Wk 13 small mammal repro

Question 1

Female anatomy of small mammals
Rabbit and rat

Answer 1

• Duplex uterus (2)
  
  • Primitive
  • Rabbit and rat
  • Two uteri fused at the vagina
  • Has two long, coiled but separate oviducts
  • Separate cervixes
    Vagina and vaginal vestibule
• In rabbits, ovarian cancer is high so de-sexing female rabbits is really important as they will get mammary cancer

Question 2

Female Anatomy: ferrets and guinea pigs

Answer 2

• Bicornuate
• Less primitive
  Distal part of uteri fuses into short uterine body

Question 3

Male anatomy of small mammals:
- Testicles
Seminal vesicles

Answer 3

• Seminal vesicles (particular rats and guinea pigs)
  
  • Large in these species (mistaken for uterine horns, and can get infected)
• Testicles can be drawn up into the body
  
  • Can push on the body and pop it back out- but need to close off the inguinal canal properly during surgery as can get hernia in the inguinal canal
• Guinea pigs have peroneal glands that secrete sebaceous material
  
  • When they get older - glands build up and strong odour and swelling
    Is in females as well but more in males

Question 4

Maturity, gestation and litter sizes in females

Answer 4

• Rabbits have longest
• Rats and mice are shortest maturity
• Gestation:
  
  • Guinea pigs are similar to dogs and cats*
  • Rabbits are bit longer for maturity, and half for gestation
    Rats and mice are 20 day gestation

Question 5

Oestrous cycle in female reptiles

Answer 5

• Ferrets bit weird
  ○ Stay in season either until mated or until day length reduces again
  If they stay in season, they will get toxic effects of long term oestrogen

Question 6

What occurs in ferrets when fail to mate after ovulation?

Answer 6

Failure for the jill to mate results in continuous hormonal stimulation of oestrogen from ovaries –> leading to hyperoestrogenism causing **bone marrow suppression and anaemia **

Question 7

Which animal has the longest gestation period?
- Rabbit
- Guinea pig
- Rats
- Mice
- Ferrets

Answer 7

• Guinea pigs have the longest gestation at 59-72days
  
  • Remember similar to dogs*
• Rabbits gestation is 31-32 days
• Rats and mice are shortest at 21-23 days
  Ferrets are 41-42 days

Question 8

Rabbits: transition to yolk sac and foetal loss percentage.

Answer 8

-rabbits are particularly prone to foetal loss at day 13 when placentation changes from yolk sacs to hemochorial, and at 23 days when the foetuses are susceptible to dislodgment by rough handling
Embryonic mortality is very high in rabbits with only about 60-70% successful births

Question 9

When does a male rabbits testes descend

Answer 9

• testes descend at 10 weeks (2 months ish)

Question 10

when do adult rats testes descend

Answer 10

• testes descend between 30 to 40 days

Question 11

when do male guinea pigs tests descend

Answer 11

• the inguinal ring is permanently open

Question 12

The duplex uterus, with two long coiled but separate branches and separate cervices uniting at the vagina is found in what animal?
- the rabbit
- the guinea pig
- the ferret
- primates

Answer 12

the rabbit and rat

Question 13

In what animal does the distal part of the uterus fuse into a short uterine body to form a bicornuate state.

Answer 13

in most mammals like carnivores (ferrets) and guinea pigs

Question 14

What is unique feature of the guinea pigs female anatomy?

Answer 14

the presence of a vaginal membrane. This is a thin, translucent epithelial membrane that seasl the vaginal orifice except during copulation and parturition. It closes shortly after oestrus or if copulation has taken place, after expulsion of the vaginal plug