Successful Mating In The Mare Part 1 Flashcards
Name the three ways horse breeding in mare/stallion can occur?
Natural (live) covering
Artificial insemination
Embryo transfer
What are horses bred for?
– Thoroughbred racing
• Natural (live) coverage only (no AI or embryo transfer)
– Purebreds e.g. Irish Draught, Shire, Dartmoor etc etc
– Sports horses
• Can be crossbred
Breeding occurs where?
• Stud farms might/might not be artificial insemination)
—Studswithstandingstallions
-Mares visit the stallion
—Boarding studs
-Broodmares and offspring
—Standingstallionsandboardingstuds
-Visiting mares and some resident broodmares
• Some native breeds
— Stallionsrunwithaherdofmares(andfoals)
• Veterinary clinics
-– Artificialinsemination
Veterinary responsibilities in horse breeding
— Routine treatment of all horses on premises
-preseason testing of resident stallions (andmares)
— Prevent any incoming spread of disease
-from visiting mares
—optimise conception rates
-determine correct time for mating/insemination
-maximise conception
-pregnancy diagnosis; re-examine uterus post covering & detect twin conception and REMOVE
—foaling duties
-neonatal care may be required
What are the 2 types of mares on stud farms. Describe each
Resident mares—>
-spend their whole time there; pregnancy+foaling+early post-partum
-may be covered on ‘foal-heat’
-certified disease free
-kept isolated from visiting mares
-treated as herd- vaccinated for specific viruses
Visiting mares—>
-arrive at stud when believed to be at start of oestrus
-either stay till pregnant or return later if not preggo
-certified disease free before arrival
What virus are resident mares vaccinated for?
Herpes virus
Breeding season of mares
Have annual rhythm of repro competency
Long day breeders
Seasonal polyoestrus- April to September
Anoestrus during winter months
Breeding season of thoroughbreds
– northern hemisphere season
• ‘official’ breeding time - 15th February to end of July
• 1st January is the official birth date of the horse (TB)
• Want foals born as close to this as possible (but not before)
– Southernhemisphere
• 1st August birth date and season September to December
How is early season breeding manipulated in mares
Photoperiod
-using artificial light to encourage early transition from anoestrus to regular oestrus cycles
-16hour light: 8hr dark from November/December
-horses need to be stabled
Hormones
-synthetic progesterone may hasten ovulator oestrus
-human hormone chorionic gonadotrophin (hCG) may hasten first ovulation of breeding season
Physical conditions
-rising plane of nutrition as go into breeding season
-Replicates spring flush of grass
Name the 2 diseases that are of main concern to UK in mares (although neither are found in UK yet)
Contagious equine metritis (CEM)
Equine viral arteritis (EVA)
Contagious equine metritis (CEM)
-low risk to who
-causes what
-of low risk to mares
-causes infertility
What 2 swabs are used to check whether a horse has Contagious equine metritis (CEM) or not?
- Clitoral swab- at home premises or stallion stud
- Endometrial swab- during oestrus at stallion stud
Equine viral arthritis (EVA)- how is it checked
Checked taking a blood sample for serology
What are some ways used to assess the mares repro tract
• External genitalia
– Perineum,vulvarseal,discharge?
• Examine cervix and vestibule – Directpalpation
– Visuallyusingaspeculum
• Clitoral swab
– Microtip–forCEM
• Sample uterus
– Swabsforcultureandendometrialcytology – Endometrialbiopsy
• Transrectal palpation and ultrasonography – Cervix,uterusandovaries
• (Endoscopy of uterus)
What does a poor perineal conformation consist of?
What does a poor perineal conformation allow?
-recessed anus
-poor vulvar seal
-allows contamination (faecal) of vagina high allows ascending infection of uterus; endometritis
What are the 3 barriers of external genitalia in a horse?
– vulval seal
– vestibulovaginal ring
– cervix
What is caslicks procedure & what does it consist of?
Procedure done on cow with poor perineal conformation
-consists of Dorsal portion of vulva being sutured shut, only ventral portion open. This reduces vaginal contamination. Can be re-opened prior to foaling
How long is mare oestrus cycle?
How long is oestrus?
During oestrus when does ovulation occur?
21-22 days
5-6 days
24-48 hours
Which hormone causes a primary follicle to mature and
ovulate?
Luteinizing hormone
What is teasing of a horse
exposing her to a stallion or androgenised gelding to determine her sexual behaviour
What are things a mare will do during teasing during oestrus
- Tail raise
- Squat, tip pelvis
- Urinate
- Evert clitoris
What are things a mare will do during teasing during dioestrus
Switch tail
Kick, Squeal
Attempt to bite/avoid stallion
What will be seen in an ovarian examination during oestrus in mare
1 larger follicles +/- soft
Follicle may start ‘pointing’ near ovulation
No corpus luteum
What will be seen in an ovarian examination during dioestrus in mare
Corpus luteum has formed
Follicles variable in size
What will be seen in a uterine examination during oestrus in mare
- uterus relaxed during palpation
-Oedematous endometrial folds
What will be seen in a uterine examination during dioestrus in mare
Uterus firm/toned
Uniform echogenicity of US
What will be seen in a cervix examination during oestrus in mare
Cervix short, wide & relaxed, pink & drooping,
Lumen open
What will be seen in a cervix examination during dioestrus in mare
Long narrow & firm cervix and pale & dry
Closed lumen
What are the different ways a mare can be examined
Ovarian examination; ultrasound & rectal examination
Uterine examination; rectal and ultrasound
Cervix examination; rectal, US, visualisation with speculum & palpation (lumen palpation specifically)
Maximum pregnancy rates achieved when breeding at what time relative to ovulation
48hrs before to 6 hours after ovulation
2 ways in which ovulation can be induced
- Human chorionic gonadotrophin (hCG)
Hastens ovulation in cycling mares
Has luteinizing hormone (LH) activity - Gonadotrophin releasing hormone (GnRH; deslorelin)
When dominant follicle ≥30mm induces ovulation within 48hrs of introduction of a subcutaneous implant
Stimulates release of FSH and LH from anterior pituitary gland
What is synchronisation of oestrus
the process of manipulating the estrus cycle that results in standing estrus (heat) in the majority of animals in a short time
Name the 2 ways of synchronising oestrus
-administered for how long
-oestrus occurs how long after injections
-ovulation occurs how long after injection
- Giving Synthetic Progestogens/progesterone
Administered for 14 days
Oestrus 4-7 days after treatment
Ovulation occurs 7-12 days after treatment - Prostaglandin F-2α
Mares with a mature corpus luteum – shortens luteal phase
Oestrus 2-4 days after injection
Ovulation occurs 7-12 days after injection
Why does breeding occur in post partum period?
In order for mare to foal at roughly same time next year, it should conceive in the next 25 days after giving birth otherwise foals are born later and later
Natural covering: in-hand breeding
Natural way of mating
Mare:
– Remove hind shoes if present
– Appropriate restraint – bridle, +/-twitch
– Tail bandage +/- hind covering boots and neck cape
– Hygiene: vulva, perineum & hindlegs (warm water)
Stallion
– Hygiene: external genitalia cleaned with warm water
• Ensure brought to stallion at optimum time – Carefulmonitoring
• After 48 hours check mare has ovulated if not - recover • Aim to minimise number of matings
– saveonstallionandsemenforothermares
Artificial insemination advantages
• One ejaculate divided into several insemination doses
–increased number of mares covered
• Mare can be bred to remote stallion
• Prevent disease transmission (especially venereal)
• Reduced uterine inflammation
• May improve fertility for some stallions
• Avoids breeding injuries
• Can assess semen before insemination
Artificial insemination disadvantages
• Can be expensive
• Increased skill levels required
• Not all stallion’s semen can be used
• Risk of human injury during semen collection
• Not for Thoroughbreds
What does artificial insemination require?
• Requires semen collection & handling –fresh/chilled/frozen semen
• Time to inseminate based on ultrasonography
• Need to inseminate 6h prior to ovulation to maximise conception
How does artificial insemination work?
Semen collected from horse and Semen introduced into uterine body using a plastic catheter
-hand inserted through vulva to guide catheter through cervix
Embryo transfer
-what is it
-advantages
-disadvantages
Implant embryos from mares unable to carry a foal
• Can collect multiple embryos per season from valuable mares
• Can collect embryos from mares unable to carry a foal
Expensive
Technically demanding
Not for thoroughbreds
Postmating endometritis
What is it
How long does it last
Transient uterine inflammation in mare
-lasts for 24-48 hours
Is postmating endometritis normal?
Yes!
What happens if postmating endometritis lasts longer than 48hours
-can reduce mares fertility
-affects embryo survival and contamination
How to minimise contamination during postmating
-Good hygiene
-Use of AI may help some
-‘Washout’ post-breeding uterine lavage- the clear out of any semen, debris and other things that could cause disease in the horse
Pregnancy
-duration
-embryo implants at what time
-pregnancy rates at 1 oestrus
320-365 days (about 11 months)
Embryo implants at 16 days
Pregnancy rates vary from 35 to 75% at any 1 oestrus
What is early Pregnancy diagnosis important for? (Ultrasonography)
• Essential for management reasons
– Ifneedfurtherattemptsforconception
• Allows identification of twins
– Wanttoavoidtwinpregnancy
– Difficulttoterminatepregnancyafter40days
– Early diagnosis allows the situation to be rectified
• ‘pinching’ of twins (destruction of one of the embryos)
• Can inject one with prostaglandin
Why can horses not have twins?
1 placenta of mare is rarely. Enough to feed 2 foals and so they will usually both be found dead during pregnancy
What are some ways of diagnosing a horse pregnancy?
—Teasing- exposing mare to a stallion or androgenised gelding to determine her sexual behaviour
—Blood hormone levels;
Progesterone- not reliable
-equine chorionic gonadotrophin
-oestrogen sulphate levels elevated after 100 days pregnancy
—veterinary exam
-ultrasonography & rectal palpation
Which diagnosis of pregnancy is most reliable
Ultrasonography—>
-immediate results (15 days) (direction palpation can only occur at 40 days or so)
-gives clear detection of twins
How many times can you scan an ultrasonography?
3 scan
At what time is each ultrasonography scan taken and what is checked at each scan
First scan at 15 days:
– confirm pregnancy and detect twins
• Second scan at 25 to 28 days:
– Confirm normal development and not twins
– Detect heart beat
• Third scan at 34 days:
– Ideally repeat at this time but often not done
– Ensure still there
Nutritional support of pregnant mare involves…
-being kept in good body condition
-gradually ^ nutrition in last 3 months
Pregnancy loss
-when most commonly occurs
-due to what
-75% by 49 days
-Most losses due to placental dysfunction
2 causes for placental dysfunction are:
Non infectious causes—>
Premature separation
Twins
Infectious—>
Placentitis
Abortion
-occurs when?
-causes
Occurs before 300 days of gestation
Causes—>
– Viral(EHV-1) – Bacterial
– Fungal
– Non-infectious
• Twins
• Chromosomal abnormalities • Mare illness
