ANATOMY - Small Mammals Flashcards
What are two of the main methods used by small mammals to thermoregulate in cold temperatures?
Burrowing
Peripheral vasoconstriction (ears and tail)
Which thermoregulatory method during cold temperatures is unique to rodents?
Rodents have brown adipose tissue which generates heat through non-shivering thermogenesis
What are two of the main methods used by small mammals to thermoregulate in hot temperatures?
Burrowing
Peripheral countercurrent heat exchange
Why is thermoregulation so important in small mammals?
Small mammals have a very hight metabolic rate and are thus prone to dehydration and hypothermia. This makes thermoregulation very important in these species
What are the main adaptations to the lagomorph (rabbit) forelimbs to allow for digging?
Lagomorph (rabbit) forelimbs are shorter and their radius and ulna are fused to facilitate the fast movements used in digging
What are the main adaptations to the lagomorph (rabbit) hindlimbs to allow for propulsion/hopping?
Lagomorph (rabbit) hindlimbs are longer and their fibula and tibia are fused to facilitate the propulsion used in hopping
What is the vertebral formula for lagomorphs (rabbits)?
C7, T12-13, L7, S4, Cd15-16
Why are rabbits prone to fractures at L6-L7 of their vertebral column?
Rabbits are prone to fractures at L6-L7 due to the hindlimbs twisting around the lumbar-sacral junction as the rabbit hops which can cause fractures if the rabbit has not been handled properly
Why do the last five to six ribs in the lagomorph (rabbit) skeleton not meet at the sternum?
The last five to six ribs do not meet at the sternum to allow for better chest wall compliance, allowing the rabbit to meet it’s high oxygen requirements
What is the vertebral formula for guinea pigs?
C7, T13-14, L6, S3-4, Cd4-7
What is one of the main unique features associated with the guinea pig rib cage?
The final two ribs (12-14) are cartilaginous in the guinea pig ribcage
How many digits do guinea pigs have on their forepaws?
Guinea pigs have four digits on their forepaws
How many digits do guinea pigs have on their hindpaws?
Guinea pigs have three digits on their hindpaws
What stance are guinea pig hindlimbs classified as?
Plantigrade
What is the vertebral formula for rats?
C7, T13, L6, S4, Cd27-31
At what age does a rat skeleton fully ossify?
A rat skeleton fully ossifies at one year of age
At what age do the growth plates at the proximal humerus and the distal radius and ulna fuse in a rat?
The growth plates at the proximal humerus and the distal radius and ulna fuse at two years of age in the rat
What are the two main functions of the rat’s tail?
Balance
Thermoregulation
Why do myomorph (rat and hamster) bones take so long to heal?
Myomorphs have a poorly developed Harversian remodelling system causing their bones to take longer to heal compared to other species
What anatomical adaptation allows for myomorphs (rats and hamsters) to have increased flexibility when gnawing?
Cartilaginous mandibular symphysis allows for myomorphs to have increased flexibility when gnawing
Why do ferrets require hindlimb support when being handled?
Ferrets require hindlimb support due to their very flexible vertebral column which can be prone to fractures if not handled properly
What does elodont mean?
Elodonts are species which have teeth which grow continuously throughout their life
What does aradicular mean?
Aradicular species have open rooted teeth
(T/F) All lagomorphs and rodents have elodont, aradicular incisors and cheek teeth
FALSE. Omnivore rodents have elodont, aradicular incisors however their cheek teeth stop growing at around four months old
What are ‘peg teeth’?
Peg teeth are the two rudimentary incisors present on the lagomorph (rabbit) upper jaw
What causes rat incisors to always appear yellow?
Rat incisors have an iron pigmentation causing the incisors to appear yellow (this is normal)
What does a loss in a rats iron pigmentation indicate?
Suboptimal diet
What are hamster cheek pouches?
Hamster cheek pouches are distensible invaginations of the lateral buccal epithelium that extend all the way back to the dorso-caudal scapula
What is the function of hamster cheek pouches?
Hamster cheek pouches are designed to carry food, bedding and neonates
Which four diseases are hamster cheek pouches susceptible to?
Abscesses
Impactions
Prolapse
Tumours
What type of stomach do small mammals have?
Monogastric stomachs
What are the three gastrointestinal anatomical structures unique to lagomorphs (rabbits)?
Sacculus rotundus
Vermiform appendix
Fusus coli
Where in the lagomorph (rabbit) gastrointestinal system is the sacculus rotundus located?
The sacculus rotundus is located at the ileocaecocolic junction