Wk 7 male & female clinical applications Flashcards
Why does testicular circumference become bigger?
- More cells producing more sperm
- Produced in the seminiferous tubules
More cells that are produced = expanding testicles
What drives spermatogenesis?
- Hormones
So if we aren’t producing enough hormones, we won’t produce sperm
What happens if testicles are not big enough?
- Defect in spermatogenesis –> low hormones etc. Which drive it
Test for testosterone and LH –> these are sperm producing hormones
What is the pampiniform plexus?
- Counter current heat exchange
What is the role of the cremaster muscle?
- 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..)
What is DHT?
Why is it important compared to testosterone?
- Dihydrotestosterone
4 x more potent than testosterone
What happens when we have too much dihydrotestosterone?
- 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
Surgical methods of male sterilisation
- Orchidectomy - remove the testicles
Vasectomy - remove part of the vas deferens
Chemical methods of male sterilisation
- 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)
What happens when we desex an animal?
Loss of negative feedback –> increased GnRH –>Increased FSH and LH with no negative feedback
Effect of chemical method: Deslorein implant
- Suppresses GnRH –> stops LH and FSH
- Prevents testosterone from being produced
Testicles get small as not producing sperm –> sperm production = teste size
Breeding soundness examination: 7 categories of this exam
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
What effect does progesterone
Blocks oestrogen and surge centre = no ovulation
What drives poor libido?
- Testosterone
Scrotal circumference
- Provides reliable estimate of testicular mass and daily sperm production
High correlation of 0.95 with paired testis weight
Is sperm concentration important? Why?
- Pregnancy rates significantly higher when more sperm is present
Higher sperm concentration = higher conception
Freezing semen - process:
- 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
Why do we freeze semen
- Insurance
- Genetic improvement
Convenience of shipping semen
Removing gonads and effect on HPG axis
Oestrus Seasonality with melatonin and light
- 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..
Surge centre in females
- Positive feedback with oestrogen
What happens if we remove gonads? Everything in the surge centre will be unregulated
Female sterilisation methods: surgical methods
- Ovariohysterectomy
- Hysterectomy
Ovary sparing spey -> leave the ovary and take the uterus out (not correct, can have ectopic pregnancy through endometriosis)
What happens if we leave the ovaries in females?
- 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
- Disaster if leaving ovaries in:
Chemical methods of female sterilisation
- GnRH agonists/antagonists
Vaccines (GnRH, kisspeptin, zona pellucida)
What happens if you take the gonads out in females
Overexpression of LH and FSH due to no negative feedback occurring on GnRH
Melatonin implant in cats - females
Melatonin decreases GnRH release and thus suppresses ovulation
Breeding soundness exam in females
- Thorough breeding history
- Vulvar conformation
- Vestibulo =vaginal seal
Cervix
What maintains pregnancy in females
- Placenta:
Prevents attachment, blood flow and nutrient exchange between the placenta and the mare
The 3 ways artificially inseminating animals
- Sperm into vagina - transvaginal
- Cervix - transcervical
- Uterine - intrauterine
Surgically can inject the sperm into the uterus through surgery -> painful and hard.
Embryo transfer and superovulation:
What hormone is required for superovulation?
What is the time period for injecting this hormone?
- 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
- FSH hormone to produce more eggs = superovulation
Recap: list differences between species and their sex glands:
- What species has 2 sex glands?
- What species have all 4 sex glands?
- 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)
