Wk 7 male & female clinical applications

Question 1

Why does testicular circumference become bigger?

Answer 1

• More cells producing more sperm
• Produced in the seminiferous tubules
  More cells that are produced = expanding testicles

Question 2

What drives spermatogenesis?

Answer 2

• Hormones
  So if we aren’t producing enough hormones, we won’t produce sperm

Question 3

What happens if testicles are not big enough?

Answer 3

• Defect in spermatogenesis –> low hormones etc. Which drive it
  Test for testosterone and LH –> these are sperm producing hormones

Question 4

What is the pampiniform plexus?

Answer 4

• Counter current heat exchange

Question 5

What is the role of the cremaster muscle?

Answer 5

• Raise/lower testicles to control temperature
  Protects the testicles as well –> fight or flight response (if a bull is scared it is going to raise and protect it etc. –> if you see a bull with very low and swollen testicles, may not be fit for reproduction..)

Question 6

What is DHT?
Why is it important compared to testosterone?

Answer 6

• Dihydrotestosterone
  4 x more potent than testosterone

Question 7

What happens when we have too much dihydrotestosterone?

Answer 7

• Can cause prostate disease
• To fix this we can reduce testosterone
• Reduce/block DHT to clear prostate disease
  Finasteride drug blocks DHT to treat prostate disease

Question 8

Surgical methods of male sterilisation

Answer 8

• Orchidectomy - remove the testicles
  Vasectomy - remove part of the vas deferens

Question 9

Chemical methods of male sterilisation

Answer 9

• GnRH agonists/antagonists
  
  • Reduces the FSH and LH which can reduce diseases in Daschounds for example who get disc disease
  • Increased FSH/LH also has an effect for cancer, bone disease, cruciate ligaments etc.
    Vaccines (GnRH, Kisspeptin, Zona pellucida)

Question 10

What happens when we desex an animal?

Answer 10

Loss of negative feedback –> increased GnRH –>Increased FSH and LH with no negative feedback

Question 11

Effect of chemical method: Deslorein implant

Answer 11

• Suppresses GnRH –> stops LH and FSH
• Prevents testosterone from being produced
  Testicles get small as not producing sperm –> sperm production = teste size

Question 12

Breeding soundness examination: 7 categories of this exam

Answer 12

1) General physical examination
2) Reproductive physical examination
3) Measurement of scrotal circumference
4) Semen evaluation - initial evaluation on collection
5) Semen evaluation - morphology and other laboratory evaluations
6) Serving ability or capacity
Testing for specific infectious or genetic diseases may be carried out on an as-needed basis

Question 13

What effect does progesterone

Answer 13

Blocks oestrogen and surge centre = no ovulation

Question 14

What drives poor libido?

Answer 14

• Testosterone

Question 15

Scrotal circumference

Answer 15

• Provides reliable estimate of testicular mass and daily sperm production
  High correlation of 0.95 with paired testis weight

Question 16

Is sperm concentration important? Why?

Answer 16

• Pregnancy rates significantly higher when more sperm is present
  Higher sperm concentration = higher conception

Question 17

Freezing semen - process:

Answer 17

• Semen prepared at room temperature then cooled at 4 degrees
• Packaged in straws/pellets
• Cooled in a step-down fashion to -196 degrees
• Stored in liquid nitrogen indefinitely
  Sperm trapped in unfrozen water channels and surrounding area is frozen as well

Question 18

Why do we freeze semen

Answer 18

• Insurance
• Genetic improvement
  Convenience of shipping semen

Question 19

Removing gonads and effect on HPG axis

Answer 19

Question 20

Oestrus Seasonality with melatonin and light

Answer 20

• horses - long day breeders, rely onlow melatonin and warmer days
• Also with sheep -> short day breeders, high melatonin and colder days
  Cats: we can use melatonin to suppress oestrous in cats instead of desexing..

Question 21

Surge centre in females

Answer 21

• Positive feedback with oestrogen
  What happens if we remove gonads? Everything in the surge centre will be unregulated

Question 22

Female sterilisation methods: surgical methods

Answer 22

• Ovariohysterectomy
• Hysterectomy
  Ovary sparing spey -> leave the ovary and take the uterus out (not correct, can have ectopic pregnancy through endometriosis)

Question 23

What happens if we leave the ovaries in females?

Answer 23

• Ovary sparing spey -> leave the ovary and take the uterus out (not correct, can have ectopic pregnancy through endometriosis)
  
  • Disaster if leaving ovaries in:
    Female still has heat when ovaries are in = still attracted to dogs = can still mate with males –> where does the sperm go when they mate? Peroneal abdomen = vagina bursting so the sperm goes into the abdomen = immune reaction as sperm is foreign = BIG PROBLEM

Question 24

Chemical methods of female sterilisation

Answer 24

• GnRH agonists/antagonists
  Vaccines (GnRH, kisspeptin, zona pellucida)

Question 25

What happens if you take the gonads out in females

Answer 25

Overexpression of LH and FSH due to no negative feedback occurring on GnRH

Question 26

Melatonin implant in cats - females

Answer 26

Melatonin decreases GnRH release and thus suppresses ovulation

Question 27

Breeding soundness exam in females

Answer 27

• Thorough breeding history
• Vulvar conformation
• Vestibulo =vaginal seal
  Cervix

Question 28

What maintains pregnancy in females

Answer 28

• Placenta:
  Prevents attachment, blood flow and nutrient exchange between the placenta and the mare

Question 29

The 3 ways artificially inseminating animals

Answer 29

• Sperm into vagina - transvaginal
• Cervix - transcervical
• Uterine - intrauterine
  Surgically can inject the sperm into the uterus through surgery -> painful and hard.

Question 30

Embryo transfer and superovulation:
What hormone is required for superovulation?
What is the time period for injecting this hormone?

Answer 30

• Suck out the embryo with fluid
• Embryo flush: super ovulating to give us more eggs
  
  • FSH hormone to produce more eggs = superovulation
    FSH over 3 days to cause superovulation

Question 31

Recap: list differences between species and their sex glands:
- What species has 2 sex glands?
- What species have all 4 sex glands?

Answer 31

• mare, bull & ram = all 4 sex glands
• Cat, dog = 2 sex glands
• boar = 3 sex glands
• Dogs = no vesicular or bulbourethral glands
• Cats = no ampullae or vesicular
• Boar = no ampullae
• Mare, bull and ram = all 4 sex glands (ram has disseminate prostate)