General Animal Reproduction Flashcards
Where does animal reproduction begin?
It begins with the reproductive system in the embryo
What are the benifits of sexual reproduction
Promotes genetic diversity
Sexual reproduction is a biological process by which organisms create descendants that have a combination of genetic material contributed from two different members of the species.
Estrus
Estrus: the period of sexual receptivity in females.
Also known as Heat’
Estrous Cycle
the reproductive cycle of non-primate females that is defined by a time interval between one Heat (estrus) to another Heat (estrus)
What makes canine reproductive cycles special?
Dogs have a rather unique reproductive cycle that differs from many other mammals
- Its estrous cycles have quite long periods of inactivity. The variation is dependent on breed.
- Puberty usually correlates to the time dogs reach adult weight and height:
- Small breed dogs: 6-10 months
◼ Large breed dogs:18-24 month
What decides the length of time in canine estrous cycle period of inactivity
This is breed dependent
What are the stages of the canine estrous cycle?
- Anestrus
- proestrous
- estrus
- diestrus (or metestrus)
Anestrus (Canine)
Period of reproductive rest.
Time between whelping (diestrus) and the next proestrus phase
Proestrus
Time: Last 6-11 days (average 9 days)
Time interval prior to estrus and characterized by increased ovarian follicular activity
- LH and FSH increases estrogen levels
- The estrogen increases growth of the uterus and vagina mucosa and increased vascularization
Change in behaviour: restlessness, increased urination, more playful with the male
Behaviour changes in dogs during proestrus
Restlessness, increased urination, more playful with males
Estrus (dogs)
Period of sexual receptivity
- First day the female will allow the male to mount (standing heat)
- End of estrus: Female will not stand for male
Estrogen rise 1-2 days prior to estrus and as estrogen levels decrease pregesterone level invrease
LH surge leads to ovulation
During estrus: vaginal secrestion progress from blood tinged to staw coloured
Diestrus (metestrus)
Canines
Lasts usually 2 months long
Corpus luteum produces progestrone
- Maintains pregnant and non-pregnant uterus
Non-pregnant uterus: diestrus ends as corpus lutea regresses (day 60-80)
Diestrus begins: female refuses to stand for male
How long does diestrus last in both pregnant and non-pregnant dogs?
Pregnant uterus: diestrus terminates at whelping (day 56-58)
Non-pregnant uterus: diestrus ends as corpus lutea regresses (day 60-80
What behaviour marks the begining of diestrus in dogs?
Female refuses to stand for male
What are the sizes of abdomen palpations in dogs (and what day do they show up)
Pregnancy Diagnosis
Day 20-30: feel ‘walnut size’ growths in uterus.
Day 30-50: uterus is large (diffuse) but difficult to palpate individual fetuses
Greater than Day 50: individual fetus can be distinguished from intestines
Ultrasound
Pregnancy diagnosis (dogs)
Can diagnose pregnancy at Day 25 gestation
Radiographs
Dog: Pregnancy Diagnosis
Enlarged uterus at Day 20:
- Day 45: radiograph can identify individual fetuses (calcified skeleton)
What are the methods of pregnancy diagnosis in dogs?
- Abdomen
- Ultrasound
- Radiographs
- Blood or Urine Hormoe Testing (NOT HUMAN PREGNACY TEST)
- Blood test
- Can measure relaxin levels in the dogs at day 24-30
What are the types of abnormal estrous cycles?
Dogs
- split heats: first proestrus/estrus: no ovulation, but second proestrus/estrus there is ovulation and normal fertility
- ovulation failure: seen in bitches with short inter-estrus periods (<4 months)
- Prolonged proestrus/estrus: (this period last longer than 21 days)
Causes: ovarian cysts
What are the common reasons for failure to conceive in dogs?
- incorrect time of mating
- stress: too much stress with the bitch and will lead to infertility
- infertile males
- Uterine problems: infection, endometriosis
Split heats
Dogs
first proestrus/estrus: no ovulation, but second proestrus/estrus there is ovulation and normal fertility
Dystocia
Difficult birthing (parturition)
Common in bulldogs → You need to do a c-section for them
Common reasons for dystocia
- uterine weakness; electrolyte imbalance, fatigue (long delivery, too many puppies)
- narrow pelvic canal (i.e. pug, bulldog)
- fetus is too large or malposition
- obstruction of vagina (scarring, tumors)
Pyrometra
Dogs
Infection of uterus
Most common in older dogs (8-10 years) and dogs with multiple births
- ‘looser’ cervix allows more pathogens iside
- If the cervix does not open during parturition
- Uterus may burst
- Prolonged progesterone; makes the uterus a great place to grow bacteria
- Treatment: surgery or if breeding animal prostaglandins (open cervix only and antibiotics)
Eclampsia
Dog Reproduction
Eclampsia: hypocalcemia (low blood calcium)
- Nervous, muscle twitching, seizures, death
When do cats reach sexual maturity?
Sexual Maturity: 6-9 months of age (best breeding performance: 1.5-7 years of age)
Photoperiod
Cats
In general; North America: queens begin cycle in Jan/Feb and will cycle every 4–30-day intervals (increasing interval time) until Sept/Oct
- At this point cycling stops.
What behaviour is associated with feline ovulation
Ovulation occurs with copulation (mounting, intromission and ejaculation)
What makes feline estrous cycles different from canine
- Photoperiod effects cycle
- can have multiple proestrus periods
Steps of the feline estrous cycle
Anestrus: occurs with short daylight (i.e. Oct-Dec)
Proestrus: increasing blood levels of estrogen. May see behavioral changes (head/neck rubbing behavior)
Estrus: sexual receptivity (2-19 days long): queens vocalize and posture for male (lordosis)
Proestrus: cycles between if queen if fails to ovulate
Diestrus: occurs following induced ovulation. Corpus lutea produces progesterone (40 days if not pregnant and 60 days if pregnant).
- following delivery of kittens or end of diestrus; progesterone levels decrease and estrus follows 7-10 days (within acceptable photoperiod)
Hormone effect of copulation
GnRH→LH→Ovulation
Copulation will release Gonadotropin releasing hormone (GnRH) from hypothalamus. This induce the release of gonadotropins from pituitary and this will induce an LH surge resulting in ovulation.
More copulations, get greater LH surge (thus queens can mate: 20-36 times with 36 hours)
- Note: need 8-12 copulations to achieve a maximal LH surge
True or False
Cats are less prone to dystocia then dogs
True
Cats gestational length
Average 63 days
Dog gestational length
Average 66 days
Control of fertility
Animal (to be clear)
Female: Ovariohysterectomy (‘Spay”)
Male: Castration (“Neuter”)
What are the stupid reasons for not spaying or nutering your animal
- Earn Extra income
- Seeing the miracle of birth
- I want another animal just like mine
- Not being able to reproduce will make the animal miss out
- We’ll find a good home for the babies
