Overview of Canine Therio Flashcards
Canine estrous cycle time period
- They do not have seasonal variation
- Will occur year round
Feline estrous cycle time period
- Long day breeders
- They will go in and out of estrus during
Breeding for profit
- Most responsible breeders don’t make money
- Value of a single puppy may be quite high, but net income is not great
- Hard to make money from breeding just one litter
Reproductive services
- Contraception (surgical and non-surgical
- Effects of age at time of surgical sterilization
- Wellness care
- Consultation on nutrition and husbandry
- Consult for equipment and facilities
- Consult for genetics
- Breeding soundness exam
- Breeding management ans assisted breeding
- Compliance with government regulations
- Preg termination
Effect of GnRH
- Stimulate LH and FSH
Effect of E2 on LH and FSH
- Negative feedback for LH and FSH
What produces estrogen?
- Follicle on an ovary
Effect of Estrogen on GnRH
- Positive feedback
Estrous cycle
- be able to draw the picture
Season or seasons
- Estrous cycle
Anestrus lay term
Between heats, not in season
Proestrus lay term
- Coming into heat, coming in, pre-standing heat
Estrus lay term
- In season, in heat, in, standing heat
Diestrus lay term
Out of heat, out, going out of season
What hormones are key during anestrus?
- FSH (typically quite elevated)
- GnRH (stimulates FSH and LH)
- LH (going through phasic increases)
- Control by hypothalamic pituitary ovary interactions
Anestrus duration
2-5 months with a wider range
What occurs during anestrus?
Time of uterine repair
Anestrus in relation to luteal/follicular period
- Starts at the end of luteal period
Progesterone during anestrus
<1 ng/mL
GnRH stimulation of LH and FSH during anestrus
- From early to late anestrus, GnRH pulse frequency increases leading to production of both FSH and LH
FSH role
- key stimulator of follicular development
- Increases LH receptors in granulosa cells in the ovary
- LH then takes over for further follicle maturation
When is FSH area under the curve greatest?
- Late anestrus
What happens during proestrus?
- Time of development and maturation of the follicle and oocyte
Duration of proestrus
9 days, but range from 3-14 days
External signs of proestrus (keeping in mind that they are quite variable)
- Swelling vulva
- Serosanguinous vaginal discharge
- vaginal mucosal thickening
- Attraction of males
Progesterone during proesterus
- For majority of proestrus, will be <1 ng/mL
- Towards the end of proestrus, as you get to the LH surge, you will have an increase
What happens during estrus?
- Time of final oocyte maturation, ovulation, breeding receptivity, and conception
- LH surge
- Ovulation
- Corpora lutea formation
Average duration of estrus?
9 days average
- Ranges from 3-14 days
Observable characteristics of estrus (keeping in mind that it’s quite variable)
- Decreasing vaginal discharge
- reduced swelling and “softening” of vulva
- Thickening edematous vaginal mucosa
- Standing for breeding
What happens to progesterone during estrus?
- It increases (but doesn’t peak until diestrus) and drives formation of a corpora lutea that will persist throughout diestrus regardless of whether the dog becomes pregnant or not
How many divisions has a canine oocyte undergone by time of ovulation?
- One meiotic division
- At this point it is a primary oocyte
How many divisions are required before fertilization can occur?
- Two
- Primary oocyte must divide once more
When do oocytes reach secondary state?
- 2 days after ovulation
When is the fertilization period for the dog?
- Two days after ovulation and lasts about 2 days
- CAN be longer due to delayed oocyte degeneration
Diestrus description
Luteal period occurring after every estrus
How long does diestrus last?
- 50 days on average, range 50-70 days
Progesterone during diestrus
- Functional corpora lutea produces progesterone
- Unlike other species, bitch has serum progesterone levels during diestrus that will be quite similar regardless of whether she is pregnant or not
Pseudocyesis - is it a disorder?
- No
- It’s normal
What is the pathogenesis of pseudocyesis?
- Decline in progesterone leads to clinical signs in diestrus (mid to late)
- Mammary gland development
- Galactorrhea
- Abdominal distension
- nesting behavior
What do pseudocyesis or elevated progesterone levels indicate?
- Indicates ovulation plus development then deterioration of a corpus luteum
Treatment of pseudocyesis
- None normally
- Do not need to spay or treat with hormones
- Unless there is galactorrhea, in which case you can use a prolactin inhibitor or decrease nutritional intake
Feline estrous cycle
- Seasonally polyestrus
- Long day breeder
- Will respond to manipulation of the photoperiod
When does ovulation occur in the feline?
- Ovulation induced by mating
- Act of breeding causes a release of luteinizing hormoen?
Where does progesterone come from during the feline estrous cycle?
- Corpus lutea and possibly the feto-placental unit
Superfecundation
- Offspring from more than one sire can occur
Superfetation
- Offspring of different gestation lengths has been reported but not definitely confirmed in the cat
Mating behavior in the queen
- Female calls out, rolls around and exhibits estrus behavior
- 20 sec to few minutes for male positioning
- 1-30 seconds for intromission and ejaculation
- Female may strike out after copulation
- She will allow copulation again to get stimulation for luteinizing hormone surge
What determines ovulations rate in the queen?
- Mating frequency and duration of estrogen elevation
Ovulation success after number of matings
60% after one mating
Up to 100% after mating 3x per day for 5 days
External stimulation of ovulation in the queen
- Vaginal stimulation with a glass rod or cotton swab can stimulate mating and induce ovulation
- hCG or GnRH have been used to induce ovulation
Female dog anatomy of the vagina
- Make sure that you can draw it out and know what you will reach first
Vaginal cytology use
- Indirect indicator of serum estrogen level
- Vaginal cytology can be thought of as a semi-quantitative estrogen assay
Vaginal mucosa cell thickness during diestrus and anestrus
- 4-5 layers thick
- Estrogen is low
Vaginal mucosa thickness during proestrus
- 15-20 cells during estrus
- Estrogen is higher
Late anestrus cytology
- Higher number of parabasal cells
- Not many RBCs or WBCs (unless another disease process is going on)
- Lower number of intermediate and superficial cells
- vulva is thin (4-5 layers)
Proestrus cytology
- Parabasal cells start to dwindle
- Higher # of intermediate cells
- By the end, starts to be more superficial cells (cornified)
- Vulva is getting thicker
- Higher number of RBCs at the end
Estrus cytology
- Higher number of RBCs then dwindles
- Low number of parabasal cells
- Fewer intermediate cells and majority superficial (cornified) cells
- vulva is thickened and then dwindles by the end
Diestrus cytology
- Higher number of WBCs
- Fewer RBCs
- Parabasal cells pick up
- Fewer intermediate and superficial cells
- Thicker vulva
