Equine Flashcards
1
Q
Where is semen deposited?
A
The uterus
2
Q
What are the 3 barriers to infection?
A
Vulva
Cervix
Vestibulo-vaginal sphincter
3
Q
What surrounds and suspends the ovary?
A
The mesovarium
4
Q
Are the ovaries fixed or moveable?
A
Fixed
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
6
Q
Where does ovulation occur through?
A
The ovulation fossa
7
Q
When does the CL form?
A
Once ovulation occurs
8
Q
Where is the fornix located?
A
around the entire cervix
9
Q
What percentage of the vulva should be below the pelvic floor?
A
70%
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
11
Q
How is a mares cycle described?
A
Seasonally polyoestrus - long day breeders
12
Q
How long is the period after parturition and before foal heat?
A
9 days average
13
Q
How long is a mare’s cycle?
A
21 days
14
Q
How long is oestrus?
A
4-8 days
15
Q
When does a mare ovulate?
A
Anytime in her 4-8 day long oestrus
16
Q
When is a CL developed?
A
Early dioestrus -> not responsive to PGF2a
5 days following ovulation responsive
17
Q
What happens to the CL in late diooestrus?
A
It becomes responsive to PGF2a (13 days)
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
19
Q
What happens in the follicular phase?
A
Oestrus -> 4-8 days long
Mare TUW -> Tail up, urinating and winking
20
Q
What is the transitional phase?
A
40-60 days long between anoestrus and normal cycling oestrus
21
Q
What hormone dominates the autumn transition?
A
Oestrogen -> follicles, some uterine oedema, but no CL and dont go on to ovulate
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
23
Q
How long is the vernal transition?
A
60-90 days
Dominated by light
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
25
How does progestagen shorten the transition?
It doesn't -> it synchs ovulation
26
How does dopamine antagonists shorten the transition?
Increases prolactin -> stimulates follicle growth
27
Do hCG or deslorelin induce ovulation in transition follicles?
No - they do not have LH receptors
28
In what animals are silent heats most common?
Wet mares - foal proud
29
How do we manage multiple ovulations?
Breed to the second follicle
| Check for twins at 14-16 days after breeding - get rid of the smaller one
30
What is a dioestrus ovulation?
Ovulation during luteal phase with high progesterone interfering with PGF2a action, resulting in long luteal phase
31
What do early or late dioestrus ovuations result in?
early -> pregnancy
| Late -> prolonged luteal phase
32
How to persistent CLs occur and how long can they last?
Spontaneously (failure of Pg release), early pregnant loss, dioestrus ovulation
Last 35-90 days
33
How do we diagnose a persistent CL?
Increased uterine tone, ultrasound
34
How do we treat a persistent CL?
PGF2a -> repeat in 5 days if no response to first dose
35
What are 2 causes of constant oestrus behaviour?
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
36
How is prostaglandin used to manipulate the cycle - when are injections given and when is the CL responsive?
Injections 14-16 days apart
CL responsive from 5-6 days following ovulation (day 13)
Shortens luteal phase to initiate new cycle
37
How are progestagens used to synchronise mares - what are the 3 methods?
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
37
How are progestagens used to synchronise mares?
Regumate -> Oral administration for 14 days and oestrus 5 days after withdrawal
Natural -> in oil - not practical
Cue Mare - CIDR can form vaginitis
38
How is oestrogen used to synchronise oestrus - Dose and time period
150mg P4 and 10mg E2 for 10 days
Ciderol + CIDR works well
Tighter synchrony with both
Follicle is 35mm -> induce ovulation
39
What 3 things can be used to induce ovulation?
hCG
Deslorelin acetate - injectable
Deslorelin acetate - ovuplant
40
How does hCG induce ovulation, what follicle size can it be used on and when will ovulation occur?
Use on >35mm follicle for ovulation in 36 +/- 6 hours
| LH like substance - increases follicle development
41
How does injectable deslorelin induce ovulation and what follicle size does it work on? when will ovulation occur?
Use on >30mm follicle for ovulation in 40 +/- 3 hours
| GnRH agonist -> stimulates pituitary release of LH
42
Can the deslorelin implant (Ovuplant) be used to induce ovulation in mares?
No - discontinued
43
List 4 methods to prevent ovulation/oestrus
1. Progesterone - no oestrus behaviour
2. GnRH vaccine
3. Oxytocin
4. Ovarioectomy - stops ovulation, not oestrus behaviour
44
How does the GnRH vaccine prevent ovulation?
Reduces LH and FSH
for 3-6 months
Discontinued -> infertility in some cases
Does not stop adrenal oestrogen
45
How does a GnRH analogue prevent ovulation?
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
46
How does oxytocin stop ovulation and at what dose for how long? What are 2 methods?
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
47
How does a GnRH agonist stop ovulation?
Discontinued - Ovuplants
Prolonged interovulatory interval due to maintaining CL and producing small GnRH
Desensitises HPG axis
48
List 6 causes of abnormal cycles
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
Advantages of paddock breeding
Teach stallions normal sexual behaviour
low labour
good selection for repro performance
Experienced stallions- 70-80% rates
50
Disadvantages of paddock breeding
Injury to stallion
Reduced efficiency of stallion
Reduced pregnancy rates
Risk of twins
51
Advantages of AI
```
Genetic progress - exploit superior male
Dont need to own stallion
International access
Safety for females
Minimal animal transport - biosecurity
```
52
Disadvantages of AI
Labour intensive $$
need special facilities and experienced technicians
Semen costly
Reliance on couriers
53
6 neccessities for live cover
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
What is equine coital exanthema?
Equine herpes virus 3 veneral pathogen
affects males and females signs 4-7d after contact
Pustules and ulcers
55
How is equine coital exanthema treated?
sexual rest for 3 weeks and topical antimicrobials
56
Name 3 bacterial venereal pathogens
1. Contagious equine metritis (taylorella equigenitalis) - not in Aus
2. Klebsiella spp.
3. Pseudomonas - water based
57
Name 3 viral venereal pathogens
1. EHV-3
2. Equine viral arteritis
3. Equine infectious anaemia
58
Name 1 protozoan venereal pathogen
Trypanosoma equiperdum
59
How long after collection should chilled, extended semen be inseminated?
24-48 hours
60
How cold should frozen sperm be stored at?
-196 degrees in liquid N
61
After 3-4 hours at 37 degrees, how many sperm will be alive?
None
62
Why do we use semen extender?
To extend motility and viability and allow antibacterial treatment of sperm
Increased lipid content -> stabilise sperm membranes from cold shock
62
Affects of cold shock
Damage to sperm membrane and acrosome
| Loss of motility and decreased metabolism
63
Name two protective agents for sperm
Egg yolk - low density lipoproteins insulate sperm
Bovine serum albumin - protect against oxidative stress
64
Disadvantages of chilling semen
Cost - transport, risk of late delivery
Not all males suitable - sperm quality
Damage during preparation
Needs to be used in 48 hours
65
3 Steps of collecting semen
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
Disadvantages of frozen semen and what is the pregnancy rate?
Pregnancy rate 40% per cycle
| Success depends on: Post thaw fertility of stallion, suitable mare, bred within 6-12 hours of ovulation
67
Ideal frozen AI mare
<12 years old, maiden and no history of breeding induced endometritis
or older mares that have recently foaled (not on foal heat)
68
How do we thaw frozen semen?
0.5ml straw - 30 degrees for 30 seconds
69
Timing of insemination
Ideally 3 hours of ovulation -> sperm do capacitation in freezing process and die 12 hours after this
oocyte viable for 6-12 hours
70
List 5 methods of insemination
1. Uterine body insemination
2. Deep uterine horn insemination
3. Surgical oviductal insemination
4. Laparotomy
5. GIFT
71
How is deep uterine horn insemination performed?
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
How is hysteroscopy performed?
$$ 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
What is involved in surgical insemination and what is it called?
Gametic intrafallopian transfer (GIFT)
Egg and sperm into uterine tube
Capacitation occurs in oviduct
74
What are 5 things we need to know about a mare's history before we breed?
1. Identification
2. Breeding status
3. Cycle histoy
4. Confirmation
5. Disease status
75
What are 3 things we look for on ultrasonography and rectal palpation?
1. Ovarian activity - CL, dominant follicles
2. Uterine tone and oedema
3. Abnormalities
76
What will the ovary demonstrate in anoestrus?
No follicular activity (<10mm)
| Dense, small ovarian tissue
77
What will the uterus show in anoestrus?
Faccid
| Thin walled, quiescent
78
What will the cervix show in anoestrus?
Pale, dry and high
| Partially open but not relaxed
79
What will oestrus cause the cervix and uterus to show?
Cervix - soft
| Uterus - oedema
80
What happens to GnRH during gestation?
It is inhibited by progesterone
81
What are 3 methods to complete an intrauterine culture?
1. Endometrial culture swab
2. Low volume uterine lavage
3. Uterine biopsy
82
What are 3 methods to complete cytology?
1. Swab
2. Cytology brush
3. Uterine lavage
83
What are 3 causes of infectious and 3 causes of non-infectious endometritis?
Infectious -> bacteria, yeast, fungus
Non-infectious -> air, urine, post breeding
84
What are 2 bacterial agents that can cause endometritis?
Streptococcus
| E. Coli
85
What months is the autumnal transition?
May-June
86
What months is winter anoestrus?
July-August
87
What months is spring transition?
September-October
88
If a mare has a 40mm follicle in September and oedematous uterus, what should we do?
Breed her (live cover) and induce with chorulon
89
When should we induce a mare that is to be bred with cooled semen?
24 hours prior
90
When should we induce a mare that is to be bred with frozen semen?
40 hours prior
91
What do we do if post breeding she has ovulated, there is fluid in the uterus and a CL present?
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
When can we use rectal palpation for pregnancy diagnosis?
Day 24 to term
93
When can transrectal ultrasonography be used for PD?
Day 9 onwards
94
What structure is unique to horses in early embryo growth?
Acellular glycoprotein capsule
95
When is the acellular glyoprotein capsule first detected and when does it persist until?
6-7d first seen
| 23d leaves
96
Does the horse go through elongation?
No - due to the presence of the capsule
97
How does maternal recognition of pregnancy occur?
Presence of the conceptus prevents PGF2a
98
How many scans are done in a practical pregnancy diagnosis?
4
99
When is the first scan done?
14-16 days for twin check
100
When is the second scan done?
21-30d to check for heartbeat
101
When is the third scan done?
40-45d
| Post-attachment and organogenesis
102
When is the 4th scan done and what are we checking?
60-70d
| Fetal sexing
103
When are endometrial cups present and what do they produce?
36-120 days
Equine chorionic gonadotrophin -> LH effect to lyse secondary follicles
104
What hormones maintain pregnancy and where are they produced?
Primary and accessory CL -> P4
Placental and foetal gonads - oestrogen + progestagens
105
What are 6 causes of infectious abortion in the mare?
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
When does EHV cause abortion and where is the most viral load found?
Last 4 months
| Aborted fetus and fetal membranes
107
What do bacterial abortions cause and what are 3 agents?
Staph
Strep
E.Coli
Ascending Placentitis
108
What type of abortions do EAFL cause and what are clinical signs?
Mid-late term catepillar associated abortions - mares grazing affected areas
Amnionitis and funisitis
109
When does chlamidya psittasci cause abortion and is it zoonotic?
Yes
| Late term
110
When does EIA cause abortion?
At the time of infection
111
When does equine viral artiritis cause abortion?
1-4 weeks after respiratory infection
112
What are 6 causes of non-infectious abortions?
1. Undiagnosed twins
2. Fescue toxicity
3. Umbilical cord torsion
4. Placental insufficiency (endometrial cysts)
5. Nutrition
5. Trauma
113
What are the 3 types of placentitis?
Ascending
Haematogenous
Unknown - Nocardiform
114
How does ascending placentitis happen?
Bacteria breach 3 barriers to uterus
115
How does haematogenous placentitis happen?
Through systemic illness or bacteraemia - Lepto, Klebsiella, Pseudomonas, staph, strep or salmonella
116
What defines placentitis?
Inflammation +/- infection of the placenta causing disruption of blood supply
117
What are 3 signs of placentitis?
Vaginal discharge
Premature mammary development
Increased thickness of the placenta on ultrasound
118
How do we treat placentitis?
Antimicrobials, anti-inflammatories and progestagens
119
When can a eCG assay be done?
Day 36-90
120
How do we prevent equine herpes virus?
Duvaxyn vaccine
Vaccinate at 5,7,9 months gestation
Not highly effective so use in valuable mares
