilla)
Females: in the genital papilla near the base of the clitoris (not in vagina)

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17
Q

What glands are present in male rodents?

A

Paired seminal vesicles, coagulating glands, prostate, bulbourethral glands
- secretions from these glands together yields a “sperm plug” or vaginal plug

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18
Q

What is the function of the sperm plug?

A

Prevents other males from mating female
-also allows researchers to determine day 1 of gestation (day the plug forms)

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19
Q

T/F: rats can pull testicles into abdomen

A

True- when stressed/cold they can pull testicles up through inguinal rings

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20
Q

What is unique about the reproductive tract of female rodents?

A

They have a cervix for each uterine horn

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21
Q

Describe the vaginal closure membrane in rodents

A

A membrane present at birth that disappears prior to sexual maturity
-once open it stays open
-in guinea pigs, it closes back after bred and after parturition

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22
Q

How do you determine the gender of rodents?

A

Anogenital distance
-shorter in females
-longer in males
-keep your mouth shut until you compare multiple animals

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23
Q

Describe the mammary glands of rats

A

6 pairs of nipples
-mammary tissue is widely distributed and may extend up onto the lateral and dorsal areas of the abdomen and thorax
-extends up over the shoulders and around the anus

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24
Q

T/F: mammary tumors are easy to remove in rodents

A

True
-does not require much hemostasis
-however, it is likely that if one forms, multiple will form

25
Q

How long do rats/mice live?

A

Rats: 2-3 years
Mice: 1.5-3 years

26
Q

Describe the behavioral characteristics of rats/mice

A

-nocturnal animals (for research studying behavior, utilize darkness during working hours)
-males are more aggressive than females
-group housed females rarely fight (prefer cagemates)

Mice
- pheromones plat a major role in marking territory and reproduction
-social dominance may be manifested by “barbering” (excessive grooming/nibbling)? more likely a form of OCD (trichotillomania) that can be treated with N acetylcysteine

27
Q

How should you feed a rat/mouse?

A

-feed and water should be available ad libitum
-adult rats eat 5g/100g BW per day, adult mice ear 1.2/10 g BW per day
-measuring feed consumption is useful for assessing animal health and determining dose received for toxicology studies

28
Q

Why is mash feed not recommended for rodents?

A

-can lead to incisor overgrowth
-animals may dig food out of feeder making measuring consumption difficult

Can be used in research if adding antibiotics/drugs as pelleting destroys some compounds due to heat and pressure

29
Q

What can obesity in rodents lead to?

A

Cardiovascular problems, diabetes, joint problems, shortened lifespan
-caloric restricted diet can increase the lifespan

30
Q

What are the main causes of PUPD in rodents?

A

Diabetes and kidney disease

31
Q

Describe the estrous cycle of rats/mice

A

5 day estrus cycle with heat occurring at day 3
-can determine stage of cycle with vaginal lavage/cytology or a vaginal impedance meter

32
Q

What are the 2 types of natural mating/breeding in rodents?

A

Monogamous pairing/breeding: one male and one female, more animals (males) needed, more costly for caging and husbandry

Harem mating/breeding: one male and 2-4 females, fewer males needed, more efficient use of males, more economical

33
Q

What is the main sign of estrus in rodents?

A

Lordosis when pressure is placed on the hindquarters

34
Q

In which species is the sperm plug more adherent and less likely to fall out?

A

Mice
- can also look for presence of sperm using an otoscope into the vagina or perform vaginal lavage

35
Q

What is unique about the appearance of rodent sperm?

A

Hooked heads

36
Q

How long is gestation in rats and mice?

A

Rats: 21-23 days
Mice: 18-21 days

37
Q

Describe parturition in rats/mice

A

-periodic stretching and extension of the hindlegs signals impending parturition
-for delivery, females stand in a semi-crouched position
-fetuses are delivered either head first or breech
-female usually eats placenta then turns attention to pups
-delivery of all pups may take 1-4 h (do not disturb them or they will take longer)

38
Q

What is the normal litter size in rodents?

A

Smallest in the 1st litter and increases in subsequent litters
-declines towards the end of the reproductive lifespan
-smaller in inbred strains

39
Q

When does weaning occur in rodents?

A

21 days

40
Q

Describe the maturation of rodent neonates

A

-born hairless, blind and toothless
-they double their body weight in 5 days
-they develop a fine lanugo hair around 7 days
-their hair coat is developed by 9-10 days
-they start gnawing by 9 days
-their eyes open around 12-13 days
-pups are weaned at 21-28 days

41
Q

What are some considerations when handling rats/mice?

A

Rats
-Tail restraint is ok for brief periods, such as when moving from one cage to another but must grasp base of tail to avoid degloving injury
- thoracic encirclement is ideal: grasp over shoulders, place thumb and forefinger behind rats elbows and make forelimbs cross and restrain tail

Mice
- Tail restraint is ok for brief periods when grasped near base of tail (mouse can climb tail and bite handler)
- scruff hold is also ok- skin between ears and as far down back as you can

can also use rigid plastic containers, decapitone

42
Q

What is the lee-boot effect? the whitten effect? the bruce effect?

A

Lee-boot: grouping of females in absence of male will lead to estrus suppression and decreased incidence of pseudopregnancy

Whitten: exposure of females to a strange male will result in induction of estrus- can be used for synchronization

Bruce: before ova implants in uterus, if female is exposed to strange male the pregnancy will be spontaneously terminated

43
Q

Where should intramuscular injections be given in rodents? subcutaneous? IP or IV?

A

IM- hindleg
SC- scruff over neck
IP- into abdomen (inject along midline of top of the lower 2 quadrants to avoid the bladder, dont use overly long needles, dont insert needle to its hub, insert needle at shallow angle and never reuse needles)
IV-tail vein

44
Q

What are some general rules of thumb regarding injections in rodents?

A

-warm any replacement fluids given SQ or IP
-dilute potentially irritating drugs before giving IP
-avoid giving ketamine IM

45
Q

What are the options for blood collection in rats and mice?

A

Facial vein- wont be sterile
Lateral saphenous
Submandibular
Lateral tail vein

46
Q

What is the limit for safe volume of blood to be collected in a mouse?

A

<0.2 mL (0.1 mL serum), 3 mL ok for rats
-only 2 mL total blood volume

Wait 7-10 days in between blood collections

47
Q

What is gavage?

A
  • a passage of a special needle or tube into the stomach via the mouth (measure from corner of the mouth up until the last rib)
    -ensures delivery of a known amount of material
    -can be used for treatment with compounds that animals will not drink due to taste
48
Q

What are the main options used for anesthesia in rodents?

A

Isoflurane
- 3-4% for induction, 2% for maintenance
- 3 L/min oxygen flow rate
- can induce in induction chamber or convert a Tupperware
- use non rebreathing system

Injectable
- IM ketamine may cause muscle necrosis and apresis
- injectable anesthetics should be given IP
- injectable anesthetics should be diluted with sterile saline to reduce peritoneal irritation

49
Q

How can you assess anesthetic depth?

A

-check reflexes (be aware that animal may still be anesthetized with intact spinal reflexes, palpebral reflex is a good thing to use)
-assess muscle tone
-depth and rate of breathing
-HR and BP

50
Q

What is a unique option used for post op pain relief in rodents?

A

Buprenorphine jello

51
Q

What are the different approaches for ovariectomy in rats?

A

-ventral midline
-dorsal lateral approach

52
Q

What is the problem with cedar chip bedding?

A

Gives off some aromatic compounds that can affect cytochrome P450 altering the mechanism of drug breakdown
- masks the smell of ammonia which can be causing problems in lungs of animals (damage can be done at 5 ppm, humans detect smell at 25 ppm)

53
Q

Describe the ideal characteristics of a bedding?

A

-should keep animals dry between changeouts
-should not cause injury to the animal
-should not lead the animal to ingest it
-should not have properties that would interfere with the research

Corncob bedding- may be contaminated with chemicals
Sawdust may be inhaled
Tech board- used mainly for rabbits
Course, fine and hardwood chips are good options

54
Q

What are some of the main clinical problems that occur in rats?

A

Respiratory disease, anorexia, lethargy, overgrown teeth, tumors
-mites, heart disease, kidney disease, obesity, pododermatitis

55
Q

What is ectoromelia or mouse pox?

A

A viral infection in rodents that is so painful and irritating that animals will gnaw their own limbs off

56
Q

What is the type of tumor that most commonly results in mammary masses in rodents?

A

Fibroadenoma
-inbred strains are at higher risk

57
Q

What are the diseases that are most commonly responsible for stunting/runting or death of pups due to effects on immune system and GI tract?

A
  • Mouse parvovirus type 1
  • mouse rotavirus
    -reovirus type 3

Diagnose with serological testing and treat with fluids and supportive care

58
Q

What respiratory diseases can cause stunting/runting or death of pups, pneumonia, or death in immunocompromised mice?

A

Pneumonia virus of mice
-sendai virus

Diagnose with serological testing

59
Q

What are some bacterial diseases of the digestive system in rodents?

A

Helicobacter, citrobacter rodenticum (causes diarrhea and prolapse of rectum–> quick death), clostridium piliforme (Tyzzers- will see white spots in liver), salmonellosis (can see white spots in liver), pseudomonas aeruginosa (infects inner ear)

Tyzzers and pseudomonas both zoonotic

Pocket Pets (3 decks)

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