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Y3 MOD Reproductive > The Oestrous Cycle and Sterilisation > Flashcards

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

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2
Q

How long is the average total oestrus cycle in a bitch?

A

6 months

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3
Q

Define Monoestrus

A

A mammal that has one oestrus period per breeding season, as the dog

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4
Q

Describe the length of each phase of the oestrus cycle in a bitch

A
  1. Proestrus = 9 days
  2. Oestrus = 9 days
  3. Dioestrus = 60 days
  4. Anoestrus = 100-150 days
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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
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6
Q

How is Classic ‘in-heat’ cycle described by owners?

A
  • Combination of Proestrus + Oestrus

- Usually lasts 21 days in total

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7
Q

‘In heat’ is a combination of which stages?

A

Proestrus and oestrus

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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
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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
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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
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11
Q

Describe anoestrus and its signs

A
  • Variable length (3-4 months)
  • Sexual inactivity between cycles
  • Optimum time for OVH
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12
Q

In which stages of the oestrus cycle is a pyometra most likely?

A

Dioestrus

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13
Q

In which stage of the oestrus cycle is spaying optimal?

A

Anoestrus

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14
Q

Which stages of the oestrus cycle have the most significant endocrine changes?

A

Proestrus and oestrus

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15
Q

Which 3 hormones are most involved in the oestrus cycle?

A
  • Oestrogen
  • Luteinizing hormone
  • Progesterone
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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
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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
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18
Q

Levels of which hormone begin to rise following an LH surge?

A

Progesterone

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19
Q

The oestrogen peak signifies?

A

The end of proestrus

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20
Q

Describe the endocrine changes that occur during dioestrus

A

End of fertile period

Dioestrus is the time of progesterone dominance

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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

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22
Q

How long is the gestation of a dog?

A

Approx 63 days

58-68 days

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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
Q

Describe behavioural changes and clinical signs seen in Dioestrus/anoestrus

A
  • Male not accepted/attracted, no sexual activity

- Normal vulva and no discharge as long as no pseudopregnancy

26
Q

Describe how to perform vaginal cytology

A
  • 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
Q

Name the 4 cell types seen on vaginal cytology

A

Anuclear
Superficial
Intermediate
Parabasal

28
Q

Describe the appearance of parabasal cells

A

Large nuclei with minimal cytoplasm, round with smooth edges, non-cornified

29
Q

Describe the appearance of intermediate cells

A

More cytoplasm, starting to get slightly spikey borders of the cytoplasm

30
Q

Describe the cytology of a bitch in proestrus

A

Plump round parabasal and intermediate cells.

Contaminating RBC and neutrophils

31
Q

Describe the cytology of a bitch in oestrus

A
  • Almost 100% cornification* (anuclear cells + superficial cells)
  • No neutrophils, very clear background
32
Q

Describe the cytology of a bitch in dioestrus

A

Abrupt drop in cornified cells from 100% to 50%
Other 50% of cells are parabasal cells and
neutrophils (clean up job!)

33
Q

… is the principal hormone assay used for oestrus detection in dogs

A

Progesterone

34
Q

Describe vaginoscopy and its uses

A
  • Must be performed under general anaesthesia – feasible? ethical?
  • Assessment of colour and texture of the vaginal mucosa
35
Q

How can vaginoscopy determine the phase of the oestrus cycle?

A
  • Oestrogen rising during proestrus causes oedema of vaginal mucosa (longitudinal folds)
  • Rapid decline of oestrogen in oestrus, oedema deflates causing wrinkles (crenations
36
Q

The feline oestrus cycle occurs every?

A

2-3 weeks

37
Q

What are the main features of the feline oestrus cycle?

A
  • Seasonal polyoestrus
  • Induced ovulators
  • No obvious valval discharge
38
Q

Describe proestrus in the feline cycle

A

Brief and rarely observed

39
Q

Describe oestrus in the feline cycle

A

Induction of ovulation by mating

40
Q

Describe interoestrus in the feline cycle

A

If not induced to ovulate (↓ progesterone and oestrus)

41
Q

Describe dioestrus in the feline cycle

A

If induced to ovulate (↑ progesterone)

42
Q

Describe Anoestrus in the feline cycle

A

Only when daylight is less than 8 hours

43
Q

What are the benefits of neutering female dogs?

A
  • 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
Q

Describe how timing of spaying can reduce the risk of mammary tumours

A
  • 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
Q

If animals are diagnosed with Diabetes mellitus what action should be taken?

A

Spay

46
Q

What are the risks of neutering female dogs?

A
  • Surgery risk
  • Ovarian Remnant Syndrome
  • Urethral sphincter mechanism incontinence
  • Transitional Cell Carcinoma
  • Obesity?
  • Osteosarcoma
  • Cruciate disease
47
Q

Describe Urethral sphincter mechanism incontinence

A
  • 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
Q

What can be used to manage Urethral sphincter mechanism incontinence

A

Propalin (Phenylpropanolamine)

Incurin (Estriol, only licensed for spayed bitches)

49
Q

Describe Ovarian Remnant Syndrome and its consequences

A
  • Functional residual ovarian tissue after spay
  • Continued secretion of reproductive hormones
  • Oestrus/proestrus behaviour noted
  • Neoplasia (ovarian, mammary, vaginal)
  • Uterine stump pyometra
50
Q

When is the best time to neuter small breed dogs?

A

Lower risk of USMI so spay before first season at around 6mo of age UNLESS: juvenile vaginitis or recessed vulva

51
Q

When is the best time to neuter medium breed dogs?

A

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
Q

When is the best time to neuter large breed dogs?

A

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
Q

What are the benefits of neutering male dogs?

A
  • 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
Q

What are the risks of neutering male dogs?

A 
GA risk
Surgery risk - Post-op haematoma
Prostatic neoplasia
Transitional cell carcinoma
Obesity
Osteosarcoma
Worsening behaviour
55
Q

Describe the optimal timing for neutering male dogs

A
  • 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)

Y3 MOD Reproductive (11 decks)

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