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Equine Flashcards

1
Q

Where is semen deposited?

A

The uterus

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2
Q

What are the 3 barriers to infection?

A

Vulva
Cervix
Vestibulo-vaginal sphincter

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3
Q

What surrounds and suspends the ovary?

A

The mesovarium

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4
Q

Are the ovaries fixed or moveable?

A

Fixed

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5
Q

How do the cortex and medulla differ in the horse compared to other species?

A

The cortex is on the inside - germinal epithelium

The medulla is on the outside

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6
Q

Where does ovulation occur through?

A

The ovulation fossa

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7
Q

When does the CL form?

A

Once ovulation occurs

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8
Q

Where is the fornix located?

A

around the entire cervix

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9
Q

What percentage of the vulva should be below the pelvic floor?

A

70%

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10
Q

How does luteolysis differ compared with a cow?

A

It is exerted via a systemic pathway rather than local venoarterial exchange in cattle
Significance -> need smaller doses of prostaglandin for luteolysis

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11
Q

How is a mares cycle described?

A

Seasonally polyoestrus - long day breeders

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12
Q

How long is the period after parturition and before foal heat?

A

9 days average

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13
Q

How long is a mare’s cycle?

A

21 days

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14
Q

How long is oestrus?

A

4-8 days

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15
Q

When does a mare ovulate?

A

Anytime in her 4-8 day long oestrus

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16
Q

When is a CL developed?

A

Early dioestrus -> not responsive to PGF2a

5 days following ovulation responsive

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17
Q

What happens to the CL in late diooestrus?

A

It becomes responsive to PGF2a (13 days)

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18
Q

What happens in the luteal phase and how long does it last?

A

Dioestrus -> time after ovulation
Progesterone increases due to CL presence (ready to accept potential embryo)
18 days long

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19
Q

What happens in the follicular phase?

A

Oestrus -> 4-8 days long

Mare TUW -> Tail up, urinating and winking

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20
Q

What is the transitional phase?

A

40-60 days long between anoestrus and normal cycling oestrus

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21
Q

What hormone dominates the autumn transition?

A

Oestrogen -> follicles, some uterine oedema, but no CL and dont go on to ovulate

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22
Q

What is a vernal transition?

A

AKA spring transition
First heat of the cycle -> no ovulation, oestrogen dominance
Pineal gland picks up light cues

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23
Q

How long is the vernal transition?

A

60-90 days

Dominated by light

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24
Q

How can we shorten the transitional period?

A

Drugs -> GnRH analogues, dopamine agonistss, oestrogens or progestagens
Light -> for 60 days from July-September

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25
Q

How does progestagen shorten the transition?

A

It doesn’t -> it synchs ovulation

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26
Q

How does dopamine antagonists shorten the transition?

A

Increases prolactin -> stimulates follicle growth

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27
Q

Do hCG or deslorelin induce ovulation in transition follicles?

A

No - they do not have LH receptors

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28
Q

In what animals are silent heats most common?

A

Wet mares - foal proud

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29
Q

How do we manage multiple ovulations?

A

Breed to the second follicle

Check for twins at 14-16 days after breeding - get rid of the smaller one

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30
Q

What is a dioestrus ovulation?

A

Ovulation during luteal phase with high progesterone interfering with PGF2a action, resulting in long luteal phase

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31
Q

What do early or late dioestrus ovuations result in?

A

early -> pregnancy

Late -> prolonged luteal phase

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32
Q

How to persistent CLs occur and how long can they last?

A

Spontaneously (failure of Pg release), early pregnant loss, dioestrus ovulation
Last 35-90 days

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33
Q

How do we diagnose a persistent CL?

A

Increased uterine tone, ultrasound

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34
Q

How do we treat a persistent CL?

A

PGF2a -> repeat in 5 days if no response to first dose

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35
Q

What are 2 causes of constant oestrus behaviour?

A

True nymphomaniacs -> alternate oestrogen source (tumour, adrenal gland)

Granulosa theca cell tumour -> depends on predominant cell type (testosterone, oestrogen, inhibin) - will produce normal progesterone in early stages - elevated AMH has tumour

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36
Q

How is prostaglandin used to manipulate the cycle - when are injections given and when is the CL responsive?

A

Injections 14-16 days apart
CL responsive from 5-6 days following ovulation (day 13)
Shortens luteal phase to initiate new cycle

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37
Q

How are progestagens used to synchronise mares - what are the 3 methods?

A

Often used with oestrogen
Regumate -> Oral administration for 14 days and oestrus 5 days after withdrawal
Natural -> in oil - not practical
Cue Mare - CIDR can form vaginitis

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37
Q

How are progestagens used to synchronise mares?

A

Regumate -> Oral administration for 14 days and oestrus 5 days after withdrawal
Natural -> in oil - not practical
Cue Mare - CIDR can form vaginitis

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38
Q

How is oestrogen used to synchronise oestrus - Dose and time period

A

150mg P4 and 10mg E2 for 10 days
Ciderol + CIDR works well
Tighter synchrony with both

Follicle is 35mm -> induce ovulation

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39
Q

What 3 things can be used to induce ovulation?

A

hCG
Deslorelin acetate - injectable
Deslorelin acetate - ovuplant

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40
Q

How does hCG induce ovulation, what follicle size can it be used on and when will ovulation occur?

A

Use on >35mm follicle for ovulation in 36 +/- 6 hours

LH like substance - increases follicle development

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41
Q

How does injectable deslorelin induce ovulation and what follicle size does it work on? when will ovulation occur?

A

Use on >30mm follicle for ovulation in 40 +/- 3 hours

GnRH agonist -> stimulates pituitary release of LH

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42
Q

Can the deslorelin implant (Ovuplant) be used to induce ovulation in mares?

A

No - discontinued

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43
Q

List 4 methods to prevent ovulation/oestrus

A
  1. Progesterone - no oestrus behaviour
  2. GnRH vaccine
  3. Oxytocin
  4. Ovarioectomy - stops ovulation, not oestrus behaviour
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44
Q

How does the GnRH vaccine prevent ovulation?

A

Reduces LH and FSH
for 3-6 months
Discontinued -> infertility in some cases
Does not stop adrenal oestrogen

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45
Q

How does a GnRH analogue prevent ovulation?

A

Overload of GnRH -> downregulates HPG axis to switch off GnRH production
Doesnt work in all horses and will cycle after 3-4 months
Does not stop adrenal oestrogen production

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46
Q

How does oxytocin stop ovulation and at what dose for how long? What are 2 methods?

A

60IU oxytoxin for 7 days starting 7 days post ovulation
Prolonges CL life - longer luteal phase (fake maternal recognition of pregnancy)
Marble -> high failure rate 70%
U-POD -> magnetic and better retention

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47
Q

How does a GnRH agonist stop ovulation?

A

Discontinued - Ovuplants
Prolonged interovulatory interval due to maintaining CL and producing small GnRH
Desensitises HPG axis

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48
Q

List 6 causes of abnormal cycles

A
  1. True non-seasonal polyoestrus (20% cycle all year)
  2. Multiple ovulations during oestrus (delay/lengthen luteal phase)
  3. Lactational anoestrus (does not happen in horses)
  4. Constant oestrus (tumours producing steroids)
  5. Genetic (may not have 2 X)
  6. Silent heat
49
Q

Advantages of paddock breeding

A

Teach stallions normal sexual behaviour
low labour
good selection for repro performance
Experienced stallions- 70-80% rates

50
Q

Disadvantages of paddock breeding

A

Injury to stallion
Reduced efficiency of stallion
Reduced pregnancy rates
Risk of twins

51
Q

Advantages of AI

A 
Genetic progress - exploit superior male
Dont need to own stallion
International access
Safety for females
Minimal animal transport - biosecurity
52
Q

Disadvantages of AI

A

Labour intensive $$
need special facilities and experienced technicians
Semen costly
Reliance on couriers

53
Q

6 neccessities for live cover

A
  1. Pre-breeding swab for STI
  2. PPE
  3. Cleanliness - wash mare and stallion
  4. Ovulatory drugs to minimise serves
  5. Teasing
  6. Ultrasound exam - identify ideal breeding time and pregnancy/twins at 15 days
54
Q

What is equine coital exanthema?

A

Equine herpes virus 3 veneral pathogen
affects males and females signs 4-7d after contact
Pustules and ulcers

55
Q

How is equine coital exanthema treated?

A

sexual rest for 3 weeks and topical antimicrobials

56
Q

Name 3 bacterial venereal pathogens

A
  1. Contagious equine metritis (taylorella equigenitalis) - not in Aus
  2. Klebsiella spp.
  3. Pseudomonas - water based
57
Q

Name 3 viral venereal pathogens

A
  1. EHV-3
  2. Equine viral arteritis
  3. Equine infectious anaemia
58
Q

Name 1 protozoan venereal pathogen

A

Trypanosoma equiperdum

59
Q

How long after collection should chilled, extended semen be inseminated?

A

24-48 hours

60
Q

How cold should frozen sperm be stored at?

A

-196 degrees in liquid N

61
Q

After 3-4 hours at 37 degrees, how many sperm will be alive?

A

None

62
Q

Why do we use semen extender?

A

To extend motility and viability and allow antibacterial treatment of sperm
Increased lipid content -> stabilise sperm membranes from cold shock

62
Q

Affects of cold shock

A

Damage to sperm membrane and acrosome

Loss of motility and decreased metabolism

63
Q

Name two protective agents for sperm

A

Egg yolk - low density lipoproteins insulate sperm

Bovine serum albumin - protect against oxidative stress

64
Q

Disadvantages of chilling semen

A

Cost - transport, risk of late delivery
Not all males suitable - sperm quality
Damage during preparation
Needs to be used in 48 hours

65
Q

3 Steps of collecting semen

A
  1. Collect - dummy, AV
  2. Process and analyse -> extend in dilutent, certifuge and resuspend in media
  3. Pack, chill + send -> 50ml falcon tubes or whirl pack bags
    Labels, lids + semen assessment
66
Q

Disadvantages of frozen semen and what is the pregnancy rate?

A

Pregnancy rate 40% per cycle

Success depends on: Post thaw fertility of stallion, suitable mare, bred within 6-12 hours of ovulation

67
Q

Ideal frozen AI mare

A

<12 years old, maiden and no history of breeding induced endometritis

or older mares that have recently foaled (not on foal heat)

68
Q

How do we thaw frozen semen?

A

0.5ml straw - 30 degrees for 30 seconds

69
Q

Timing of insemination

A

Ideally 3 hours of ovulation -> sperm do capacitation in freezing process and die 12 hours after this
oocyte viable for 6-12 hours

70
Q

List 5 methods of insemination

A
  1. Uterine body insemination
  2. Deep uterine horn insemination
  3. Surgical oviductal insemination
  4. Laparotomy
  5. GIFT
71
Q

How is deep uterine horn insemination performed?

A

Atraumatic flexible catheters 0.5-1.5ml
100 million sperm
Eliminates uterine transport - rectally guided to anterior uterine horn - ipsilateral to impending ovulation
Routine for frozen sperm

72
Q

How is hysteroscopy performed?

A

$$ equiptment and labour - need 3 people
Sedate + ensure it goes up one horn
Use with low dose insemination
Young healthy mares and ovulation induction

73
Q

What is involved in surgical insemination and what is it called?

A

Gametic intrafallopian transfer (GIFT)
Egg and sperm into uterine tube
Capacitation occurs in oviduct

74
Q

What are 5 things we need to know about a mare’s history before we breed?

A
  1. Identification
  2. Breeding status
  3. Cycle histoy
  4. Confirmation
  5. Disease status
75
Q

What are 3 things we look for on ultrasonography and rectal palpation?

A
  1. Ovarian activity - CL, dominant follicles
  2. Uterine tone and oedema
  3. Abnormalities
76
Q

What will the ovary demonstrate in anoestrus?

A

No follicular activity (<10mm)

Dense, small ovarian tissue

77
Q

What will the uterus show in anoestrus?

A

Faccid

Thin walled, quiescent

78
Q

What will the cervix show in anoestrus?

A

Pale, dry and high

Partially open but not relaxed

79
Q

What will oestrus cause the cervix and uterus to show?

A

Cervix - soft

Uterus - oedema

80
Q

What happens to GnRH during gestation?

A

It is inhibited by progesterone

81
Q

What are 3 methods to complete an intrauterine culture?

A
  1. Endometrial culture swab
  2. Low volume uterine lavage
  3. Uterine biopsy
82
Q

What are 3 methods to complete cytology?

A
  1. Swab
  2. Cytology brush
  3. Uterine lavage
83
Q

What are 3 causes of infectious and 3 causes of non-infectious endometritis?

A

Infectious -> bacteria, yeast, fungus

Non-infectious -> air, urine, post breeding

84
Q

What are 2 bacterial agents that can cause endometritis?

A

Streptococcus

E. Coli

85
Q

What months is the autumnal transition?

A

May-June

86
Q

What months is winter anoestrus?

A

July-August

87
Q

What months is spring transition?

A

September-October

88
Q

If a mare has a 40mm follicle in September and oedematous uterus, what should we do?

A

Breed her (live cover) and induce with chorulon

89
Q

When should we induce a mare that is to be bred with cooled semen?

A

24 hours prior

90
Q

When should we induce a mare that is to be bred with frozen semen?

A

40 hours prior

91
Q

What do we do if post breeding she has ovulated, there is fluid in the uterus and a CL present?

A

Flush the uterus with a sterile saline lavage - can do this up to 72 hours post-ovulation

Give Oxytocin in small frequent doses 4-6 horus post breeding

92
Q

When can we use rectal palpation for pregnancy diagnosis?

A

Day 24 to term

93
Q

When can transrectal ultrasonography be used for PD?

A

Day 9 onwards

94
Q

What structure is unique to horses in early embryo growth?

A

Acellular glycoprotein capsule

95
Q

When is the acellular glyoprotein capsule first detected and when does it persist until?

A

6-7d first seen

23d leaves

96
Q

Does the horse go through elongation?

A

No - due to the presence of the capsule

97
Q

How does maternal recognition of pregnancy occur?

A

Presence of the conceptus prevents PGF2a

98
Q

How many scans are done in a practical pregnancy diagnosis?

A

4

99
Q

When is the first scan done?

A

14-16 days for twin check

100
Q

When is the second scan done?

A

21-30d to check for heartbeat

101
Q

When is the third scan done?

A

40-45d

Post-attachment and organogenesis

102
Q

When is the 4th scan done and what are we checking?

A

60-70d

Fetal sexing

103
Q

When are endometrial cups present and what do they produce?

A

36-120 days

Equine chorionic gonadotrophin -> LH effect to lyse secondary follicles

104
Q

What hormones maintain pregnancy and where are they produced?

A

Primary and accessory CL -> P4

Placental and foetal gonads - oestrogen + progestagens

105
Q

What are 6 causes of infectious abortion in the mare?

A
  1. Equine herpes virus
  2. Bacterial abortion
  3. Equine amnioitis and fetal loss syndrome (EAFL)
  4. Chlamidya psittasci
  5. EIA
  6. Equine viral artiritis
106
Q

When does EHV cause abortion and where is the most viral load found?

A

Last 4 months

Aborted fetus and fetal membranes

107
Q

What do bacterial abortions cause and what are 3 agents?

A

Staph
Strep
E.Coli
Ascending Placentitis

108
Q

What type of abortions do EAFL cause and what are clinical signs?

A

Mid-late term catepillar associated abortions - mares grazing affected areas

Amnionitis and funisitis

109
Q

When does chlamidya psittasci cause abortion and is it zoonotic?

A

Yes

Late term

110
Q

When does EIA cause abortion?

A

At the time of infection

111
Q

When does equine viral artiritis cause abortion?

A

1-4 weeks after respiratory infection

112
Q

What are 6 causes of non-infectious abortions?

A
  1. Undiagnosed twins
  2. Fescue toxicity
  3. Umbilical cord torsion
  4. Placental insufficiency (endometrial cysts)
  5. Nutrition
  6. Trauma
113
Q

What are the 3 types of placentitis?

A

Ascending
Haematogenous
Unknown - Nocardiform

114
Q

How does ascending placentitis happen?

A

Bacteria breach 3 barriers to uterus

115
Q

How does haematogenous placentitis happen?

A

Through systemic illness or bacteraemia - Lepto, Klebsiella, Pseudomonas, staph, strep or salmonella

116
Q

What defines placentitis?

A

Inflammation +/- infection of the placenta causing disruption of blood supply

117
Q

What are 3 signs of placentitis?

A

Vaginal discharge
Premature mammary development
Increased thickness of the placenta on ultrasound

118
Q

How do we treat placentitis?

A

Antimicrobials, anti-inflammatories and progestagens

119
Q

When can a eCG assay be done?

A

Day 36-90

120
Q

How do we prevent equine herpes virus?

A

Duvaxyn vaccine
Vaccinate at 5,7,9 months gestation
Not highly effective so use in valuable mares

Reproduction (9 decks)

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