The Oestrous Cycle and Sterilisation Flashcards
1
Q
At what age does the bitch start cycling?
A
Between 6-18 months
Larger breed dogs tend to start cycling later
2
Q
How long is the average total oestrus cycle in a bitch?
A
6 months
3
Q
Define Monoestrus
A
A mammal that has one oestrus period per breeding season, as the dog
4
Q
Describe the length of each phase of the oestrus cycle in a bitch
A
- Proestrus = 9 days
- Oestrus = 9 days
- Dioestrus = 60 days
- Anoestrus = 100-150 days
5
Q
Describe the flexibility of the oestrus cycle
A
Dates and timings are very changeable:
- Each have characteristic clinical changes
- Also have associated hormonal changes
6
Q
How is Classic ‘in-heat’ cycle described by owners?
A
- Combination of Proestrus + Oestrus
- Usually lasts 21 days in total
7
Q
‘In heat’ is a combination of which stages?
A
Proestrus and oestrus
8
Q
Describe Proestrus and its signs
A
The ‘in-heat’ stage, along with oestrus Lasts nine days on average (3-17) Clinical signs noted: - Serosanguinous vulval discharge - Vulva swelling - Males attracted but rejected
9
Q
Describe Oestrus and its signs
A
Lasts nine days on average (3-21) Fertile period, potential for coitus Clinical signs noted: - Reduction in vulva swelling - Vulval discharge becomes serous/brownish - Willing to accept male
10
Q
Describe dioestrus and its signs
A
- Approx. 70 days
- End of fertile period
- Male not accepted or attracted
- Normal vulva size, no discharge
11
Q
Describe anoestrus and its signs
A
- Variable length (3-4 months)
- Sexual inactivity between cycles
- Optimum time for OVH
12
Q
In which stages of the oestrus cycle is a pyometra most likely?
A
Dioestrus
13
Q
In which stage of the oestrus cycle is spaying optimal?
A
Anoestrus
14
Q
Which stages of the oestrus cycle have the most significant endocrine changes?
A
Proestrus and oestrus
15
Q
Which 3 hormones are most involved in the oestrus cycle?
A
- Oestrogen
- Luteinizing hormone
- Progesterone
16
Q
Describe the endocrine changes that occur during proestrus
A
- Associated with stimulation of follicle development by FSH and LH pulses
- Subsequent secretion of oestrogen from growing follicles
- Oestrogen concentrations continue to rise and then peak at the end of proestrus
17
Q
Describe the endocrine changes that occur during oestrus
A
- Oestrogen peak causes LH surge: occurs 24-48hrs into oestrus
- Ovulation takes place 24-48hrs after LH surge
- Immature oocyte undergoes 2nd mitotic division to mature (this takes 48hrs)
- Oocyte is then fertile for 48-72hours
18
Q
Levels of which hormone begin to rise following an LH surge?
A
Progesterone
19
Q
The oestrogen peak signifies?
A
The end of proestrus
20
Q
Describe the endocrine changes that occur during dioestrus
A
End of fertile period
Dioestrus is the time of progesterone dominance
21
Q
Describe the endocrine changes that occur during anoestrus
A
- Basal levels of oestrogen and progesterone
- Late anoestrus likely has LH pulses and FSH pulses
22
Q
How long is the gestation of a dog?
A
Approx 63 days
58-68 days
23
Q
Describe behavioural changes and clinical signs seen in proestrus
A
- Male is attracted but rejected (sitting down or aggressive towards male)
- Increased urine marking, roaming
- Vulva swells as oestrogen ↑
- Serosanguinous discharge
24
Q
Describe behavioural changes and clinical signs seen in oestrus
A
- Male is accepted
- Standing to be mated
- Movement of the tail to uncover the vulva (Sometimes known as ‘flagging’)
- Spinal lordosis
- Vulva swelling reduced significantly, so quick that it becomes wrinkled
- Discharge becomes darker red/brown
25
Describe behavioural changes and clinical signs seen in Dioestrus/anoestrus
- Male not accepted/attracted, no sexual activity
| - Normal vulva and no discharge as long as no pseudopregnancy
26
Describe how to perform vaginal cytology
- Moisten cotton swab with sterile saline
- Introduce swab to proximal vagina, aiming dorsally
- Firmly roll the swab onto microscope slide
- Assess at low power to establish trend of cellularity and cell types
27
Name the 4 cell types seen on vaginal cytology
Anuclear
Superficial
Intermediate
Parabasal
28
Describe the appearance of parabasal cells
Large nuclei with minimal cytoplasm, round with smooth edges, non-cornified
29
Describe the appearance of intermediate cells
More cytoplasm, starting to get slightly spikey borders of the cytoplasm
30
Describe the cytology of a bitch in proestrus
Plump round parabasal and intermediate cells.
| Contaminating RBC and neutrophils
31
Describe the cytology of a bitch in oestrus
- Almost 100% cornification* (anuclear cells + superficial cells)
- No neutrophils, very clear background
32
Describe the cytology of a bitch in dioestrus
Abrupt drop in cornified cells from 100% to 50%
Other 50% of cells are parabasal cells and
neutrophils (clean up job!)
33
... is the principal hormone assay used for oestrus detection in dogs
Progesterone
34
Describe vaginoscopy and its uses
- Must be performed under general anaesthesia – feasible? ethical?
- Assessment of colour and texture of the vaginal mucosa
35
How can vaginoscopy determine the phase of the oestrus cycle?
- Oestrogen rising during proestrus causes oedema of vaginal mucosa (longitudinal folds)
- Rapid decline of oestrogen in oestrus, oedema deflates causing wrinkles (crenations
36
The feline oestrus cycle occurs every?
2-3 weeks
37
What are the main features of the feline oestrus cycle?
- Seasonal polyoestrus
- Induced ovulators
- No obvious valval discharge
38
Describe proestrus in the feline cycle
Brief and rarely observed
39
Describe oestrus in the feline cycle
Induction of ovulation by mating
40
Describe interoestrus in the feline cycle
If not induced to ovulate (↓ progesterone and oestrus)
41
Describe dioestrus in the feline cycle
If induced to ovulate (↑ progesterone)
42
Describe Anoestrus in the feline cycle
Only when daylight is less than 8 hours
43
What are the benefits of neutering female dogs?
- Population control
- Prevention of pyometra
- Reduced risk of mammary tumours
- Diabetes mellitus management
- Increased life expectancy
- Prevent pseudo-pregnancy
- Being ‘in-heat’ isn’t nice for anyone involved
44
Describe how timing of spaying can reduce the risk of mammary tumours
- If neutered before the 1st cycle there is a 99% reduction in the chance of mammary tumours
- After the 2nd there is a 97% reduction
- After the 3rd you cant claim it is to reduce the risk of mammary cancer
45
If animals are diagnosed with Diabetes mellitus what action should be taken?
Spay
46
What are the risks of neutering female dogs?
- Surgery risk
- Ovarian Remnant Syndrome
- Urethral sphincter mechanism incontinence
- Transitional Cell Carcinoma
- Obesity?
- Osteosarcoma
- Cruciate disease
47
Describe Urethral sphincter mechanism incontinence
- Reduction in urethral closure pressure
- Can occur immediately to 10 years after spaying
- Conflicting evidence on relationship between USMI and spaying
- Increased risk if spayed <3months old
48
What can be used to manage Urethral sphincter mechanism incontinence
Propalin (Phenylpropanolamine)
| Incurin (Estriol, only licensed for spayed bitches)
49
Describe Ovarian Remnant Syndrome and its consequences
- Functional residual ovarian tissue after spay
- Continued secretion of reproductive hormones
- Oestrus/proestrus behaviour noted
- Neoplasia (ovarian, mammary, vaginal)
- Uterine stump pyometra
50
When is the best time to neuter small breed dogs?
Lower risk of USMI so spay before first season at around 6mo of age UNLESS: juvenile vaginitis or recessed vulva
51
When is the best time to neuter medium breed dogs?
Lower risk of USMI so spay before first season at around 6mo of age
UNLESS: breed at risk for cruciate disease, then delay until growth plate closure OR: juvenile vaginitis or recessed vulva
52
When is the best time to neuter large breed dogs?
Higher risk of USMI so spay after at least one season
| If breed at risk for cruciate disease/OSA then delay until growth plate closure
53
What are the benefits of neutering male dogs?
- Population control
- ‘Behavioural’
- Prophylactic and therapeutic effect on:
Benign prostatic hyperplasia
Chronic prostatitis
Perineal adenomas
Perineal hernias
Testicular neoplasia (especially cryptorchid)
Increased life expectancy
54
What are the risks of neutering male dogs?
```
GA risk
Surgery risk - Post-op haematoma
Prostatic neoplasia
Transitional cell carcinoma
Obesity
Osteosarcoma
Worsening behaviour
```
55
Describe the optimal timing for neutering male dogs
- No reproductive cycle so neutering not dependent on this
- Consider allowing to mature before neutering/only neutering if medical issue requiring it
- Behavioural development allows maturation and stable behaviour to base decision-making
- Skeletally, closure of growth plates to reduce cruciate/OSA risk
- Unless cryptorchid! Always castrate cryptorchid testicle 1st (Risk of abdominal testicle becoming neoplastic is 14x higher than scrotal)
